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SPORATIC 1980 5HP. B&S Pulsa-jet Carb.


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03-07-10, 02:35 PM   #1  
SPORATIC 1980 5HP. B&S Pulsa-jet Carb.

Hello people, I have an Antique Wards 24" snow thrower, with a 5hp Briggs. I have done Everything to the Carb ... You name it ... it was done, Just short of replacing it.
Somehow the engine has NO-power to clear the snow, and Don't know if another carb might solve the problem.
THE STRANGE THING .... is that with a "small fuel leak between the carb, and gas tank" .... IT HAS THE MOST POWER ! Of course this is a fire hazzard, so I resealed the carb/tank, and then the engine starved for power again. In order for it to run, the choke must be 7/8 applied/closed. Indicating to me a "Lean fuel condition."
I ran a Hot compression test, pulling the cord until I got my highest reading, this was 73 PSI. with the choke off, and throttle at 1/4 open.
Here are the Engine numbers: ... 130292 ... 1061 02 ... 80090806.
Please Focus on "the strange thing," It may be Key to Solving this Mystery!
Thanks-To-All, Nitrojc.

 
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03-07-10, 04:43 PM   #2  
Compression test should be choke off, throttle wide open.
As far as your "strange thing", it sounds like your gas tank vent is clogged. Try running with the gas cap loose. If that works, you need to buy a new gas cap. Usually $5 or less.

 
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03-07-10, 05:06 PM   #3  
New gas cap

Posted By: indypower1 Compression test should be choke off, throttle wide open.
As far as your "strange thing", it sounds like your gas tank vent is clogged. Try running with the gas cap loose. If that works, you need to buy a new gas cap. Usually $5 or less.
Hi, The cap is new, and I think it also leaks gas.
Eliminating the cap, With the fuel leaking, How do you explain the available full power with no choke as it should be. When before it leaked (No leaks).... The engine would only run at 7/8 closed choke with No power? This (Did) actually happened ! Thanks, Nitrojc.


Last edited by NITROJC; 03-07-10 at 05:10 PM. Reason: Typos
 
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03-07-10, 11:56 PM   #4  
How did you reseal the carb ?? If you used a sealant instead of a gasket, some of the sealant may have squished out & is maybe now blocking a passage in the carb??? Just a thought... Roger

 
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03-08-10, 12:15 AM   #5  
Hopkinsr2, My thoughts as well. Use a new gasket.


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03-08-10, 09:28 AM   #6  
MY Cup Runnith .. Over

Hopkins / Cheese, I used the new gasket (from last yr.) and resealed it with Permatix Silicone Red RTV. There were no breaks, or flaws.
Good question regarding fuel holes, and blockage. All is Clear. What I did was check the fuel pump output while it was running at idle. I took off the gas cap, the tank was 1/4 full, and shinned a 750 CP latern into the opening of the gas tank at an angle towards the fuel cup. Whalla ... I witnessed a mini-water-fall of gas. Just a steady stream of fuel dumping over the top. I increased the RPM's a bit, but the flow didn't increase. Just a Little Positive News.
SO-WHAT-SAY-YOU--FELLAS NOW ? Thanks, Nitrojc.

 
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03-08-10, 08:29 PM   #7  
I'm still thinking the Permatex you used has blocked a passage even tho the gasket is O.K... Silicone & gas don't live well together & the silicone (or Permatix) will cause problems.... Pull the carb apart again & really clean it well in a bath cleaner,, blow it out with compressed air & use new gaskets with no sealant.. If it still leaks between the tank & the carb, than we'll look into that,,,, the fuel pump may work O.K. but I kinda think there is a passage blocked in the carb... Roger

 
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03-08-10, 11:15 PM   #8  
I agree, you have a blocked passage that needs cleaning. Get a new gasket too, sealers should not be used on gaskets in contact with gas. The gas eats at the sealer and it makes a mess in the carb.


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03-09-10, 05:58 AM   #9  
Iagree with Cheese & Hopkins. NEVER use sealant of any kind on a carburator. It will ooze out and clog up the tiny pinhole passages and carb cleaner will not dissolve it making it virtually impossible to remove and you end up having to buy a new carb.

 
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03-09-10, 06:46 AM   #10  
" CARB Pin-holes in the bottom."

HELLO Fellas,
Do any of you know just how many holes there are in the bottom of the carb where it mounts to the tank? Because, If there is only the one that feeds the "Fuel cup," and it is clear. This I know .... Having witnessed the "fuel waterfall flow" in the tank at idle. Now, If there are other holes on the bottom, I need to know where they are.
THIS WHOLE CARB BUSINESS Comes down to 2 things.
(1) I Either clear the snow with full engine power, and let the fuel leak out of the tank top, Or (2) Fix the leak as I did, and have Minimum power to try and clear the snow. Which is what I have been doing in the past yrs. with No leak.

I called, and Spoke to Lee at B&S Tech. Dept. I told him what was Happening with this "Fuel leaking Issue." His Thought on this was that when the fuel is leaking ... IT SEALS OFF THE AIR LEAK, Between the carb, and fuel tank. Therefore, Permitting the engine to run/function properly.
So, What I think He's saying is - With no fuel leak, there is an Air-leak. However, Sealing the carb to tank area, even with No fuel leaking, THERE STILL IS AIR LEAKING.
DOES THIS MAKE ANY SENSE TO YOU GUYS'.
Please Evulate this, and give me you take. Thanks, Nitrojc.

 
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03-09-10, 09:56 AM   #11  
Oh man, you are making this harder than it really is. There are several holes and jets in a carburetor. Just because you see a gas "waterfall" in the tank has nothing to do with clogged jets and passages in the carb. All you are looking at is return fuel from the fuel pump. That's not related. There are passages you can't even see in the carb. If you think air is leaking badly enough to cause running problems, spray carb cleaner or even water around the areas where you suspect it leaks and see if running conditions change. If so, it's leaking air, if not, it's not. It's possible, but not likely.


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03-09-10, 11:25 AM   #12  
Missed the point !

Hello, At the Carb Bottom where it mates with the fuel tank ... How may visable holes are there ? I am Fully Aware that there are many internal .. Not-Visable passageways, I AM NOT REFERING TO THEM. You guys believe by using goop to seal the tank that it probally ooozed into those external bottom holes plugging things up. That's why I asked how many holes, Simple isn't it ? I know of 1, the gas-afall driven by the fuel pump. Where are the others, if there are any others ?
What are your thoughts on what Lee @ B&S had to say about the fuel leak Problem .... DO YOU AGREE, or NOT ??

THE FACTS ARE: As I stated before "THIS CARB BUSINESS" comes down to 2 things that "Actually Happened."
PLEASE, Review again the facts, and give me your best answer. Thank-You, Nitrojc.

 
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03-09-10, 12:42 PM   #13  
Ther are at least 3 holes, possibly more. Ther are 1 or 2 pin holes. These are the ones that would get clogged up using sealant.

 
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03-09-10, 07:33 PM   #14  
Indy has you on the right track.. Study the carb & don''t use any sealant...You'll have to look close to find the holes that have to be clean.. Get a kit with new gaskets & you should be O.K. after cleaning the carb in a bath type cleaner & blowing it out with compressed air ,, The sealant may have blocked passages in the tank as well as the carb so look close there as well... Roger

 
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03-09-10, 08:17 PM   #15  
NitroJC, you are the one that said :QUOTE:"Good question regarding fuel holes, and blockage. All is Clear."...in post number 6 in response to Hopkinsr's reply #4 regarding red silicone blocking a passage. Indyower also mentioned the tiny passages in post #9. So, my reply is that there are other holes in the carb to pay attention to, since you already said the ones in the bottom of the carb are clear. Do you now want me to backtrack and focus on the holes you already said are clear? If you aren't sure anymore if they are clear, then you should remove the carb and check them. Watching a waterfall of gas doesn't verify that they aren't restricted. If yours is the type with the barrel choke, it should have 4 holes in the bottom alone, one with a pin in it from above.

No, I don't believe the goop necessarily closed off one of the small holes in the bottom of the carb. It may have, or it could have gotten sucked up inside the carb into the internal passages that I'm talking about. Simple you ask? Yes it is. However, as simple as it is, you keep placing importance on the fact that the holes are all clear because you see the waterfall of gas, and that does not mean all the holes are clear. The holes in the bottom of the carb aren't so much the one's I'm referring to. The fact that you see gas pumping means at least 2 of the holes are at least partially open. That's about all it tells us.

I have already read the facts, and have given you my best answer already. QUOTE:".... DO YOU AGREE, or NOT ??"....no need to shout. I told you what I think of the answer about the air leak and how to check for that. There is not enough information for me to agree or disagree with the briggs guy on the phone. Do the diagnostics provided, post the results, and then I can agree or disagree with whether or not that's the problem. It sounds more like grasping at straws though, rather than a logical explanation for your problem.

This is a very, very simple carb system. I am going to say once again that the carb needs to be removed and cleaned properly, then re-sealed with a new gasket absent of silicone or any sealers. Once this has been done, if there are still problems, we can move forward. Otherwise we sit here theorizing about what could be be wrong with it instead of finding out what is wrong with it. You came here and asked, we answered with accurate, experienced answers. It's the best we can do.


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03-10-10, 05:45 AM   #16  
Engine Numbers are posted on first post.

Well, I really don't mean to stir things-up. The premise the Briggs guy had was that there is an air-leak between the carb, and fuel tank. All I was asking is "Is that possible for air to leak-in-between causing a lean A/F mixture?" He thought because of the fuel leak on the tank top, that this sealed off the air leak, and eliminated the lean A/F mixture, That's It. I simply asked if you Guys agreed, or disagreed. It's just a Freaky occurance/coincidence, that the Engine had plenty of power to plow, when the Gas was flowing on the tank top. This happened at least twice, and the other times when removing snow, with No power the tank was dry. ALL Of This Happened Before, Way before, I sealed the carb/tank gasket.
What I am Trying to tell you People is that there is an "Interminant Lean fuel condition," THAT IS THERE MOST OF THE TIME, and That I Can't pin-point.
Hopefully, I made myself clear this time. Thanks, Jim.

 
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03-10-10, 09:37 AM   #17  
With the engine running spray carb/brake parts cleaner along the mating surfaces between the tank, carb, intake etc. If the engine tempo changes you have an air leak and can take the appropriate action. Using sealer is not one of them. Have a good one. Geo

 
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03-10-10, 11:32 AM   #18  
Possibly Mechanical Problem ?

Hello there, I believe there are other things that may be defective, or bad parts that might contribute to a "Lean A/F Mixture." What about - "A Loose valve seat", could that cause a Lean fuel condition, or some other part ?
This business regarding the gasket between the carb, and fuel tank, whether it leaks, or not has nothing to do with the Lean fuel condition.
What about the Ign. coil, or is it just Good or Bad?
Again, It might be something else, Any thoughts ?
Thanks, Folks, Nitrojc.

 
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03-10-10, 04:42 PM   #19  
Nitro, The coil will NOT cause a lean running condition. The coil either fires or it doesn't. What does cause a lean condition is:
1). Blown head gasket. Can suck in air.
2). Faulty gasket between the carb & engine or between the carb & gas tank.
3). Dirty carb.
4). Spark plug not tight.
5). Intake or exhaust valve not opening all the way.
6). Yes it could be the needle valve, seat or "O"ring or the brass washer on you engine.
Buy these parts:
1).297615 gasket kit.
2).66594 sealing washer.
3).65978 needle valve o-ring seal.
4).23433 neddle valve.
5).230591 needle valve seat.
6).22235 needle valve brass washer
7). 26336 needle valve spring.
8). 27355 carb to engine gasket.
9). 270026 pump diaphram.
10). 260455 pump diphram spring.
Remove the carb, tear it a part, soak it in a carb cleaning soaking solution, blow out all holes with compressed air and reassemble using all the new parts.
If it is a carb problem, this will fix it.

reading your posts, you never said what color the spark plug was. Black, white, coffe brown. This is a tell tale sign of how the engine is running.

We are trying to help you, but you refuse to do what we suggest. Cheese, Hopkins, Geo, & myself make our living fixing small engines. We work 8 hours/day 6 days/week doing this. If we did not know what we were doing, we would not have any customers. We try the best we can to help here, but not having the piece of equipment in front of us to look at, does make it a bit difficult to try to fix. We only have what you tell us to go by. We do our best to help.

 
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03-10-10, 07:38 PM   #20  
Nitro, not to be rude, however it seems you are more interested in creating conflict between the other posters than to fix your engine, I have yet to see any response from you as to the recommendations made by those on this forum or the other forums where you have posted the same problem, as such I wish you well with solving your problem. This is my last post on the subject. Have a good one. Geo

 
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03-11-10, 06:35 AM   #21  
" Hats off to yah "

TO ALL WHO ARE HELPING: More often than not, most of the suggestions have been tried for the past 2 to3 years. It's just that one day it runs fine, and the very next day I am Lucky to keep it running. SO SPORATIC that it makes No sense. Come on a carb isn't going to varnish, or plug-up in a day or two. Then a few days later run with full power.
Indy, The spark plug is coffee brown, and the coil could fire sporatically under load conditions. This happened on my son's 2-cycle enduro motorcycle. Also, many yrs. ago with my 1970 Ford Maverick 6 cyl. It ran fine until it warmed up, then started missing, and it turnd out to be the Ign. coil.
I don't think any of you guys have said whether you believe the Briggs tech. Lee's theory. Now Indy's #2 on the list indicated a lean a/f mixture could be the result of a bad gasket between the carb, and fuel tank, What about the rest of you ?
With the needle valve there is control, and very little change to the engine rpm, but when closed it does kill the engine.
If the head gasket were blown there wouldn't be any, or very little compression, and not enough for it to run, right?
Checking the valve seat was not my idea, rather it was a Briggs MST who suggested it.
" IF NOTHING ELSE BECOMES OF THIS:" I would like to know where I can get a sketch of an Exploded View of the Carb Passageways ... Air, and Fuel, Internal, and External. Of course this would be a "Cross-Section of the Carb."

Well I am Truely sorry to have caused so much havic, but Please keep in mind, what I have already gone through with this carb. Thank-You, Nitrojc.

 
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03-11-10, 01:35 PM   #22  
Correct on the carb not varnishing up in a couple of days.
Now at least we are getting somewhere. The spark plug is coffe brown. This is what it should be and indicates the carb is NOT running lean. If it was white, it would be a lean running problem. We were all trying to correct a lean running problem which is not your problem. Now we can eliminate a carb problem.
A coil can heat up and stop working until it cools down. This is a fairly common problem. Try a new coil.

 
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03-11-10, 02:33 PM   #23  
The coil doesn't care if the carb is loose or not. I don't think a new coil will change anything except the weight of your wallet.

I also told you what I think about what the briggs tech said.

An engine can run with a blown head gasket, but I don't think that is your problem either.

The carb can become clogged and unclogged sporadically as you have mentioned, whether you believe it can or not, and if the engine has been running cool and with the leaking carb, the plug could be tan and still have a lean issue.

You still haven't tried anything we suggested. We are trained experts in the field, and you won't take our advice. We had our turn to give you advice, now it's your turn to take it or decide not to. As far as I'm concerned, I'm done until you take the initiative to actually DO something, rather than second guess everything everyone tells you. At this point I think we have gone as far as possible and this thread is becoming useless to the forum. If it continues to go on with no outcome or useful exchange, I am tempted to lock or delete it.


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03-11-10, 03:10 PM   #24  
FOUND a mechanical problem.

Cheese, Indy recommends trying a new coil, but before I try that, after pulling the plug it was dry with powered carbon. Prior to that it was coffee brown. So, Now it's too Rich ??
The mechanical problem I discovered are worn valve guides, or stems, maybe both. With each valve wide open, I checked the Wobble / from side to side. My best guess is a solid 1/16," That's a lot of free play at the Top of the valve. Do you guys know what the Spec. is ?
This may contribute to part of the lack of power problem.
Well cheese, I Did something, What say you now ?
Thanks, Nitrojc.

 
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03-11-10, 08:07 PM   #25  
Who told you to pull the head off it?? I don't think the play in the valve guides is enough to give you the problem you describe... But now you have the engine torn apart (for whatever reason???).. Just for a goof pull the valve (Tappet) cover & measure the valve clearance when the piston is 1/4 inch past T.D.C. compression.. Post the measurements & we'll tell you if they need adjusting as not enough clearance will hold a valve open.. Have you properly cleaned the carb & put a gasket in it & got rid of all the red silicone yet?? Not to insult you,, but the silicone seems like a real Hillbilly fix for a $3.00 gasket & as posted earlier,, ((& don't use silicone on the head gasket either...)) Silicone & gas don't mix... & can very well cause a carb to plug today & run fine tomorrow.. The silicone turns to MUSH when in contact with gas... Take your carb apart & look @ it.... Just more thoughts.. Do what ever you like as it sounds as if you know more than any one here does.. Sorry all... Roger

 
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03-12-10, 05:50 AM   #26  
Head is still intact

ROGER, CALM DOWN, Nobody told me to pull the head on this forum. I simply removed the exhaust muffler, rotated the crank until the valve was fully open, took a pair of needle nose pliers (no teeth) through the exhaust port, and gently, but firmly wiggled the valve side to side, and Noted excessive play. My best guess from the feel of it was 1/16". Then I closed it (solid on seat) and found imperciptable .. No movement, Which is what I expected it should be.
I found out that the cold tolerance on a new valve, and guide is .004 / or 4/1000. So If I could feel "Any wobble movement" it's Badly Warn.
I do fully realize you Guys are the Experts/Pro's With small engine repair, but I do have a little background with auto-engine build. Also, I ran Engine dyno, and the chassis rolls for exhaust emissions at Ford's. Are you Guys' familiar with Engine Dyno power runs, where you manually control the fuel, and spark to maximize the power output of the engine ? This is called an " LBT / MBT Power run." For those who don't know " Leanest fuel best torque / Miminum spark best torque." You Simply Go back and forth with the spark, and fuel Until there is no change, and then you take your set point info. From there you calculate your " BSFC and HP." Again for those who don't know "Brake specific fuel consumption, and of course Horse power." WELL ENOUGH OF THAT.
I am Focused in on Pin-pointing the problem. Thanks, Nitrojc.

 
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03-13-10, 08:40 AM   #27  
" Follow - up "

Hello-Gang, Yesterday, I did an Ignition test, using an In-line spark plug tester. At idle the engine fired a bright "Orange flash,"
(color of tester light) consistently without missing a beat. So, Apparently the Ign. is OK.
Don't Tell Me You Guys' are Stumped ! Thanks, Nitrojc.

 
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03-13-10, 10:22 AM   #28  
A lot of problems and their fixes have to be generalized and fixed accordingly as some of those are composites of a number of small deficiencies.

A weak ignition has variations of failure up to and including the point it gives out altogether. So you may have a good spark for a while, but an ignition that fails the longer it's running. That ignition can be sporadic and may not deliver at all when subjected to a compressed air environment. An in line tester allows you to test the spark under those conditions, though and you likely have an accurate picture of the ignition at the time it was tested. So, if the power level was low when the spark was good, the ignition probably isn't the problem.

You compression reading of 73 lbs is low and should be rechecked with full throttle and open choke/no air filter. For the most part, the compression will be pretty consistent.

Anytime you have the choke on to get power, 95 % of the time it's in the fuel/air mix going into the engine.

You should do what has already been suggested, take off the carb, do a thorough cleaning of it with a complete kit (without sealers) or replace the carburetor altogether. I would leave everything else alone until you do.

In addition, the spark plug color will not change immediately to a tan color. That is a deposit on the porcelain that takes a little running time.

 
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03-13-10, 11:58 AM   #29  
" General Consensus "

Marbobj, Aren't you overlooking the worn valve guide, which definately would affect the compression readings. If you haven't already, Please read from post 1.
I have taken up these deficiencies with 2 other forums, and the overwhelming diagnois is a tried/worn engine. I don't want to believe it, but this is almost definitive. I fully believed it to be the carb, because it has All the Symptoms pointing to it.
The Biggest factor in their Conclusion are the Low compression readings, and this was before I discovered the worn valve guide. So, this additional info would tip the scales even more.
My perspective on the tired engine is very Iffy. Mainly because, one day it runs with No-Choke with ALL-OUT-POWER, and the next day 7/8 choke to keep it running. Then Visa-a-versa all over-again.
IN CLOSING: This Sporatic behavior has been going on Now for 3 years ! Thank-You for yout input. Nitrojc.

 
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03-13-10, 12:21 PM   #30  
This why you have to establish what the compression is with a good test. Compression isn't prone to variations. If the valve guide is worn it's worn all the time. You wouldn't get what you're seeing because of a worn out guide especially getting an increase in power with the choke.

Just shaking the valve as you did to establish the degree of wear is too generalized to reach a conclusion. If you had the equipment to test it the first time, test it again with the throttle and choke open. Then you make a logical decision on what to do with it.

The problem consistent with the symptom is fuel delivery to the engine. The most logical solution to your problem would be to work on that area. If you can find a kit it shouldn't be too expensive.

If the engine and it's running isn't worth the time you'd have to take to work on it and it is indeed completely worn out, I would discard it.

 
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03-13-10, 04:40 PM   #31  
E-Bay carbs

I believe a Good used carb probably will correct the problem. DOES ANYONE HAVE A GOOD USED PULSA-JET CARB THEY WANT TO SELL, or DONATE ?
E-BAY HAD A FEW RACING CARBS, but I'm not interested in them.
All that has been mentioned, Has been tried, did, and done over the past 3 yrs. to No Avail, and I am done.
I think the engine when it runs, IT RUNS WITH FULL POWER - NO CHOKE. HOWEVER, When it doesn't run properly, I HAVE ALL I CAN DO to keep it running, and then it requires 7/8 choke. I did not say it ran with power choked, at Best the power is Marginal that's it.
The tolerance for the NEW Valve is 4/1000. If I can feel Any movement (from side to side) at all it's going to be excessive, No matter what. THE QUESTION IS: Will, or could this cause Sporatic Engine Performance, and power loss ?
Well, I could debate this debate for another 3 yrs, but I choose not to. Thanks-To-All for your help. Nitrojc.

 
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03-18-10, 07:15 AM   #32  
Briggs mst / tech info ?

Hello Guys, As I have already stated ... You guys are the Pros. This small engine repair stuff is a little out of my ball-park, and that's why I use these forums.

What I find Strange is ... That Nobody has been able to Answer some of what I feel are "Technical - questions," or follow thru the fuel system to "Determine the outcome," of a bad / defective part. For Example: The needle valve shut off/closed still flows fuel ... WHAT IS THE EFFECT OF THIS? It stills runs so who cares, again What Effect ? If there is a pin-hole in the fuel pump diaphram .... What is the Adverse Effect ? What Negative thngs happen, More Specifically ... Pin-point what the effects are.
Look, I am not trying to beat anybody down, but most of the answers that I am getting are in the "Service Area" as Fixes. This approach doesn't help pin-point anything.
Well, I am still asking ... If anybody out there can answer these questions, then Please, by all means come forward, and give me the answers. This would give me "Peace of Mind."
Many Thanks, Nitrojc.

 
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03-19-10, 01:35 AM   #33  
What? Nobody has been able to follow through the fuel system to determine the outcome? That's your job my friend... to determine the outcome. We told you what is wrong and that's what you asked for. Now you have to give us the outcome...it's not our machine.

We don't have time to play games or give you answers to questions you never even asked, like what is the "adverse effect" of a "pinhole in the fuel pump diaphragm". Why would we discuss the adverse effects of a pinhole in the fuel pump diaphragm when the diaphragm obviously does not have a pinhole since it is working.

You want to know the adverse effects of a pinhole in the fuel pump diaphragm? Here it is: It won't work. How do you get technical about a simple little fuel pump diaphragm? I'll try... The positive and negative pressure variances between the membrane of the diaphragm designed to propel gasoline from the appropriate container to the orifices and venturi of the fuel metering device are necessary to be contained within the chambers on each side of said membrane in order for it to operate in the manner for which it was designed. If these pressure variances are allowed to transfer from one chamber to the other, the flexing of the membrane will be reduced. As the action of this membrane flexing is reduced, the efficiency of the membrane's ability to transfer gasoline is also reduced in direct proportion to the transfer of pressure variances from one side of the membrane to the other. A pinhole, depending on the selected size of pin you use to create the pinhole, would have a greater probability of creating enough equalization of the pressure variances to render the membrane inoperable. .....or in other words it leaks, which is self-evident by nature and unnecessary to explain...you already know a diaphragm with a hole in it will leak.

The effect of fuel getting to the engine with the needle valve closed? Nothing, except fuel is still getting to the engine from another source, which it should be able to to normally anyway.

Your carb has problems, go do something about it. I have a lot of patience, but it grows thin with people coming on this forum intentionally wasting our time. This thread is closed.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!


Last edited by cheese; 03-22-10 at 06:21 PM.
 
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