Hey Geo,


I have a mower with a newer but cheap Briggs engine (4.5 HP-- plastic carb and such)


It's not putting out much power, and if I put more tension on the fixed throttle spring it speeds up but starts surging as the governor reduces power and then it speeds up again.


Any ideas for that one?

 

You really need a new thread about this one...it's a different model, style, and even brand of engine. You need to change the carb diaphragm.

 

No...that didn't happen. I advanced the throttle by hand and it speeds up with the same boggy sound and still a bit rough.

Cheese...was your post about starting a new thread and changing the diaphragm meant for me? Can't find a diaphragm part number on the parts break down. Just a number to replace the whole carb.

And where would the diaphargm be located in the carb?

 

Cheese was referring to SeattlePioneer. Have a good one. Geo

 

Sorry, I didn't specify. I was responding to Seattle pioneer, but there are a lot of posts about brands and problems other than the original problem in the originators' post. Not that they aren't welcome questions, just hard to sort through a bunch of different problems on different engines going on at once in one thread.

 

I understand. I started a new thread with my post. Do you have any ideas on what my problem is?

http://forum.doityourself.com/outdoo...ml#post1753845

 

You should have started a new thread, I almost missed this, when they get a lot of posts I don't normally check them, anyway.
You need to install a new diaphram kit, it is Briggs part # 795083 or old # 495770 also Lowe's has a kit #5083 which has the same parts.
Here we go;

Remove air cleaner, there are 2 bolts that hold things together, one on the front of the tank 3/8" and one into the block 1/2", remove these bolts, now "slowly" slide the carb/tank off the intake tube and breather tube, now tilt the tank in to release the throttle linkage and waalaa the carb/tank is removed. Check the intake tube to see if the “O” ring seal and plastic retainer are still on the intake tube, if so remove them and re-install them into the carb. Remove the 5 screws from the carb/tank remove carb(don't loose the spring) now spray all holes, cracks and crevases in both the carb and tank surface with brake parts cleaner, remove the main screen(looks like a thimble), now with a small screwdriver pry out the main jet(carefully) and clean it, check the “O” ring on the main jet for damage, if it is damaged it must be replaced, reinstall the jet, it can be difficult some times to get it to snap back in place(I use the rounded end of a screwdriver handle). Remove and clean the fuel pickup stem(not necessary if the fuel tank was clean). Clean any junk/rust from the tank. Install the diaphram on the tank then the gasket(no goo or sealer) now carefully replace the carb(the spring will try to misalign the diaphram), tighten all screws a little at a time so as not to crimp the diaphram until they are all tight. Install the carb/tank in reverse order and you are done. If I missed something one of the real mechanics will correct me. Have a good one. Geo

 

I am having a similar problem to what's been mentioned before. It has been working perfectly for many years until after my wife lifted it to clean the bottom. It was pushed forward on the front wheels and rested against a wall on the handle. I couldn't get it to start at all, tried to clean out the carb with no improvement. Now I've replaced the carb and primer button and it starts for a few seconds and dies out. Since the carb is all new I can't imagine what else it could be. Filter, plug oil are all good. Any tips would be greatly appreciated!

 

Could be a number of things. Sounds like your primer is working, and sounds like you've got spark.

Start by loosening the nut on the bottom of the carb. Catch any gas that comes out into a small dish. Is there water or dirt? Maybe tipping the mower disturbed something in the tank. Replace the gas.

If there's no gas, you need to figure out why. Blockage between the fuel tank and the float valve. A very badly misadjusted float could hold the valve closed even when there is no gas in the bowl.

Check the float height. I've forgotten the correct setting, but it should be easy to Google.

Just to be extra sure, pull the jet out and be sure it's completely clear.

If it's not one of those, check for air leaks around the intake pipe.

 

Thanks for the great info! My mower would start and run for a few seconds, then die. As suggested, I removed the bowl on the carb, cleaned the holes in the nut, and presto! Awesome job folks.

 

Congrats bunzai!

I was super stoked when I pulled the mower out of the garage for the first time since early last summer (it's been super dry in Texas, no grass to mow ), put some gas in it, primed it, and started it with one pull! Not bad for a 34-year-old mower.

 

Another "Thanks" for the great info. Same as all other posts. Mower was working, but today 1 pull fires it up and it stops right away. replace fuel,filter,plug - no go. Check this thread, pull out bolt, clean, put back in. 1 pull fires right up & keeps going! Just finished mowing the lawn! Thanks for the great info! 12-year old mower!

 

I am a forty five year old lady that took your advice on taking out the bowl and cleaning the bolt that was in there with an old toothbrush. I got gas all over my hand but the lawn mower started right up. now can you tell me how to replace the fly wheel. For a girl I think I am pretty mechinical.

 

I also have an Eager-1 (may not be the exact model as ones mentioned above) and this would probably be a problem that could happen on many other models: I decided the carb had to come off due to the same symptoms (started but wouldn't run more than a second or two) and discovered that the thin tube from the priming bulb to the carb was broken, probably due to heat + vibration + aging of the rubber. Replaced it ($2 at local small engine supply place), reassembled all, and voila! Bingo! Zowie! I'm a lawn-mowin' fool! Must have created a severe vacuum leak, causing an insanely lean mixture.
Runs like this little puppy dog now!

 

mstarr555,

Why do you need to replace the flywheel? Flywheels should never need to be replaced, and you said yours runs. Is it broken?

 

Same problem as the others.

I bought a used Eager1 20" 4.0HP Tecumseh engine. The guy I bought it from was a dead ringer look-a-like as Clarence Darby from Law Abiding Citizen so I was skeptical at first. haha. This turned out to be a Great Mower! Virtually no problems. A few times it conked out on me so I took the gas bowl off thinking the float was getting stuck. Maybe, maybe not, but whenever I took the float off and put it back on it started right up. It happened again last week and after a frustrating 2 hours I noticed the gasket from the carb to the bowl was broken. I ordered the gasket last week and got it today. I also ordered a new spark plug and filter. Now, I'm getting the ONE SECOND run thing.This NEVER happened before. I tried everything previously suggested in this thread. I never noticed the pin hole in the bolt so I took a pin to as one previous poster did. I didn't really give it a thorough cleaning though. After a few more attempts with basically every suggestion mentioned in this thread, still no luck. Well being the impatient guy I am I didn't let the gasket sealer to dry enough so I re-glued it and gonna let it sit overnight. I'll give all the carbs holes a good cleaning and let's see how I make out tomorrow. Wish me luck!

 

I do not know of any small engine carb that requires sealer, using sealer on a small carb will always get where it doesn't belong. Use the wire from a bread twist tie to clean the tiny hole near the top thread in the bowl nut and your problem will be solved. Have a good one Geo.

 

Geo,

You're right. The sealer was unnecessary. Anyway I replaced the cup (bowl) and still NG. Now I'm not even getting a start. I pulled the carb and cleaned it out. All of the jets were clean and the carb was in good shape, zero gunk or build up. When I reattached the carb still NG. Gas was coming out of the cup seal. The seal seats right on the carb but not on the cup. It's a smige too big. I have more cup gasket seals coming to me tomorrow(hopefully). If this round doesn't work I think I'll get a new cup. It doesn't look bent but may have a few deviations since I took it on and off 20+ times.

Gary

 

Great, the valve pin fell out and the tiny seal (gasket) is gone and is MIA. I'll never find that thing since I was doing most of the repairs on my back lawn . Well, tomorrow I'll try to get the valve pin kit and a new bowl.

Well a few GOOD things is happening from this experience. I found a local dealer who has parts for every engine imaginable. By the end of the week I should be an expert on a Tecumseh Carb.

 

Clean the tiny port shown in the pic below. However it seems you have bigger problems now if you lost the seat. Have a good one. Geo

 

Like I said earlier. I cleaned out all the jets. The carb is/was immaculate. The pin seat was in the carb, it was just barely visible. Anyway I noticed the priming bulb was split and when I took out the plug to test that I was barely getting a spark. I took the mower to a local place and he replaced the bulb but they said I needed a new coil plus a few other thing. He wanted like $160 for the whole job. I told him in my NY accent "FORGET ABOUT IT". I ended buying a new mower at Sears Saturday. I got a Craftsman 21" 50 States. It has a nice B&S 6.75 engine. It listed for $279.99 but was on sale for $218. After the $30 bonus points I received it ended up costing me $200 with tax. Problem solved.

Anyway, down the road I'll get the ignition coil and mess around with the old mower.