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engine starts then dies...


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04-16-07, 01:45 PM   #1  
engine starts then dies...

Briggs 18 hp apposed twin runs for a minute or less then dies. But starts right back up. Then dies again. Starts up again. Then dies. etc...
Playing with the choke doesn't help, fuel cap is venting, and there is plenty of gas. I set the carb jet at 2.5 turns? Could probably use an oil change, but that shouldn't do this. It's been running great up until now.

 
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04-16-07, 03:03 PM   #2  
Azis
If you have an inline fuel filter check and clean or replace. It could also be the fuel pump which should be part of a carb kit for your engine.
If you have no filter or other fuel line issues you might clean the carb.
If no help you need to post the engine #'s for better diagnoses and parts.

 
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04-16-07, 08:40 PM   #3  
I've had a coil do this to me once on an opposed twin briggs. It was very difficult to diagnose because it would have spark at cranking rpms, but it would lose it at running rpms. So it would start, but die as soon as running rpms were reached. I basically checked to be sure everything else seemed to be working as it should, then replaced the coil just because of process of elimination, and a hunch. These coils are troublesome on the opposed engines anyway. I think the transistor in the coil got weak and couldn't switch fast enough to keep up with engine rpms.

I think I've only seen this once, so I suppose that it's not a common occurrence. It may not be the problem in this case, but though I'd mention it. If everything else checks out, I'd go for the coil.


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04-17-07, 03:08 PM   #4  
I suspected the coil so I put in another one I have laying around. The same thing happened again, but it's an old coil and I'm not sure if it works properly.

I took off the fuel hose from the carb and gas flows freely.

 
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04-17-07, 09:08 PM   #5  
Chances of 2 coils doing that are pretty slim I'm sure. I don't think the coil is the problem. When it dies, does it slowly die, or just shut off like you switched the key off? Any black smoke from the exhaust when it dies?


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04-18-07, 05:49 AM   #6  
Right now it dies quickly like I turned the key off. But the first time this happened, it died slowly and I could "catch" it with choke and keep going a few more seconds and then it would die. But now it just dies with choke or not. But it always starts right back up.

No black smoke, but a little blue smoke on first start that goes away in a few seconds

 
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04-18-07, 01:23 PM   #7  
I found the problem but don't know how to fix it.

It's in the throttle control. The throttle will stay steady for a few seconds but then a lever in the throttle control seems to take on a mind of its own and decides to throttle up. Problem is, it throttles to quickly and the engine dies.

If I hold the lever so it doesn't move, the engine stays running.

I might be able to post pictures if you need them.

 
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04-19-07, 01:05 PM   #8  
I'm guessing the problem is in the governor. The throttle controls the engine as it should, but after a few seconds the governor? pushes the throttle all the way up and kills the engine.
I don't know to much about these things so any help is appreciated.


Last edited by DIYaddict; 05-17-07 at 11:26 AM. Reason: Mistake post has been deleted
 
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04-19-07, 02:00 PM   #9  
Azis
I think the govenor is acting as it should. The govenor reacts to the throttle setting and engine rpm to control engine speed by controling the movement of the butterfly valve in the carb.
I would make sure you don't have a fuel restriciton in the carb. The main jet is easy enough to get to.
See if you can keep it going for a bit longer by bottle feeding it some fuel in the carb.


Last edited by DIYaddict; 05-17-07 at 11:27 AM. Reason: Mistake post deleted
 
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04-19-07, 02:53 PM   #10  
Yes, it stays running as long as I pour gas into the carburetor.

 
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04-19-07, 05:18 PM   #11  
Azis
Then you need to service the carb or possibly the fuel pump, which in your case is part of the carb.
If you will post the numbers of your engine it would help for instruction.
Also you may have a fuel solenoid that could cause similar problems.

 
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04-19-07, 05:58 PM   #12  
Model: 422707
Type : 1525 01
Code : 9311175A

It doesn't SEEM like the carb is the problem because if I hold the governor with my hand, it stays running. I could be wrong though.

 
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04-19-07, 06:39 PM   #13  
Azis
Will it stay running with the throttle at idle?
That is basically what you are doing by holding the govenor lever.

 
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04-19-07, 06:41 PM   #14  
You do, in fact, have a restriction in the carb, as evidenced by your ability of using the "bottle feeding" method and keep it running. The Briggs rebuild kit is part number 693503 and includes a fuel pump repair kit in such rebuild kit. You may get away with simply blowing out the main jet though and ensuring a clear passageway through such. The access to the main jet is by way of a plug requiring a 5/8" wrench and the jet can be removed with a torx driver, either T-25 or T-30, I forget exactly which.

 
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04-20-07, 05:53 AM   #15  
{quote}(Azis) Will it stay running with the throttle at idle?
That is basically what you are doing by holding the govenor lever.{quote}

No. It still dies at idle in the same way unless I hold the governor.

 
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04-20-07, 06:13 AM   #16  
Azis
Well I, and apparently now, Puey, believe it is a fuel delivery problem and not spark or ignition related.
Try cleaning the main jet as Puey instructed.

 
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04-20-07, 06:20 AM   #17  
OK. How do I clean the jet? Do I just unscrew it and stick a blow gun in?

 
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04-20-07, 06:23 AM   #18  
Azis
You should be able to see the orifice once you remove the jet. Compressed air is good. If its bad you may need to soak it or use a small wire, but I rarely see em get that bad.

 
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04-20-07, 02:57 PM   #19  
I unscrewed the jet and blew compressed air in and gas shot out the top of the carb. I put the jet back in and it started almost instantly. It stayed running longer so I started to drive around and then it shut off as before and now I'm back where I started. Now it won't stay running for any length of time without full choke.

There is a large screw next to the jet that I took out and under that is another screw that needs a hex key. What does this do? It was tightened all the way.

 
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04-20-07, 03:47 PM   #20  
Azis
Actually you could be time ahead to just clean and install the kit Puey listed. It could be new restriction in the jet, or elsewhere in the carb and the fuel pump may be getting weak.

 
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04-21-07, 12:18 AM   #21  
You'll need to disassemble the carb and clean it out. There is most likely junk in the bowl getting in the main jet.


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04-21-07, 07:04 AM   #22  
I just had a thought. Could water in the gas do this? Just before all this happened, I filled the tank at a nearby gas station. (at $2.99 a gallon I might add)

Sorry Azis, I like to exhaust every possible free option before spending money.

There is no junk in the carb bowl and the whole carburetor is in good condition. It was just serviced a few months ago.

So could water in the gas do this?

 
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04-21-07, 07:24 AM   #23  
Azis
No worries, its your time

 
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04-21-07, 07:30 AM   #24  
Azis
One last thing you might verify. See if you have a fuel solenoid on your carb. The drawing shows a solenoid but I am not sure the older ones have them. I don't recall having seen one on these engines but if you have one it could cause similar problems.

 
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04-21-07, 05:50 PM   #25  
Almost fixed...

I tor down the whole carb and completely cleaned it with a can of carb and choke cleaner. The engine now runs very smooth and stays running, but only with the choke at about half-way.

 
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04-21-07, 05:51 PM   #26  
BTW, there is no fuel solenoid on this carburetor.

 
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04-21-07, 06:37 PM   #27  
You'll then want to soak the carburetor in a bath cleaner for 15-20 minutes. I use Napa's #6402 which includes a handy basket to cradle the carb in the gallon can. You'll then spray it down with your spray can of cleaner. Do yourself a favor and buy the Briggs carb kit and install it after soaking and spraying!

 
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05-03-07, 02:33 PM   #28  
The rest of the carb is ok. The problem is with the fuel pump. One of the gaskets looks damaged and it sprays gas out the front through two small holes. Can I get a carb kit for just the fuel pump? and if so, what part number?

Are those two holes supposed to be on the front of the fuel pump? I never noticed them before, but then, I never looked that close.


Last edited by msidan; 05-03-07 at 02:49 PM. Reason: Added more information
 
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05-04-07, 12:49 AM   #29  
If gas is coming out those holes (yes, they should be there...they are for ventilation for diaphragm operation), then the diaphragm has a hole or tear in it. You can buy a repair kit for the pump at most any small engine repair shop.


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05-04-07, 04:41 PM   #30  
I realized I put one of the springs in the fuel pump wrong! Installed a new fuel pump kit and it ran without choke and no gas comes out the fuel pump. The longer it runs, the smoother it sounds. I think I got this thing fixed! Thanks for all your help guys.

 
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05-04-07, 10:36 PM   #31  
Great! Glad you got it, and thanks for the update!


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05-17-07, 07:53 AM   #32  
It seems I spoke too soon. While the engine stays running, it still sounds just a little rough and I THINK it's using more gas than it used to. On the side of the carb near the jet is a hex cap screw with a hex screw underneath it that would appear to drain gas from the carb bowl when open. It is tightened all the way. What is this supposed to do? Heres a couple pics.

http://img337.imageshack.us/my.php?image=1001380jr8.jpg

http://img408.imageshack.us/my.php?image=1001382nc9.jpg

 
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05-17-07, 08:22 AM   #33  
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Should be an allen or sloted screw I think, and looks to me like where your main jet is....?

 
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05-17-07, 08:46 AM   #34  
It's an allen screw. I don't think it's the main jet. I think this is the main jet here. It is a slotted screw with a spring on it. (green circle) The other thing I showed is orange circle.

http://img265.imageshack.us/my.php?image=1001388wu6.jpg

 
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05-17-07, 10:03 AM   #35  
Azis
No that is your mixture adjustment. It should be around 1 1/2 to 1 3/4 turns out from lightly seated. You might even go a bit further if needed.
The allen is your main jet.

 
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05-17-07, 11:27 AM   #36  
So how should the main jet be adjusted? The mixture adjustment is set as you have said it should be.

 
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05-17-07, 01:06 PM   #37  
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The main jet should be secure and there is no adjustment. The "jet" is the orifice in the screw. If you remove it to clean, you should notice a hole runs the shank. This is a calibrated sized hole and any small restriction will change the fuel/air mixture. The mixture screw is meant to adjust for some buildup and peak performance. This is becoming an icon only now a days as most carbs no longer have this adjustment and the only solution is to service and clean the carb.

 
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05-17-07, 01:38 PM   #38  
Azis
Does your mixture screw have any effect when you screw it in or out with the engine running?
1 1/2 turns is just a starting point. Then with the engine running at full throttle, adjust it out until the engine starts to stumble, then back in until it again stumbles, then back it out 1/4 turn.

 
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05-24-07, 05:51 AM   #39  
I adjusted the carb again the right way.

I replaced the two fuel intake gaskets and the engine runs a lot smoother; not perfect, but better. A complete carb kit is on it's way.

On a side note, the battery does not charge. Even after running 3+ hours. If I charge the battery with a charger, it holds it's charge enough to start the engine a few times. The alternator works because the headlights do, right? Could this be caused by the irregular engine running? Or could the battery be bad. It's at least 2 years old.

 
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05-24-07, 06:58 AM   #40  
This engine should have a dual alternator. One is a low-amp circuit that powers the lights only with AC current. The other is a 9 amp or higher circuit that provides the DC charge to the battery. This is usually the one that burns out, especially if the battery has been connected in reverse polarity at some point in time. Measure the battery voltage with a voltmeter, then crank the engine up and check for higher than battery voltage at the battery posts (with engine at full throttle). You should attain around 13.5+ volts there in a few minutes of run time. If the reading gets no higher than battery voltage, then go to the alternator wiring coming out from under the flywheel. Unplug the connector and measure voltage at the wire with the "lump" in it covered with black shrink wrap at the connector. This one is the DC charging wire. Check here with the engine running. If you have sufficient voltage here with the engine running, then the alternator is good and there is a wiring issue. If there is no voltage here, the alternator is bad.

If the engine is surging too much, it can affect the charging, but it shouldn't keep it from charging altogether.


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