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Briggs 20 hp - HELP!!!

2582 Views 14 Replies 9 Participants Last post by  Tractor Tucker
I have a B&S V 20 hp engine that is giving me problems.

When it starts it, I put it in the start position and it fires, but runs very weak. Almost loping or surging. It also puffs out a bit of smoke not a lot, but some. It will die either after a few seconds or when it is put in gear.

Have been working on this problem a while and here is what has been done so far:

Rebuilt carburetor
New fuel filter
Cleaned out tank and gas lines
New gas
New coil/plug wires
New spark plugs
New battery

A few observations.

The fuel pump is working. Took the top half of the carb off and turned it on - gas does come out like a geyser.

The first time I put the carb on after rebuilding, it ran strong, turned if off, 4 hrs later, back to hardly running.

When I check to see if it was getting gas by taking to top of the carb off, I put it back and it ran strong for 10 min with no smake. Drove it around the yard. Then it died and was back to the same problem.

I have played around with the needle screw on the carb but that does not seem to make a difference.

This is a tractor that was sitting for a while and am trying to get it running. The Briggs model # is 460777-1279 and the engine year is 95.

Thanks for the time and all the help!
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Have you checked the compression on both cylinders?
Did you clean and blow out the jetting and internals on the carb?

I did clean the jetting out and when done, hit it with some compressed air. I will check the compression tonight. Not sure the best way but I can pull the plugs and see if I feel the same pressure coming out of both.

I remember doing this once on a BMW in line 6 with a bad head gasket. For some reason I stuck my face down by my hand. Spark jumped over and about blew my eyebrow off!!! Don't think that will happen with a Briggs and I hope that I am smarter from that experience.

I feel your pain as I've been there-done that many times.. It's always some little thing that you missed.. :fing20: Try this: start it up and ground out the plug wire @ each cylinder to see if it isn't that new coil.. (heard about it before) Get a in line spark tester form HF tools for a few bucks to check the coil output.. Another thought that comes to mind is to measure the voltage of the power wire to the coils to ensure it is 12V DC as lower voltage will cause weak spark.. Just a couple thoughts.. :goodl:
I checked the compression by hand. I cannot find all the parts to my compression tester. By hand, both cylinders felt strong. When I pulled the plugs, I was a little surprised by the amount of black that was on them. It was not crusty, but a covered in black slime which most of it wiped off.

When I put the carb back together, I did not put the 3 screw fuel pump back right... the gasket that made what I will call the bladder was bunched. I changed the oil (not the filter).

Not sure if that may be a cause to the problems. :banghead3
One more note....

Take the plugs out to check the compression, put them back in and on the first attempt to start the engine, it does better then attempts after that. That seems to be the theme when I take off the top of the carb or open the engine in anyway. Not sure if that means anything or if it is just coincidence.
Hmmmm. I think we found it. One of the two bolts act as if it was overtightened. It never grabs hold and gets snug. I put some gasket sealer on it but just went out and looked at it and after pushing down on it some I noticed gas was leaking out. Took it apart and the black silcon did not hold.

Any idea on how to get the bold to grab hold... never had this problem so I am guessing.

Thanks larrybl. I am sure that is it.
I don't know which bolt you are referring to, but either get a longer bolt so it can grab "clean" threads or tap it out to the next largest size.

Or Heli-Coil it.
Unfortunately, that was not it. I took the lock washer off the bolt which gave me enough height to grab on to some good threads. Snugged it down but still has the same problem. I checked and there was not sign of gas coming out between the carburetor and manifold. This engine was made in 95 and it has the orig gas lines. going to replace the tomorrow. Maybe there is crack that is letting our pressure. At this point, I am just guessing.
Pull the float bowl again, to make sure you didn't wash some garbage back into it after the carb rebuild. I would blow out the needle and seat area again, especially if you see ANY junk in the bowl. Just my $0.02.
You might try changing the plugs,they're cheap and it cant hurt.There might still be some crud in the system that's fouling them.
Success!!!! I went to blow out the carb and I noticed that gas was blowing out of the seal between the carb and the manifold. Not sure why, but put some sealer on it and it works find.

Thanks for all the help and patience.


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