Briggs Vanguard Surging

TimWafer · Jul 12, 2018

I have a 18HP Briggs vanguard #350447 in a UTV that surges at higher throttle or under load. Ive removed disassembled and cleaned the carb by soaking in carb cleaner, blowing it out with compressed air and putting it in an ultrasonic cleaner. Also using aerosol carb cleaner.
Ive replaced the fuel filter (& air filter) but the same issue remains. Adding a little choke to it while it does this seems to help. Its driving me nuts. It just seems like its starving for fuel. I was thinking of trying a temporary fuel tank above the motor so its gravity fed and see if that makes a difference. That would eliminate the fuel pump.
Any other ideas?

guido · Jul 12, 2018

Hello Tim Wafer,

Look at the gas cap. It has a vent hole. Make sure it is not blocked. I am
leaning towards the carb though. Usually the idle jet gets clogged and the
engine will surge. Either way it is a fuel delivery issue,

Guido.

old · Jul 12, 2018

As Guido say and or you could have a weak spring in the linkage which will also cause that

jeffcat · Jul 12, 2018

First, is this a single or twin cylinder? As forwarded, that little
soft spring on the throttle linkage from the govenor must be there and
free to move a little. If this is a twin cylinder see if it has a NIKI
carb on it. That most likey is your problem. Get back to us so we can
do further diagnosis.

rlp in Co. · Jul 12, 2018

I had an engine do that too. There is a
chamber that can plug up and you have to
remove a plug to clean it. I sharpened an
old screwdriver to a point to remove the
plug and cleaned it out. There is a new plug
in the kit. It is a little flat piece of
aluminum. This was on a different engine so
yours may not be the same. Did you poke a
wire in every hole? Just cleaning won't get
the job done.

Ken Combs · Jul 12, 2018

Yep, sure sounds like fuel. Does it have the pulse pump? They are known to fail and/or the line to the crankcase from the pump can be leaking, so weak pulse/low fuel delivery

ss55 · Jul 12, 2018

Restriction in the idle circuit? Does adjusting the idle screw make any difference or the adjustment screw capped?

tim s · Jul 12, 2018

A little water in the float bowl will cause that too, some bowls have a drain in them..

Janicholson · Jul 12, 2018

I have had that experience (my own and neighbors) my end game was to drill out the main jet with number drills. I used a drill
that "just" fit the hole, then used the next size larger to enlarge the hole a tiny amount. In some cases it requires 2 sizes to
level out the mixture. Jim

TimWafer · Jul 13, 2018

This is a twin cylinder 18hp Vanguard horizontal shaft. yes it has a pulse type pump. Thats why I thought running a gravity feed tank to test it might be a good idea.
I will have to look again to see the brand of carb and check that spring.
Thanks

TerryB Illinois · Jul 13, 2018

Go to you tube and search for Steve's Small Engine Saloon. Go to videos and I think it is the second one that says how do I fix a surging engine. I had one surging and tried what he shows and it fixed the surging. Good luck.[/url]

TerryB Illinois · Jul 13, 2018

Go to you tube and search for Steve's Small Engine Saloon. Go to videos and I think it is the second one that says how do I fix a surging engine. I had one surging and tried what he shows and it fixed the surging. Good luck.

Briggs Vanguard Surging

TimWafer

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guido

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old

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jeffcat

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rlp in Co.

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Ken Combs

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ss55

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tim s

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Janicholson

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TimWafer

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TerryB Illinois

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TerryB Illinois

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