16 hp briggs intermittent surging?

[dzg]

Yesterday me and the wife went to Bundy hill to do some riding. The machine was running great till I splashed through a mud hole....it started bucking and surging.....like I got the ignition wet....I stopped for a few minutes and it was fine. About 10 min later after doing all dry riding it did it again, I pulled the choke a little and it kept running but then it wouldn't even like that ...I shut it down for about ten or fifteen mins it was fine.....and it kept doing that.

Obviously its a fuel issue of some kind.....weak pump? Csrb? Vapor lock? Help would be appreciated....wanna have it running good before ashtsbula

[ARGOJIM]

Almost sounds like a fuel filter or a piece of dirt in the carb., another east possibility is the fuel cap vent, if it does it again try unscrewing the cap and see if that fixes it for a while.

[blown84gt]

What fuel are you putting in it? Mine did that on 10% ethenol back during hunting season. My buddy owns a repair shop and services small engines and he kept telling me a Briggs will not run on that crap and I didn't believe him, after all it had been running fine. I finally drained it and put in 100% gas and as soon as the fresh hit the carb it straightened out and has run like a top ever since.

[dzg]

I checked the cap vent and its all the way open. I did put fuel in it but it was from the same station as last time. I'll pull the filter off and see if that's the culprit. Any more suggestions?

It started messing up at the worse time though....right as I got into the worse part of the dare ya pit with an audience
I still made it though

[dzg]

OK...fuel filter seems good, cleaned and blew out the cap vent.....float seems to be working ...

Its surging at idle and if you nail it and let off till stall. I seen on the data plate it says "premium gasoline recommended"...I put 87 in it could that possibly be the issue?

[thebuggyman1]

Pull the pluggs and look at them, check gap, clean etc. I'd still bet carb though. You may have to pull the top off it and spray cleaner through all the little holes.

[dzg]

OK I'll did into it a bit more tomorrow. For what its worth turning the idle screw made no effect on anything. I turned it all the way in and out and it still was surging at idle. I know on a vehicle carb it should die with the screw all the way in....same deal on these?

[anotheramature]

Is it possible that you may have just picked up some bad fuel the last time you put fuel in it. Try drainning and refueling with fresh fuel.

[hydromike]

For what its worth turning the idle screw made no effect on anything. I turned it all the way in and out and it still was surging at idle.

Hey DeeZee',

If it doesn't change its behavior after cranking in the idle mixture screw all the way, it leads me to believe that you've got a plugged idle circuit in the carb somewhere. You should be able to have the top off of the carb in a matter of minutes. Pull the idle mixture screw out completely and blow out the orifices with air and snake the circuits with a very fine piece of wire (you can take an individual strand out of a piece of 12-16 gauge conductor and it works fairly well for the really small holes.)

Another thing to check is to see where the fuel level is in the carb when it's surging. Let it sit there and surge away, shut off the ignition and remove the top of the carburetor. If the fuel level is at the appropriate level when it's surging, you can basically eliminate fuel delivery to the carb as an issue. That mean the pump is fine, the filter is fine, the tank is fine, the lines are fine, the gas cap is fine (etc....). If she's still surging, the issue lies within or after the carburetor. If it's actually *running* fine while it's surging (no stumble or misfire) I'd lean toward ruling out the ignition as well.

You might just want to pull the whole darn carburetor off and take the whole thing apart and see what makes it tick and where the problem areas might be. I'm really interested in seeing what you find in there, if anything.....

::EDIT:: Oh, and check to see if you've accumulated any water in your float bowl. It's weird, but I've seen water hang out in a float bowl for a long time without getting consumed. I'm not that familiar with the geometry of the Nikki/Tikki Vangard carbs, but I wonder if it can operate under a limp condition with some volume of water in the carb. I know the Keihin carbs I run on the Kubotas will run (poorly....) with almost 1/16" of water in the bottom of the bowl.

[dzg]

Took the carb apart, blew it out, cleaned it, drained fuel tank, put in a couple gallons of 93, cleaned and gapped plugs, now its running good again....it still idles kinda bad though but midrange to wide open is majical. I can deal with the rough idle. Thanks guys!

[hydromike]

Awesome.... now just keep her going strong for another four weeks and we'll see you in Ashtabula....

[dzg]

I'll do my best lol