Rough ride = Backfire

[Joker]

I directed the crankcase vent away from the carburetor (into a bottle) and this has fixed the problem of gettng oil into the carb at WOT.

Now my problem is that if it get into rough terrain (ice ruts on the lakes), the engine will backfire, loose power, and generally let me know it isn't happy. I was wondering if my float could be set too high and excess gas could be splashing around causing trouble.

The engine is an 18hp Vanguard.

Any thoughts?

J

[Roger S]

I had that symtom before I put an electric fuel pump on the argo. I assumed the gas in the tank was low enough that when sloshing around in rough terrain it would pick up some air, and then take a very long time to recover.

It might be a weak mechanical pump, or the filter that's under the seat.

[Joker]

Thanks Roger. At the time, the tank is full and the filter is relatively new. But you raise an interesting question. I was thinking the bowl level could be too high - causing sloshing. But could your "sucking air" scenario be caused by too low of a bowl level - allowing air to enter one of the jets when the gas is bouncing around?

I'll search the forums to determine if there is a good way to test the mechanical pump and what it will take to replace/rebuild it.

[Roger S]

You could take the top off the carb and look around. I think your symtoms sound like lack of fuel. There might be a drop of water, or some debris that intermittently blocks the fuel passage in the bottom of the bowl. An aerosol can of carb cleaner and compressed air to blow through everything would be a good idea. I like to take the idle screw out from the side and clean that passage, too.

[Joker]

Well, I pulled the top off the carb today. Found out that the float level is not adjustable on this engine (I should have read the manual first, says it right there), but there were some debris sunk on the bottom of the bowl. I cleaned that out - we'll see how it does next time out. Hopefully it was like you said and some of that junk was stirring up and clogging a jet.

[buckhntr17]

i have a 1998 response with 18hp vanguard i went to use it the other day and fuel pump went out .well i have a 16 vanguard brand new that had a fuel pump on it so i swapped them out now i get the same problem after reading this I'm leaning toward the fuel pump because it didn't happen until i swapped them. the original was square pump the one off 16 is round one. i don't know if this helps but I'm gonna order a rebuild kit or new replacement pump ill let you know my outcome and watch this thread for updates from others

[buckhntr17]

havent got to fuel pump yet been working anyone got any ideas

[buckhntr17]

hook the line back up it is what the fuel pump works off of,the engine gets vacuum power for the pump from the crankcase i changed mine and cleaned out the carb. it is alot better but i have not yet totally solved the problem. i think the pump that i had sitting on the other engine could have got bumped and cracked I'm going to go buy another, if that solves it great if not then at least Ive totally ruled out the pump. since you didn't have the problem till you took the hose off put it back on.its what drives the pump also make sure your filler cap and dipstick tube are on tight and have a good seal hope this helped

[buckhntr17]

I directed the crankcase vent away from the carburetor (into a bottle) and this has fixed the problem of gettng oil into the carb at WOT.

Now my problem is that if it get into rough terrain (ice ruts on the lakes), the engine will backfire, loose power, and generally let me know it isn't happy. I was wondering if my float could be set too high and excess gas could be splashing around causing trouble.

The engine is an 18hp Vanguard.

Any thoughts?

J

the tube running from the aircleaner goes to a tube on the engine . the tube on the engine is the egr and pvc system for the block.there is a reed valve in this assembly that sticks open and causes the cranckcase to hold vaccume pressure and in turn also lets oil get to the carb.the engine should run around 13-14 lbs of vaccume mine had 7 .i orderd the part about 25$.i will post back if this solves my problem hopefully this helps

[Roger S]

Ahh you may have discovered something here..

[buckhntr17]

i talked to a guy who put on an electric fuel pump who loved it untill starting and winching and lights ran his battery dead then he said he was too.have you had that problem? im gonna put an altenator in after i get some more things caught up around here. ive hated my charging system since ive had my machine.

I had that symtom before I put an electric fuel pump on the argo. I assumed the gas in the tank was low enough that when sloshing around in rough terrain it would pick up some air, and then take a very long time to recover.

It might be a weak mechanical pump, or the filter that's under the seat.