13hp Vanguard shutting down

[Keoki 14]

I recently got a PW used and the engine sputters out after about 5 minutes. The unit, including the 13hp vanguard engine look new, the air filter is not even dirty(the guy I bought it from said he bought it to start a moble detail biz, but he never got it going) he told me he only started it a few times in the last year or so, to "keep it running". I'm pretty sure the pump is fine, as while it is running, it is strong. I have checked all of the oil levels and they are fine. I drained the gas and put in new. It runs for about five minutes then it sputters out, it has backfired a couple of times also. I have not found any PW dealers up where I live, and when I called a local small engine(lawnmower) shop that I found on the B&S website, they didn't sound like they work on PWs. Where should I look to find a shop to service the engine? Thanks for any help.

[RMedbery 26]

Stuck float or crap where it aint supposed to be, take the bowl off the carb and clean everything.

[Joe Ortiz 14]

Check and see if theres a fuel filter. Also check the water supply. pressure might be to high or to low. hope you figure it out bro.

[Paul Kassander 26]

First check the fuel cap to make sure the vent is not sticking that could be the problem. just take it off or loosen it up and see if that fixes it.

If that doesn't work pick up a can of 'sea foam' and add it to the fuel system if there is a buildup of lacquer from the old fuel it will dissolve it an make it run like new.

[Keoki 14]

Thanks for the advice guys, I took the carb bowl off and there was a brown build-up on the bottom. I cleaned that out and made sure the float was moving freely. I did not see any fuel filter. It is still doing the same, it runs great for a few minutes then it starts to shutter and then it starts backfiring, then it stops. I am assuming that if it were the timing, it would not run fine at all, right? I will have to look around for the 'sea foam'. I will probably have to take it to a shop, but like i said earlier, I don't know of any shops that service PWs up here and the shop that is close didn't sound like they work on anything but lawnmowers. Thanks again....

[RMedbery 26]

The float may move but does the needle valve? And is the opening to the needle valve clear? If fuel comes in much slower than its supposed to your engine will empty the bowl of fuel after running for a few minutes and die.

[MMI Enterprises 289]

Some gas tank cocks on bikes work of vacuum and so if things are clogged the fuel won't pass..

Besides gas flow, some engines will do a sputter type stalling when oil is low and as it warms up.

[Keoki 14]

Ok, I will check the fuel supply better. Do you guys think that could cause the backfiring?

[RMedbery 26]

Backfire or afterfire? When you first start it up or when its about to die?

[Dave O 15]

Does it run the same on and off the trigger?

One of my machines has a 18 HP B&G

The reson I ask is the machine starting running rough about 10 minutes in. It would act like it wanted to shut down, or it would shutter, and then in the end after it finally shut down it would backfire and sputter when restarted. Then it would run fine again for a few then the same.

Changed everything from filters to plugs and even the oil since it had a low level shut down sensor, and then checked choke, and other.

It still did the same thing after all that was done.

In the end it was my unloader straining the engine even when on the trigger.

Just a thought

[MMI Enterprises 289]

That's odd Dave.. off trigger with unloader not passing should blow a burst disk or such. Such issue should present all the time shouldn't it. Would like to hear more on this and from others that may have experienced such.....Case here has a 5min. time table so I doubt it applies...

Korey,

The gas flow scenario talked about would be that after so many minutes the fuel in the float bowl runs dry due to lack of inflow. The point of stall is when you acheive too lean a mix causing a popping or spitting up through carb if throttle is open or through exhaust if throttle is suddenly closed. Since it's probably dieing rather quik on you at this point of running out of gas you probably no chance to try traditional methods of covering intake or removing air filter to see if she smoothes out from going richer or leaner. Other traditional test is by way of installing new plug, running it, then inspecting it's color to see how rich or lean she ran.

If bowl has a bottom drain tap you may be able to install a clear hose that you bend up alongside of throttle body to monitor gas level. The level of gas in tube will be same as that in the bowl and likely should be right near where the bowl meets the throttle body. Carbs will have a few different circuits and depending what that one consists of and all that goes along with it in way of sensors you may be running at a choked situation until she starts to warm up.

Without knowing that system is all about I would say you have to confirm whether ya got fuel starvation by way of restrictions or clogged filters, or misadjusted/stuck float and or needle, or the oil level/temp sensing problem. I'd yank the whole carb and get ub into the jets and passageways with carb cleaner as well.

[Keoki 14]

Ok, today I changed the spark plug and used a product called LMT by blaster(I think it is similar to sea foam) it is supposed to loosen and burn any 'varnish'. The engine ran a minute or two longer but still died in the end. The engine strained while I pulled the trigger and reved up and down no matter what was going on(this was only after the first few minutes of running fine). I have not adjusted the unloader... The oil is kind of dirty(and was a little over filled), would that mess with the 'low oil shut-off'? Thanks again everyone for all the great info.

[Russ Johnson 141]

The brown buid up in the bowl is most likely varnish. I use a pin drill to ream the main jet. Don't oversize the jet or it'll run too rich.

[Rick2 42]

Try some carb cleaner, the one with the little straw attached and blow out the jets. Even compressed air will work fine. Watch the pressure, not too much. It really sounds like it's starving for fuel.

[MMI Enterprises 289]

Have you tested that both cylinder are firing? Pulling either spark wire with insulated plier while running should show running difference.

Any word on a bowl drain or no? Is yer gas supply filtered?. If not, install one.

Is tank elevated to where yer gravity feeding the gas?...

Try to pull up an expanded view online somewhere of that carb so you know what's in there exactly. Some carbs have just a simple main jet/draw tube that you would want to be real careful not to damage on removal. They just brass and ya want to use proper screw driver to remove. Some primaries in certain carb applications are more complex using needle jets, needles from above that work off engine vac, as well as the screwed in tube. If designed as such you could accidentally pull the tube and the jet will remain inside due to the tension the gas creates around it. After few minutes of drying the jet will fall out and be lost. That said, I doubt these are such design. Probably like an old briggs with just a tube going up. If tube is not set all the way or it has a leaky seal you can have problems. There really isn't much to such simple carbs besides initial setting of the float followed by main mixture screw adjustment. If either is adjusted to compensate for the other along with a tinkered choke it will never run right.

Some carbs will have fuel mixture set at factory and a plug will be installed. If plug has been drilled or pryed out then you know it's been messed with before probably in hopes of solving some other undiagnosed problem. Seems the first thing tinkerers tend to mess with. These mixtures are usually for the slow jetting/idle only aside from the main jet. It get's what it wants by engine vacuum. Generally settings for such are between 1.5 and 3.5 turns out from all the way in...depends on carb or application though. Besides fuel mixture adjust, some carbs would have an air screw. Think those are for 2 cycles though.

So get a exploded view of the thing, clean carb, and then drum up the float clearance measurement and adjustment procedure for it. Usually that involves bending tab at the needle valve ever so slightly with needle nose plier.

..about all I got..good luck!

[Keoki 14]

Wow Kevin that was a lot of info... I am usually not afraid to pull stuff apart (sometimes I can actually put things back together w/o extra parts), and I only paid $300 for the PW. But I think you guys are right about the fuel, and even though the carb diagram looks fairly simple, I may just have to bite the bullet and look for a good engine shop. I would hate to really mess up the engine rather than pay a few bucks to get it done right. I am just a little apprehensive because the first shop I called, the person that answered made it sound like they don't work on PWs but then gave me a "probable" diagnosis and price ($250 valve job) when I gave them a brief description of what was going on. You guys have been a lot of help, Thanks. I will probably mess with it a little bit longer but I will let you guys know what the problem is as soon as I figure it out...

[Rick2 42]

One other thing you might want to try: Just as it starts to stall close the choke somewhat and see if that keeps it running. This will show you if it's a fuel starvation problem. Let us know how it turns out.

[Keoki 14]

When it starts to run rough(after a few minutes) it idles up and down but keeps running, when I pull the trigger it strains then dies. If I don't pull the trigger and close the choke it also dies. does that mean it is not getting the fuel?

[scottwash 14]

In your gas tank check to see if there is a fuel filter at the bottom. I have one in mine. Also run your gas line to a diffent tank. I had crap in mine and what happen was it was enough to fill the bowl. But not enough to keep it running so it would run for 3 or 4 min and die.

Change your oil, and check the low oil shut off wires. My honda says not to srew in the dip stick when checking oil.

Edited December 7, 2008 by scottwash

[Beth n Rod 1,279]

The symptoms sound like water in the gas tank to me but I have to rule that out since you said you drained the old gas and put in new. I could question whether that got it out or not but still a possibility.

Another possibility could be that the mix is set too lean. It runs for a few minutes then sputters out as you put it could be another indicator of this being the cause.

The last possibility is a bad float valve either sticking or being obstructed by lacquer build up. Run a gas treatment through it to help remove the buildup.

Rod!~

[RMedbery 26]

I think the consensus is a fuel problem. Take the carb off, completely disassemble it, clean it. Remove the fuel line, clean it. Remove the tank, check strainer, clean it. Its really simple and easy to do.

[MMI Enterprises 289]

If I don't pull the trigger and close the choke it also dies. does that mean it is not getting the fuel?

No..that just means you've cut air flow into an engine that is already warm enough to opperate without a rich mix. It should die when choked so do as everyone has said by cleaning it all up.

Hunting is usually a too rich mixture but your other symtoms when dieing show as lean. I really think your trying to run an engine that has had tinkering done to it in order to compensate for misadjustments elsewhere. See after main problem of low flow is found you may then end up really really rich as that is how someone adjusted it or how it's internal leaking past the main jet might present.

...clean carb,lines, filters....confirm good gas flow, adjust float, make sure main jet is seated and not leaking, adjust mixture, slap back together and fine tune.

Hey people, what a rebuild kit for that carb run..like 20 bucks or what?

Edited December 7, 2008 by MMI Enterprises

[Keoki 14]

Ok, so I found the fuel filter today and it was coated w/ 'varnish'... Thanks everyone for all of the great advice. I am sure you guy know this already but I am attaching a pic of the filter, the screene is in the top where I didn't see it. Thanks again.... Korey