Vanguard 18HP Engine Won't Start

[getwilde]

I have a 94(?) Max IV with a B&S Vanguard 18hp engine (model 350447). I'm slowly learning about small engines with this machine, but have a long way to go. So thank you for your patience.

This summer (and previous winters) I've had it running fine. But with the recent cold weather, now it will not start. I've replaced the fuel filter. I've also pulled apart the carburetor and sprayed out the jets -- at least, as many as I could see without completely removing the carb from the engine block. I did notice that the carb body's cardboard gasket was "torn" in one place (it's not a "nick" -- there's no material missing -- but the layers of cardboard have separated in one place).

If I pour a bit of gas into the carburetor directly (down past the open choke valve), I can pull-start it and it will run solidly for several seconds until the gas burns off.

So, a few questions:
1. Is the damaged gasket the cause of my problem, or a red herring? (Seems like it might still provide a good seal when everything is bolted together tightly, but I dunno'. The rebuild kit that I've found costs over $200 because I have an old carb model)

2. Does the fact that the engine runs on "direct-fed gas" eliminate any carburetor-related issues?

3. Might it be a bad fuel pump, and if so, what part should I replace it with? (Right now its fitted with a square metallic "Minuki" pump, co-branded with the B&S diamond logo. I assume it's an original part. No model number that I can see.)

I've seen other threads here where people found issues with old/disintegrating fuel lines. And bad vents on their gas tank cap. I'll investigate those issues as well.

I have to hike a long distance, in the snow, carrying my tools, to get to my machine, so I'm hoping to collect some good troubleshooting tips and bring whatever parts I need before I make the long journey.

Thanks in advance.

[racerone3]

If at all possible, I would try to Run an "I.V." of gas directly to the carb inlet. I have an old lawn tractor gas tank mounted on a metal pole for this. If the engine ran ok off the IV, you would know that the issue was between the tank and carb. Fuel pump is a possibility. to check it, remove the line from the pump to the carb and crank the engine. fuel should spurt from the line. Clogged lines are also a possibility. remove the line at the pump and get the end of it lower than the tank. then blow into the fill hole and see if fuel is flowing freely out of the line. Try these and let us know what you find. Fule straight down the carb really only eliminates an ingnition or compression issue, doesn't really tell much about how the carb is working

[lt250rdude]

Also could be a fuel shutoff solenoid on the bowl of the carb which has a wire that needs 12v + to it to open up (if equipped).

[msafi65]

Ive had a lot of tractors and atv's that are used to plow snow run and die after a while with no fuel delivery. It's usually condensation in the pulse tube to the fuelpump freezing. Remove the pump and clear the line from the valve cover. With the engine cranking you should be able to feel a vacume and pressure pulses at the valve cover port. If you have good pulse and no fuel delivery the pump is probably bad. A 1/4 inch primer bulb like those used on outboard boats,installed near the fuel tank will bring you home. Helps to have someone to squeeze the bulb and supply fuel to the engine. Good luck

[tattooman]

Will the machine run with the choke on? If so, you might want to try seafoam in your gas. There is also seafoam deepcreep. Spray right into Carb as the motor is running with the choke on. May take most of the can! The needle that is operated by the float will get a buildup on it and will not seat right. The motor will not run if this is the case.(ethanol) seafoam can be purchased at autozoan. I have had the exact problem. I do not run gas with ethanol. I pay more for it, but a lot less headache!

[getwilde]

Thank you for the prompt and extremely helpful responses. I will check all of these things you guys have mentioned, and report back.

@racerone3: Thanks for the ideas on checking pump and clogged lines. I'll start there.

@lt250rdude: I don't think this carb has a fuel shut-off solenoid. But I'm looking at the parts manual, and do see it listed as an option. So I'll have to look at mine again. What am I looking for... just a wire coming out of the carb somewhere? Where would the other end of that wire terminate?

@msafi65: Heh, I never would have considered condensation in the pulse tube. Thank you! I'll try your suggestions.

@tattooman: Right now, even with the choke on, it won't stay running. But I'll try some seafoam anyway.

Incidentally, I found this article that suggests fuel pumps should be rebuilt/replaced every couple of years...?
http://www.800-airwolf.com/pdffiles/.../part%2053.PDF Dunno' if that's true or not, but I'm pretty sure the fuel pump I have is the same one that was on there in '94. Here's a photo:
IMAG0154.jpg

Even if the pump hasn't gone bad yet, I'm willing to rebuild or replace it. But, where can I find a replacement? One that uses the same mount holes? (I've seen other threads about using a electric fuel pump but I think I'd prefer to stick with the pulse type.)

Thank you again.

[getwilde]

I had time this weekend to work on my machine. I tried the many suggestions above. I also checked to make sure all my line connections are tight. And I replaced the short, stiff impulse hose (just to be safe) and verified that I'm getting a positive/negative pulse there. I also tried running with fuel cap off (to rule out a blocked vent). It indeed appears to be the fuel pump that is failing. The Muniki fuel pump I have on there is likely original, which means its 17 years old! (Perhaps the previous owner rebuilt it at some point, but I doubt it.)

From my research, it looks like I have pump model #491922, which has been replaced by a plastic, round model 808656 (which I can pick up for around $25).

Or it looks like I can buy a new aluminum, square, aftermarket pump for about twice the price of a plastic one... 22-10876-H2 - Fuel Pump replaces B&S 491922 | MFG Supply

Or I can rebuild my current one for $17. 22-8674 - Fuel Pump Gasket Kit For Mikuni | MFG Supply

Any opinions on this? Will the round plastic pump fit my existing recessed mount, and is it durable? Or am I better off rebuilding?

Thanks

[lewis]

Just a suggestion. The fuel pump bracket looks standard but you can not tell dimensions on a picture. Just take it off and go to the lawn mower shop and try one(New Pump) for fit. You will probably find they are the same.

[msafi65]

I use pumps from Tulsa Engine Whse. #22-1009 or 22-1019 for the metal body or 22-1012 for the plastic ones. Ive found that the plastic body pumps on briggs and kohler are more prone to leaking fuel out the vent hole. Have you tried to fill the carb bowl throught the inlet line with a squeeze bottle? I sounds like fuel pump failure but it should run if gravity feed fuel. I got home once with a five gallon can on top of a roll cage to feed fuel to the engine. good luck