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Hi All,
I've got a 98 or 99 Craftsman 42" with a B/S 42E707 twin cylinder with L-Heads and a vacuum fuel pump carb that will only start if I prime the carb directly. It will run until that fuel is consumed then die again. I've removed the air filter and looked to insure the jet is spraying and it is. Clearly the plugs and timing are good because it runs. This happened the last time I tried to use the mower which was 3-4 months ago and after I disassembled and inspected the carb and it checked out ok I adjusted the idle screw on the carb and it worked but that's not getting it running this time. Any and all help will be appreciated. If this is a duplicate post I apologize and would welcome a link with a fix. Thanks in advance.

On the bottom side of the carb should be a plug that can be removed with a 5/8" wrench, take it out and watch the hole as someone cranks the engine, liquid should pulse out of it, look and see if it has water in it. In that hole is the main jet, remove it with an allen head wrench, 3/16"
I believe, and blow the crud out of it, reinstall and see if the engine will run.

Thank you for your quick response. I pulled the plug and it DID smell more like stagnant water than fuel so I pulled the jet and it was clean as a whistle. Reinstalled the jet and verified fuel shot out and it did so I shot some fuel and shook the water out until it smelled like pure fuel again but the problem still persists. Any more thoughts?

You will still have water in there. Drain your tank, change the fuel filter, take the top of the carb off, [easy to do], leave the front fuel pump alone. You will likely tear the top gasket, so take the top with you to the mower shop to get the correct one.
While the top is off, dry out and clean with clean rag.

Ok crap what a bummer thanks for your help will update when it's done.

Take out all the old fuel, clean out the tank and fuel lines, then check to see if the fuel PUMP is delivering fuel, you may need to service the PUMP. make sure you have fuel going into and out of the pump and then check and make sure you have it going into the carb. photos should help you see what you are looking for.

That is why I request that they crank the engine with the carb plug out, if fuel comes pulsing out, then the fuel pump is pumping.

A first timer going through the fuel pump never seems to go too well, so I have them avoid it if possible.

Hi EngineMan thank you for joining in to help. I appreciate your advice and feel a brief moment of back story is in order. The only only reason I seemed upset by the diagnosis Fish gave is b/c it involved purchasing parts. This mower has already cost WAY too much. I'm completely comfortable with any maintenance required because I'm a helicopter mechanic. I've already disassembled/inspected/and reassembled the fuel pump the last time this happened. The main reason I'm in this predicament is because I have no clue how to trouble shoot this issue because helicopters typically don't have carbs and that's really my weak point. The jet is pumping I can see it delivering the fuel while I'm turning it over which is why I was so confused by this issue. Fuel/Air/Spark and I seemed to have all 3. Fish's Diagnosis of there being water in there seems solid because like I said I smelled water behind the carb plug not fuel. I have already drained and disconnected everything to let it all dry out. Please don't think I'm arrogant or ungrateful I really do appreciate and need the help on this lil bastard engine I just wanted you guys to know that I've turned a wrench or 2

Does it have a fuel solenoid because you say "will only start if I prime the carb directly." and also you say that you have given the fuel pump a service and the carb, and yet you still don't have fuel where you need it, in the float bowl.

Check delivery of fuel from pump again, and the float and needle valve in carb. Are you 100% sure that you cleaned out the carb...? and that it is functioning the way it should be..!

More information Disassembly, Cleaning and Repair of Briggs and Stratton Opposed Twin-Cylinder Carburetor - Part 1 I had one apart on a snapper YT earlier this year, if you take the fuel pump apart be careful with the little springs. Is the choke linkage closing the choke all the way, mine had to be primed and would only run on choke when I got it.
Cannon

There was fuel or should i say water in the float bowl. But all is well let her dry out for a few days primed the fuel bowl and fuel line and she fired right up and ran strong. The only question I have left is did the water get in the fuel system from condensation and me not running it for a while or do you think the top of my tank may have a leak. Thanks again for all your help. I feel silly thinking this was a mechanical failure and it was something so simple as watered down fuel.

I am sure some of it was condensation, other, just water in the gas.

And never leave a half full can (tank) out in the sun....!:thumbsup:

This sounds exactly like what's happening with my 42" Craftsman with the same engine. I will have to see if I can find the fuel tank drain tomorrow. That will be fun, the way the tank is ensconced in the rear frame. I'm guessing with all the rain we had recently, and it sat outside, probably some water got in the tank. If that's all it is, hopefully draining the water out of the tank will do the trick.

Very rare to get water entering via the tank.
Condensation is the most common and of course water entering via the air filter when the mower is left in the rain.
A fuel tank should always be left either empty or full.
Over time a lot of water builds up in fuel cans which unless you have a water trap funnel will end up in the fuel tank.

bertsmobile1 said:

Very rare to get water entering via the tank.
Condensation is the most common and of course water entering via the air filter when the mower is left in the rain.
A fuel tank should always be left either empty or full.
Over time a lot of water builds up in fuel cans which unless you have a water trap funnel will end up in the fuel tank.

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Thanks, Bert. I got mine going after a while.

Just had to choke it a lot. Finally got it going good. I think it got swamped in the heavy rain storm we had here, and water must have gotten into the air cleaner area. I've got it tarped now.