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I have a 20hp Briggs on a craftsman LT1000 on that has an issue. Like clockwork it quits after 5-10 minutes of operation. Seems like it's starved for fuel but not sure.

Things I have checked and eliminated.
- Fuel tank vent
- Diodes in coil wires ( still quits after 10 mins with kill wires disconnected)
- fuel shut off solenoid (bypassed)
- fuel pump pulse line, pumps fine
- fuel filter
- air filter
- plugs
- runs fine on one coil with plug wire disconnected, don't think they are the problem
- carb fully cleaned and inspected
- all cooling fins cleaned
- crankcase vent replaced

Any ideas? This one is starting to stump me, I'm thinking of running a gravity tank to eliminate the entire fuel system, any issues with blocking the pump discharge when disconnected?

Thanks for any help!

Adjust the valves. if it is OHV.
Post the engine's model numbers.

rusty1778 said:

still quits after 10 mins with kill wires disconnected

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Time for new ignition coils.
If you've removed the kill wire, it should run till the tank is empty.

slomo

rusty1778 said:

all cooling fins cleaned

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Did I read this correctly? Let me get my glasses on..... Yup he cleaned the fins. BRAVO to you sir. First post I've read on this IMPORTANT subject. Guessing you cleaned the top of the engine block too not just the fins right?

slomo

slomo said:

Did I read this correctly? Let me get my glasses on..... Yup he cleaned the fins. BRAVO to you sir. First post I've read on this IMPORTANT subject. Guessing you cleaned the top of the engine block too not just the fins right?

slomo

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Yep, covers off, everything I could get to washed up.

Fish said:

Adjust the valves. if it is OHV.
Post the engine's model numbers.

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It's a Briggs and Stratton 407777 type number 0174-E1. Has overhead valves. Do you know the intake exhaust specs? are they set from TDC?

rusty1778 said:

Yep, covers off, everything I could get to washed up.

It's a Briggs and Stratton 407777 type number 0174-E1. Has overhead valves. Do you know the intake exhaust specs? are they set from TDC?

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Work you way down the page. Click on the 3 links below.

Specifically

slomo said:

Twin Cylinder OHV | PDF

Section 1 IGNITION is the process by which an electric motor is ignited. Section 2 CYLINDER HEAD and VALVES are the processes by which an electrical motor ignites. Section 3 ELECTRIC STARTER is the method by which a battery is ignited by an electric motor. Section 4 ELECTRONIC STARTER and...

www.scribd.com

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Thanks for all the info, I'm going to give the valves a shot.

Is it running proper now? Time for an update.

slomo

slomo said:

Is it running proper now? Time for an update.

slomo

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I hooked it up with a pony tank and it ran it dry, no issues. I removed the main fuel tank and replaced the line. Honestly couldn't find what the issue was. I haven't had it for a long run since switching back to the main tank. I've also since set the valves but they weren't bad, right side was maybe 2 thou loose. I'll check back if there is still a problem running it on the main tank.

rusty1778 said:

I hooked it up with a pony tank and it ran it dry, no issues. I removed the main fuel tank and replaced the line. Honestly couldn't find what the issue was. I haven't had it for a long run since switching back to the main tank. I've also since set the valves but they weren't bad, right side was maybe 2 thou loose. I'll check back if there is still a problem running it on the main tank.

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Grass clippings find their way into the tank.
Over time fuel replaces the water in the clippings which makes them transparent and almost the same density as the fuel so they float around in the fuel.
As fuel is drawn out of the discharge hole they get sucked into it blocking off the holes like hair in a shower drain.
As soon as you turn the mower off they float away so they can repeat this little trick on a regular basis & drive you mad.
Tank has to be allowed to dry fully then I use an long air duster to blow them all out , takes a lot longer than you would expect.

bertsmobile1 said:

Grass clippings find their way into the tank.
Over time fuel replaces the water in the clippings which makes them transparent and almost the same density as the fuel so they float around in the fuel.
As fuel is drawn out of the discharge hole they get sucked into it blocking off the holes like hair in a shower drain.
As soon as you turn the mower off they float away so they can repeat this little trick on a regular basis & drive you mad.
Tank has to be allowed to dry fully then I use an long air duster to blow them all out , takes a lot longer than you would expect.

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You may have been right on this, we removed the tank, emptied it and flushed it and blew it out. I replaced the fuel line as well. Never seen and obvious problem but it runs like a top for hours now. Thanks for all the help

I learned this the very hard way
The Landlord has 5 2000 series Cubs that we use to mow the pasture & orchards with
They were all bought 2nd ( or more ) hand and we spent a very long summer ripping into these engines & replacing all sorts of things
These are Horizontal engines so getting to the coils is a big job.
We changed the oil for heavier one twice , filters, fuel lines you name it , even thought of putting auxillary fan to get better air flow over the engine.
Turned out to be grass clippings in the fuel tank and the tanks are a PIA to remove
So now it is an annual job, take the rear guards off, clean around the hydro and clean the tank.