Cranks but won't start, what to do next?

[TEH]

20 hp B&S twin, Husqvarna 46":

Enging started "surging" after a few minutes of running but could be smoothed out by adjusting the choke. When the blade was engaged engine would stop soon after, but would start back after a few minutes. After checking the gas pump (working fine), checked the carburetor. Disabled the solenoid on the carburetor. Engine started, ran for about 3 min. but stopped, and then would not start again. Does crank but doesn't "fire" at all...

1. changed oil/spark plugs
2. Replaced the carburetor (new solenoid switch included)
3. Used spark plug tester to check for spark (has spark)
4. coils ok (reset gap to fly-wheel)
5. fuel pump (ok)
6. valves (replaced broken gasket on one valve cover. Valves are ok)

Engine still cranks but does not fire at all. Is it possible that a broken head gasket would keep it from starting? It has compression, spark, fuel... at a total loss.

 

[ILENGINE]

So I would start with possibly bad fuel/ water Not much would effect both cylinders at the same time. Fuel, faulty engine ground or clogged air intake

the other explanation would be it has been running on one cylinder and the other one has now failed.

 

[TEH]

Thanks Ilengine, I will look into your suggestions. The fuel is new, so I'll investigate the engine ground and the possibility that the cylinders are bad.

 

[Tinkerer200]

You know it would help tons if you would give the engine model number when asking a question.

Walt Conner

 

[TEH]

You know it would help tons if you would give the engine model number when asking a question.

Walt Conner

44H777 E1

Here's what' I've discovered since first posting. I removed the cylinder heads and discovered that one had a severely bent rod. I replaced it, but still wouldn't start. I found that the gas pump isn't working, though it's new. I dripped some fuel down into the carburetor through the vent holes on top and the engine started with no problem, and ran about 10 seconds. Obviously gas isn't getting into the carburetor. The gas pump is not electric. It plugs into the valve cover of the same cylinder that had the bent rod. The valves move up down when the fly wheel turns. Does someone see the relationship between these things? Is it possible that the bent rod damaged the cylinder in some way that it isn't compressing and causing the gas pump not to draw gas?

 

[Tinkerer200]

The vacuum operated fuel pump works on crankcase vacuum. I don't see how a bent push rod affects that as it is dependent on the piston going up and down. Problem could be bad fuel pump, bad vacuum line between fuel pump & valve cover, failed crankcase vent valve (haven't heard of that with this engine), badly leaking valve cover gasket, bad fuel line, plugged gas tank outlet.

Walt Conner