Fuel leaking into cylinders and crankcase

[Macster]

Has anyone had this problem?

I have a Weiand Intake (square Bore), Edelbrock 500 CFM (1406), standard stock mechanical fuel pump; pushing around 8 psi.

I plan on a fuel pressure regulator since Edelbrock claims pressure not to exceed 6 psi.

I am getting a new carb on warranty, but do not believe it is soley the carberator.

Any idea's????

[71meangreenc10]

From what I have heard, 8 is way too much and probably is your problem.

Smitty

[screamin_c10]

I would run a phenolic spacer under the carb as they will percolate like an old coffee maker if they get too hot leaking fuel into your engine after shutdown.

As mentioned earlier you need to drop that fuel pressure, Edelbrocks hate more than ~5.5 PSI and can dump fuel into your engine after you shutdown as well.

Also, check your float level on the new carb as they get bounced around pretty bad and can lose their setting. If the bowls are overflowing then you will have the same issue.

[Ole Greenie]

One last item I'd like to submit for consideration would be a cracked intake manifold.

[Macster]

Thanks for the inputs;
Had not heard of the phenolic spacer; good idea and theoary.

Cracked intake; did not think of that.

Correcting the fuel pressure with a fuel pressure regulator.

Thanks again!!

[screamin_c10]

Phenolic spacer is basically just a plastic spacer that insulates the carb from the intake heat. They come in several thicknesses from 1/4 to 2" thick.

[OhOneWS6]

Originally Posted by Ole Greenie

One last item I'd like to submit for consideration would be a cracked intake manifold.

There should not be raw fuel sitting in the intake. Even if it was cracked there would be nothing to leak.

I'm with the others on this one. Too much fuel pressure or float level. Float could either be trash in the needle and seat or improperly adjusted.

[Ole Greenie]

His first post mentioned that there was fuel getting into the crank case as well...so If the bottom of the plenum is cracked, it could allow seepage of fuel into the motor...right?

[OhOneWS6]

Originally Posted by Ole Greenie

His first post mentioned that there was fuel getting into the crank case as well...so If the bottom of the plenum is cracked, it could allow seepage of fuel into the motor...right?

Only if there is raw fuel to leak. There should only be fuel in the intake as vapor. If there is raw fuel, there is another issue.

Fuel in the crankcase is usually from flooding or from a bad mechanical fuel pump diaphragm.

EDIT: I was thinking he said electric pump. To the OP, You need to check that mechanical pump as well.

[Ole Greenie]

I had thought about the fuel pump as well but if he has more than ample fuel pressure, I would not suspect a mech. fuel pump diaghram failure.

However, if the carb being used is not designed for the pressure he is running, the fuel will not be atomized correctly or completely as it enters the plenum...too much fuel for the amount of air. Just some food for thought.

Over tightening of the carb mounting nuts have cracked a bunch of intakes.

[OhOneWS6]

Originally Posted by Ole Greenie

I had thought about the fuel pump as well but if he has more than ample fuel pressure, I would not suspect a mech. fuel pump diaghram failure.

However, if the carb being used is not designed for the pressure he is running, the fuel will not be atomized correctly or completely as it enters the plenum...too much fuel for the amount of air. Just some food for thought.

Over tightening of the carb mounting nuts have cracked a bunch of intakes.

Interesting thought. Good discussion for sure. I would think if the intake was cracked at a location between the runners and the crankcase it would smoke like crazy. Seems to me it would be more likely that oil would be sucked into the runners rather than fuel leaking into the crankcase.

What I have seen in the past from flooding issues, either because of too much fuel pressure or float level issue, is raw fuel entering the cylinders via the intake and washing by the rings into the crankcase.

One other issue to consider is a faulty fuel pressure gauge. 8 PSI seems kinds high for a stock mechanical pump.

I'm still putting my money an too much fuel pressure. Once he gets a regulator on it I bet the issue is resolved.

OP. Be sure to change the oil. You can wash the bearings out in no time with fuel in the oil.

[rbagley]

This is more for me than for you but isn't edelbrock 1406 a 600 CFM ?

[gonzo6869]

^ Yes the 1406 is a 600cfm