Engine Spitting Fuel Through Intake

[rebeltaz]

I had a zero turn come into the shop. The guy said that they had had the engine "rebuilt" and since then no one could get it running. I finally got it running - it had a lot of electrical issues - but once I did, it wasn't running right. Without the air breather installed it runs OK, but it is spitting fuel out through the carburetor. A lot of fuel. When you re-install the air breather, the engine runs bogs down and and runs rough.

I checked the carburetor. The float is not adjustable. The carb is clean and the needle and seat are functioning properly.

I checked compression and both cylinders are running at 150 psi.

I still want to think that it's a leaky intake valve - or one that isn't seating right - but with the compression so high....

I don't own a leak-down tester. I was thinking about getting one, but I was wondering if I couldn't just attach a compressor to the cylinder? I'd really only need to listen for leaking air, not necessarily read a gauge.

Any thoughts?

 

[bertsmobile1]

As it has just been "rebuilt" and by the sounds of it quite badly, I would suspect the cam being out of time.
Remove the air filter & any air horn then secure the carb.
Put your pinky in front of the carb and run the engine.
If the exhausted gas feels hot then suspect that the cam is 1 tooth advanced
If it is cold then suspect cam 1 tooth retarded.

If there is a lot of venting from the breather check that it is only blowing & not sucking
If sucking as well then reed valve is bad if only blowing then probably a blown head gasket.

 

[rebeltaz]

As it has just been "rebuilt" and by the sounds of it quite badly, I would suspect the cam being out of time.
Remove the air filter & any air horn then secure the carb.
Put your pinky in front of the carb and run the engine.
If the exhausted gas feels hot then suspect that the cam is 1 tooth advanced
If it is cold then suspect cam 1 tooth retarded.

If there is a lot of venting from the breather check that it is only blowing & not sucking
If sucking as well then reed valve is bad if only blowing then probably a blown head gasket.

The guy is trying to decide whether he wants me to go any further, but I will check that cam gear. Thank you!

 

[rebeltaz]

Just an update... The cam is in time. I also rotated the pistons to top-dead-center with both valves closed and injected air into the cylinders. There is no air leaking anywhere... I am stuck...

 

[Scrubcadet10]

I just wonder if something is up with compression release on the camshaft
If it releases on the intake valve it might blow fuel back...

Just an uneducated guess..

 

[cpurvis]

Where does the crankcase vent system re-enter the intake?

 

[rebeltaz]

I just wonder if something is up with compression release on the camshaft
If it releases on the intake valve it might blow fuel back...

Just an uneducated guess..

I'm going to have to disassemble quite a bit to get to that, but before I do, if that were the case, wouldn't I hear leaking when I pressurize the cylinder?

Where does the crankcase vent system re-enter the intake?

It goes directly into the intake side of the carburetor.

.........

 

[cpurvis]

If you can, disconnect the EGR hose start the engine and see if that makes the problem go away.

 

[rebeltaz]

If you can, disconnect the EGR hose start the engine and see if that makes the problem go away.

I'll put it back together Monday and let you know.

 

[Scrubcadet10]

I'm going to have to disassemble quite a bit to get to that, but before I do, if that were the case, wouldn't I hear leaking when I pressurize the cylinder?



It goes directly into the intake side of the carburetor.

View attachment 45996 ......... View attachment 45997

Ahh, yes you would hear it leaking....