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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?

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.

bertsmobile1 said:

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.

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

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...

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..

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

Scrubcadet10 said:

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..

Click to expand...

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?

cpurvis said:

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

Click to expand...

It goes directly into the intake side of the carburetor.

.........

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

cpurvis said:

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

Click to expand...

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

rebeltaz said:

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

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

cpurvis said:

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

Click to expand...

Hey... I was thinking. Before I put this back together... if that does fix the problem, what would the cause be? The only thing that I can think would be if compression was leaking past the rings. If that were the case, I shouldn't have such high compression (150psi), would I?

150 is about right.
I have a 1 cylinder 9 Horse engine with a spec of 176 psi.

Scrubcadet10 said:

150 is about right.
I have a 1 cylinder 9 Horse engine with a spec of 176 psi.

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Scrubcadet- Does the 9 horse have a lot of carbon in combustion area, including piston top ?

rebeltaz said:

Hey... I was thinking. Before I put this back together... if that does fix the problem, what would the cause be? The only thing that I can think would be if compression was leaking past the rings. If that were the case, I shouldn't have such high compression (150psi), would I?

Click to expand...

It can get in the crankcase through a worn exhaust valve guide.

7394 said:

Scrubcadet- Does the 9 horse have a lot of carbon in combustion area, including piston top ?

Click to expand...

Lol! That's the spec in the manual for the Kawasaki Fe 290
But I mis typed,it's 160.

10-4..

cpurvis said:

It can get in the crankcase through a worn exhaust valve guide.

Click to expand...

OK... so I put everything back together, disconnected the crankcase ventilation hose and started it back up. Still got the gas spraying out the intake and running way rich.

You've checked that the cam timing is correct, and that the compression release is working as it should?

cpurvis said:

You've checked that the cam timing is correct, and that the compression release is working as it should?

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I have checked the cam timing. There's a photo earlier in this thread that I took of that. The compression release, no... to look at that, I'm going to have to pull the camshaft out to see it. I did inject air into the cylinders, though, and I couldn't hear any leaks with the valves closed and the piston at top dead center.

rebeltaz said:

I have checked the cam timing. There's a photo earlier in this thread that I took of that. The compression release, no... to look at that, I'm going to have to pull the camshaft out to see it. I did inject air into the cylinders, though, and I couldn't hear any leaks with the valves closed and the piston at top dead center.

Click to expand...

I don't think that's a valid check of the compression release but I'm not familiar with your engine. There wouldn't be much point in a compression release still being open at TDC.

cpurvis said:

I don't think that's a valid check of the compression release but I'm not familiar with your engine. There wouldn't be much point in a compression release still being open at TDC.

Click to expand...

Back to the workbench I'll pull it back down and pull that cam out.

Did u ever resolve this issue? I’m having the same thing happen

Did you by chance check the lift of the cam to see if the valves are opening as they should.

This would indicate a worn out cam

Might not get a response, that member has not been here since Nov 5, 2019.