Help Me Please. Carb Issues?

[km2x]

Here is my situation.

Yesterday I went to install a crankcase ventilation kit. Engine was running great before this....

Installed the backing plate. Connected everything up and went to start the engine. It started slightly and then died. I cannot get the engine to start unless the throttle is advanced forward pretty far. If I back off the throttle the eingine will falter and shutdown. Also I seem to hear a sucking sound when it is running.

I did mess with the idle mixture quite a bit hoping that it would help. What is a good starting point?

So....THoughts.

Question is the throttle arm supposed to be very loose? Like almost no resisitence?

I am very frustrated that I had a good running engine and now I it runs very poorly and we are supposed to Race on Wed. Any help would be appreciated.

Thanks

Krister

[David Masury]

I think that you will find that you have an air leak between the carb and the new flat plate above it or between the flat plate and the manifold. Try replacing both gaskets and snugging them well and your problem should go away.

Some folks like to put a little sealant on the gaskets though it is not necessary.

David

[km2x]

Originally Posted by David Masury

I think that you will find that you have an air leak between the carb and the new flat plate above it or between the flat plate and the manifold. Try replacing both gaskets and snugging them well and your problem should go away.

Some folks like to put a little sealant on the gaskets though it is not necessary.

David

David,

I did snug it up pretty good. I don't have replacement gaskets do you think gasket selant would help the problem? What do you recommend?

Thanks.

Krister

[SEMIJim]

Originally Posted by km2x

Also I seem to hear a sucking sound when it is running.

Sounds to me like you have a vacuum leak. Below the area in the carburetor where the air and gasoline mix there has to be a vacuum--that's how the fuel/air mixture gets drawn into the intake manifold and, subsequently, into each cylinder (during its intake phase). Any air leak(s) below the carb throat(s) will result in reduced performance--for what should, by now, be obvious reasons.

Later, you write:

Originally Posted by km2x

I did snug it up pretty good. I don't have replacement gaskets ...

So, from this, I'm guessing we're talking about a PCV retrofit that adds a plate (to which the PCV hose connects) between the carburetor and engine intake manifold? Are you suggesting there are no gaskets between each piece?

Ok, I hate to ask this, but: You didn't have a "Duh moment" and forget to install the PCV valve, did you?

Jim

[km2x]

Thanks for the comments.

It wasn't a "duh" moment(Thanks goodness)

I started troubleshooting with my last option being to take off the carb and clean.

I noticed that the copper fittings from the fuel pump to the carb was flattened when I rebent to fit the new PCV valve. I replaced with some rubber fuel line and the problem seems to have remedied itself.

The sucking I heard was just the carb looking for fuel.

Thanks for all the advice.

Krister

[MikeB.330]

You should replace the rubber fuel line with the proper OEM brass tubing. Don sells them in the online store. If you used regular automotive fuel line, chances are it will fail and well, you know the rest of that story....

Mike

[km2x]

Thanks for the words of wisdom Mike.
Actually the rubber tubing was from Don's Store since it was for an inline polishing filter. He also sells marine grade tubing that is meant for going between the fuel pump and carb.

On another note: The problem is still not fixed. I ran the engine yesterday for about 15 minutes before it started experiencing the same problems again.

Sounds fuel starved and will not run until you have 1/2 or more throttle applied then when I throttle back the engine sounds really fuel starved.
I did drain about 2 Cups of fuel out of main passage plug via by activating the fuel pump.

The only other thing besides taking apart the carb would be that the drainage tube(scavenge tube?) seems to be leaking a bit after I bent it. Could that be a problem?
Another hint. When I took the carb off there seems to be a puddle of fuel in the bottom...Am I getting a rich rich rich mixture rather than fuel starve?

Krister