too much fuel or not enough spark?

[thompson1600]

I have been trying to get an 036 Pro going. Put a carb kit in and it just keeps spitting out too much fuel. I have fuel coming out the muffler and decomp valve when I pull it over.

I had to put on a new cylinder and piston because the prior owner had fried the piston on the exhaust side.

It has good pressure test, good vacuum test. Has spark, not sure how to tell if it's enough or not.

Carb has limiters on it. Took them off and turned them all the way down. It then didn't send any fuel obviously. Turned them back out 1 turn each and then it was spitting fuel again.

Any ideas what may be causing this?

Any suggestions on what to try?

Thanks

Tom

 

[Fish]

When you put in the kit, did you replace the inlet needle?

 

[thompson1600]

Yes I did.

 

[glens]

Did you put the metering diaphragm in right-side out and did you check the metering lever height?  How about pop-off pressure if those two items are okay?

Glen

 

[thompson1600]

yes on the first two questions, how would I check pop off pressure?

Tom

 

[thompson1600]

I got it running briefly. I took the plug out and drained the gas from the cylinder, quite a bit came out. Then completely closed off the carb and it ran off the gas in cylinder I am assuming, or else the carb was still pumping gas to it. Wouldn't idle but would stay running if I kept revving it slightly up from idle.

Tom

 

[glens]

There's an article <a href="http://www.aerocorsair.com/id28.htm" target="_blank">here</a> about setting the pop-off pressure.&nbsp; The page can be found via a link in <a href="http://www.aerocorsair.com/id27.htm" target="_blank">this page on carburetors</a> at the same site.

I would not think it would be a problem, however, unless somehow the metering lever, it's pivot, or spring, have been damaged, which is possible.

It could also be that you have a corroded bore for the inlet needle, causing it to stick, or a corroded seat...

Glen

 

[Fish]

You may have a piece of junk under the new needle tip.

Also you may have the gasket on the wrong side, it should go on
the carb first, then the diaphragm, then the cover.

 

[glens]

Oh, yeah.&nbsp; Simple things first...

 

[thompson1600]

OK, it is the carb. I got frustrated and took it all apart again. Put it back together and still had trouble. I flushed the carb out and then blew it with compressed air. Same problems.

Went to the dealer and got a new carb, saw started right off and ran like a charm.

Now to really tear into this carb and find out what's wrong if I can.

Tom

 

[thompson1600]

No, I didn't check the pressure yet, should have done that though. Didn't realize that was called pop off pressure. Will do that later tonight. I've seen where that was done in fluid to see leaks, have you tried that?

Tom

 

[cbfarmall]

I have had this happen on four separate saws and each time it was the needle. Sometimes I could clean it, sometimes replace it, never had to check the spring. Once the screw that held the lever axle down was gone but that only proves my point. That particular carb FILLED the crankcase. I mean, the gas tank was empty and it all went through the engine, while sitting.

I clean them with carb cleaner or brake cleaner. Not air.

Chris B.

 

[thompson1600]

I replaced the needle and it still did it.

You just sprayed brake cleaner into the hole and then let it dry? Any other tips?

Thanks

Tom

 

[jokers]

Sounds like you could have the metering diapragm and gasket reversed with one another. Have you checked this?

Russ

 

[thompson1600]

Yeah, I took it apart again and checked everything. Was on correctly. I'm gonna put it in a jar of carb cleaner for a couple days and see if it will dissolve whatever might be in there. Thanks for all the help. Any other suggestions, please let me know.

Tom

 

[Al Smith]

Metering lever

Just for a test,try lowering the metering level a tiny bit.I have found on a Tillotson Hl,this is critical.I assume the 036 has a Zama?

 

[Al Smith]

correction to my last

I meant to say a Tillotson Hs,but the same applies to all

 

[thompson1600]

It is a Zama C3A carb. I checked the lever with the Zama tool and it was at the proper clearance, have you found that a little lower is better? Does that make it run leaner or richer?

Tom

 

[glens]

Is there something special about this carb?&nbsp; You've already got more time invested in it than it's worth.&nbsp; It seems there is something mechanically/physically wrong with it.&nbsp; If the needle seat is okay and the needle is okay and the needle bore is okay and the lever and pivot and spring are okay and the diaphragm is okay and is installed okay and the HI and LO jets haven't been torqued to 100 ft-lbs and/or they and their seats are okay you're running real short of possibilities.&nbsp; Maybe Ripley's would like to hear about it?&nbsp; hahaha!

Glen

 

[Al Smith]

Metering lever

It doesn't do any thing to lean /rich mixture.In a way,you can look at it like the float level of an auto carb.Too low,it starves for fuel.Too high,and it floods.A very good website,for the explanation of how a diaphram carb works,is the one Tillotson has.Very informative.All diaphram carbs,work on the same basic priciple.In a way,they act very simalar to a mechanical fuel injector.If you go to that website,and study,pay heed to the impulse stroke,and you will see what I mean.This should explain the flooding.Good luck.