1985 CH150 - getting gas/spark... won't fire By dryshave (Read 893 times)

[dryshave]

I've had the engine apart, checked all tolerances, cleaned and honed. Double checked the timing and no issue there. I know the carb is getting gas and the float fills up properly, but it's clearly not getting any fuel through to fire.
I've cleaned the jets and soaked all components and air dried all parts and checking to the best of my ability all passages.
I've also sprayed quick fire into the cylinder and it still doesn't pop (used to before I started messing with the vacuum lines)
Vacuum lines appear to be correct (thanks alleyoop) and it is pulling gas from the tank properly.
It is getting spark when I pull the plug and check it.
I'm getting 4 ohms at the electric choke.
I've been working with two old carbs that were pretty gummed up when I got them. I've soaked all parts overnight in a carb cleaner and air cleaned them properly.
Does the air cut off valve have anything to do with the pressure required to move fuel in the carb?
Is it worth my time to order a complete carb kit and new jets? or just bite the bullet for a new carb.
Am I wasting my time by ordering a carb kit?

[Alleyoop]

Carb kits are a waste of time unless of course something is broken or missing. A Carb for a 150 can be had pretty cheap under $50.00 . The ACV has nothing to do with starting the motor it comes into play when you let go of the throttle when your cranking and by cutting off some air it gets more fuel at that point so it does not run lean with the butterfly closeing so quickly.

Here is the thing when you cleaned out the carb did you make sure the TINY holes by the butterfly were clear and when you sprayed into the PILOT JET spray came out of the Pilot Jet passages by the Butterfly?
Here is where spray should come out. The other item to make sure is clear is take the Fuel Ratio Screw completely out and spray in that hole as well Spray should also come out by the butterfly. Then screw it back in until it stops and then turn it counter clockwise 2 1/2 turns.
With 2 1/2 turns it is a starting point but with that the motor should idle and run.
Alleyoop




You can get a mush simplier carb I have had mine for 3 years now they work great and are easy to adjust and hook up, 1 Vacuum hose for the ACV and the fuel hose that is it going to the carb. On Ebay you can find them for under $40.00 just like mine
Alleyoop.

[Bashan]

Like Alley says carb kits are a waste of time. You get a jet that may or may not have a number, a sorry vacuum tube, a needle that probably won't fit, etc. If you tear your bowl gasket you can just cut out a new one. Buy a new carb rather than a kit if it comes to that.

I also agree with Alley it could be the pilot system, maybe the float valve too. You're getting the bowl to fill so the gas is getting that far, but then it stops or it's reduced. I'd check the float valve also. Here's some videos about the enricher. You can check it by removing it and hooking it up right to a 12v battery. It should extend about 3/16" in around 5 minutes. Here's a video from Big Guy on how to clean the carb. You can see how he does the float valve. Rich

[dryshave]

I'm watching the video and the first thing I've noticed was.... when he pulled the vacuum piston, the diaphragm itself was pretty tight. On both vacuum pistons I have access to... the diaphragms look a little bacon like, not torn... maybe a little tired? Back to the video

[Bashan]

That diaphragm has GOT to seal for the carb to work right. It could leak anywhere from it's seal down on the carb, to where the rubber meets the tube. Pull it and inspect it carefully, even a pin hole will do you in. You can order just a diaphragm instead of a whole kit if the rubber is brittle or it has a hole in it. It seems like someone on the forum found something that would seal up a pinhole but it would have to be gas resistant, always a problem. Permatex black might work. Rich