YotaWoRx

Alright everyone. I searched but could not come up with any good ideas. I have a 1991 3vze. After it sits for a while and I start it, it misses stumbles for a few seconds and then clears up and purrs like a kitten. Happens when cold or warm. Just came on acutely. I'm thinking I have a leaky injector that is enriching one of the cylinders with fuel while it's not running. Then when I start It it takes a few seconds to burn the excess fuel, hence it starts running fine. Any other ideas?

wrenchmonster

Could be an injector leaking down. Can you define "sits for a while"? Do you mean an hour, two hours, overnight?

Hate to say it, but it could also be a leaking head gasket.

Have you pulled the plugs for inspection?

YotaWoRx

Sits for a while means like a couple hours. I'm going to perform a cylinder leak down test and also check to see if there is any pressure in the fuel system a few hours after shutting down. I highly doubt it's a blown headgasket since I replaced them this last march.

YotaWoRx

Ok update. Hopefully this helps someone with a similar issue.i ran some techron injector cleaner through the system and my stumbling is gone. My theory is that one of my injectors was dirty, causing it to not fully close. That's why all my fuel pressure was gone after a few minutes of sitting. Techron is good stuff!

Gevo

You my friend are very fortunate you found that so easy. I tell you, after having taken everything out, all those air hoses, vacuum and coolant lines everywhere... Diagnosing a problem like this can be a pain in the ass..

scope103

One more question; did you have to crank it a bit before it fired? A leaky injector will take down the pressure in the rail; the fuel pump doesn't start until you turn the key, and I would expect slightly extended cranking to build up the fuel pressure.

YotaWoRx

Yes had to crank a bit more than usual. Also to point me in the right direction, I loosened the banjo fitting on the CSI after letting it sit a few minutes... Low and behold no fuel sprayed out=system was not holding pressure

scope103

Keep an eye on the fitting you loosened. The crush washers are one-time-use; but if it doesn't leak "for a while" you're probably okay.