: fuel delievery problem



Boostn
05-11-04, 12:55 PM
Hello,

I have a 1970 Cadillac Deville Convertible. I have been having problems with fuel delievery. Whats happening is that it won't fire up but crank over. If I put in some gas in the carb, it would fire up and then catch on and stay running. However if I let it sit overnight, it won't fire up.

I suspect that the vacuum on the carb might be bad. Would I be correct? If so, anyone know what is the name of that rubber thing? or part number so I can ask the parts store for a new one.

Thanks! :)

Angela Desmond
05-11-04, 06:15 PM
Sounds more like the plugs at the bottom of the carb are leaking. Q-Jets are notorious for that. With the air cleaner off, have someone step on the gas pedal, or move the linkage yourself, while looking down the carb to see if you get the shot of gas from the accelerator pump. Do it in the morning when the problem happens, with the engine off, of course.If there's no shot of gas, the plugs under the carb are probably leaking and there's no gas left in the float bowl by morning.If that is the problem, you'll have to remove the carb and have someone epoxy the plugs and, preferably, rebuild the carb. If you do see shots of fuel when testing then that's not the problem. But I'd check that first.By the way, never look down the carb while it's running. Backfires happen at the darndest times :holycrap:

wojtekj
05-29-04, 05:41 AM
Hi,

I have a 1967 deville with the same problem as Boostn. I can start it up in the morning after 2 long cranks (each about 25sec long while pumping gas pedal):banghead: Would those two cars have the same carbs?
Can you explain in a little details the location of the air cleaner and the linkage - I am unexperienced with the carbs. I appreciate your help.

Angela Desmond
05-29-04, 09:28 AM
it's a little difficult to descibe these things without pictures, so I recommened getting a book on Rochester Q-Jets, such as the Haynes Rochester manual. Everything will then be explained in detail including rebuilding and power modifications. They are tricky carbs to tune, not simple like the Carters and the hi-po version of carters that Edelbrock puts out under the name "Performer Series". There are other books besides the Haynes manual that are also good books.BTW wojtekj , your aircleaner is the big round black thing on top of the engine held down with a wing nut. You can't miss it....P.S. Try this site http://www.corvettefaq.com/redir.asp?site=215

jk1000
05-29-04, 07:46 PM
If pumping gas pedal while cranking gets it started, your problem may be the choke not completely closing when cold. Check and thoroughly clean choke linkage and fast idle cam.

davesdeville
05-30-04, 12:56 AM
While the choke might be a problem, these symptoms are exactly what my QJet had before I resealed the plugs. I'd be willing to bet money on it.