'92 Cavalier NEED HELP ASAP!

[demo_deven]

Hey guys, first off I have a 92 cavalier demo car. When I start it up cold, it runs perfectly. But whne it gets warmed up (needle around 1/4) it will idle fine but then when yu give it gas, it starts backfiring like theres no tomorrow and dying out. Once it is fully warmed up, it will barely run at idle! I have a marine tank in it, no fuel filter, I think the fuel pump was out of a early 90's sonata. I had the same tank in my 94 sunbird and it ran fine. Also in the fall the cavalier was running fine with the marine tank. I figure it might be the spark plugs / wires, distributor, or possiblty the head hasket is acting up? Well tell me what you think...because im stuck. Thanks in advance, Deven.

P.S. it is supposed to be in a derby THIS FRIDAY (June 1st) so I need help soon!

[demo_deven]

Gas is a month old, could possibly be old gas???

[jakegday]

well it doesnt sound anything like a "bad gas" problem, and gas lasts ALOT more then a month before going "bad"

[demo_deven]

Lol I figured it wasnt bad gas. Could it be that it is not getting enough gas then? Thats what I figure but it doesnt make any sense that it runs and revs fine when cold but bog / backfire when warm.

[OverAllComa]

It sounds more something with the emissions control system and how it mixes fuel and air, most likely.

However, if its a demo car, I'd say the first thing you might do is cut off the cat. If that sucker has gone bad it'd clog the exhaust, but possibly only after heating up.

After that, Idle Air Control sensor, clean your throttle body, check your plugs/wires, and consider replacing that fuel pump.

[z24forlife]

an over all tune could possibly fix that up....

[demo_deven]

Yeah, the exaust was already cut off lol. I was looking at the plugs today and they look like they need replacing. I usually do a tune up on all my cars before running them (i.e. oil change, plugs, wires, crank the idle up a bit, etc.) oh and we cant forget about the Lucas in the engine and tranny...that stuff is a miracle

[demo_deven]

BTW I took a drive into town today and saw a 97 Cavaqueer with a for sale sign in the window. I stopped to have a look at it and after talking to the owner about the price, I loaded it on the trailer for 100 bucks. So needless to say, I have 4 days to completly strip and modify this car lol. I'll get to the '92 next week. Thanks guys for all ur help so far

[Young Chuck D]

i had that problem before, its definitely your spark plugs, wires, or coils.

i'm 100% sure of this

[demo_deven]

Yeah, well I went to move the car out back today, and it started up fine and everything. I figured I may as well let it sit and see what happenes. I held the engine at 2,000-2,500 RPM for a cuple minutes until it got warmed up. No backfiring! I then let it sit at idle for 10 minutes, came back and reved it up to 4,000 and no missing or anything! Since I have the 97 almost done, ill just take that one to the derby. Next week i'll try the 92 again and see if it acts up. I will definatly replace the plugs and wires, because the worst thing is when you get the the derby and find out your car is running like a bag of dick! I'll keep you guys posted!

[demo_deven]

just a little update, I put the fuel cell in the '97 and it started doing the same thing! But for some reason, I took the negative wire for the fuel pump off while it was running and quickly put it back on and it ran fine ever since! So i'm going to run new wiring just in case lol.






Just a cuple before shots of the 97.

[jakegday]

420, nice