I dunno if there has been a post on this exact problem & couldn't find it anywhere so here goes nothing...
IAfter getting my car out of storage to do some work I have noticed it likes to backfire while either revving or moderate acceleration. Under slight accelerating no problem, but if I get in it at all it backfires & sounds like it goes down a few cylinders, then rebounds to finish revving or accelerating. I've changed the plugs but they keep fouling out. I tested my coil & module & they are both good. The spark plug wires have the right resistance so they're ok. Cap & rotor are almost brand new. While it was dark I popped the hood & saw no flashover anywhere, so that's all good.
I even tried to adjust the carb & it still acts up. I dunno if the carb is beyond adjusting as I'm not too sure it's not the original one or not.
What else should I be checking? I plan on checking the timing belt tomorrow to see if it's off a tooth & the ignition timing to see if it's out at all, but I'm puzzled none the less.
Any ideas ???
Oil or gas foul?
Sticking valve/ bad "lifter"?
Too much gas?
Vac. leak?
Spark timing off?
How was it running when parked?
Bill
depending on the type of carb: stuck power valve(economizer valve)
Mine does this when its cold. Once in a while it will do it while its warm. My carbs been rebuilt but i think it needs rebuilt again as ive have it apart a few times since the first time i put it together. A Carb kit is only about $20 and its easy to install. This assumes it has a 5200 Holley 2 Barrel on it, which is found on all the 4 cylinder models. The V6's have some other carb. Might try rebuilding the carb. :D
77turbopinto:
The plugs are carbon fouled out. I know it was running rich. that's why I adjusted the carb. The car was running like crap when I parked it. Almost got me wrecked as it was running so poorly. I didn't see any vac leaks but I'll double check that today. Don't think it's got a valve/ lifter problem but I'll dbl check that as well. As stated before I'm gonna check my timing today after work.
pintoguy76; I've got a rebuilt carb ready for it I just gotta get teh tank cleaned out before I put it on the car.
dirt track demon: My carb is a 5200 Holley. Where is the economiser valve at & is it part of the rebuild kit?
OK, here's the deal now. I installed the rebuilt carb on the car & noticed right away it was idling very high until it warmed up. Still when I would try to rev it would fall on its face & act like it's down a cylinder. I drove it around the block & had no power whatsoever. I did notice the carb I installed was different than the one I took off. The one I rebuilt has the bowl vent solenoid & a vacuum hose on the choke pull off when the old one did not. Could that be an economy version of the carb? I couldn't even get the air cleaner to fit on it so now I'm rebuilding the original carb. I did check the distributor & it has no shaft play so all is good there.
The problem's fixed. I rebuilt the original carb that came off the carb, replaced the fuel pump, & a few dry rotted hoses I found. That & while I was at it went ahead & replaced the bad sending unit float. Anyways, I revved the car & it was running 100% better, but the problem was still slightly there. I thought I might need to put gas in it since none came out when I removed the sending unit, & sure enough it started to die as I was pulling up the the pump.
Filled it up with gas & it was running like a champ. & what's best is I found out the problem myself. Not that I am complaining but it was frustrating not to get any answers. Yes it's good that I figured it out on my own, but a little help could have caused me more agrivation then needed.
I am now getting down from my soapbox.
5200's dont use the economiser valve, and no they dont come as part of most rebuild kits.
3 tries are better than none.
Well, the car is back to its old tricks. It is starting to act up again & I'm not too sure as to why. It seemed to start after I installed a nos egr valve I got off ebay. The old one was plugged up beyond belief & the diaphragm was shot so it was no good.
Out of curiosity could the enrichment screw have anything to do with this? I'm gonna check cam & ignition timing to make sure it didnt jump any but I'm pretty sure it's ok.
How many turns should the enrichment screw be in or out depending how you look at it? I'm pretty confused here. :wow: