So earlier today i noticed when i went to accelerate hard like maybe 1/4 to 1/2 throttle the engine would lose all power and start popping and backfiring through the carb. Sometimes it got so bad the car stalled out. But if i accelerated really slowly (grandma style) it would run fine. I did some research and what i'm thinking is a its a bad accelerator pump.

Its a E4mc quadrajet carb with 307 computer ect. ect.

With the engine off i looked into the carb while pulling the throttle and noticed the gas stream paused a couple times while i pulled the throttle.

Based on what i said do you guys think i'm on point bad accel pump? What else could cause this if not the accel pump?

thanks

 

Accel pump, or clogged jet, or maybe sticky check valve.

And now that that beast has passed inspection, why not put the right carb on it...
until next year .

- Eric

 

Backfiring through the carb usually means it's time to install a new timing chain.

 

Yes, but he said the backfiring was while depressing the gas pedal, and that the accel pump stream was intermittent, so I'd look to the pump first, timing after that.

- Eric

 

Well i'm gonna try to replace the accel pump today and see what happens.
Yeah i'd love to do that except i find it too much of a hassle to change the carb and dist. and have to do that every 2 years, i dont mind the computer controlled system as it gives me great gas mileage when its running right. Plus i need my cruise control (which atm doesnt work unfortunately)

If i was gonna swap carbs and do all that if anything i'd install a custom homemade junkyard sourced EFI system.

Thanks for the help

 

cars fixed new accel. pump fixed it

 

Well i spoke to soon it ran great the first drive then an hour later i drove it and its doing the same thing all over again. I tried replacing the carb with another e4mc carb and its the same thing. I even tried adjusting the timing that didnt work neither.

Anything else that would cause this problem? Doesnt seem to be the carb as far as i can see.

Also i noticed it doesnt really do it when the engines cold, it seems to start acting up when the motor warms up to operating temp.

 

Just did another test took it out for a drive on a cold engine and it ran fine got all my power back, can even do burn outs, even when it got up to 200 degrees it was still running good.

Could the temperature have something to do with it? It was about 75 - 80 degrees out today and it ran like crap. Its now 60 degrees and the car was running great. Should i try for a cold air intake setup to draw in more cold denser air?

 

WOOF!! WOOF!!!

I HATE when I'm barking up the wrong tree .

New information calls for a new diagnosis:
Your ignition module is bad.
Or maybe your coil.

I'd go with the module first, though.

A weak spark will also do exactly as you describe - it will fire through a low pressure charge, such as idle or coasting, but will misfire through a high pressure charge, such as uphill or full throttle. The car will run perfectly, so long as the critical pressure isn't reached, and then when it is, it will run like crap, and blow raw fuel out the tailpipe like a closed choke valve.

The modules are sensitive to temperature variations, so that's the most likely culprit, but sometimes coils can be, too (usually to 90° day type temperatures, though).

Sorry I steered you wrong the first time.

- Eric

 

Ok cool thanks for the info i'll pick up a new module tomorrow.

The module is the pick up that sits under the dist. rotor correct?

Dont sweat it I didnt drop no money into the car today except gas so its all good. i'm just thankfully you guys are hear to help in my time of need. I hope the module fixes it

 

Is this the module?

http://www.autozone.com/autozone/par..._300759_0_5133

 

That's a seven wire module - make sure you are looking up the year and model for the distributor you are using, since I know your car is made of a variety of years.

I believe that Advance can test your old module before you spend $40 - if so, then you have to heat it up for the test, to duplicate the in-car conditions that cause the failure. Get it good and hot - 250° is good. If you can heat it up (like with a hair dryer) while it is being tested, that's even better, because you'll see it start to fail. You can do this in the car, too - drive around with the engine cold, to be sure it runs well, then pull the distributor cap and heat up the module with a hair dryer, then try to run it again - if it behaves like crap, you know you've got the right part.

Don't forget to use the right heat sink paste under the module when you install the new one.

- Eric

 

Just posting to let you guys know the module fixed it I picked 1 up at the JY for 5 bucks and sure enough car runs perfect now, no more backfiring.

Thank you Eric for suggesting the ignition module, i thought it was a carb problem the whole time. If it wasn't for you guys i probably would of just broke down and bought a new carb which cost 500 new .

 

You're welcome!

Of course, I thought it was the carb at first, too.
The addition of the temperature information changed the picture, though.

Nothing like a $5 fix for what looks like a $500 problem ,

Glad you fixed it!

- Eric

 

I have an 83 Delta with the 307 and I seem to have a similar problem. It's not as severe though, I don't have backfiring. But I do notice slight hesitation when accelerating from a stop. Seems fine when the ambient temp is cooler and engine isn't hot, but once the engine heats up after sitting in traffic or a long drive, it becomes noticable. Especially in the warm weather. We had a warm day in NJ yesterday (about 75 degrees) and the hesitation came with it.
About a year ago, I replaced the original module and that seemed to reduce the hesitation. I installed an accel module and applied the paste under it. I also replaced the condenser assembly, the only thing that wasn't changed was the pickup coil. I was told the distributor had to be removed to do so.
Any thoughts on whats causing this?
Thanks

-Rob

 

All the same things we said to 84Olds apply here as well.

In general, more subtle problems are harder to diagnose, all other things being equal.

Bad module, bad coil, bad accelerator pump or check valve, mixture problem (jets, metering rods), bad spark plug wires, bad distributor cap.

You could try heating your distributor internals with a hair dryer to see if the problem is seated there.

In the old days, you could get a lot of information by hooking it up to a Sun machine, but those are few and far between now.

- Eric

 

Listen to Eric hes on point try replacing the cheap stuff first.

If you dont wanna spend lots of money for trial and error do as i did go hunting in the junkyard for a cheap module and coil. I got a module for 5 bucks and a almost brand new coil for 11 at the yard the other day.

The junkyards around me are loaded with olds powered cars now, mostly cutlasses and olds powered wagons and such, let me know i can give you directions or even take a trip with you if you want

And rob your in Jersey? Where at maybe i might be able to lend a hand if needed.

 

I'm up in North jersey, hudson county. Are you south Jersey? There's a junkyard up this way that I used to go to, big place and I always seemed to be able to find what I needed. Last time I was up there was 5 years ago when I got my Delta, the flywheel cover was missing and I found one there. However at that time, it looked like a lot of the older cars were gone and more and more plastic junk cars had arrived. I can only imagine what is there now, I'd like to go check it out again when I get a chance

 

Yeah i'd down in south Jersey Atlantic county. If your junkyard up their doesnt have anything i can suggest a couple places down here depending on if you dont mind a drive. These are all U-pull-it kind of places

1. Dirkes in mays landing on the blackhorse pike, very organized and has loads of 80's cutlass'es and they also have a 77 cutlass with a 350 w/ 3a heads and a 72 cutlass with a 350 w/ 7a heads and headers (if you got some extra cash maybe a 350 swap is up your alley i passed state inspection with my 350 combo)

2. Shortys in williamstown blackhorse pike, good prices very organized and very helpful staff,
these days they dont have many olds powered cars but sometimes they'll have what you need.

3.Friendship or friendly's (cant quite remember the name) its in tabernacle on new rd. i believe. they have atleast 5-7 80's olds delta 88's and 98's but the problem with this place is the guy is such a rip off artist (charged me 65 bucks for a grille) and if you try and haggle with him or tell him you can get a part at another place for cheaper, he'll just say go somewhere else then if you dont like his prices. guys a **** IMO. But unfortunately hes the only junkyard around here with delta 88's,

4. I cant remember the name of this yard but its in Berlin on berlin cross keys rd. they have quite a selection but not organized too well so you have to walk up and down the rows of cars, but i remember they had a couple cutlasses and a custom cruiser

Thats all i can think of ATM hope it helps some, Dirkes and shorty's are my favorites they have a big selection, and fair pricing