I just got this car after it sat for 4 years. I flushed the tank, replaced the fuel pump, fuel filter, plugs and points thing in the distributor. I got it running with plenty of fuel pressure but anytime i try to hit the throttle it backfires through the intake. If I slowly press the throttle it gains RPM but then same problem when I try to hit the throttle again. It has a very minor misfire that is inconsistent also. Anyone have any ideas???
Thanks all

 

Sounds like your running lean, most likely the timing is off.

 

Thanks for the reply. I did adjust the timing quite a bit. I don't have a light but in the field of adjustment, the more I retarded it the better it got but it never went away. The backfire got replaced by hesitation and shutdown. It also idles very high unless I retard the hell out of it and then it just runs bad. I'm totally lost. I want my 383 in it now!!! lol

 

Welcome to ZDriver!

Did you check all the basics? Spark plugs? (what do the tips look like?), AFM? TPS? Coolant temp sensor? Vacuum leaks?

 

I replaced the plugs but I dont know how to check the coolant sensors or afm. It shows that the car is cycling properly on the heating and cooling. i checked the TPS visually and the cover was off and the little wires are bent so im assuming its bad. How can I go about checking the afm? Thanks for all this help so far guys! This is great! Im new to the whole forum thing =)

 

I just finish working on my with the same issues. i had a fuel pressure regulator that was bad and it was sucking gas thru the vacuum line. It was causing my car to idle with a miss and running rich. Try this first.

Jesse

 

i have the same problem did full tune up fuel pump fuel pressure is good i noticed though when i took off the afm cover it wasnt moving along with the throttle so im assuming its the afm but lowest cost i can find is 300 take the cover off and see if the gauge moves with the throttle but i thinbk we have same prolblem

 

If you think it is running lean and it has proper fuel pressure. You can pry the cover off the AFM and increase throttle until it starts to cutout, then rotate the AFM counter weight to open the flap further. this should increase fuel delivery unless the injectors are clogged. If it runs better your AFM sprinf might be worn and need adjusted.

 

I had this happen to me back in '89 on my 76 Z. I had replaced the intake mani gasket & didn't notice that it was for carb'd not EFI. There were no notches for the injectors to squirt & fuel would just drip in.. I could hold a rag in the intake & rev it with my other hand and it was smooth, remove the rag and it would backfire. I drove it for a day and had to accelerate slowly from a stop. It was hard to start too. The next morning I took the gasket off and found the problem.