Back fire???

[DJ'S MJ]

I have a 1989 jeep Comanche 4.0 which I have rebuilt the engine. It now has a slightly higher compression ratio, TBA bored to 58mm, Cold Air, and a Competition Cam. I have replaced the fuel filter, done the later open coolant system, and now it runs but when you get up to any speed it backfires? Anyone have any suggestions?

[Warren Mohler]

1 hour ago, DJ'S MJ said:

you get up to any speed it backfires

does it pop through the intake or out the exhaust?

[Eagle]

Have you put a timing light on it to check the timing?

 

[cruiser54]

Have you indexed the distributor?

Are all the grounds at the dipstick tube stud clean and shiny? Or painted over? 

[DJ'S MJ]

Thanks everyone. I was using a Fire Power Distributor and I think that was the problem. I bought a stock distributor and new coil. I will install them after the holidays and hope that cures the backfire. Again, thanks for your replies.

[cruiser54]

20 hours ago, DJ'S MJ said:

Thanks everyone. I was using a Fire Power Distributor and I think that was the problem. I bought a stock distributor and new coil. I will install them after the holidays and hope that cures the backfire. Again, thanks for your replies.

Make sure you index it properly.

[DJ'S MJ]

I have attempted to solve this backfire issue. Changed sensors, had a garage index the distributor, nothing has worked! I am done with this Renix system. I have a 0630 head, 1995 exhaust manifold, and 1999 inlet manifold. I am thinking about modifying the inlet manifold to accept the Sniper EFI 2 barrel, Sniper Management, and Distributor. My thinking is to strip our all the Renix and run with the Sniper EFI. What challenges will I have to face?

[cruiser54]

Keep us in the loop.

[cruiser54]

checked fuel pressure? 

[DJ'S MJ]

Yes. Now I have called it quits with the Renix and going Holley Sniper!