5.7 gxi-e backfiring

[jbauman102]

I have a 2004 Volvo penta 5.7 GXI-E and when I first start it backfires and makes a popping noise out of the throttle body for about 30 to 45 minutes while cruising. It eventually clears out and runs smooth any suggestion on what is causing that. I run non ethanol gas. I have new plugs, wires, cap and rotor. Fuel/Water seperator is about 6 months old.

 

[alldodge]

You either have an intake valve which is not closing, or your out of time. My first guess is your out of time.

 

[jbauman102]

If it was out of time wouldnt it not clear up after a while?

 

[Maclin]

Dump contents of filter into glass container and inspect. Could have some kind of fuel contamination.

Fuel injector may be clogged or otherwise compromised, maybe from the fuel contamination.

Could be an intake valve problem. Do a compression check then a leakdown test on any cylinder(s) show lower than the others. Though it seems that would not clear up after warming, I have had a vicarious experience many years ago like that through a friend's engine, early 70's 307 Chevy. It sounded like a tractor motor for about 10 minutes or so, was a head problem.

 

[Dave-R]

Any chance that you might have moved the distributor when pulling plug wires? Also are the plugs the right ones? If you just had this problem after changing the cap, rotor, wires ect. I would make double sure the firing order, and the distributor wiring to the plugs is correct. Just a thought, is there any chance you might have a low battery or bad connections when first starting? Intermittent problems are the hardest to find. I would check everything including ignition switch screws, kill switch, and the fuses and relay sockets. Good luck Dave-R