So I had posted a topic a while ago about how I'm kisfiring around 3-5k and then under full boost feel like I'm running on 3 cylinders. What I failed to mention is I had a shop put in a AEM 320 fuel pump and they didn't direct battery wire it. They just used the stock wiring and I didn't think much because it was running like a champ for a week or more. Then it started misfiring. Can that be my problem? I already changed spark plugs and they seemed fine, and my injector cables are good too. So is it as simple as doing a direct battery wiring?

 

How much boost are you running? I ran 14.5 psi through the factory wiring on my FB340 for over a year; even ran it on e85 for some time. My IDC did drop after I wired it directly to the battery, but on pump gas it did ok...
Can you monitor your fuel pressure?

 

Running 18psi on e85. And no I don't have a way. But before this fuel pump my other one was direct wired and it didn't have this problem.

 

I think you should always rewire a fuel pump if you upgrade. Its only an hour worth of work. Might or might not be the problem.

 

Did you gap your spark plugs down? Mine was misfiring on the dyno until they were gapped down. They were gapped down to .025 at the time, but .018 felt better. I run e85 too.

 

not sure the amperage... but anything over 13 amps i believe should have upgraded wiring. Id check the gap on the plugs before you rewire the Fuel Pump.

 

I already gapped mine to .20 and still am having the problem.

 

Anyone?

 

Did you end up rewiring the fuel pump? I think you'd be okay on pump gas but I'm sure there would be added strain on the pump for E85

 

I haven't yet. I don't get back in town until next week and the SOS wiring kit is waiting for me when I'm back. I just want to see if you all think that's what the problem is. Because in a different thread someone said that they replaced their fuel pump and had the same problem then direct wired it and it went away