Hey guys, what would cause a loud backfire at WOT? It sounds like a loud fire cracker. Kinda scary actually. I notice it when my cutout is open. I did install a walbro 450 and I haven't had it tuned yet. Could that be making it a tad rich?

 

is it back firing when then truck shifts or still accelerating?

 

Good question. Not sure really. Very well could be when it shifts though.

 

New fuel pump, no tune, no wideband I'm assuming.

Just stop now before you blow the motor. Park it until it's tuned.

 

What year?

 

If it does it on the shifts, it can be the TQ MGNT reducing the timing down.
You will really notice that with the cut out open.

The fuel pump shouldn't matter, as long as your fuel pressure has stayed the same.

 

If it's a returnless system then with a 450 pump his pressure will be higher as it will overpower the stock regulator.

 

Its untuned, stop driving it before you hurt the motor.... Why would you go WOT with a force inducted untuned? Im surprised if it didn't hurt its self already.

 

If it's forced induction ( missed that part) then STOP. What is your setup and what was changed besides the pump.

 

Guys, the only thing thats changed since the last tune was the fuel pump. Its still returnless and running off the stock fuel pressure regulator, pressure relief valve and fuel filter. There are a few other members on here that have installed this pump and it ran fine without a tune. Besides, its a variable voltage pump. I would assume if the pressure was too high the FPR would lower the voltage. Truck is turbo by the way and it will be getting tuned once the new intake goes on. Truck will also not see anymore boost until it gets retuned. And the plugs look fine. But this is my dd.