If the engine is running too rich it would cause performance issues, but you'd probably smell that in the exhaust. Your fuel pressure regulator should still be able to deal with that though. Curious as to why you changed the pump?

 

 

Check the fuel pressure at idle, should be 28-30, and with the vacuum disconnected from the fuel pressure regulator it should be 38-40. The PCM will still adjust the fuel trims to compensate, but if it's too far out of whack it won't be able to adjust for it.

 

 

What year truck is it? It might not have a port.

 

Voltage rating of fuel pumps?

My 48 gph pump is rated at 12vdc.
I probably see 13 VDC so it' pushing more than 48 gph. Probably closer to 52 gph.

If yours is rated at 12vdc you are pushing more than 60 gph.

I am not sure at what point the stock fpr will over run but I suspect your new pump is not working right.

 

Does that change the working pressure on the output side of the pump, or is it just capable of more flow?

 

I'm not really sure....I assume the fpr regulates the pressure. Unless the pump is so big it over runs the fpr. In that case I guess pressure and flow go up.

So, pressures are regulated via fpr. If fpr is too small it will be over run and pressure will increase.

flow is kinda irrelevant if fpr can do its job, on my return style system anyhow. Any flow not used goes back to tank....

Saying this IMPLIES the return line is not the limiting issue. It should be capable of returnng all fuel the motor does not need, without increasing fuel pressure do to being too small.

I assume the pressure between tank and fuel pressure regulator is higher with a bigger pump and flow past fpr is more ........up until the fpr is over run.

 

In this case GPH does not directly translate to higher pressure since our trucks have a return line. Any extra flow not used by the injectors just gets returned to the tank. As long as it's within range, the FPR should still be able to compensate.