aftermarket fuel pump

[svairman]

I've read some past threads and been searching a bit but haven't found anything conclusive or anything that has been followed up on. Is it possible to bypass the FPCU and run an aftermarket pump with with the same flowrate? I figure you'd want to use a pump with the same rate of flow as the highest setting, wire it in using a relay and figure out a way to securely mounting it in the take keeping the location as close to factory as possible using a similar style strainer. My only concern is with the pump running at full pressure all the time instead of the three setting like the stock, that at idle and partial throttle the fuel map will be two rich. I'm basing that assumption on the idea that the pump runs at a lower rate while at those two conditions. Is this correct and has anyone else successfully tried this?


I'd probably go with a walbro unit, I know they're less expensive but I've used them before in the past on both my turbo charges LS and lightly modified SR with no difficulties or reliability issues.

[dana0330]

It should work the fuel pressure is also regulated by the vacuum fuel pressure regulators at the fuel rail. Most cars of that age have the pumps on at full speed. and the regulator makes the pressure go up under a load.

[svairman]

It should work the fuel pressure is also regulated by the vacuum fuel pressure regulators at the fuel rail. Most cars of that age have the pumps on at full speed. and the regulator makes the pressure go up under a load.

Then what exactly is the function of the three step controller? I think if I understood it better I'd be able to answer some more of my questions on my own. I'd use my FSM if I could but unfortunately it didn't come with the car when I bought it, and I've looked through the didn't see much in the EF&EC section, and saw nothing in the EL section. I need to go through the whole thing more thoroughly.

[Q45tech]

High speed [wide open] fuel pumps really heat the gasoline up higher and faster in summer..............no use sending 20 gallons of fuel thru engine comparment every 20 minutes..........when you can cruise thru at low speed exposing only 1/10th as much to 176F heat.

Primarily a pump wear thing as high speed may reduce operating life by 4 times depending on fuel brand lubricity.

[dana0330]

Most of the earily fuel injected cars have a return line for the fuel system and all the pressure is regulated on the return sied by the vacuum controled regulator Infinity may have put the controler in to modulate the ground out put to the pump so it will not run on full speed all the time to extend the life of the pump like most of the newer fuel systems witch use a returnless system they do what is called duty cycle the ground it is never constant to run the pump. That being said if you put a external pump in you are using a pump that is designed to run all the time and the fuel demand should be controled bu the regulator. If you want to check if the regulator in the Q45 boosts fuel pressure put a fuel pressure gauge on and when the car is running disconnect the vacuum to the regulator ad the pressure should go up.