How to test fuel pumps

[Bmaughan]

I just recently purchased a used sai li fuel system.. apparently it only has less than 1k miles on it... my question is: is there a good way to test the fuel pumps before I install them? I'm sure they're in fine shape...i'd just love to confirm that before they go in.

Any ideas/advice?


thanks!

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[rANDIANDI]

There is a way to test its kinda annoying but you can.

Looking at the fuel hat unplug one of the power cable from the pumps and from the top of the fuel hat, at this point only one pump will be getting power, you than place the hat inside the car and turn it on it should start, at this point you can turn it off and take the hat out again and do the same thing to the other pump, plug the cable into the second pump and unplug the original one and see if it turns on. if it does you have tested that both pumps turn on and work. at this point you can take the hat out again and plug all the cables in and put the hat back in and run the car.

tldr:
1. unplug one pumps work wire
2. put fuel hat into tank and secure everything.
3. turn the car on
4. turn the car off and take the fuel hat out again.
5. unplug the 1st pump and plug in the original unplugged pump
6. put fuel hat into tank and secure everything.
7. turn the car on.
8. turn the car off and take the fuel hat out again.
9. reconnect both pumps and drop the hat back into the car and secure everything

shouldn't take more than 30 minutes

 

[Bmaughan]

There is a way to test its kinda annoying but you can.

Looking at the fuel hat unplug one of the power cable from the pumps and from the top of the fuel hat, at this point only one pump will be getting power, you than place the hat inside the car and turn it on it should start, at this point you can turn it off and take the hat out again and do the same thing to the other pump, plug the cable into the second pump and unplug the original one and see if it turns on. if it does you have tested that both pumps turn on and work. at this point you can take the hat out again and plug all the cables in and put the hat back in and run the car.

tldr:
1. unplug one pumps work wire
2. put fuel hat into tank and secure everything.
3. turn the car on
4. turn the car off and take the fuel hat out again.
5. unplug the 1st pump and plug in the original unplugged pump
6. put fuel hat into tank and secure everything.
7. turn the car on.
8. turn the car off and take the fuel hat out again.
9. reconnect both pumps and drop the hat back into the car and secure everything

shouldn't take more than 30 minutes

Thanks a ton!... super helpful!
So would I be right to assume that if the fuel pump starts the car then it’s working fine?
No such thing a fuel pump halfway working, or losing flow rate over time?

 

[rANDIANDI]

So on that note i have read about fuel pumps working at at normal load but after some time they lose that power and pressure up top during a WOT pull or hard driving.

i have yet to exp this, i would recommand a fuel pressure guage so u can monitor it

 

[Bmaughan]

So on that note i have read about fuel pumps working at at normal load but after some time they lose that power and pressure up top during a WOT pull or hard driving.

i have yet to exp this, i would recommand a fuel pressure guage so u can monitor it

Yeah that’s what I was worried about...
The system came with a fuel pressure gauge but that will obviously be under the hood.

What would be the best way to monitor it?
And where would you tap off of the fuel line to read pressure?

 

[rANDIANDI]

I bought a fitting that had the size hose i was using but had a 1/8 ntp port so screw a sensor into, than a ran a fuel pressure sensor and harness to my A Pillar and have it mounted there.

PM Me if you need more info i can text you photos

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