Fuel Pump - How To Check Its Working?

[Masekwm 2]

I want to check the fuel pump is working as it should on my Mi, the car was running lean when at a RR, it's been serviced now, but I'd like to check the FP is getting the power and putting though the fuel it should.

 

I guess the fuel is measured by guage but what power should the pump be getting?

Edited December 30, 2009 by Masekwm

[EdCherry 34 1 Cars]

The pump should be getting a full 12v. Get your multimeter, find the positive pin, earth to the chassis and measurement the voltage while the cars running, will tell you how much its getting.

[petert 588]

To check flow, take off the regulator return hose and place in a bucket. You should get 540ml (or more) in 15 seconds with the engine running. To check pressure, place a gauge before the fuel rail, on the inlet hose. You should get 3 Bar with the vacuum disconnected from the back of the regulator.

 

Common fault nowadays is the small internal hose, that connects the pump to the pump body.

[Masekwm 2]

Thanks guys.

 

The pump should be getting a full 12v. Get your multimeter, find the positive pin, earth to the chassis and measurement the voltage while the cars running, will tell you how much its getting.

 

I hate electrics, I unpluged the plug to the FP with the engine running and I can quickly measure a reading but the engine then dies, I did this twice and got 12.05 and 14.xx. How do I stop the engine from cutting out so I can get an accurate reading?

 

 

I'll have to try the bucket and grab a guage

[EdCherry 34 1 Cars]

Dont unplug it, probe into the wire through the sheath while its connected.

[superted 0]

Dont unplug it, probe into the wire through the sheath while its connected.

 

 

I am assuming that doing this a reading will be achieved even if the engine is not running, i.e just from a switched live which is what it will be?

 

I only ask as I seem to have an issue with my pump, it works ok, well sort of, then no response. I have measured at the relay and also at the pump (disconnected) and my meter reads 0000.

 

At the relay there are of course 7 pins, overall I get 12v reading at 3, one at perm live and 2 at switched live, should this be the case?

 

The wire colours that show a reading are, Brown (perm live) Yellow (switched live) and Green (switched live) the two White, Blue and Green (with Yellow dotting) show nothing at either perm or switched?! Confusing it is, as the White and the Green (Yellow dotting) appear to lead to the pump!

 

Sorry to raid this thread but saves starting a new one when the issue seem to be the same............

 

Cheers

[RINRIN 1]

To check flow, take off the regulator return hose and place in a bucket. You should get 540ml (or more) in 15 seconds with the engine running. To check pressure, place a gauge before the fuel rail, on the inlet hose. You should get 3 Bar with the vacuum disconnected from the back of the regulator.

 

Common fault nowadays is the small internal hose, that connects the pump to the pump body.

 

You should have 3 bars not only at idle it should be 3 bars for all engine revs. So you should check it on dyno or you should have a long hose to check it in the car when going.

[petert 588]

You should have 3 bars not only at idle it should be 3 bars for all engine revs. So you should check it on dyno or you should have a long hose to check it in the car when going.

 

That's not true actually and hence why I suggested to disconnect the vacuum whilst checking it. Fuel pressure is relative to manifold vacuum. Thus at wide open throttle, 0kPa, there would be 3 Bar, but if there was 0.5 Bar of vacuum at idle there would be only be 2.5 Bar of fuel pressure.

Edited January 6, 2010 by petert

[Tom Fenton 1,542]

I agree with Peter. The fuel pressure regulator is vacuum referenced.