Picture of where/how to prime the fuel pump?

[Fendamonky]

Could anybody please post up a picture/how-to for priming the fuel pump?

I need to flow test my new (to me) fuel pump before I hit the dyno and I'm not 100% on how to prime the pump and keep her pumping so I can run the test.

I figured it would be best to ask, as opposed to just randomly connecting wires I thought might be right until I got something

Thanks!

[mazpower]

Find the diagnostic connector under the hood.

IIRC, you run a test wire from the fuel pump pin to ground. If you look on the underside of the cap for the connector, you'll see abbreviations for the pins. Fuel pump is FP, ground is GND. Make sure the ignition is turned on otherwise the fuel pump relay will not power the pump.

[Fendamonky]

Thanks Glenn!!

I'll snap some pictures tomorrow and post them up so that others with the same question will be able to use this

[Fendamonky]

Finally got around to posting back on this...

Here is a pic of where the Diagnostic box is under the hood. You can see it just in front of the driver side strut tower.



And heres a shot of the map for which input is for what.


And finally with the two inputs connected, the fuel pump will start running. Like Glenn said you've got to have the key in the ignition and the ACC powered on (but obviously not have the car running).




One little thing to keep in mind as well... I kinda retarded out when I tried to flow test my pump on Thursday night. You CAN NOT accurately test the fuel pumps flow unless you have your car attached to a running vehicle by jumper cables. If you try to test the pump without that then you will be sorely disappointed by the results (it will take you a good 5-6 minutes to fill 5-gallons, where it should normally take just around/below 1 minute). The battery alone will only supply 11-12v (enough to crank over the engine), in order to do the test you need to have your car seeing at least 14v (a working FD alternator should be pushing out 14.3-14.5ish volts) so that your pump can operate with its full power.

[Rotary Evolution]

yes and also consider the pump should be tested at the peak pressure you intend to operate the car at and that requires a working pressure regulator as well as all the plumbing in place. you can leave the car running and run a hose from the return line into a bucket away from the car and fire hazards. run up your fuel pressure regulator to static psi(pressure the regulator pushes with the car off or vacuum line disconnected) plus your target boost pressure.

in short say your static pressure is 40psi at atmospheric pressure at the regulator port, your peak target boost level is 15psi, so you should test the volume of the pump at 55psi@13.5volts(or whatever voltage your car charges at with all electrical loads on while running AT the fuel pump connector).

this will tell you within reason what to expect from the pump, it will be slightly skewed because the engine is actually using a very small percent of the fuel(usually about 5% or less at idle). you can do it with the car off but the numbers will again be lower since the voltage will be less without the charging system active.

[Fendamonky]

Thanks =)

Yeah, I'm honestly getting a bit confused now that I'm trying to calculate out my times. I figure either A) I did something wrong, B) I'm doing my conversion/calculations wrong, or C) the practically new 2nd-hand pump I bought is crap from the start =(


Some quick background: I'm at the very tail end of a rather long rebuild/winter build. In the process of the rebuild we went with full AN fuel lines (-8 feed, -6 parallel lines in the engine bay, and a -6 return).

I pushed my FD out of the garage today and pulled my DD up along next to it. I then disconnected my return line from where it would connect to the tank and added another 3' of -6 line to it with a male/male connetor. I then fed that line into a 5 gal jerry can that I had previously pumped 5 gallons into, and marked, at the gas station.




From there I timed filling up the can at 43psi, and then again at 70psi, both times I had my DD running and hooked up to the FD's alternator with jumper cables.

[Rotary Evolution]

well the single -6 return may be your bottleneck if you aren't getting the expected results.

i would also check the pump voltage to be sure it is getting near battery voltage.

[Fendamonky]

Originally Posted by Rotary Evolution

well the single -6 return may be your bottleneck if you aren't getting the expected results.

The only alternative I can think of to that would be if I were to fit together a 4'-5' hose that connects directly to the FPR so that I could mitigate the possibility of flow loss as the line travels the length of the car. That seems a bit off though, because I wouldn't guess that the distance should make THAT much of a difference.

i would also check the pump voltage to be sure it is getting near battery voltage.

Honestly I'm thinking that this may be the most likely culprit. Unfortunately I don't have an Ohm meter or anything like that (I'm admittedly retarded when it comes to wiring or electronics) to confirm the voltage above the pump

I'll get her figured out though.

[speedjunkie]

You can also jump from the GND that is just a spot away from the F/P tab. I use a mini blade fuse to jump it, fits perfectly.

[Rotary Evolution]

keep in mind that the FD has a load variable voltage output, so you may only be seeing 10v with the key on even while charging(unless you bypassed the relay system, even when bypassed it is a redundant system and usually drops a full volt from charging levels when under a load).

jumper the pump to the charging system to see what it will put out when closer to actual loaded voltage figures. and also be sure the ground strap is attached, the pump may run but it will be very slow due to poor tank grounding without it(if it even runs at all).

and of course check your math. a 255lph walbro for example would be similar to: 1 gallon = .264 liters, 255 liters X.264= 67.32 gallons per hour. 67.32/60 minutes= 1.122 gallons per minute, so it should take about 4.5 minutes to fill a 5 gallon container at maximum loaded pump efficiency. of course we want to think it's going to geyser out and fill the 5 gallon tank in 30 seconds, but that isn't the case.

[Fendamonky]

How would I jump the pump directly?

I recently changed fuel pumps (worried that I may have run a pocket of air through my previous 044) and I was careful to ensure that everything was connected back properly and tightly.

One thing that *does* concern me slightly is that the sock on the pump is old, that may be stifling some flow.

One of the local guys said he could bring by a multimeter so we can check the actual voltage that the pump is seeing.


If my pump were only seeing 10v, how much would that skew my readings? One thing I did notice is that my PFC Commander was reading 13.2v for the 43psi test, and 14v for the 70psi test.

The last two pages of this thread have all the pertinent information.

[Rotary Evolution]

this is about the best chart i could find for the 044 without spending too much time digging:



i can't validate it without doing a full blown test on one so assume it is close to accurate. the test is done at 14 volts as per the picture title, at 10v the output would be about 25% lower but varies depending on the pump and its design and will drop more dramatically the more the voltage is reduced.

at 3 bar(43.5psi, 3.0X14.5) the 044 puts out just over 300 liters per hour@14v. using the same math conversions above it should drop down to roughly 4 minutes to fill the 5 gallon tank.

to wire the pump directly you should disconnect the pump connector and ground the ground wire to the chassis of the car and jump the power feed wire to the charging system(black/white wire). to test the voltage the pump is actually seeing wired to the car backprobe the black/white wire by stabbing it(reseal the puncture afterwards with liquid tape) and measuring the voltage with the key on.

[88turboii]

or bypass the fuel pump relay and circuit opening relay (both in engine bay). each relay has a pair of silver and gold terminals. short the terminals that are silver with a short jumper wire. that will bypass the factory resistor bs too

[Fendamonky]

Originally Posted by 88turboii

or bypass the fuel pump relay and circuit opening relay (both in engine bay). each relay has a pair of silver and gold terminals. short the terminals that are silver with a short jumper wire. that will bypass the factory resistor bs too

This sounds like it may help, would you mind posting a picture of what you're talking about?

[88turboii]

Originally Posted by Fendamonky

This sounds like it may help, would you mind posting a picture of what you're talking about?

found this pic of the fuel pump relay


the circuit opening relay is near the drivers tower