ebr

Short of doing flow tests ect. I would at least like to ck the pump for leaks under presure becouse I built it my self.

hammeron

well if you do test it, be careful
and take all necessary precautions

ebr

NO SPARKS! LOL

hammeron

[sm=icon_ladiesman.gif]

157dB

If it leaks, wont it just leak into the fuel tank?

Quote, "The FPDMmodulatesthe voltage to the Fuel Pump."
Quote, "The PCM commands a duty cycle to the Fuel Pump Driver Module."

I dont get it, are you calling me out as being wrong, Hamm?
Its not the voltage but the PWM or PulseWidthModulation that
controls pump pressure. I verified this with a scope before posting this.
Not bad Hamm, but no cigar on this one.

I would suggest using a PWM motor speed control.
The voltage needed to start the pump pumping will
be nearly 8V or so and just who has a variable
power supply capable of the amperage needed to
run the fuel pump at leaktest pressures. But then
who has a PWM motor control at their fingertips also. []
Of course, I have both in my junk bin but they are not
for loan.

hammeron

that did make me laugh.....and no i'm not calling
you wrong at all....

aren't we both saying the same thing tho really....isn't
PWM just another form of a varying dc value

maybe my theory was off.....i will gladly stand
corrected if it is

it just seems like you could use a DC power supply,
to run a pump.....


where's jared when you need him

hammeron

ok, db was kind enough to explain
the way it works in more detail and
i think he's got it nailed.

for the record, db does get the cigar
and i learned something new

ebr

Yes it would just leak in the tank but I would stand to loose psi as well. Wouldnt I ?

moosestang

Yes you would loose psi or rather you'd only be able to reach a certain psi. My pressure does start to drop slowly after the pumps prime for 3 seconds. I'm not sure if you were planning to run them for a few seconds and then see if the pressure holds. I'm pretty sure that it's normal for the pressure to slowly leak back through the pump, otherwise why would the pumps need to run for 3 seconds every time you start the car.

Now the question is how will you know if you have a leak? A big leak will be obvious, but what about a small leak? I've seen my fuel pressure reach 76psi at WOT and i've never seen the duty cycle go over 50%. If you can maintain 70psi, then you're probably good for no leaks.

Off topic, but if you have 60lb injectors, what would your fuel pressure be at idle/cruise? Is it always the same regardless of the injectors?

ebr

I think I will just wait till I tune the car and see what it does on the dyno . Im going to tune more localy now at HPP instaed of the long drive to JPC so it is not as big of a concern now I guess . And Moose I did not have the fuel pres. gauge in the car with the old setup so I do not know about the fuel psi with different injectors but someone else will probably chime in on this one.