robert78.5

I started my 2001 truck this morning with remote start and was having coffee waiting for it to warm up, it went o high idle as normal. It than started to sound like it was running out of fuel so i ran outside and got in and my fuel pressure was at zero. I shut it off and did the key bump thing and the electric pump started and pressure went to 15. I have a Faass pump that is about 4 years old. I started it and watched the gauge gradually go all the way back to zero. I shut it down and bumped the starter again and the pressure went back to 15. I started it and watched the fuel pressure go down to zero again. I shut it off. I have an Edge fuel mizer on it. Could this be causing the electric pump to stop working if faulty? What harm could it do if i run a live feed wire to electric pump?

AlpineRAM

If you have fuel pressure while not consuming fuel, and no pressure while consuming fuel this points towards a restriction.
I'd start with the simple things- change fuel filter, Blow through fuel lines with compressed air. Get new fuel.
If none of that works then you can re-wire your truck.
AFAIK the fuel mizer does not interfere with the lift pump. It would not be logical to do so, lower fuel pressure can only lead to retarded timing and higher fuel consumption.

robert78.5

new filters last month, canister and inline filters. i am thinking i am losing my 12 volt power to electric pump when engine starts running, thats why i was going to run a live wire to pump to see if pump stays running.

AlpineRAM

I'd rather add a light parallel to the pump to see if the power is there, because the ECM will shut down the pump in a crash-your live wire won't.

robert78.5

I started truck last night and ran for five minutes, all good , pressure stayed at 15, I suspect maybe corrosion starting in wire plugs. or would a reflash of ecm help ?

AlpineRAM

Well, the ECM can just turn the pump on or off.
Do you have a relay for your pump?
Bad contacts and plugs need to be fixed.

Some folks here had Fass pumps go bad.

robert78.5

Fuel pressure went down to zero again yesterday, I made a jumper wire with clips direct from battery to pump, pump runs and pressure goes up, I start engine and slowly goes down to zero pressure while running, I will check filter tonight and change again, if filter is clear I guess my pump is worn, I installed it in April 2014,, Fass DP 02,,

AlpineRAM

Maybe brushes in the pump motor worn out.

robert78.5

i took pump apart and yes brushes look pretty short, armature looks good, the gerotor and gear have a bit of play. are there any specs on these pumps to check things out? I have 75000 kms on this pump. It was mounted to engine block in factory position. I have read that they should be mounted to truck frame. Any thoughts on that ??

AlpineRAM

Gerotors (like many other designs) hate to suck, so the pump should be at the lowest level that is possible.
I don't have specs for your pump, but I'd try it with new brushes and maybe new bushings if you can get these parts easily.
Gerotor tightness should not influence flow, only attainable pressure and lift heighth.

robert78.5

Ok i wired in a relay to run electric pump. works great, i took the signal red wire from ecm to feed relay, i than put ground to battery and left the black wire from ecm empty, will this do any damage to ecm??

AlpineRAM

I wire the solid state relay so that it is plugged in in place of the pump. That way I do not need to care whether the stock ECM switches plus or ground.
Doing it like this will reduce the electrical load on the ECM.
You need to use a relay with a suppressor diode, or a solid state relay with equivalent protection.

robert78.5

so just using the red wire from ecm is okay??

AlpineRAM

If it works it seems OK.
Using red and black from the ECM with a solid state relay gives you all the features of the ECM concerning the lift pump operation.
I do not know if the ECM will shut down the lift pump by turning off plus or by cutting minus in case of an accident.
I do not know if the ECM does the PWM reg for lower fuel pressure while starting through plus or minus.

So you may be OK, it's a 50/50 chance. You might need to crash two trucks to find out the difference.

robert78.5

yes it operates the same as before ,when i hit the key it bumps a bit of pressure when i start it the pressure builds up and stays up while running. when i turn key off pump stops turning, i haven't tried crashing it yet"....