No fuel pressure

[Dave.O]

99 cobra
Fresh engine swap. Upgraded to 03 tank and pumps.
only short duration of fuel pressure at rail. When cranked, fuel pressure will jump to 34 psi (ish) then immediately drop off, car fires for a second then immediately stumbles and dies.
I have confirmed little to no fuel pressure at rail via cracking the Schrader port and FRPS location.
fuel pump fuse is good
fuel filter is new
connections at ECM are tight, nothing loose
I partially dropped the tank and jumped pins on pump harness, pump filled a 32 oz cup with gas in seconds, so not a fuel pump issue.
any else I should check before spending $ on CCRM replacement?

thanks

 

[01yellercobra]

Did you check the shut off switch in the trunk?

 

[DSG2003Mach1]

Id check into the FPDM as well

 

[Dave.O]

Yup, that was 1st check


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[Dave.O]

Trunk switch that is.
How do I check fpdm?


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[DSG2003Mach1]

Trunk switch that is.
How do I check fpdm?


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because its stalling out so quick probably need two people.

I would have one person starting the car/trying to keep it alive and one in the trunk with a test light or volt meter.

Personally I would find out - which pin on the harness going into the FPDM (behind the driver side interior trunk panel) and which pin out of the fpdm are power.

You just want to see where you lose power - if its pre FPDM then maybe its a CCRM issues. If the power only drops out post FPDM then its probably bad etc... You just wanna see where in the line power to the pumps is dropping.

 

[Dave.O]

Which wires on fpdm to test?


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[DSG2003Mach1]

I dont have a diagram handy. I believe if you search for something like "fuel pump wire upgrade" or "FPDM power wire upgrade" there are posts that tell you which wire has power on each side. Or try a google search for 1999 Cobra FPDM pinout.

Just read carefully because many posts are terminator specific and the wire colors ARE different! I know my mach does NOT have the same color wires as the terminator but the write ups I found had the alternate colors listed

 

[Dave.O]

still trying to work my way through this...

yesterday measured voltage a fuse, key in run 12.7 volts constant.
measured a rear harness at center top two pins for fuel pump power, 12.5 volts constant.

so if I am getting a constant 12.5 volts why is pump not pumping?

If I hook the battery up directly to those pins on pump side of harness pump runs.... I'm confused...

also I noticed my fuel level sender is reading wrong as well

does any one have wiring diagram with color codes for pump circuit? I am wondering if I spliced the 03 connector in wrong...

 

[DSG2003Mach1]

to be clear - are you seeing that 12.5 volts at the harness where it plugs into the fuel hat or where?

 

[Dave.O]

where it plugs in harness on rear bumper support. the larger harness with multiple pins

 

[DSG2003Mach1]

where it plugs in harness on rear bumper support. the larger harness with multiple pins

ok, just making sure because that does put you AFTER the fpdm, crash cut off etc...

If you spliced wires from the pumps to the hat that being done wrong is the only thing that makes sense. You know which pins to put battery power too on the pump side, it should be pretty easy to count pins and see if they match up to the pin(s) giving you 12 volts from the body harness.

you may have grounded the fuel level sender incorrectly. I made that mistake

also, just FYI it can help get you quicker responses if you use either the "quote" or "reply" button under someones post. If you had used the reply option under my post it would have notified me you replied to me so I could come see what you said. I just happened to see the thread get bumped again.

 

[Dave.O]

ok, just making sure because that does put you AFTER the fpdm, crash cut off etc...

If you spliced wires from the pumps to the hat that being done wrong is the only thing that makes sense. You know which pins to put battery power too on the pump side, it should be pretty easy to count pins and see if they match up to the pin(s) giving you 12 volts from the body harness.

you may have grounded the fuel level sender incorrectly. I made that mistake

also, just FYI it can help get you quicker responses if you use either the "quote" or "reply" button under someones post. If you had used the reply option under my post it would have notified me you replied to me so I could come see what you said. I just happened to see the thread get bumped again.

Thanks for heads up on reply/quote, I did not know that...

regarding the power to the pumps, if I can get them to run by applying battery directly to the correct pins on pump side of harness and get it to run, and I have correct voltage on those same pin on car side of harness.... why doesn't it run when I plug them together....?

please describe how to ground fuel sender properly, when I spliced I basically cut the 4 wires off the 03 fuel pump connecter and soldered them on to the 4 wires of the 99 connector in the same order. is it possible they are in a different order on 03 vs 99?

wish I could find a color coded wiring diagram

thanks for your input this car is just fighting me on getting completed.....

 

[DSG2003Mach1]

i really don't know to be honest, I would think it should be good to go

maybe with the fuel level issue as well maybe theres an issue with the ground side to the pumps?

Im using a lethal performance/division X dual pump hat so I would imagine its a bit different.

I would not assume that the wires are in the correct order. I dont know if the Hayne's manual has the wire colors or not.

You could always make a new thread or two - fuel pump wiring diagram for 99 cobra in that section and fuel pump wiring diagram in the terminator section. Or try doing a google search for installing terminator pumps in a 99 cobra so it can pull from other forums as well

 

[Dave.O]

i really don't know to be honest, I would think it should be good to go

maybe with the fuel level issue as well maybe theres an issue with the ground side to the pumps?

Im using a lethal performance/division X dual pump hat so I would imagine its a bit different.

I would not assume that the wires are in the correct order. I dont know if the Hayne's manual has the wire colors or not.

You could always make a new thread or two - fuel pump wiring diagram for 99 cobra in that section and fuel pump wiring diagram in the terminator section. Or try doing a google search for installing terminator pumps in a 99 cobra so it can pull from other forums as well

Another thought, are fpdm different from 99 to 03? Could the 99 fpdm just not be giving enough amps?


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[DSG2003Mach1]

Another thought, are fpdm different from 99 to 03? Could the 99 fpdm just not be giving enough amps?


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I rhink they’re the same, I think the stocknone is fine until dual GT supercar pumps

 

[Brutal Metal]

Another thought, are fpdm different from 99 to 03? Could the 99 fpdm just not be giving enough amps?


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99-04 are all the same even the GT's use the same FPDM. If you were in my area I'd let you borrow a spare fpdm to rule that out. Have you pressed the inertia switch button?

 

[01yellercobra]

Did you get a tune for the new pumps? I've heard of some 99's not liking the dual set up and needing a new tune to work properly.

FWIW, I've ran the old GT pumps with my stock 01 FPDM and they're currently in my 04 with the stock FPDM. I just ran the wire upgrade to the FPDM. I haven't run a wire to the pumps yet.

 

[Dave.O]

I took it all back apart last night. Turns out the line that merges to two pumps split...

Got it all back back together Around 12:30 last night and had 45 psi after priming. To late to fire it up, I'll try tonight


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[Brutal Metal]

I took it all back apart last night. Turns out the line that merges to two pumps split...



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Cool you found it, your not the first person that has happened to.