FUEL PUMP PROBLEM NEW HERE AND TRYING TO LEARN

weezall97

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Aug 1, 2019
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I have a 2002 Mustang GT and dont know where to start I purchased used .The person I got from had put a used wiring harness allready on I believe all connectors are correct but not 100% sure Heres the problem when I try to start car will turn over but not start.I got someone to spray fuel in throttle body and car will then start for a few seconds then die.I purchased fuel pump but when I turn over again no start. Caint here fuel pump in tank coming on. I have worked on car some but mostly older car so not sure where to start checking first I know about inertia switch and fuel pump driver module and ccrm and how it works but never learned about the volts that come to and from them and have never started checking volts or anything like that and would appreciate the help on were to start at PLEASE HELP ME LEARN
 
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tsemmett

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Jul 2, 2019
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Should be a valve on the fuel rail to test fuel pressure. I'd probably start there to confirm the pump isn't working. If not, start checking wiring. This thread has a pinout for the CCRM attached. Confirm you have solid power/ground connections where you should. Voltage usually varies on these systems as the system voltage does (from the battery and alternator).
 

wmburns

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Aug 14, 2009
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Test for +12 volts at the trunk mounted IFS switch at initial key on. Best to use a test light that will "load" the circuit. Do you have confirmed key on +12 volts into and out of the IFS switch?

What to do next depends upon this results.

IF no power at the IFS, suspect a problem upstream towards the CCRM.

IF there is power at the IFS, suspect a problem down stream towards the fuel pump OR some other problem.
 

Shuttleman83

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Check vapor vanister and all connections to purge and solenoid, make sure emissions tube isn't capped. Inertia Switch, also try priming fuel pump by turning key on 3 times before starting.
 

weezall97

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Test for +12 volts at the trunk mounted IFS switch at initial key on. Best to use a test light that will "load" the circuit. Do you have confirmed key on +12 volts into and out of the IFS switch?

What to do next depends upon this results.

IF no power at the IFS, suspect a problem upstream towards the CCRM.

IF there is power at the IFS, suspect a problem down stream towards the fuel pump OR some other problem.
I
 

weezall97

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Aug 1, 2019
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I checked at inertia switch had 10.9 volts on both wires with key on I checked while turning car over and had 9 volts at inertia I unplugged connector at rear bumper and had not over 6 volts on any wire there I had battery charger hooked up so battery may be little low but it was turning car over What would you have me to do next Thank you for helping me
Test for +12 volts at the trunk mounted IFS switch at initial key on. Best to use a test light that will "load" the circuit. Do you have confirmed key on +12 volts into and out of the IFS switch?

What to do next depends upon this results.

IF no power at the IFS, suspect a problem upstream towards the CCRM.

IF there is power at the IFS, suspect a problem down stream towards the fuel pump OR some other problem.
 

weezall97

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Aug 1, 2019
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Just to let you know I had battery charger hooked up before I did this battery was low but had enuff juice to turn car over good I checked voltage at inertia switch it was 10.6 on both wires with key on . Checked while turning engine over it had 9 on both Unplugged connector at back bumper going to fuel pump 1 had 6volts all the others where below that with key on.What would you recommend me trying next. THANKS FOR ANY HELP YOU GIVE ME
 

wmburns

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Aug 14, 2009
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Power at IFS switch. We need to look down stream.

From the opening post, you don't HEAR the fuel pump run at initial key on. With power at the IFS switch, the likely problem areas:
  • bad fuel pump. Just because it's a new fuel pump doesn't necessarily mean that it's good.
  • wiring problem between the FPDM and the fuel pump. Do you know if a complete fuel basket was used or JUST the fuel pump replaced? Why is important? Because it opens up the possibility of a bad wiring splice.
  • Are you positive that the correct fuel pump was used. If a return style FP was used on a return-less system a return style FP may not start when connected to a FPDM.
  • A bad FPDM
  • A bad PCM.
What would be handy to know is IF the fuel pump will run when powered directly from 12 volts. At the round connector (C463) in the middle of the gas tank are the RD/BK (pin #7) and BN/PK (pin #6) which goes straight to the fuel pump. IF 12 volts is injected towards the fuel pump this should cause the fuel pump to run at full speed. IF not, the diagnosis is confirmed. Be careful not to short power to any other terminals as this could damage the fuel tank sensor or the fuel level sensor.

Once we know that the fuel pump positively works, the trouble shooting gets more difficult.
 
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weezall97

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Aug 1, 2019
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Power at IFS switch. We need to look down stream.

From the opening post, you don't HEAR the fuel pump run at initial key on. With power at the IFS switch, the likely problem areas:
  • bad fuel pump. Just because it's a new fuel pump doesn't necessarily mean that it's good.
  • wiring problem between the FPDM and the fuel pump. Do you know if a complete fuel basket was used or JUST the fuel pump replaced? Why is important? Because it opens up the possibility of a bad wiring splice.
  • Are you positive that the correct fuel pump was used. If a return style FP was used on a return-less system a return style FP may not start when connected to a FPDM.
  • A bad FPDM
  • A bad PCM.
What would be handy to know is IF the fuel pump will run when powered directly from 12 volts. At the round connector (C463) in the middle of the gas tank are the RD/BK (pin #7) and BN/PK (pin #6) which goes straight to the fuel pump. IF 12 volts is injected towards the fuel pump this should cause the fuel pump to run at full speed. IF not, the diagnosis is confirmed. Be careful not to short power to any other terminals as this could damage the fuel tank sensor or the fuel level sensor.

Once we know that the fuel pump positively works, the trouble shooting gets more difficult.
Connector 463 would that be connector that comes out at back bumper if so can i connect hot wire there also it was the complete canister not just the pump. I been gone for few days but will check power and let you know Thanks again for your help
 

weezall97

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Aug 1, 2019
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.
Power at IFS switch. We need to look down stream.

From the opening post, you don't HEAR the fuel pump run at initial key on. With power at the IFS switch, the likely problem areas:
  • bad fuel pump. Just because it's a new fuel pump doesn't necessarily mean that it's good.
  • wiring problem between the FPDM and the fuel pump. Do you know if a complete fuel basket was used or JUST the fuel pump replaced? Why is important? Because it opens up the possibility of a bad wiring splice.
  • Are you positive that the correct fuel pump was used. If a return style FP was used on a return-less system a return style FP may not start when connected to a FPDM.
  • A bad FPDM
  • A bad PCM.
What would be handy to know is IF the fuel pump will run when powered directly from 12 volts. At the round connector (C463) in the middle of the gas tank are the RD/BK (pin #7) and BN/PK (pin #6) which goes straight to the fuel pump. IF 12 volts is injected towards the fuel pump this should cause the fuel pump to run at full speed. IF not, the diagnosis is confirmed. Be careful not to short power to any other terminals as this could damage the fuel tank sensor or the fuel level sensor.

Once we know that the fuel pump positively works, the trouble shooting gets more difficult.
One more thing the vent hoses at the fuel tank have not been connected back yet wanted to get fuel pump working first before I reconnect them will fuel pump still come on if they are not connected
 

wmburns

SN Certified Technician
Aug 14, 2009
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One more thing the vent hoses at the fuel tank have not been connected back yet wanted to get fuel pump working first before I reconnect them will fuel pump still come on if they are not connected
Yes. The fuel pump will run normally with the EVAP system disconnected.
 

weezall97

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Aug 1, 2019
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Ok Mr Burns I connected 12 volts to pin 6 and 7. I pulled those two out of connector and plugged connector back up and had those two by there self had 12 volts and couldnt here no pump at all i listened good but no pump running would you say fuel pump first
 

wmburns

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Aug 14, 2009
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Just to confirm the specific source of the 12 volts. I just wanted to make sure that you are not using a new(er) battery charger with polarity reversal protection. Why is that important? Because a battery charger with polarity reversal protection will not "power up" unless it senses battery voltage. This makes it not usable as a power supply. In fact, I keep an "old school" battery charger around just for things such as this.

If this were my car, I would also double check the wire colors are as expected (RD/BK (pin #7) and BN/PK (pin #6)). Perhaps even make a Ohm measurement of the fuel pump winding. If the fuel pump doesn't run from direct power, then the FPDM can't run it either. The next step is to drop the gas tank. So double check your work.
 
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weezall97

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I used just the battery not charger I charged overnight so it would be completely charged and ran wire straight from battery and checked voltage with a tester while I had the two wires connected and had 12 volts there
 

wmburns

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Aug 14, 2009
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If this were my car, I would have tested the fuel pump with everything plugged in before re-mounting the gas tank. Especially considering all of the problems you have had leading up to this moment.

I highly doubt I would have bought a new fuel pump IF the old one tested OK.

If asking for an educated guess. YOUR problem is not with the fuel pump itself. I suspect that it's in the wiring. Pay attention looking for crushed or damaged wires. How about where the wires pass through the fuel pump hat?

I have helped MORE than one person whose problem ended up being a pinched wire inside the gas tank between the gas tank and fuel pump hat. Depending upon which wire is pinched it will cause the fuel pump to blow a fuse or run 100% of the time.

I helped one guy who tested it while on the ground but would fail once the gas tank was mounted. His problem turned out to be a pinched wire that was grounded. However with the tank was off of the car, the tank did not have a real path to ground so it would work. Once mounted on the car the tank itself was grounded and it would fail.

I also have to encourage you to double/triple check your work. After all, you reported that you could not get the fuel pump to run when powered directly through C463 RD/BK (pin #7) and BN/PK (pin #6).

Further consider something like a damaged wiring harness. This could create a situation where the FP itself tests fine out of the tank but does not run once in the tank. Again. Does the fuel pump run when powered directly through the round C463 RD/BK (pin #7) and BN/PK (pin #6) while the gas tank is off of the car?
 
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weezall97

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Aug 1, 2019
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Is there anyway you could show me how many volts i should have with the key on and with the key off at the ccrm and fuel pump inertia switch anywhere that would cause a problem I want to check all of them just to make sure that all of them are right and write them down.So i want waste no ones time and maybe find the problem in a few short questions
 

wmburns

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Aug 14, 2009
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key on and with the key off at the ccrm and fuel pump inertia switch
For switched power circuits the "key on" value should be "battery voltage". The "key off" value should be zero.

The output of the CCRM fuel pump relay goes directly to the trunk IFS switch. it's POINTLESS to test the CCRM if you have confirmed full key on battery voltage at the trunk mounted IFS switch. Under these conditions, a fuel pump problem isn't going to be inside the CCRM.

The difference between 12.2 volts and 12.6 volts (for example) isn't going to be your problem.

Don't over think this. If the fuel pump runs when test powered directly but will not run when powered through C463 RD/BK (pin #7) and BN/PK (pin #6) TOWARDS the fuel pump the problem MUST be somewhere in the gas tank wiring.

If you are trying to learn, also study the voltage drop method as it can be useful in trouble shooting a circuit that test fine with a VOM meter but does not power a high current device.

Howto perform charging system voltage drop test
 
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