Fuel Pump not running, electrical diagnosis... - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 13 Old 09-24-2018, 08:26 AM Thread Starter
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Fuel Pump not running, electrical diagnosis...

I tripped on a barn (garage) find, a 1998 Mustang convertible with only 7,500 miles on the odometer. Owner died and his wife just kept the car in the garage. Had not been started or driven in at least 6 years. Car has a 3.8L V6 engine. I made a deal with her to buy the car, pulled the drive shaft and used a dolly to bring it home.

First thing I did was install a new battery, turned the key and I did NOT hear a fuel pump running (also note, the fuel gauge sits a ĺ and does not move). I checked the fuse under the hood, it was good, then I check the inertia cut-off switch in the trunk, also good (I actually tripped it and re-set it to make sure). I pulled apart the electrical connector in the rear behind the fuel tank, there are 4 pins, one had 12 volts, one had I think 7, the other two nothing. Is this correct?? (I saw a youtube video that implied I should have voltage on all 4?)

As far as a fuel pump relay, I learned that it is housed in Constant Control Relay Module (CCRM). I pulled the passenger side wheel & tire liner to expose it and pulled it out (looks like new, and my research says they are pretty reliable). I did check for voltage going to it (pin 5) and it was 12 V, but Iím not sure if there is a way to actually check the CCRM itself?

I did siphon the gas out through an upper vent tube opening in the tank and Iíve got the fuel filter off, ready for a replacement. Before I install the filter, I was planning on putting a hose on that fitting to drain the rest of the fuel out (if there is any left) once I get the fuel pump to run.

So whatís next to check to determine if the fuel pump is trash or itís an electrical problem. Again, not sure if the electrical connector in the rear is suppose to have voltage on all 4 pins?

Thanks for any help you can offer!
Art

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post #2 of 13 Old 09-24-2018, 09:03 PM
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return system?


89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #3 of 13 Old 09-24-2018, 09:12 PM
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Under the dash fuse

Itís up in the corner of the fuse box under the dash. Ccrm fuse. I chased it for three weeks. Amature move on my part.
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post #4 of 13 Old 09-24-2018, 09:19 PM
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the fuel assembly will have seven wires

this pump is driven by a module, driver module

its pwm, pule width modulated

you can check the inputs to the module

easiest would to use a scan tool to bidirectionally control it and see what is missing

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #5 of 13 Old 09-24-2018, 09:21 PM
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Quote:
Originally Posted by Sac1776 View Post
Itís up in the corner of the fuse box under the dash. Ccrm fuse. I chased it for three weeks. Amature move on my part.
fuse?

why did it blow?

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #6 of 13 Old 09-24-2018, 11:52 PM
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My fuse blew because I had the coil + wire shorting on the block. it was the radio interference connector plug on each coil pack itís the little square black box that grounds to the motor, then connects to the 12v hot wire to each coil pack to prevent the radio from buzzing. Fuse blew 3 times till I wiggled the wires and it stoped. So I traced the wires back and found my problem.
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post #7 of 13 Old 09-26-2018, 10:02 AM Thread Starter
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Sac1776,

Is this fuse you mention "within" the fuse panel, or is it beside/next to the fuse panel in a separate block? Because I don't see a fuse listed for the CCRM....
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File Type: jpg Inner_Fuse_Panel.jpg (145.7 KB, 4 views)
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post #8 of 13 Old 09-26-2018, 11:38 AM Thread Starter
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Actually I will have to check, I might have this fuse box under my dash...
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File Type: jpg 98_Mustang_Oweners_Manual-002.jpg (80.5 KB, 3 views)
File Type: jpg 98_Mustang_Oweners_Manual-003.jpg (68.2 KB, 3 views)
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post #9 of 13 Old 09-27-2018, 12:53 AM
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Yes I believe itís under the dash number 18. constant control relay module. Look up fuse panel 98 Ford Mustang on google images sorry donít know how to upload photos other wise Iíd send u the picture. You under the dash fuse diagram isnít right.
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post #10 of 13 Old 09-27-2018, 09:45 AM
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why is a fuse being looked for?

first post says there is power at the ccrm?


89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #11 of 13 Old 09-28-2018, 09:55 AM
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IMO it's far easier to test for +12 volts of key on power at the Trunk mounted IFS cut off switch. Use a known good ground.

IF there is no power at the IFS switch then there's an electrical problem upstream such as:
  • fuse
  • CCRM
  • ignition switch
  • Bad ground
  • wiring fault

If there is power at the IFS switch this proves the electrical CCRM and everything else is likely OK. Focus on the fuel pump on the fuel pump itself.

Note, the 1998 is an odd model year as it has a two speed fuel pump relay with a ballast resister.
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post #12 of 13 Old 09-28-2018, 09:58 AM
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duplicate post.

Last edited by wmburns; 09-28-2018 at 10:01 AM. Reason: duplicate post
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post #13 of 13 Old 10-10-2018, 09:51 PM
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Do you get that thing figured out?
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