fuel system diagnosis fun! help!

achesonm8

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93 MarkVIII Gen I

Hi,
I haven't visited here in a while. My Mark sat for about a week and would not start, the tank was near empty last time I drove it and my rear bags had deflated (bad sensor?) sometime during that week so the car was on a slight incline. Car cranks and cranks continuously but will not start. Put the battery charger on the battery and is on low amp charger. I am assuming fuel is the problem. Here is what I have done so far with my observations and where I am at the moment.

1) Filled tank with 8 gallons of gas
2) Checked for gas at the shrader like valve on the drivers side fuel rail by by releasing it with a small phillips head while my daughter cranked the motor. No gas at that port.
3) Removed the fuel line at the incoming/lower side of the fuel filter. A few ounces of gas drained out of the filter. Cranked motor several times no fuel coming from the open fuel line.

At this point I am assuming something is wrong with the fuel pump. There is a fuel cut off switch on the drivers side in the trunk. The red button on this switch was depressed. It is described as an inertia switch. It has two pk/blk wires running into it. I assumed the depressed red button was the "off" position so I popped it up with a screwdriver. I tried cranking the motor again but still no fuel. I read on the other forum about a Fuel delivery module and the cutoff switch, etc. The FDPM (?) I can't seem to find! On the passenger side in the trunk there is a well insulated black exterior line that has a connector with red and pk/blk inputs. The black exterior line runs through a large rubber grommet and I assume this is the line that powers the fuel pump.

I am going to do the following

1) swap fuel relay in main fuse box and test (crank motor)
2) have my daughter turn the ignition to run to see if I can hear the fuel pump coming on or off (sound ?)

With the ignition on I get 4.8V at the red lead wire connector coming from the wiring harness when it is grounded to chassis. I also get 4.8 V when i put black wire from the voltmeter to the pk/blk wire in the connector. the pk/blk wire from that connector has connectivity (ohm meter near zero) to one of the pk/blk wires of the fuel cutoff switch.

I thought I could test whether or not the fuel pump was working by adding 12V to it somehow but I don't understand the wiring system or electrical stuff well enough to know how the switch(es) works(?). Don't want to damage anything in the wiring system w/o understanding what I am doing! I would appreciate any ones thoughts and diagnosis with the information I have provided...Have not looked at a wiring diagram for the fuel system. At any rate comments help would be appreciated!

Thanks!
 
The fuel pump makes a distinct noise when you turn the key, priming itself. It should be pretty obvious when you listen for it. If it's not making that noise then something's up with the fuel pump.
 
The fuel pump makes a distinct noise when you turn the key, priming itself. It should be pretty obvious when you listen for it. If it's not making that noise then something's up with the fuel pump.

Or the fuel pump driver module or fuel pump relay.
 
The fuel pump makes a distinct noise when you turn the key, priming itself. It should be pretty obvious when you listen for it. If it's not making that noise then something's up with the fuel pump.

Is it a "clicking noise" I hear that when turning the ignition key from off to first position. I also here it when I have negative ground black wires to battery disconnected and reconnect the negative ground wires. If that is the correct sound for the fuel pump then I need to consider further up stream. I swapped relays and that did not make a difference either. Inertia switch is down in correct position. Will look upstream from pump. Where is the FDPM (?) Thanks!
 
first gen Mark VIIIs don't have a FPDM like the 2nd gens do.
the fuel pump is controlled by the ecu and the vrcm.

best way is going to be to check for power at the pump. if you have power there, you need a new fuel pump.
 
first gen Mark VIIIs don't have a FPDM like the 2nd gens do.
the fuel pump is controlled by the ecu and the vrcm.

best way is going to be to check for power at the pump. if you have power there, you need a new fuel pump.

OK, no FPDM...good to know! AYE!!! where is my FPDM...you don't have one Scott. I am Gen I, the Ford gods didn't hand them out to Gen I er's! :(

So next question is do I have to drop the tank to check for 12V at the pump?

I am not sure what the pump is supposed to sound like upon turning the key to first position. I have been hearing a 2-3 second clicking noise whilst futzing around with the battery from the rear of the car. As I described in my first post, in the trunk, there is a 2 pin barrel type connector that has inputs with a red wire and a pink/black wire. The pink/wire has conductivity with the one of the pk/blk wires of the inertia switch. These red and pink/black wires run towards the front over the wheel wheel and become part of a another group of wires. The downstream side of the connector has a large black insulated wire that runs into and through a large rubber grommet on the trunk floor. This wire must contain two wires. Can I assume the red is positive and the pink/blk is negative and apply 12 V here to see if I here the pump run? I'll try that and see...if the pump runs I should hear it and I should get gas coming out of the line where I have disconnected it from the fuel filter...make sense? All my fuses are good and securely fastened and the fuel pump relay is good. Thanks! :)
 
OK, no FPDM...good to know! AYE!!! where is my FPDM...you don't have one Scott. I am Gen I, the Ford gods didn't hand them out to Gen I er's! :(

So next question is do I have to drop the tank to check for 12V at the pump?

I am not sure what the pump is supposed to sound like upon turning the key to first position. I have been hearing a 2-3 second clicking noise whilst futzing around with the battery from the rear of the car. As I described in my first post, in the trunk, there is a 2 pin barrel type connector that has inputs with a red wire and a pink/black wire. The pink/wire has conductivity with the one of the pk/blk wires of the inertia switch. These red and pink/black wires run towards the front over the wheel wheel and become part of a another group of wires. The downstream side of the connector has a large black insulated wire that runs into and through a large rubber grommet on the trunk floor. This wire must contain two wires. Can I assume the red is positive and the pink/blk is negative and apply 12 V here to see if I here the pump run? I'll try that and see...if the pump runs I should hear it and I should get gas coming out of the line where I have disconnected it from the fuel filter...make sense? All my fuses are good and securely fastened and the fuel pump relay is good. Thanks! :)

I thought I needed a new pump so I have a new pump and everything reinstalled. I need to check for power to the pump. there is a 4 pin connector (female) up under a small heat shield that I will check for current from. If I don't have current there then it must be further upstream than the IFS(depressed)...thanks!

I posted a bit earlier today from a much older thread about specifically which pins to jump the fuel pump relay switch. Thanks.
 
ever figure this out?

http://www.lincolnvscadillac.com/fo...-t-start-actual-diagnosing-has-been-performed

Yes it was the VRCM. I posted in the above thread more detail. The VRCM, from a 96 Cougar, I got for $29 from the Pull-A-Part seemed to work fine. It does not have the same prefix or suffix but the internal part of the number is the same as the one that came out of my 93 Mark 8. It doesn't have the same housing with fins but I can use the original housing with fins. Haven't tested the other three functions of the VRCM but will do that.
 
http://www.lincolnvscadillac.com/fo...-t-start-actual-diagnosing-has-been-performed

Yes it was the VRCM. I posted in the above thread more detail. The VRCM, from a 96 Cougar, I got for $29 from the Pull-A-Part seemed to work fine. It does not have the same prefix or suffix but the internal part of the number is the same as the one that came out of my 93 Mark 8. It doesn't have the same housing with fins but I can use the original housing with fins. Haven't tested the other three functions of the VRCM but will do that.

VRCM but only those from Gen 1--I am looking into seeing if I can rehab the original. There is a burn area on the PCB near four small capacitors. Why it failed there is another question/problem. Thanks for all the help!
 

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