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Topic: HELP! Fuel pump primes when headlights are turned on... (Read 6764 times) previous topic - next topic

HELP! Fuel pump primes when headlights are turned on...

Reply #30 –
I cleaned up the contacts a bit more and i did get a reading, a .611
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #31 –
Quote from: Loaded87IROC;319550
sorry, alright...

On the cluster itself pins 1 and 13 show no reading, just a 1

This is with one meter probe on pin 1 and the other on pin 13, with the meter set to OHMs.
Is this correct?
If it is reading 1 ohm, that's not good. What does the meter read when it's not hooked to anything?
I am working on page 98 of the EVTM. Are both of the connectors show there on the cluster?

HELP! Fuel pump primes when headlights are turned on...

Reply #32 –
I got a reading of .611 after cleaning up the contacts a little.  The cluster only has spot for a connector. 

1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #33 –
Looks like you have a connection between those two circuits. That's not good.
On page 98 in the lower left side they show "Instrument Panel Illumination" with two bulbs. You can see pin 13, labled on the top side of the box, is the power source for the bulbs.

On page 117 you have pin 1 on the cluster going to the brake indicator bulb.
You are going to have trace the land patterns for these two circuits and see if you can find someplace where they have been bridged together.

HELP! Fuel pump primes when headlights are turned on...

Reply #34 –
Supper time here on the East Coast. I'll check back with you in an hour or so.

HELP! Fuel pump primes when headlights are turned on...

Reply #35 –
So, I need to physically inspect all the wires coming from #18 on the fuse panel?  Like the diagram on page 27?
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #36 –
Awesome, thanks again.  I owe you a beer/dinner ;)
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #37 –
Ok here is what I did while you were away.  First I followed the red wire with yellow stripe out of the fuse box.  It went a few different places but nothing looked to be in bad shape.  Then I hooked up my test light to ground (frame that the steering column bolts to.)  I stuck the dangerous end into the fuse panel in spot #18.  When I did this the light lit up very dim and the headlight chime sounded (very faint.)  I put the fuse back in and connected the cluster.  I tested the lights and the fuel pump turned on.  I then unplugged the chime box and tried it again and no fuel pump.  I tried this several times and got the same results.
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #38 –
The two circuits that are getting tied together do both go to the Warning Chime Module.
Not where I was trying to steer you to. I was trying to get you check for the circuits being tied together on the cluster itself.
I can't see how with the problem being in the chime box that disconnecting the cluster made it go away.
But you can't argue with success.

What's next?

HELP! Fuel pump primes when headlights are turned on...

Reply #39 –
I assume the car doesn't need the chime box for anything?  If so, I would just as soon leave it out. 

Hmm, I guess next would be cluster illumination.  Turning the lights on does turn on the dash lights now, but the cluster lights do not light up with the exception of the right turn signal indicator lights up solid.
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #40 –
Quote from: Loaded87IROC;319375
I used some test leads I made and tried applying 12v to the different wires in the cluster plug.


dont do this again,, even on a toaser.. its wrong and will cause you more harm than good no matter what your working on.  I meant to mention this the other day but had to take off, been looking at the evtm and following along.  I like a good puzzel to work.

the only thing i can think if you both dont mind my saying is I would have started at the starter solenoid in the following manner.

-disconnect all output wiring on the solenoid except the small slip on wire boot, lay the starter wire to the side
-turn on headlamps
-leave cluster connected
-touch each wire to the starter relay post and observe when headlamps came on
    -if headlamps came on and no fuel pump, you can isolate circuits easier
    -if headlamps came on and fuel pump also rans, you have a common source circuit.

the reason i say this is because we do have several unfused circuits in these cars.  using the evtm is great but if someone else tapped into a hot wire or a ground in an incorrect spot, its gonna take exactly what your doing, one step at a time.

HELP! Fuel pump primes when headlights are turned on...

Reply #41 –
You know, I observed some very strange behavior once on my 87 TC.  I had just removed all the carpeting, and after I was finished, I attempted to drive the car.  When I turned the car on, the headlights came on, I think the door chime sounded, and I believe the right turn signal indicator on the gauge cluster was permanently lit.  I believe there were other wacky things, I just can't remember them now.  Anyhow, I traced it back to a ground, located at the bottom back passenger side corner of the center portion of the dash (radio, AC), that I forgot to reconnect.

HELP! Fuel pump primes when headlights are turned on...

Reply #42 –
Thanks for that step by step Scott. I may still end up following it I can't get all of my issues resolved.  Removing the warning chime did seem to take care of the fuel pump running when lights were on issue.  I really have no need of the chime so I would like to just leave it out.  Hopefully with everyone's puzzle solving help I can get this stuff sorted out.

That ground hasn't been connected since I did the engine/wiring swap but I suspect it may have been laying against the frame of the dash allowing it to ground.  I went ahead and bolted it to the firewall.  I am still getting an always on right turn signal and no other cluster lights. 

Thanks again to everyone who has responded.
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #43 –
Ok, a new piece of information.  I tried the extra chime box that I had and the outer lights came on without the fuel pump.  I switched back and forth several times and every time the first chime caused the fuel pump to turn on with the lights and the second chime box did not. 

I also noticed that I forgot to put the high beam indicator bulb back in at some point during this fiasco.  So I put it back in, and now both turn signals indicators as well as the high beam indicator are on when the lights are turned on.  I also noticed something else.  When the high beam indicator bulb was out of the cluster, the fuel pump primed with turning the key to run as normal.  When I put it back in I noticed the fuel pump turned on when turning the key to run as normal and it turned on again when I shut the key off.  I tried it several times both with the bulb in and out and the results were the same.
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

HELP! Fuel pump primes when headlights are turned on...

Reply #44 –
I have run down all the wires on the cluster connector. This is from the 86 EVTM. Connector is shown on page 98. Page referances below are EVTM pages.

[LIST=1]
  • R/Y Hot in Start or Run---Fuse 18--Page 117
  • W/PK Overboost Warning Lamp--Page 124 & 36-(Ground side of lamp)
  • P/W Brake Indicator Lamp--Page 117 (Ground side of lamp)
  • Y/W Fuel Gauge Sender--Page 117
  • R/O Ammeter--Page 22--Hot at all times
  • Y/LG Ammeter--Page 22--Hot at all times
  • BK/LG IVR Voltage through an 8.5 ohm R--Hot in run--Page 117
  • W/R Oil pressure sensor--Page 117
  • R/W Temp gauge sender--Page 117
  • DG/W 5 volts from IVR to low fuel warning module (optional indicators)--Page 117
  • DG/LG Fasten seat belts lamp--Page 131
  • BK  Ground
  • LB/R Panel Illumination--Fuse 13--HL Swt--Fuse 4--Page 98
  • W/LB RH Turn Indicator--Page 88
  • LG/W LH Turn Indicator--Page 88
  • DG/Y Tach Input--Page 36
  • LG/BK Hi Beam Indicator Page 71
  • DG/W Speed Sensor--Page 175