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92 mustang fuel pump ISSUE

Foxman

Foxman

Well-Known Member
OK i have got everything hooked up and the fuel pump isn't coming on.. I check the voltage at the pump and its only 6.54 Volts... voltage at the battery is 12.7.... cant figure out way im losing half my Voltage to only the fuel pump.... any Ideas guys?????
 
HisPony

HisPony

Wondering where I am!?!?
Did you solder any of the connections?

If so, remelt them, a "cold" solder joint will sap a lot of voltage.


EDIT: Dirty connectors will also cause problems. Measure the resitance of each wire to make sure it is damn close to zero. Also measure each wire to chassis ground, should read open.



Jack
 
Foxman

Foxman

Well-Known Member
the grounds is what i was thinking... stopped after dropping tank and new pump didn't fix it...Old pump was bad...

No soldering was done so that's not it.. But i need to check the Resistance of the wires... So the grounds by the Computer and the grounds at the battery are the only ones... I know there is one from block to fire wall and the injector harness ground .... does anyone know where the ground is for the fuel pump???

good advice thanks guys i will start on this in about another hour
 
HisPony

HisPony

Wondering where I am!?!?
Getting some of the voltage means you have high resistance somewhere. Even though the soldering was done at the factory, it is still a good idea to check.

Electrical Gremlins are real hard to track down.

Please tell us what you find when you get it working!!


Jack
 
Foxman

Foxman

Well-Known Member
oh trust me i will let you guys know... Whats funny is I'm ASE certified in a electrical (a6), I understand it but i hate it... was really just hoping someone has had this same problem and they knew what it was...
 
HisPony

HisPony

Wondering where I am!?!?
Foxman said:
oh trust me i will let you guys know... Whats funny is I'm ASE certified in a electrical (a6), I understand it but i hate it... was really just hoping someone has had this same problem and they knew what it was...
Click to expand...

Well damn dude! That info would have helped from the start! LOL

Any where you can get the fuel pump checked?
 
M

Mustangcwo

Guest
You should also try bypassing the fuel pump shutdown relay. If there is a ground in the relay itself, it could zap your voltage. If it's installed.
 
Foxman

Foxman

Well-Known Member
Great info guys thanks

one thing though... i keep hearing about this Fuel pump relay... my car doesnt have one... nothing under the seat or next to the starter relay... No parts house has one... there computers read no part found for a 91 or 92 mustang.. and my Chilton and haynes doesnt say anything about a relay for a 92...... also have searched Google and have found more then one topic saying that 1992 mustangs do not have fuel pump relays...


orange395w said:
If my memory serves me correct, the fuel pump ground is on the pump itself.
Click to expand...

Great
correct... it connects to the wiring harnes and goes somewhere... just dont know where the wires stops... im thinking Computer...


Right now im going to look in to bypassing the Fuel cut off switch.. thanks guys! oh and start checking more grounds!
 
O

Oestang-2008

Well-Known Member
Relay

Foxman said:
Great info guys thanks

one thing though... i keep hearing about this Fuel pump relay... my car doesnt have one... nothing under the seat or next to the starter relay... No parts house has one... there computers read no part found for a 91 or 92 mustang.. and my Chilton and haynes doesnt say anything about a relay for a 92...... also have searched Google and have found more then one topic saying that 1992 mustangs do not have fuel pump relays...




Great
correct... it connects to the wiring harnes and goes somewhere... just dont know where the wires stops... im thinking Computer...


Right now im going to look in to bypassing the Fuel cut off switch.. thanks guys! oh and start checking more grounds!
Click to expand...


Fuel pump relay under the mass air wiring... 2 Square boxes one is a AC relay and the other ties into the fuel pump some how... Plug is white and black..
 
Foxman

Foxman

Well-Known Member
ok found were the problem is.... dont know how to fix it...

there is a single wire that comes off the battery ground wire... it plugs in to a wire by the starter solenoid... its a junction of ground that go to I believe O2 sensor, ECU and i dont know where the other to go but once i unplug it i have 12 volts at the fuel pump but still the pump doesnt come on and the EEC power relay no long clicks when ingiton is turned to the on position which makes me think the one of the 4 ground wires is for the EEC power relay...

Well im tired and will mess with it a little more


oh and there is only one relay and only on plug for a relay on the passenger side strut tower and it is A/C! oh yea... the last of the 4 wires taht goes tto the plug on the negative battery wire is for the A/C compressor.......

Hope that makes some kind of sense.... im very tired and cant really think striaght! to much BEER LOL!
 
Foxman

Foxman

Well-Known Member
I think my wiring is missing something

I keep hearing about this Fuel pump relay that is suppose to be a on the passenger side fender well and there isn't one there only the A/C relay is there... This harness isn't in that great of shape so i might try and pickup a new one or a good used one... but hey Emilio I would love those wire diagrams...

ThE car is a 1992... harness is out of a 1991
 
Foxman

Foxman

Well-Known Member
FIGURED OUT MY PROBLEM!!!

You can not use a 91 mustang 5.0 engine harness in a late model 92... mid year 92 they changed the location of the Fuel pump relay from under the driver seat to the passenger fender well... so a 1991 engine harness will not have the correct wiring for the fuel pump because my 92 doesnt have the fuel pump relay circuit wired to under the the driver seat.... 91 has the FUEL pump relay under the Driver seat

****!!! I need a late model 92/93 5.0 engine harness!!! if anyone has one let me know.....


Of f!cking course i get the car that has the one f!cking change done to it!!!
 
O

Oestang-2008

Well-Known Member
Harness

Foxman said:
FIGURED OUT MY PROBLEM!!!

You can not use a 91 mustang 5.0 engine harness in a late model 92... mid year 92 they changed the location of the Fuel pump relay from under the driver seat to the passenger fender well... so a 1991 engine harness will not have the correct wiring for the fuel pump because my 92 doesnt have the fuel pump relay circuit wired to under the the driver seat.... 91 has the FUEL pump relay under the Driver seat

****!!! I need a late model 92/93 5.0 engine harness!!! if anyone has one let me know.....


Of f!cking course i get the car that has the one f!cking change done to it!!!
Click to expand...

Here is what the harness should look like... One of the boxes is for AC and the other is for Fuel pump... Sounds like you have the wrong harness..

http://i679.photobucket.com/albums/vv155/Oestang/Picture672.jpg
 
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