i have a 92 lx 5.0 fox body that is not receiving any power to the fuel pump . I did change the fuel relay on the car . still no luck on power . Is the relay grounded by the bracket and bolt that it sits on under the mass air flow sensor ? i was driving the other day and just lost power in the gas pedal and then it would not start. Any ideas where to start to pin point why no power is getting to the fuel pump would be helpful . i did check the switch in the trunk and it is pressed all the way down . thanks guys for your help
-
Sponsors (?)
Multimeter and the tried and true "Cranks OK, but No Start Checklist for Fuel Injected Mustangs"...all hail jrichker (think Men in Black here).
stangnet.com
You need to run through the parts of the list that make sense. For example if you have spark then skip those steps.
Cranks OK, but No Start Checklist for Fuel Injected Mustangs
Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...
stangnet.com
You need to run through the parts of the list that make sense. For example if you have spark then skip those steps.
TIGGER
Founding Member
I would take a meter or test light and verify there is power at the fuel pump. Basically verify that the inertia switch is not open. They do go bad for whatever reason. This happened to my buddy on the 89 that I bought from him. He drove it to work, parked it and went in. Came out to go home and it would not start. Fuel pump was not priming. He did not have a meter but he had a phillips screwdriver and a paper clip. He took off the rear panel, unhooked the pigtail to the inertia switch and shorted the wires together with the paper clip and the car started. It got him home. Hope you figure it out.
There's 4 main wires at the fuel pump relay. They change every year so need to consult the 92 EVTM to give you colors. There is also a fuel pump monitor wire on the 89+ cars. i will have to post the 1992 evtm wiring diagram tonight
Feeding the pump, there is a wire that comes in from a fusible link. This wire is constant 12V+ to ground. When the relay closes, it feeds another wire out to the pump. Some years had the inertia switch before the relay, and others had it after.
On the coil side of the relay, one wire should have Key on 12V fed from the EEC relay next to the computer. When you turn the key on, you should hear this click. The other side is a switched ground connected to pin 22 on the ECU. When the ECU commands the pump on, this will close to ground you can test by testing continuity from this wire to ground (relay disconnected) and turning the key to on. Should have continuity for 2 seconds.
Feeding the pump, there is a wire that comes in from a fusible link. This wire is constant 12V+ to ground. When the relay closes, it feeds another wire out to the pump. Some years had the inertia switch before the relay, and others had it after.
On the coil side of the relay, one wire should have Key on 12V fed from the EEC relay next to the computer. When you turn the key on, you should hear this click. The other side is a switched ground connected to pin 22 on the ECU. When the ECU commands the pump on, this will close to ground you can test by testing continuity from this wire to ground (relay disconnected) and turning the key to on. Should have continuity for 2 seconds.
Similar threads
