Changed fuel pump, now no start?

rzimmerl

Registered User
so I changed my 255 pump to the 255 FI pump today and now it will not start. The pump is turning on and it won't start. The exhaust is still off, it almost sounds like it does when the inertia switch has been activated but I have reset that, and there is a 1/4 tank of gas. Any ideas????
 
0 fuel at all, non in filter and non in the lines. Tank is back out again.

Edit old pump pack in still no pressure, there is some dielectric grease on the pump sendor harness pins. Don't think that will cause a problem.

I am going to jump the inertia switch and see if that will rule it out
 
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You can force the fuel pump to run by grounding the test port on the EEC testing harness. I don't have the specific pin. But it should be documented in the haynes manual.
 
I'll try that next, thinking maybe the fuel pump relay. I just drove about 75 miles last night with this thing and no problems at all. I also installed a new fuel filter, it isn't doing anything since no fuel is even getting to it.
 
I checked the inertia switch last night by turning it up side down to activate it. It seems that what ever is inside that contacts the button was stuck on the bottom side of the switch, and would not pop the button until I tapped and loosened it. The button popped out and I then depressed it. If I ground the test pin does that indicate a bad relay? Does the inertia switch allow the pump to run at all, if it is activated?
 
When I changed out my pump, it would not start. I got good at dropping the tank, since I did it three times to figure it out...
On mine, the harness at the fuel tank had been over-stressed by the bad pump (I assume). The negative connection was intermittant at best. (Checked with my trusty analog ohmmeter).
Ford wanted $75 for the harness...ouch
Went to my boneyard and found a T-bird tank laying there with the connector still attached...$1 later, problem solved...
 
Change the end connector on the harness also, was $8 for a new one. I repinned it as I upinned the old one.
 
The Relay should be able to be swapped with a different one. Jumping the fuel pump test point to ground should force the relay on to drive the fuel pump. If you ground the test point and the pump doesn't run, you can search for voltage starting at the relay and working back.
 

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After hooking up the tank again, jumping the relay...still had pump power but no pressure.

So I pull the pump back out inspect all the connections, and noticed the pump harness is pinned backwards. The pump was spinning in reverse. So I repinned the connector and reinstalled. I get about 37psi with the key on and right around 40 idling.

Thanks for help.
 
Okay, what is the most likely cause of an intermittant?
Went to start the car this morning (it has been bucking under boost when warm), and nothing.
Depressed the shrader valve, no fuel whatsover in the rail.
Read this thread, and decide to jump the EEC connector, and the pump runs.
Start car, and runs like normal.
Any likelys?

Nick
 
That's one of the two relays in the trunk, correct?
Which one, the one on the long wiring section, or the short one?

Nick
 
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