32FFF150

Need to ask the WWW for this one.

My truck, I luv it, but right now she's being a bitch.

Won't stay running. Will only run and rev up as long as she is cranking ?

No voltage coming out of V-PWR at PCM to power FUEL relay, tab, tad etc? It's only at 0.15v when should be >10.5.
Done a continuity test from PCM to all of these connections and all ok.

I have tested EEC relay and it's all ticks.
I have tested FUEL relay, ticks again , except for low voltage from PCM.
Tfi module ok.
Coil ok.
New battery so that's ok and charging @ 14.3v.


If I jump the WHITE/BLUE wire from EEC relay to RED wire on FUEL relay she runs ok.
Obviously this is good but I don't know what kind of long term damage this would do.

But according to Mr HAYNES both relays EEC/FUEL should be getting >10.5v so I'm guessing this should not do any harm as the WHITE/BLUE wire only powers through the EEC relay once ignition switch is turned on?

To be honest I am lost and slightly scratch my head......

Any ideas appreciated.

LobstahClaw

I'm reminded of something Ymeski posted awhile back.

It's just a thought, but have you opened up the case of the PCM to examine the circuit board for any signs of burned spots or leaking electronics parts ?

Would it be possible to run the EEC in for testing somewhere nearby like a parts store or Ford dealership ?

Nitehawkjr

Have you checked the fuse links going to the EEC and Fuel pump relays? Link N goes to the EEC Relay, Link W goes to the Pump Relay

Warlockk

Have you checked actual continuity on the relay? Or use some jumpers and check for a voltage drop. Sometimes they tick but have high resistance so no power. I believe you said good supply power and switched power so the relay or a connection in the line sounds like the issue. Check ground side voltage drop as well.

32FFF150

Ok done all the suggested checks

PCM smells ok
Done the inline fuse checks and all the continuity checks and ok!
Done the grounding checks on the EEC & FUEL relays and ok!
But a low 0.25v from EEC relay to PCM which i am guessing is the problem so off to the auto wreckers tomorrow for a EEC relay
Ill let youse know how I get on

Thanks for the suggestions
Fingers crossed for a cheaper way out!

LastHurrah88

I will follow this thread closely, I am having the same problem with my 89 F250 7.5L. I have already replaced the fuel pump relay and throttle position sensor and got no improvement.

32FFF150

Well All I can say is thanks WWW for support
A ten dollar EEC relay fixed the problem
She started right up and seems to be running a bit smoother
Don't forget the little things!!!
And when in doubt ask!!!

Big thanks to all that posted.

LastHurrah88

My truck is now running! I am jumping for joy over here! It was the EEC relay, now I just have to sort out this leaky exhaust system.