Fuel Pump Power?

[JackLikesTrucks]

Hello again. Got the '94 cranking like a champ but now...

Won't start due to no fuel delivery.

No fuel pressure at the Shrader Valve.

Can feel the EEC and Fuel Pump Relays kicking in when I do the KO/EO test.

Did the test where I ground the EEC Diagnostic Port FP Contact to ground and redo the KO/EO test but no change.

No pump sounds, no Shrader pressure either. Ever.

Is there a way to check the power AT the pump or to power the pump to see if tis that before I drop a 15 year year old tank?

Thanks guys. Lost my Haynes manual. Ugh.

 

[lil_Blue_Ford]

If you got a skinny arm that you can get up on top the tank and pull the plug for the tank power, you could hold a test meter on it while a buddy turns the ignition to the run position (not start). I did that with a BII before, but I also had access to a lift and was able to get the test leads on the pump itself to see if it had continuity as well. I ended up with power to the pump but no continuity at the pump.. when I pulled it out of the tank I found someone replaced the pump and used crimp on splices...which fell off and were laying in the bottom of the tank... lil soider an I was good to go.

You could also pull the bed off, with the help of a friend, a few bolts and a plug or two, it's much easier to work on the fuel pump and tank than trying to drop the tank. I cut a hatch in the floor of two of the BIIs I've had to access the pump after I tried dropping a tank once and discovered that it dang near has to be cut out cuz of the rust around here.

 

[snake]

Check the relay first... more common problem and easier fix.

 

[AllanD]

Power to the fuel pump fails at specific discrete points.

You've already determined that the relays switch when you go to
Key On, Engine Off, but do they stay on while cranking or do they
cycle off?

you MAY be able to reach over the top and unplug the pump to
snake the connector out and check power, but frankly I'm a fan
of the unexpected frontal assault.... I'd pull the bed rather than
dropping the tank... half as many fasteners involved and NONE
of them require me to be UNDER the truck with dirt and rust
falling into my face to remove them.

AD

 

[JackLikesTrucks]

Well, with the EEC diagnostic FP connector grounded, and the key on/engine off, I am getting 12V at the pink/black connector 4 pole wire connector under the brake booster.

This tells me the pump relay has been tricked into staying "on" and am getting juice at least up to the connector before it goes under the cab to the pump.

Am I right in my thinking? Is the next step pulling the bed?

If I pull the bed up a coupla feet, what do I do about the filler neck?

 

[feellnfroggy]

94 tank you shouldn't have to drop it. just lift off the bed and make sure the wires on the pump arent corroded and shorting out.

 

[lil_Blue_Ford]

Filler neck has three lil bolts holding it on, just open up the gas door and undo them, should pop right through then

 

[JackLikesTrucks]

Well, I drowned the (6) T55 bolts of the bed with PB Blaster and loosed the filler neck and pulled the bed. Boy it was easy compared to dropping the tank.

Put 12V 20 fused power to the fuel pump and NO GO.

So off to ebay for a new fuel pump. I'll take the next week and de-scale the frame and give it a nice coating of Enseign 365 metal preservative while I'm waiting. Maybe some new shox while I'm there.

THANKS GUYS!