1992 e-150. I6 4.9 FI standard length, 35 gal midship tank

Question: What are the possible reasons my replacement fuel pump works NOT being attached to the van, but when I connect it to the van and turn on the key, it does not seem to do anything? I expect the pump to spit liquid (in this case H20) when the key is first turned. What is possibly wrong ?

Background: Doing a fuel pump replacement, dropping the fuel tan... the "by the book" way.
I got an aftermarket fuel pump, comes with a pigtail as do most fuel pumps to attach that specific fuel pump electrically.
I tested the fuel pump "externally connected" and "van connected" and when connected to the van with my new wiring connector, it doesn't spit out liquid while it does "externally connected"

Definitions:
Externally connected : Remove battery from van, submerge pump in a small bucket of water. Connect + and - terminals from battery to pump appropriately with test leads. Pump spits out water. Seems good

Van connected : Same battery back in the van connected as normal. Pigtail connection made for fuel pump with "bullet" type crimped connectors.
Pump + and - leads seem to have about 6.9 volts between them. I connect the fuel pump in a water bucket to the wiring harness as it would be when I actually put the fuel tank back in. I turn the key and the pump doesn't spit out water. I would expect it to spit out water at first when I turn the key.

Any help is appreciated.

 

Offhand, I'd say you need to find out why there is only 6.9 volts there.

 

So where would I start troubleshooting getting SOME voltage but apparently not full voltage ? I dont know where to start. I am assuming 12v is the target voltage ?

 

+1 on that. If you ground the fuel pump test pin in the EEC TEST connector the circuit is continuously energised for troubleshooting, if you don't do this it only gets power for about a second after the key is turned to run.
Also check that you have the pump wired with the correct polarity, if you have it wired backwords it will run but it's trying to push back into the tank instead of out.

 

Oh awesome this sounds promising. Where is the EEC test commector ? I saw it in the full blowm $200 fsm that I have, but no indication of where itnis actually located. Also, I see in the manual it has 4 pins. Do I just stick a wire into ome of the pins and commect thay to a groumd somehow ? Any good directions are much appreciated.

 

It's mounted on the inside of the fender to the right of the battery and above the coolant reservoir tank.

That connector is used to hook up a code reader. If you plan to work on your van much, you should invest in one as they are reasonably priced.

Refer to manual for pin layout.

 

Any time you read low voltage on these Fords, to the pump, one thing to check is the inertia switch. Bad contact inside drops the voltage, yet will read continuity, if checked. Read voltage on both sides of the switch.

 

You had better check the fuel pump relay
If you have 6.9 volts at the pump, the system is working and you have either bad wiring or a bad fuel pump relay
Check the fuel pump relay contacts in particular (pull the cover off and inspect)( the contacts)
They turn green with a little water intrusion after time

 

Thanks for the reply, but I don’t understand what you said. If 6.9 V at the pump means “the system is working”, why does it also mean I have bad wiring or a bad pump ? I must be misreading or something. Could you please clarify ?

 

Bad wiring or a bad pump relay. Not a bad pump. You need to understand what relays do. Take a look at the links below:

https://www.aa1car.com/library/fuel_pump_diagnose.htm

https://www.google.com/search?client...uel+pump+relay

 

I think what he's saying is,6.9V says you're getting power but not the full 12V. So it could be wiring corroded or bad connection, or you're relay contacts are dirty. Or your fuel pump is bad, Clean everything all connections grounding points, etc, etc and recheck voltages before coming to the final conclusion it's a bad pump.....I hope I interpreted that correctly??

Kind of give you an idea, I replaced the rear pump on my 90, and wouldn't start, no fuel, go back down the line, recheck everything and come to find out, when my son plugged the harness back in to the pump, he didn't seat it all the way and it wasn't getting power to the pump.

 

The processor and the relay and the inertia switch is doing their thing is what I mean
The 6.9 volts means there is still a problem because it is battery voltage you are looking for at the pump
Used to see the connector at the pump fail and the relay contacts fail
You might have voltage drop from old wiring or any bad connection

 

Ok gotcha - Everything is not Ok is what you were saying. There should be 12V at the pump, which there is not so that is a problem. Given that I am getting SOME voltage at the pump sort of eliminates all the elements prior to the pump within the circuit (fuel pump relay, i ertia switch) completely failing.

To find out where the bad connection is, I am going to do a voltage drop test. In doing this, I need some long wires to connect my meter to, say the (-) terminal on the battery and the (-) wire at the pump harness. Wont these long wires introduce some voltage drop in the reading ?

 

Yes, but only about .1 - .2v
You need 60 to 80 feet of wire to drop 4 volts

 

It's under the hood on the drivers side inner fender, it may be clipped to something or simply laying or hanging and looks like this...