fuel pump headache

[nesralyrrej]

so its a 1991 2.3 2wd 5 speed ranger, it was driving fine then cut out out of no where, first thought was out of gas but not the case, the fuel pump doesn't prime when they key is turned on but the interesting part is when you remove the battery cable you can hear it prime but no matter how many times you cycle the key it doesn't pump. if you ground the lb/o in the diagnostic harness the pump goes and you hear the relay tick, if you put 12v into the dg/y yellow wire in the fuel pump relay it also goes, its got voltage in the red and the bk/y wire in the relay. im basically on my wits end lol any help would be great guys. ill post a few picture of things shortly

 

[RonD]

Fuel pump power looks like this

Battery--30amp fuse--(blk/y wire)--Relay--(green/y wire)--inertia switch--(pink/blk wire)--fuel pump--Ground

Green/yellow wire also goes to Computer so it can monitor if 12volts is going to inertia switch/fuel pump

The Relay power is like this:

Battery--(30 amp fuse)---EEC relay----(red wire)--Fuel Pump relay--(blue/orange wire)--computer--ground

So the relay gets 12volts when key is on, but it has no Ground so doesn't click, the ground is operated/controlled by the computer.

Grounding the blue/orange wire in VIP test port gives the relay its ground that the computer should provide for 2 seconds when key is first turned on or when engine is running, this reads like what you are missing.

Doing that test means the fuel pump relay and fuel pump are working, problem is the computer circuit not grounding the relay, or wire on computer is bad, or one of the grounds at the computer is bad.



This is a diagram of the computer connector, pin 22 is the "control wire" for the relay.
With key on that pin will show 12volts, if you ground that pin fuel pump should come on, that would mean the wire is OK.

http://www.auto-diagnostics.info/ford_eec_iv

Then test the ground on that connectors as listed

 

[nesralyrrej]

Good answer, A few questions still, am I supposed to ground the 22nd pin in the pig tail? And what would cause it to have no spark? I'm failrly sure it's the icm though. And what on gods green earth is causing the fuel pump to prime when I switch the key from on to off? So it primes when the key is in the off position..

 

[nesralyrrej]

I've checked all the grounds and they all tested good could it be the icm? It tested bad for threshold

 

[SRich]

Sounds like the contacts inside the relay are not providing continuity. Mine started doing that and I have found that taking the relay and striking the top firmly on a counter or sidewalk then reversing and gently striking on spades side it will work fine for about 3 mo.
If you have the cash to get a new one I would recommend it. I am cheap because college sucks up any spare cash.

 

[nesralyrrej]

I have tried a new fuel pump and EEC relay with no improvement

 

[Andy D]

Wild @$$ed guess. Have you checked the timing belt?