Gentlemen,

After the euphoria of fixing my injectors not working on the passenger bank had passed went out to the shed today to move the truck out so I coud start work on another project and it wouldnt start.

Symptoms first.

• Cranks but wont start
• Fuel pump doesnt run.
• No spark
• Injectors not pulsing

What I have checked

• All fuses - good with none blown
• Ohmed pump relay 86 to earth - was negligible so thats good.
• Jumped pin 30 -12v to 87 pump runs
• Checked power to PCM at pin 20(?) - the orange one - 12V
• Checked continuity between PCM - pin 2 - green and white wire - and the CPS plug - All good.
• CPS was changed as part of the prior trouble shooting
• Plugged in other known good PCM - still no start
• There is no voltage on the CPS plug with ignition on - I was lead to believe that there should be 12 volts.
• Battery voltage is 11.8v

The amount of frustration I am feeling towards this damn truck is beyond description. As it was running and now isn't I am hoping that it is something really simple and one of you clever soles will go "Ah Ha you Bald Twit its...."

Over to you Gentlemen, what have I missed.

Paul.

 

Does the fuel pump even prime with key on?

 

No.

Turn the key to run and nothing. It will crank from the key.

Paul

 

If the fuel pump isn't priming, I'd first jumper the fuel pump relay and see if the pump runs that way. If it does, I'd be checking the wire going from the ignition switch to the PCM to make sure it's sending a 12V signal when you turn it to key on. The pump prime is solely based on the PCM receiving a 12V signal from the ignition.

 

Pump primes when relay is jumped - its 9pm here so will check the ignition switch in thre morning.

I have 12v at pin 20 will check if that is key on or constant - if that makes a difference??

Thanks for the reply.

Paul

 

Update.

After 8 hours of trouble shooting, testing the continuity of all lives, earths, triggers etc back to the computer, stripping the loom down and looking for any breaks etc I had that 'oh ****' moment when the pump started running as we started fixing everything back in place.

With #3 son on the key and my head on the passenger side where the computer, engine fuses and relays are positioned, wiggling the wires (technical) caused the pump to start and stop accompanied by an electical clicking. This was traced back to the Current Performance engine loom fuse box and eventually to the green and white trigger wire on the fuel pump relay.

Turn the key, pump runs, wiggle wires, pump stops. continue wiggling wire and pump kicks back on. The clicking sound was the relay energising.

Took the fuse and realy block back off the fire wall and the pump relay is not a great fit. Bent the pins and still not a great fit, but better.

Wiggled wires and same result.

This is where it gets weird.

Check the fuel pump fuse and there is no power across the fuse. Take the fuse out and test - its good - replace fuse, no current across fuse but power to back of fuse.

Wiiggle the wires, truck starts check power across fuse - nothing. Take fuse out whilst engine running pump and engine stops.

Put fuse back in and it starts. BUT THERE IS NO POWER ACROSS THE FUSE!!!!!!

What the actual F**********K!

I am not impressed with the quality of the Current Performance loom. The fuse/relay box is very poor quality so I am going to replace it with a better quality version as this seems to be where the problem lies. Whilst there is no actual 'Smoking Gun' the finger of guilt is pointing towards this cheap block.

Anyway, lets if this fixes the issue - cant help but think this could have been the underlying problem I have had all along.

A very frustrating weekend to say the least, will report back when I have upgraded the block and let you know what I have found.

Paul

 

Thanks for letting us know what you found. I will say, I have a Current Performance harness in my car and I was really happy with the quality. They also have good customer service. I would contact them and see what they have to say.

 

Maybe I have a Friday afternoon build but my experiance has been vastly differant to yours.

Anyway, going to build my own fuse and relay junction box and see how we go from there.

Paul

 

I have a current performance integrated harness on my truck along with holley and I haven’t had any issues that werent self inflicted. The only issue I can say i did have is that I had a 12v supply power wire that I had on a distribution block that the nut was slightly loose and my truck was doing exactly what your explaining. My pumps would not get 12v for the life on me, i finally found that loose wire and tightened the nut and have not had an issue since.

 

Have you check the fuel pump connector to make sure it isn't melted?

 

I have a remote relay within 2ft of the fuel pump with a dedicated power wire from the battery (rear mounted) all using Deutch connectors.

This is triggered by the fuel pump relay in the fuse/realy block, I will check it however just to be sure!

Dont have an axe to grind with CPI, just comparing the quality of the compents to the Amercian Auto Wire loom and it is night and day.

Paul