I am aware of the fuel pump setups on a 1989 versus a 1990. As stated several times Ford is notorious for small wiring changes between model years. You have a wiring issue, not a computer issue. You made this a much harder swap by using the later model year engine harness. I can tell you again, like the others have stated, you need an EVTM for a 1989 and a 1990 model year truck to fix your issue.

 

ok gotcha I will do that and sorry don’t mean to be anoying or question you at all just my first time doing a swap and not good with wires so was tryna find a way to avoid that all together but I guess this is where I learn lol

 

and what would make the 1989 harness work easier would I still be able to use the 1990 pumps or ur saying to just go back to the 89 fuel tank set up

 

1989 harness and use the 1990 pump setup.

 

ok and now what about the harness in side the cab behind the dash does that one has to be changed also ? Or can that stay the 90

 

Does everything else work? If so, leave it alone.

 

[QUOTE=rla2005;21489141]Does everything else work? If so, leave it alone.[/

yes I belive it did I will try with it again and if somthing isn’t right I will switch that to if needed I really appreciate your time man thank you so much

 

so I took your advice and used the 1989 harness all the way and the front and rear pumps work and switch between eachother but I still don’t build fuel pressure after the first start up they prime and don’t seem to stay running when the truck starts when the truck starts it feels grate no misfire but quickly dies do to no fuel after the truck shuts off i check the fuel rain valve and it just like drips out instead of my other truck where it sprays hard even when the truck is off

 

When the computer is first energized, by cycling the key from the Off to Run position, the computer is programmed to apply a ground to the fuel pump relay for 1-2 seconds. This is the 'priming" you hear.

When you advance the key to the Start position the starter is energized, the engine starts to turn over/crank. The distributor starts to turn which produces the PIP signal. When the computer senses the PIP signal it will re-energize the fuel pump relay for the same 1-2 seconds as well as tell the Ignition Control Module (ICM) to fire the coil (SPOUT signal). The computer will also start firing the injectors to add fuel. As the engine continues to crank more PIP signals are produced, which resets the timer for the fuel pump relay for keeping the relay energized and the computer continues to tell the ICM to fire the coil and pulse the injectors On/Off.

The amount of fuel introduced during the prime cycle is quite small. Since you are getting at least a little bit of run time on the first start after the prime cycle that indicates the computer is firing the injectors. But as you stated the fuel pumps are not staying energized. You can validate that with a fuel pressure tester/gauge or use a DVM/test light to see if the relay is staying energized while cranking or that short run time.

First test: Cycle the key from the Off to Run position. Does the Check Engine Light (CEL) illuminate and stay on?

Second test: Advance the key from the Run to Start position. Does the CEL turn off while cranking?

If the answers to both tests above are yes: Use a jumper to tie Pins 2 & 6 together on the diagnostic port (the connector you use to initiate the KOEO/CM Display and KOER tests). Turn the key to the Run position. Do the fuel pumps turn on and stay on?

Pins 2 & 6 jumper info (courtesy of Subford:

 

ur the man gona give this a shot tomorrow and get back to you had to work late tonight

 

what’s up budy so I did the test engine light came on when in on position and went off when in cranking position I used the jumper wire to tie pin 2 and 6 together and the pump stayed running I also hooked up a fuel pressure gage and when priming it goes to 30 it seems to hold pressure but does not move from 30 wether cranking it or just priming and the pressure does drop pretty fast within two minutes it drops 10psi to 20

 

So it appears the computer is getting the PIP pulses, that is why the CEL goes out while cranking and the injectors/coil are firing. With that said it is looking like a possible bad computer to me. The timer circuit is working for the initial priming cycle. The PIP pulses are at least satisfying the logic to trigger the injectors, the coil and keep the CEL off, but the computer is not internally sending the signal to ground the fuel pump relay while cranking. Odd failure mode.

30 PSI KOEO is on the low side. I would expect 35 to 40 PSI. A 10 PSI drop in 2 minutes Key Off is a bit much, but not that much out of the ordinary IMHO.

 

ya seems like an odd thing I do have a 1989 f250 computer with the same trans and engine as mine I can try that one and see if anything changes I will pull engine codes to and put them here incase that tells u anything also

 

so I pulled the codes and got 23 ,10 ,53, 96 I also got the truck to stay running but have to pump the gas like crazy just to get it to start and keep it down to keep it running rough but did notice my throttle position sensor looks bad due to a wire almost being pulled out the copper is showing so going to replace that next

 

Also tried the other pcm I had and the fuel pumps wouldt run they ran with the jumper wire but not by the key turning weird