OK I'll try to keep this short, I have an 88 F150 w/351 blown, I got a complete donor truck 90 w/302-E4OD, I swapped Engine, Trans, Wiring harness (Front on Rad. Support) Wiring harness from front to taillights w/fuel wiring. Tank sending units. When I turn key to on pos high beam lights come on till front fuel pump stops. start truck high beams stay on (No control over high beams)
Turn key off pull on headlight switch rear fuel pump runs. The only thing I did not change was the Dash Harness, are they wired different from 88-90??? ANy other help would be appreciated

 

I have no contructive answers but gotta say that made me laugh. I'm sure it's frustrating though.

 

Might help if you post a more exact list of what you used from each truck.

I've been going over the diagrams for both and see no connection so far. No reason the two circuits should interact with each other via the fuel pump relay or instrument cluster. Clusters are slightly different yea but the two items you seem to have crossed are on the same pin locations on both years.

Kinda a pain though, both model year/components involved are over several pages worth in the book, that and need/use a magnifying glass just to see the tiny print! LOL

 

From the 90, Used 5.0, E4OD, Complete Front wiring harness, ( on RAD Support), Frame wiring harness (Fire Wall to Tail lights) ,ECM, Both Fuel pumps

From 88, Frame, Body, Interior Wiring & Steering column

Truck starts and runs

Could the power be back feeding through Ground?

 

No wires were cut and spliced any where 1990 had no issues before the change and it ran fine

 

I'm gonna have to go with "its in the cluster", there is some differences but I can't see a exact point as of yet. Just darn hard to follow it all in this book.

You could just try a fairly quick and simple test, unplug it and see if that corrects the problem. See if the fuel pumps and the high beams work normally without the instrument panel connected.

You'd have zero instrumentation, but it should run. You'd need the fuel tank switch connected during the test so it will pump fuel.

 

I'm going to change the harness tomorrow, I need the OD switch, and the steering column is in better shape in the 90, Thanks for your help, I'll let you know how I make out, I tried to read the prints in Haynes but didn't have much success!

 

Yes it sounds like there were some inconsistent pin locations between the two under-hood harnesses where they interface with the cab wiring. Swapping that or figuring out the differences should take care of the issues you are having.

 

Do you know what pins are different. I know this post is old but currently having this issue and can't find a clear answer anywhere. Ive came to the conclusion I need to find high beam indicator circuit at the round cab connector and replace with fuel pump but that all I know and it's very vague any help is very much appreciated

 

Holy thread resurrection! 17 years!!

I doubt you will get an answer from the OP.



You did this exact same swap? My suggestion to to start your own thread describing what you did and the problem you have.

 

Off the top of my head I have no idea what wire goes where. You may need to find a factory service manual (or equivalent) for both years to be able to determine the differences.

 

No I didn't do same exact swap I put engine wiring and ecm from a 1990 into my 87

 

Check this, when having E4OD, they change pin outs, the E4OD is going to need a PSOM in cluster to shift.
Ford Fuel Injection

 

Why did you do that? Did you change something else?

 

So to be honest I have a 87 with i6 and not sure if it like wiped a cam lobe or what but would constantly burn the whole end off the sparkplug #6 no matter what I did and when I say the end like the electrode and even a couple threads would be gone within 5 minutes of a new plug so it had a constant miss and hurt the power and mpg alot . Then the ecm went out and that was basically the final straw. Love the truck couldn't afford to get another so a friend of mine made me a steal of a deal on a 90 302 with new pistons rings . Comp cam that is soposed to have very similar to factory power band with more bottom end . Completely gone through by a local shop with paperwork and recipes and approximately 3000 miles on rebuild until the frame on his truck rusted in two so to me it just seemed like it made sense to put the 302 in since I already had it bought it about a year and half ago and was just running the 300 until it died . Witch technically it never did just ran like **** with the miss and I didn't just buy the engine I actually bought the whole truck but the frame perches was pretty ruff so I had to buy some and the ecm sold before I got it so I had to buy an ecm besides that already had everything on my thing was to do it . And only issue I've had is with the headlights and fuel pump . And currently I just ran the fuel pump off its own temporary circuit and will do the same with lights if I have to