[jwstott01]

I have an 88 GT, and did a MAF conversion yesterday. I used an 89 computer and harness and MAF housing. I ended up with a few extra connectors that had nowhere to plug into. The main reason Im posting is that when all was finished, I had no power to fuel pump. I know everything is hooked up, and know that everything is from an 89. I hot wired the fuel pump relay under my driver seat, and it started right up. Took it for about an hour test drive and didnt have any issues that I noticed. So, any ideas as to why I dont have power to my fuel pump??? Any info or advise is appreciated. Thank you

[jwstott01]

I need help please...Anyone got any input???

[Uber88GT]

Hmm....could be alot of things, is the relay blown?

[jwstott01]

No, the relay is fine...A buddy of mine told me that the guy I bought the harness from might have lied to me about it being an 89 harness because it had a few extra plugs on it that I had nothing to plug em in to...2 of those connectors are for airbags.

[Uber88GT]

When I did mine, I just bought a conversion kit and followed the instructions...worked perfectly for $30. Have you jumped the test plug to see if the pump will run?

[1NVERTED5.0]

if it has hook-ups for an airbag its at least an 90+ ecu because thats the first year they had airbags on them..

[jwstott01]

Hmmm...What is this test plug you speak of???

[jwstott01]

Im pretty sure the eec said 89mf(0r something like that)...The harness I now believe is questionable...So if it isnt an 89 harness and it happens to be a 90 or so harness, can I make it work...I also noticed that my oil press. is reading thru my temp guage...UGGGHH...What else could be wrong...

[fogged306]

I've never seen a 90 harness so I could be incorrect here, but I can't say I've ever seen a vehicle where the airbag harness is tied in with the ECU/PCM/EEC whatever you want to call it. They always have their own seperate controller and at best are tied into a BCM which these cars don't have. I just removed my entire EEC harness out of my car for a re-wire and it is completely separate from the rest of the cars harnesses. Sounds to me like you have some wiring backwards or not hooked up. Here is a pin-out for the harness. I would start by checking to see if the fuel pump output on the EEC is sending a signal when it should.

[1slo5.0]

Originally Posted by jwstott01 No, the relay is fine...A buddy of mine told me that the guy I bought the harness from might have lied to me about it being an 89 harness because it had a few extra plugs on it that I had nothing to plug em in to...2 of those connectors are for airbags.

Then its a 90 or newer harness. 1990 is when air bags first appeared in Mustangs.

[jwstott01]

So will the 90 harness work or should I get an 89 harness???

[1slo5.0]

Originally Posted by jwstott01 So will the 90 harness work or should I get an 89 harness???

It should work just fine. Realistically all you needed was a MAF plug and harness which is available for about $60. Then you just wire it in and make a couple pin changes on the factory computer harness.

However since you swapped harnesses, that is what we have to address right now. First things first, lets check the computer. Can you pull it and post the numbers that are on it? Next, how exactly did you hot wire your relay?

[flyin ryan]

FYI

1987-1988 Speed Density. All the speed density engine harnesses are interchangeable. Ford used a different computer in 86, but the engine harness is the same. The dash harness in the 86 is specific to that year car and will not work in the 87-93.

1989 Mass Air and No Air Bag. One year only harness. Only car with mass air and no air bag. The dash harness is the same from 87-89 on all models, but the engine harness is specific to the 89. The 89 harness can be used in place of the stock 87-88 harness for anyone looking to do a mass air conversion.

1990-1992.5 Mass Air with Air Bag. Fuel pump relay is under the drivers seat. All the dash harnesses for all models from 90-93 are interchangeable.


What you have is most likely a harness from an 89 but actually a 90 model harness. They switched over to the 90 style harness towards the very end of production on the 89's and I found this out the hard was as well like you are. I ended up pulling the damn harness out since I couldn't get it to work and selling it as a 90 harness, then converting my 88's harness and reinstalling that.

[jwstott01]

Ok thanks for that info. I have a Guy that's gonna sell me a non airbags 89 harness. I've already looked at it, so I know for sure its the right one. Thanks again for all the info fellas.

[vette eater]

funny, i dropped in a 94 5.0 and used a 89 computer and harness to convert my 88 to a mass air car . . . . i only have idle down issues. i have an 88 harness for sale if you wanna try to mod it without ruining your original.

[jwstott01]

No thanks *eater*, I have a guy thats got an 89 harness with out the air bag plugs. Thanks tho/

[AdderMk2]

Originally Posted by vette eater funny, i dropped in a 94 5.0 and used a 89 computer and harness to convert my 88 to a mass air car . . . . i only have idle down issues. i have an 88 harness for sale if you wanna try to mod it without ruining your original.

you used an 89 harness to convert an 88... which is exactly what the OP is trying to do... but he got the wrong harness.

and the year of the engine doesnt mean shit btw

[jwstott01]

Hey Adder, you think I should pick up the eec with the new 89 harness...or is the 89/90 eec I have now gonna work???

[AdderMk2]

any fox maf computer should work fine. Just double check the 60 pin connector pin diagrams to make sure everything is in the same place

[TooSlo86]

There are a couple wires you need to add, one I believe was the fuel pump, along with the vss. I do remember having to run one over under my seat. Just google MAF conversion. I think I found the article at TCCOA. I don't have time to find the specific article right now, but if you didn't change pinouts at the ecm or run an added wire, that's your issue.