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Discussion Starter #1
So....... Of course I'm having fuel pump problems (so it seems) with my 89 lx 5.0

I feel bad even bringing a fuel pump issue up with all of the past threads that should probably answer my question somewhere in all of them. Its just that I'm such a mechanical novice a lot of the diagrams look greek to me at times, & then the ones that look fairly straight forward I seem to either get ahead of myself, doubt myself on what I'm exactly needing to test with the volt meter, & other just novice crap & doubts on what I'm doing.

I am so frustrated with a friend of mine who has gotten pretty good with fixing cars. I spent 5 hrs. with him the other night helping him move some of his part jeeps & running jeeps into different bays in in big garage he built in return for him to just come & run some voltage tests for me. With his new found mechanical knowledge & his expert knowledge in electrics (being he does heat & air he is very good at finding where the problems are in this area. For him it would prob. take him 30 minutes to find my now 2 week on/off hunt. SORRY...... Had to vent on that.

Anyway here is the original thread problem I posted.

"I bought this 89 mustang lx 5.0 about a month ago. I drove it for 4 days with it running flawless. Then went to crank it one morning and all it would do was turn over with no intentions of starting. I have some how managed to crank it 3 times since this problem started. Looking back it seems like the 3 start times were after me tinkering with things like the fp relay, the inertia switch, &/or misc. tinkering. So after (I guess prematurely) dropping the tank & replacing the fuel pump, then next replacing the relay. I am still not getting any response from the fuel pump when I turn it on.

Do you think being that it has started a few times for me after tinkering this could mean its more than likely a short somewhere? Or does anything I have done or said make you guys think of something more obvious to check out? I'm almost to the point of handing it over to a mechanic as I am getting so frustrated.

How can I go about putting in a temporary turn on/off switch for the fuel pump. Is this an option for me or even advised? If so at least to check problems out, how would this be done?

Any and all answers or advice would be greatly appreciated."

So anyway here is where Im at now. I still have my fuel tank dropped just in case the problem is closer to the actual fuel pump itself.(However everything is still connected to the car bar the tank being strapped back up) Ive now replaced the fuel pump relay, I tested the inertia switch( im assuming that when someone suggested to check the power in & out of the switch that they were referring to the 2 red wires leading from the pug that plugs into the switch) this showed power on both red wires when connected to the switch using the volt meter)

So the next thing I feel I should be testing is the ECM?? I am a bit weary of this step b/c to check into the ecm directly thats a pretty tight area that I feel I might do some kind of damage to if i run into problems getting it into a position i feel i could actually test it from. Or am i supposed to be testing the leads/ plugs that are running from the ecm?? See how Im doubting my next step or just not sure of it??
If someone could address what I should do here at the ecm that would be helpful.

I just hate being this deep into fixing the problem both money & time wise, to just bolt the tank back up & send it to a "real" mechanic to just kick myself in the butt when they find the problem somewhere I should have easily found myself in the first place. But on the other hand I dont wanna keep tinkering with stuff til i finally short something out & then get my self into needing some serious electrical parts.

I'd like to know what you guys feel is the best thing for me to do for this problem & for the sake of my car. Of course I want to do it myself BUT I also would like to drive the damn thing again.
 

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I was having the same problem about a year ago. It turned out I had a bad ecm. I checked and/or replace the same parts you mentioned with no luck. Is your check engine light dim by any chance?
 

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Discussion Starter #5
I was having the same problem about a year ago. It turned out I had a bad ecm. I checked and/or replace the same parts you mentioned with no luck. Is your check engine light dim by any chance?
No, but I do think it is on tho.

How much was the new ecm?
 

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I found mine on craig's list for a 100 bucks. Pulling it from the kick panel was a little bit of a pain but the wires are pretty straight forward.
 

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Discussion Starter #7
OK I just feel like giving up! Honestly I need to know what the eec is, whats the tfi? whats the ecm,???? What do these acronyms stand for?

Then if Im not getting power to my fuel pump where do i start testing?? Not just say check #20 on your eec or ecm, I need to know like where do i look for these components to even start to check them out??

So ok I gotta loose my frustration here. What I need is step 1) start checking at this component located at this specific spot in the car type answer.

I just need a where to start this trouble shooting for dummies kind of answer. I just don't understand what & where to start checking now?
 

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Discussion Starter #9
ECM=ECC= Computer. Its located in the passenger kick panel. TFI= The module on the side of the distributor.

Here is my write up: Get lost during that, just let me know. It covers just about all that you need.

http://www.allfordmustangs.com/foru...nosis-101-1986-1993-mustangs.html#post2018655
Thanks so much for taking the time to educate me. I had already been using your thread you included it really has been the only thread that made since to me.

I do still have one question in that fuel pump thread you said

"88-90 ECM relay wiring
Black/Orange- Constant power from Blue fuse link at starter relay
Red/Green- Gets its power from the Igniton Switch
Black/Green-Relay ground
Orange/black- Powers up when relay engages"

Am I looking for these wires directly from the "big wire component" area (which I assume is the ecm or the main computer module) with all the wires coming from it or from one of the plugs running from it?

Thanks again for your time.
 

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Those wires are what's part of the ecm relay connector. The connector the ecm relay plugs into.
 

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Discussion Starter #11
It ended up being a fried shorted wire just near where the fuel pump assembly fits into the tank. replaced the wire & knock wood its been running fine for 3 months now.:bigthumbsup
 

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Congrats and sometimes you gotta take a step back and breathe. Always the best bet is to check out the free and obvious things first before you start throwing money at the problems.
 
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