88 lx 5.0 needs help!

[pearce9906]

Yes, the fuel relay under the drivers' seat, the mist/vapor is coming from not from the injector, but from the intake around the injector seat, but only after the motor has started loading up with fuel, running rich.
If the fuel pump were running correctly, would it pulse on and off, or would it run all the time?
I know that GM fuel pumps pulse on and off based on back pressure in the line.

[USMC302]

Your injectors control the pulse of fuel on the stangs, not the pumps. Swap the regulator out and check the injectors O-rings, make sure you don't have any dry rotting and need replacement...

[pearce9906]

Ok, thanks. I will try that, I've gotta work the next coupla evenings. It will probably be saturday before I can do much more work to it. I'll post what I find. Thanks.

[pearce9906]

Ok, more info. Took the Ignition module to be tested today, turns out it was bad, replaced it with a new one. No change to my current problem. (just a refresher, pump relay out and pump still runs, two hots, one constant, one switch one power) Turns out the switch on power is the supply to the fuel pump, pink and black, started checking the harness, past owner had byassed inertia switch, hacking into the pump harness with direct switch on power, also bypassing the relay. I fixed all the hacking, put new relay in, but now have no power to the pump.

Trying to track down problem, this is what I have so far:
1. at the relay, there are five wires, one is constant, two pink and black (one runs in harness towards front of car, unsure of where it goes, i would like to find out if anyone knows, the second pink and black goes to fuel pump), one wire comes into relay from the inertia switch, and one goes from relay to the ecm.
2. Constant power is constant, obiously. Switch on sends power through the inertia switch back to the relay, then this power goes to the ecm.
3. How does the ecm open the gate to the pump?
4. If I probe the wire going to the ecm with a test light, the relay clicks open and the pump runs, still doesn't prime and shut off like I think it should when the car isn't running though.

Anyone have a GOOD wiring diagram of the fuel relay circuit? Good being the operative word there.

By the way, code 87 is now the only code being pulled.

[pearce9906]

Ok, I replaced the EEC relay, still nothing from the pump. I shorted the test terminal out on the test plug and the pump fired up and worked fine, this leads me to believe the EEC is either not grounding good, or is fried. Anyone have anyidea where the EEC grounds at, other than the little black wire behind the kickpanel on the passenger side? I still don't want to believe the EEC is bad because everything else works on the car except the fuel pump and the cruise control, it just seems the EEC is not sending the signal to open the gate in the relay and send power to the pump, I have to believe that it is a failty ground. Any suggestions?

[pearce9906]

Ok, I finally made it to the junk yard today to get another EEC, the guy there told me not to replace the computer, he says he thinks there is what he calls a "multifunction module" on the car that controls fuel pump, a/c compressor, cc, and cooling fans. He told me that he believes starting in 86 they put these on all ford module excluding pickups, says it sounds like it is bad, also says he thinks it is on the left front of the engine compartment. I have looked and can find nothing so far, but it was getting dark out and I have no garage. Anyone have any idea what this "multifunction module" is, or where/if this car has one? It sounds to me like this should be on a newer model to me and not the 88 eec-iv speed density.

Any help is really appreciated. Thanks.

[Dark_5.0]

Originally Posted by pearce9906

Ok, I finally made it to the junk yard today to get another EEC, the guy there told me not to replace the computer, he says he thinks there is what he calls a "multifunction module" on the car that controls fuel pump, a/c compressor, cc, and cooling fans. He told me that he believes starting in 86 they put these on all ford module excluding pickups, says it sounds like it is bad, also says he thinks it is on the left front of the engine compartment. I have looked and can find nothing so far, but it was getting dark out and I have no garage. Anyone have any idea what this "multifunction module" is, or where/if this car has one? It sounds to me like this should be on a newer model to me and not the 88 eec-iv speed density.

Any help is really appreciated. Thanks.

Well I have never heard of a multifunction module...

[pearce9906]

Thanks Dark_5.0, I haven't heard of on either, other than OBD II.

[pearce9906]

Alright, I replaced the EEC today, got the fuel pump running, like it should be. Finally! Now it is just time for a tune up and voltage check of tps again and another stang will return to the road! Idles a little rough, but plugs need changed again do to fouled condition, possibly replace IAC and MAP sensor. Maybe tweak the timing a little and install an adjustable fuel pressure reg. and I'll be one happy man. Next is a little body work. I hope to get it painted this coming spring. I'll post some pics when I can, maybe try to do the before, during, and after thing most of us always wish we would have done. I'll try to keep updating as I go. Thanks for all the comments.

[Chap]

Did you check all your gaskets for leaks around the fuel system?

[pearce9906]

Chap, thanks for the reply. I just replaced all the fuel injector o-rings and pintle caps, also while I had the plenum off, I went ahead and pulled the intake and replaced the intake gasket, turns out it was leaking in several places also. I would say this will fix all of my problems, when I put the car back together, I had one injector that is leaking, so I need to fix that before I can drive the car. Bad thing is, I had to start back to work on Sunday, my next day off is Friday before I have time to work on it again. But yes, I think it will be an easy fix. Thanks again.

[pearce9906]

Alright, I know it has been awhile since I last posted. I have the car running great. I fixed the fuel problem, and since I have moved on to even greater things. The clutch was givving me fits, harder than hell to depress the pedal, I pulled the motor, turns out the car was originally an automatic, they did a great job converting it to a five speed, but they used an 83 t5, no big deal right? wrong! it wouldn't have been a big deal if they had used all the proper parts when they converted it, but they used an 83 flywheel and an 88 clutch kit. Why is this a big deal? well, it turns out the earlier model used a ten inch clutch, whereas the later model used a 10.5 inch clutch. big difference. The center of the clutch disk was always grinding on the flywheel and therefore the clutch was never fully engaging. I went with the ten inch clutch kit, turned down the flywheel to get rid of the wear and burn marks, and wow did it ever liven the car up!
As of now, the car is in the body shop, complete paint job! A buddy who has his own garage owed me a favor or two, so he is re-doing the whole car for 1200 bucks, can't beat a deal like that! I hope to post a few pics after the rejuvination is complete.

By the way, does any one know where I can get a good deal on some new upholstery, I have some new seats to put in but the upholstery is so damn expensive.