88 lx 5.0 needs help!

USMC302 · 12-19-2007, 11:45 AM

It's supposed to run all the time when the engine is running.. What makes you say the FPR is bad again? You need to set the TPS, before we try to point fingers at anything else....

pearce9906 · 12-19-2007, 06:33 PM

ECM says relay is bad. Trouble code 87. Also, even with the relay removed, fuel pump still runs when ignition is turned on, TPS voltage is now set at .96. Car runs, but still surging after about 3 minutes, also, fuel injecters are getting wet with fuel, on the outside. Not a leak on the fuel rail, it is a mist/smoke coming from around the injectors at about five minutes idle time, after the motor starts loading up with fuel.

Any idea why the fuel pump would run all the time (without the relay)?

USMC302 · 12-19-2007, 06:39 PM

two things......The pump should NOT run with the relay out. Your referring to the relay under the seat right? That is the fuel relay.

Second, if you see fuel mist from the injectors, something is def wrong. I would pull the injectors and get them tested or serviced, where on the injector is the fuel mist coming from, can you see it exactly?

pearce9906 · 12-19-2007, 06:46 PM

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 · 12-20-2007, 10:30 AM

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 · 12-20-2007, 01:57 PM

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 · 12-22-2007, 05:55 PM

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 · 12-22-2007, 10:09 PM

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 · 12-27-2007, 12:07 AM

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 · 12-27-2007, 09:55 AM

Quote:

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...

12-19-2007, 11:45 AM	#1
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: 88 lx 5.0 needs help! It's supposed to run all the time when the engine is running.. What makes you say the FPR is bad again? You need to set the TPS, before we try to point fingers at anything else.... __________________

12-19-2007, 06:33 PM	#2
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! ECM says relay is bad. Trouble code 87. Also, even with the relay removed, fuel pump still runs when ignition is turned on, TPS voltage is now set at .96. Car runs, but still surging after about 3 minutes, also, fuel injecters are getting wet with fuel, on the outside. Not a leak on the fuel rail, it is a mist/smoke coming from around the injectors at about five minutes idle time, after the motor starts loading up with fuel. Any idea why the fuel pump would run all the time (without the relay)?

12-19-2007, 06:39 PM	#3
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: 88 lx 5.0 needs help! two things......The pump should NOT run with the relay out. Your referring to the relay under the seat right? That is the fuel relay. Second, if you see fuel mist from the injectors, something is def wrong. I would pull the injectors and get them tested or serviced, where on the injector is the fuel mist coming from, can you see it exactly? __________________

12-19-2007, 06:46 PM	#4
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! 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.

12-20-2007, 10:30 AM	#5
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Re: 88 lx 5.0 needs help! 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... __________________

12-20-2007, 01:57 PM	#6
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! 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.

12-22-2007, 05:55 PM	#7
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! 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.

12-22-2007, 10:09 PM	#8
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! 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?

12-27-2007, 12:07 AM	#9
pearce9906 Registered Member Join Date: Nov 2007 Location: OHIO Posts: 20	Re: 88 lx 5.0 needs help! 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.