Need troubleshooting help

[87Mark7LSC]

My 87 LSC has DTC codes 23-TPS out of range, and 95- Fuel pump circuit open pcm to motor. Car started out hesitating and would take longer to start, then it wouldn't start every once in a while, now it won't start. With my fuel pressure gauge hooked up at the rails though it reads 42 psi when cranking.

I'm not sure how to go about this. I looked in my owners manual and there is a fusible link at the starter solenoid but I'm not sure how to test it or even where it is at the solenoid. I was going to check the pin out at the ecu for a loose connection first since it is relatively easy to get at. I don't think code 23 means anything.

I don't have the service manual so I was hoping someone could give me some steps to follow.

Thank you

 

[87Mark7LSC]

I forgot to mention that my car was converted to MAF. I was reading that if you don't connect pin 19 to the fuel pump relay you will get this code so that code might not mean anything either. But should I be suspect of my fuel pump relay?

 

[NYC LS8]

TPS out of range means that the throttle position sensor is, well, out of range. You need to check it with a voltmeter.

 

[87Mark7LSC]

I meant to say that it shouldn't have anything to do with the car starting should it?

 

[87Mark7LSC]

It seems to me that the fuel system is ok as there is enough pressure in the rails to at least start the car. I have a new MSD coil, MSD cap and rotor and wires that are 2 years old. With an inline spark tester, it lights up at every terminal on the cap. I was thinking that maybe either the timing has gone out of alignment somehow or the injectors are not firing/firing at the wrong time. The TPS is a non-adjustable unit on a 65mm throttle body.

 

[OldSchool1]

Fuel, Spark, Air

It seems to me that the fuel system is ok as there is enough pressure in the rails to at least start the car.

Replace your fuel filter. You could have mega pounds at the rail and still have an old collapsed filter that will maintain pressure but restrict flow.

I have a new MSD coil, MSD cap and rotor and wires that are 2 years old. With an inline spark tester, it lights up at every terminal on the cap.

Nice additions. Add a new ignition module to it. Intermittent starts are a sign of a TFI going south.

I was thinking that maybe either the timing has gone out of alignment somehow or the injectors are not firing/firing at the wrong time. The TPS is a non-adjustable unit on a 65mm throttle body.

Actually it is the same adjustable harness as our stock 50s and 55s. The TPS comes with a miniscule amount of play around the rearward screw. Total adjustment range is less than a cm clockwise or counterclockwise, but this thing reads in miliamps across a the resistance of wires so even a millimeter turn registers a lot of movement. Search here for calibrate or adjust TPS.

 

[87Mark7LSC]

Old School,

I replaced the fuel filter and still nothing. Then I hooked my timing light up while I was trying to start it and the marks are real close. So I think ignition circuit would be okay then. I put my stethoscope up to a couple of injectors and I don't hear them clicking and when I touched them I didn't feel clicking when I tried to start the car. However when I put my multimeter in the two prongs of one of the injector connectors when I put the key to run the voltage was about .4 mV and the number jumped around when I tried to start it. I am skeptical about how accurate my multimeter is because the numbers jump around a lot even if the probes aren't touching anything. The TPS was slightly loose so I tightened it and pulled codes again and this time got only 95 which is because I never ran that one wire when I converted to MAF

 

[87Mark7LSC]

Okay,

None of my injectors are firing but there is power to them. EEC is therefore getting power and EEC relay is working. That leaves the ECA processor or bad grounds which I believe are G100, G 402 and one or two more that I haven't been able to find yet in the electrical manual. I'll check these out tomorrow and I'll go from there.

 

[Elessee]

My 87 LSC has DTC codes 23-TPS out of range, and 95- Fuel pump circuit open pcm to motor. Car started out hesitating and would take longer to start, then it wouldn't start every once in a while, now it won't start. With my fuel pressure gauge hooked up at the rails though it reads 42 psi when cranking.

I'm not sure how to go about this. I looked in my owners manual and there is a fusible link at the starter solenoid but I'm not sure how to test it or even where it is at the solenoid. I was going to check the pin out at the ecu for a loose connection first since it is relatively easy to get at. I don't think code 23 means anything.

I don't have the service manual so I was hoping someone could give me some steps to follow.

Thank you

I have a '88 LSC, and had a similar problem.
My symptoms got worse with time. If i recall, the first was hard starting in cold weather. Then it was hesitating and dying at a stop sign. Restarting was tough. Cold starts in the morning were problematic. I began carrying a can of Starting Fluid (pure ether plus lube) in case it died.
Removed the air intake hose, open the thottle plate, a 2 second squirt and it'd start up. It seems to need a lot of fluid because of the convoluted intake pathway.. Anyhow, replaced the hose and it ran OK, until it died again..

After a while (months) the problem got progressively worse and starter fluid rarely worked. Tried a remote starter.. Around this time i got singed eyebrows from a backfire.. i recall an orange ball of flame..
----------

I did just about the same diagnostics as you.. checked fuel pressure, put in a new fuel filter, pulled codes, put a meter on various things, etc, but had no luck.. Finally gave up and took it to my mechanic.

About an hour (and $100) later he said it was the "fuel injector relay". Huh?
I didn't know it had such a thing.. i guess he meant the C.F.I. Power Relay.
I looked and can't find my receipt. I looked under the hood but this was a couple years ago and any new parts have gotten dirty since then.

A quick look at the service manuals told me nothing about the electrical.. (Group 24, 24-04-1 (5.0L SEFI)
So, i looked at the electrical schematic sheets (a service manual extra) and found the CFI Power Relay. The manual didn't mention anything like that, nor does it have a fuel-specific diagnostics section..
-----
The C.F.I Relay is mounted on the passenger side firewall in the corner near the hood hinge. I see two devices under that black plastic cover. One is that relay. (I think the other device is something called a "T.F.I. Module" according to the wiring diagrams.)
The CFI relay shows 4 wires:
R
Bk/O
R/LG
BK/LG

The TFI Module shows 6 wires..

Take it for what it's worth.. i'm going by faded memory.. but i'm sure he did say "fuel injector relay".

 

[87Mark7LSC]

Tonight I pulled my TFI module and tested it according to my Haynes manual and it tested ok. I swapped my speed density computer back in to see if the injectors would actuate. When the EEC relay kicks on I feel a surge when I hold the injector but they still do not actuate. If it was a computer problem, I believe the injectors should have worked when I swapped the computers since the pinouts are identical for injectors. When I cranked the car I held a stethoscope to the injectors and they weren't clicking. I think it must be a problem with the ground circuit. If the injectors have power at them which they do, they would have to be grounded to actuate them I think. But I am confused because looking at the electrical schematics the ECA would ground them I think.

I have a new TFI module should I put it on and try anyways? I am running out of ideas. Haven't tested all of the grounds yet but G402 has continuity to the block and the strap connected to it has it up to the firewall. It started to rain so I called it quits.

 

[OldSchool1]

Fuel, Spark, Air v1.0.1

...
I have a new TFI module should I put it on and try anyways?
...

Dude,
Replace the Thin Film Ingnition Module! They can 'test' normal when cold and normally fail only when hot or when you're 200 miles from ythe store.
Double check you new wiring.
Pull and correct your code.
Fuel pressure and fuel flow are two different things.
When you've done these things, let us know.

 

[87Mark7LSC]

I put a new distributor and new TFI module in and no luck. Wiring for MAF conversion is secure in ECA pins. I have already corrected the TPS code. Code 95 I am going to let go, I've had that since I converted to MAF. I am going to try and get a Ford dealer to take a look at it. I've been trying to figure this out for 3 weeks and just want to be able to drive my car again.

 

[vegaswheelman]

Wow. Sounds like you've got a real Frankenstein on your hands. Hey, just to verify a fuel starvation issue you can remove a vacuum hose from the intake manifold and with the tittle red spray tube installed on a can of carburetor cleaner, spray into the vacuum port while cranking and see if the engine wants to start. If it were me i'd check the wiring, like Oldschool1 mentioned. But I mean REALLY look. All the grounds too, including the engine compartment. How did you check injector voltage? did you use a noid light too? just curious.

 

[OldSchool1]

Loose the modification and start the car.

If it starts then it was your mod.

If it doesn't, THEN we trouble shoot it at as a STOCK car.

Troubleshooting modifications over the web is sorta like pissing in the ocean to kill fish. No offense meant or anything but I/We/They can only tell you the way it's SUPPOSSED to work. Unless you find someone with THE SAME modification, it's really going to be hit or miss until you either get pissed and sell the car or you pay ABC Lincoln/Mercury/Kia $90 per hour to tell you that you need your motor replaced at $5400.00

Start over.
Battery, voltage regulator, alternator, coil, cap, firing order, wires, plugs. Do you have juice from point A to point B?

Fuel tank, fuel pump, fuel filter, fuel regulator, injector. Do you have 40 pounds at the rail?

Air intake, air filter housing, air filter, tube, throttle body, upper and lower intake. Will the intake inhale air?

The way it's suppossed to start is with everything mentioned above working. That's really it.