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..
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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..
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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".