Troubleshooting!

[rob78]

Hey guys.

So i'm the proud owner of a new-to-me 1987 FC tII! Towed it on a trailer this past weekend. The car cranks all day long but doesn't seem to even try to 'catch'. It will run with a little bit of MAF sensor cleaner sprayed into the intake. The motor has good compression, and originally had no power to the fuel pump. We ran a new wire from fuel pump relay to the pump since the wiring diagram showed no connections or breaks between the relay and pump.

Would a bad clutch switch allow me to turn the motor over but kill fuel? I tested the resistance on the clutch switch and i get 650 ohms of resistance whether the clutch is up or down. It WILL crank without pushing the clutch pedal. So i'm replacing the switch today.

So now i think the injectors aren't pulsing and putting the fuel down. (Unless the clutch switch just kills fuel and not the ability to crank the car.) Does anybody know of a way to check this without taking apart the upper intake manifold? I'm wondering about a relay or set of wires i might be able to take a power probe to.

If you have any info or ideas, please, let me know! Thank you.

Robert


P.S. - quicklist of things i've checked so far.
1. resistance on the connector at the Air Flow Meter.
2. Resistances, power and ground on the fuel pump relay and resistor.
3. clutch switch (tested bad).
4. power and grounds at fuel pump.
5. Fuel pressure going into the fuel rail is good (mid 80's on pressure tester).
6. emptied tank and replaced with new fuel, purged lines up to fuel rail.
7. spark and compression is good.
8. Battery power is good (recharged and did all start attempts with a jump)

[NoDOHC]

First - the clutch switch only interrupts the cranking circuit.

I would look at the fuel injector resistor pack (under the air cleaner). You could also test the injectors for 12 Volts on one side, 10.7ish Volts on the other. It sounds like the car is not getting fuel.

It is also possible that your ECU-engine grounds are disconnected or severely corroded and the injector drivers are unable to sink enough current to ground (although this should kill your spark too).

Look at the FSM sticky at the top of this forum, there is a lot of useful information there, including wiring diagrams.

Congratulations and good luck.

[RETed]

No, clutch switch will just prevent the starter from engaging.

1) Scan for error codes - this is easy and quick to do.

2) Once you eliminate the ECU and error codes, start with the basics - fuel and spark.

It's easiest to check spark...
Having a friend really helps here.
Unplug the spark plug wire from the spark plug end and put the boot near a known, good ground point - I pop the strut tower covers and use the studs there for convenience.
Crank the motor - check for spark on all 4 leads.
Once you check spark, if you get sparks, you just eliminate the spark side of the equation.

Move on to fuel...
Check fuel pressure...
Quick&dirty test is to pinch the fuel SUPPLY line - look for the fuel filter on the firewall on the driver's side.
Key ON and crank - the fuel line should get pretty stiff.
If you can pinch the line enough to block it totally, there's something wrong with the fuel pump or the power to the fuel pump.
If you get fuel pressure, then you need to check fuel injectors.
This where it gets messy - you need to remove all the stuff on top and get the fuel injectors out of their holes.
Wire tie or use pieces of wire to secure the primary fuel injectors to the fuel rails.
If you don't do this, the fuel injectors will pop out of the holes from the fuel pressure and leak gasoline all over the place!
Again, have a friend handy...
Crank and watch the tips of the fuel injectors to see if there is fuel.

If you get fuel and spark, it's most likely ignition timing...
You'll need an inductive timing gun to spec out your ignition timing.


-Ted

[rob78]

Thanks for the info guys, I appreciate it. I'll have time Sunday to check the injectors and I'll give an update.

Robert