I had to dust off the old Login profile. Here's the skinny:

1. Cold night a few nights ago, started the truck to warm up and clear the windshield. Let it idle for about 15-20 minutes (duct seals in dash have disintegrated many moons ago).
2. Turned off truck to use the keys to lock the house.
3. Truck would start, but horrible idle then die. I repeated this several times, but could not get the motor to rev.
4. Removed battery cables, reset ECM (ECU?, PCM?), now just cranking, no start

Next Day

1. Got it to fire with starter fluid, would not stay running
2. Cannot check fuel pressure, no schraeder valve test port, don't have fittings to adapt gauge, don't want to cut and splice the fuel lines, they are expensive and hard to get.
3. Can hear fuel pump relay driving the pump for initial phase prior to cranking
4. Have spark at the plugs (rules out coil, crank and cam sensors, not sure about IAC and TPS)
5. Have not pulled O2 sensor to check for plugged exhaust, was running good before this

Next Day

1. Recalled similar symptoms from a prior episode, corrected that time with new OEM ground cable. Have not replaced positive cable yet. I did purchase a new battery prior to installing the cable, did not correct the problem.
2. Cleaned up all ground connections in the engine compartment
3. Cleaned up positive connection at the battery and the power distibution block
4. Now the ASD relay is chattering
5. Charging the battery now
6. The battery is 6 years old in this Texas heat - time compresses as I get old. I didn't realize that the cable change and the "new" battery had been completed that long ago.

I will purchase a new battery, but this old truck is my primary transportation at the moment until my insurance settlement for the 2013 Fiat 500 Abarth comes through. I do have a good ebike and may run up to the WalMart on that.

What am I missing?

 

How old are your plugs? What do they look like? Distributor cap??

Get the battery charged up, see which cylinders it is missing on. (if it is missing....)

 

The ignition system is old, but very low mileage, maybe 6k. I will pull some and look while the battery is charging.
Something else. I have been cleaning all my grounding points and have been checking them to the negative terminal. Having the battery positive connected is throwing off the readings - I did not know this but will remember. Here are some pics:


Cab Ground

Unexpected DCR wtih battery in circuit

Remove negative lead

Removed positive lead expected DCR

Removed negative lead expected DCR at terminal clamp

 

Here are the spark distribution components. I pulled one plug, it looks good. The rotor looks pretty good. The distributor cap shows the most age, but the arcing has been even across all of the poles. I will clean the faces and put the parts back together.

Distributor, signs of arcing, most of material still in place

Good Plug, only pulled one

Rotor

Rotor closeup

 

After charging the battery until the charger read 0 amps, I turned on the key and the ASD relay is still chattering. Not much point in cranking the motor until I can get that sorted. Here are my thoughts:

1. The battery could easily have a problem, given it's time in the heat. I will perform a load test as best I can and see how low the voltage goes when I crank the truck.
2. Why is the DCR reading so different on the negative terminal with the battery in the circuit? Is this affecting reference to ground for the ECU?
3. I will measure control voltage at the ASD socket across the relay control connections, both with the socket empty and with the relay in place
4. I will measure control voltage at the the ASD socket from each of the relay control connections to ground, both with the socket empty and with the relay in place.

 

Your meter measures resistance by passing a known voltage thru whatever wires you are testing, and seeing what the return voltage is. With the battery hooked up, it's possible that is throwing the return voltage off. But, I would expect that only if there was a short somewhere, and there was battery voltage on the wire you were testing. Might not hurt to set your meter to 20 volts, and test a few spots.....

 

I was thinking along these lines. That's why I'm going to make all those measurements tomorrow that I mentioned in my prior post. If there's a short somewhere and it's causing the chassis have a different potential to ground , then it's very possible the PCM has lost its reference as well and that could be what is causing the related chatter on the relay.

 

Usually, chattering relays is low voltage..... at least, that's the only cause I have see for it.....

 

Going to take further measurements in the morning. I checked both of the load voltage and the control voltage at the relay and that measured right at 12 volts. I'm going to check it again tomorrow just to be sure though. A floating ground could also do it, but the voltage measured to ground would fluctuate and what I measured was stable.

 

Put a load on it when you're measuring voltage. A battery can read 12v but not be able to supply enough current.
Turn on the headlights.