Hello all, I am trying to help my neighbor with their 86 740. It has the gasoline motor, it has not run in quite sometime. Here's the basics of what I understand so far.

Key on, fuel pumps do not prime
Took out the fuse box, can feel relay physically clicking.
Check to see if relay is outputting power, it's not
Jump power to fuel pumps, still can't hear either pump prime.
Jump power and check for power at the tank fuel pump, it has power.
No fuel at all in the fuel rail in engine bay.AllData - Technical Service Bulletins

The car has been sitting for quite some time, it's in the yard, half sunk into the dirt. Also, when the motor is cranking, it doesn't seem to be getting any spark either. Any help would be appreciated, car is a manual transmission.

Keyul

 

an 86 is likely LH 2.1. our 2.2 car (a 87 240) doesn't prime on key on either but my LH2.4 car (a 92 740) does. the 'fuel pump" relay is actually TWO seperate relays in one, one half of it provides power to the ECU and comes on with the key, the other half powers the fuel pumps and comes on when the ECU says so (when it sees the engine is turning via the pulses from the hall sensor)

Anyways, it looks like you diagnosed it right there, you jumper the fuel pumps and they don't run, but there's power at the tank pump... you should also verify there is power at the main pump. whats in the gas tank? likely sludge if this thing sat for years.

spark is controlled by the hall sensor in the distributor on a LH2.1/2.2 car... no pulses == no spark. this goes to the ICU (Ignition Control Unit) which in turn drives the 'power module' which drives the coil which makes the spark.

86 is in the window for 'bad wiring harnesses'. aka 'biodegradable wiring'. a year or so earlier they had switched plastics for the insulations in an attempt to be more 'green', and this new plastic turned out not to last very long. in late 87, they switched again to a better plastic, so 88+ cars don't have this problem.

which ICU does this car have? our 87 240 has the 'chrysler' ignition unit that has a vacuum bellows near the bottom, the connector into this ICU is a 8(? maybe its 10?)) pin rectangular block connector, the pins are notorious on this for loosening up and stopping it from working. pull the connector STRAIGHT out (don't wiggle it), then use a small tool to tighten up the sleeves of each of the pin sockets (on the cable/connector side), squirt it full of dielectric silicone grease, and reinsert it straight, without wiggling.

if the ICU isn't working and doesn't see the hall sender pulses, it won't send them to the ECU, which won't even try to turn on the fuel pumps.

 

Thanks for the info! I just went and messed around with it a bit more, followed the instructions in the tech book for testing the relays and circuits. I went back to the tank pump, unhooked it from the harness and ground, tried giving it power directly, no noise what so ever. Hooked the meter up to it, not sure what the value should be but my meter read over 20M ohms. Think the tank pump is dead.

5 Gallons of fresh gas was put into it. Upon jumpin the power to the fuel pumps again, think I clould hear what sounded like the main pump trying to run, it was more of a thud noise than anything. I cant access this pump directly, have to jack up the car outta the ground & weeds! My buddies neighbor is gone until the 8th, so I'll see what she wants to do with it then!