I have a 90 Dakota with a no start problem similar to alot of those listed here by others. Intermittant fuel pump operation. Checked the hall effect pickup and its ok. I do have spark. I jumpered 12V from the hot relay terminal (30) to the Green/Black wire terminal (87) and the pump still wouldnt run. I tested the ASD relay and it switches fine. Checked the harness splice and it too seems fine. I ran the diagnostics and it gives me (among others) a 42 code and says: Open or shorted condition detected in the ASD relay circuit. ALso it says: 42Code :No Z1/Z2 voltage when Asd relay is energized. Does this mean that the computer is not energising the relay? Could i have a bad wire on the coil sides of the relay? Any suggestions would be appreciated. I dont think the fuel pump is faulty (although its possible but intermittant) and I'd rather not pull down the tank if thats not the problem (its below zero here in Alaska and Im working outside which makes working with plastic wire plugs somewhat tricky!!)

Thanks for any suggestions.

 

1990 Dakota, I'm assuming a 3.9L V6.
From your post, I'm assuming you tested for voltage at terminal 30 of the ASD relay, of course, there should have been battery voltage.

Remove the ASD relay.
When the ignition switch is ON, there should also be voltage at terminal 86. (This voltage comes from the ignition switch)
Turn ignition switch off and wait for at least 5 seconds. Remove the connector from the PCM. At the connector of the PCM, test continuity between pin 51 (dark blue/yellow) and a known good ground. There should not be continuity.
Than, test continuity between the same pin of the PCM connector and terminal 85 of the relay connector. There should be continuity.
Now, test continuity between terminal 87 of the relay connector and pin 8 of the PCM (dark green/black). There should be continuity.

Also, while taking these readings, wiggle the connectors (and wires), and see if the readings change at all.

Do that, and post the results back.

 

Thanks for the reply Dodgerules, It is a 3.9 V6. I have 12V at terminal 30 of the ASD relay plug at all times. I believe I checked for 12V at terminal 86 with ignition on and there was no voltage. I did cut the pump wires back by the tank and tried to run the pump directly from a battery and it wouldnt run so I pulled the tank down and removed the fuel pump. The pump ran fine about 20 times then stopped running directly off a battery. After a few seconds the pump would run again so I think theres a short in the pump. I will pick one up today and install it to see if that solves it since I already have it all apart.

I tried checking for voltage at the injectors and had none (even jumping terminal 30 of the relay plug to terminal 87). That seemed odd. Tonight I will double check the PCM connector continuitys like you mentioned and post back.

THanks again for the reply.

 

It was the fuel pump. The pump would work fine then just cut out. Makes it hard to diagnose when you check the pump and it works fine. Damn electrical stuff... Thanks for the help

 

Did the trouble code go away after you replaced the pump?

 

I dont have the scanner anymore so didnt check the codes again. 5 days and the trucks still running fine. Fingers crossed.... I have to say, of all the trucks I'ved owned the Dakota is the one Ive gotten to know intimately... Seems like every 4 months Im under the hood fixing or replacing something. Dodge did a hell of a job designing these trucks as far as winter handling, load carrying, ease of repairs, but it sure does seem to have alot of problems. Oh well, at least its fairly easy to work on. Thanks for the help.