I'm the same way, I had to do it myself due to lack of money and now that I'm older, I still do it because the "technicians" today wouldn't qualify as "mechanics" when I worked on cars as a side line. I like to collect old automotive literature myself. My oldest is Audel's Answers for the Automobilist from 1901. Next is a trouble shooters handbook from 1934. Some of the things in there are way out of date but the basics still hold true.

 

Received new relays today. Replaced all three old ones (fuel pump, ASD, and AC clutch) with new. Truck fired right up. So we'll see if this solves my problem with the engine cutting out every six months or so. If not, I dig into the PDC.

Thanks y'all!

 

Say @RalphP . Question. What components does the ASD control in my 1993, 5.2L engine? Do you know? Is it fuel pump shutdown, injectors, and coil? All of these or some of these? I'm just curious because if replacing the ASD relay does not fix my random/intermittent engine cut out then a bad connection in the relay harness or any of those other components would be the next logical possibility. It would be nice to narrow down the possibilities if it comes down to it. BTW, I benched tested all my old relays. They all click and they all have no resistance when energized and 80ish ohms when not energized. So the bench test suggests all the relays are good but I suppose that doesn't mean they wouldn't have an intermittent problem due to corrosion or something.

Ed

 

80ish is bad; they should be OPEN when open.

You'd have to pull out the factory service manual, but basically, the ASD does coil, injectors, and on some years, the "Part WOT Unlock Solenoid" on the transmission. (I would not be surprised it also does the OD solenoid).

Your year has a separate fuel pump relay, but its coil is in parallel with the ASD relay; older trucks put the fuel pump on the ASD.

(There's a metric ****load downstream on my 1988; a lot of that was moved off by 1993 from my reading of the FSM, but I Could Be Wrong.)

RwP

 

All the relays were 80ish. Old ones and new ones. Saw a vid suggesting anything between 50 - 120 is spec. Don't know how true that is.

OK, I thought the fuel pump relay and the ASD both controlled different aspects of the fuel pump. Sounds that is untrue. The fact that I can hear the pump come on even while the truck wont start suggests the fuel pump relay has always been fine (and also would eliminate the possibility there is a bad connection or short to the pump). But if the ASD does the injectors then that would be consistent with the healthy crank but no start problem too.

In the few days since I've changed out the relays with new ones the truck has started and performed flawlessly. Gonna be awhile before I can feel confident the problem is solved. But for some reason this problem has captured my curiosity. Perhaps because I'm not sure it's fixed yet. When something goes bad I prefer smoke pouring out and springs flying everywhere so there is no doubt it's @#%!ed up. Hate intermittent problems! But it is nice to learn new things. Especially about electrical which is a weak point for me.

Thanks!

 

OK, replacing all the relays didn't work. Just went out and fired up the truck. Ran for 10 seconds, cut out, and I cannot get it to start again. Even after playing musical chairs with the relays. I'm sure it will start later. Just has to rest awhile. Might need a 10 minute rest, might need a 24 hour rest. Never know. It lasted about five weeks since the last time the engine cut out on its own. Seems to be getting more frequent. I'm out of ideas.

 

So what's missing when it won't start? Fuel, or Spark?

 

Make sure it's an electrical or fuel issue. Take the air filter lid off (unless someone monkeyed with it, you should have a pie pan air filter assembly) and shoot some starting fluid into the intake when it won't start. If it wouldn't start but starts and runs for a bit then dies when the fluid is used, you have a fuel delivery issue.

 

Has to be spark. First thing I check is to be sure I can hear the fuel pump coming on. It always does. The fuel pump is only a year old.

This problem has gone on a few years. Getting more frequent though. Sometimes I fire it up, it runs 5-10 seconds then dies. Sometimes it dies while I'm driving. If I wait 5 - 30 minutes it usually will start back up and I'm good for a few months. I'm on OBD1. Never throws an engine code. Here is what I have replaced to date:
1) Fuel Pump (that definitely went bad a year ago and my current problem existed before and after pump was replaced).
2) Plugs, wires, cap, rotor, coil
3) Crankshaft sensor
4) Camshaft sensor
5) All relays including fuel pump relay and auto shutdown relay.

I'm clearly taking stabs at it. About the only thing I know to do is replace the PCM. Don't know if the 5-30 minute wait before it starts up is thermal related or electrical related (capacitor?). I tried disconnecting neg batt cable, turning headlights on for 5 minutes then reconnecting but still wouldn't start. Waited 10 more minutes and it fired up.

 

Just because the pump is charging the system doesn't mean the injectors are working. Make sure first before getting into the ignition system.