Engine quit for several seconds

[IdahoJim]

Driving into town this morning, and the engine quit. Coasted down to about 20 from 50, and then it took off again, and drove fine. Noticed a little
lag in it starting on occasion the last couple of weeks, too. Codes set 1689 and 1693. Could the APPS cause this? Installed Blue Chip injector
pump about 20,000 miles back. Truck runs great, other than the problem.
Jim

 

[IdahoJim]

Yesterday I pulled the connectors to the ECM, and PCM, and cleaned the contacts, and applied a new coat of a dielectric grease to everything. I went to town before doing that, and the truck ran fine, so I don't know what's going on. I also removed, cleaned, and re-installed several of the ground points. Nothing to do now, but keep driving it, and see what happens.

Jim

 

[Tractorat]

If this were a gasser I might suspect the fuel filter.

 

[IdahoJim]

Naah...not fuel. Fuel pressure is fine. Problem showed up again yesterday. Started fine, went to town, had coffee for an hour and a half, and it took 3 tries to get it to start. Once it fired up, it ran fine back home. Check engine light on...codes 1689, and 1693. I'm starting to wonder if my ECM is puking. Today, I'm going to run it above idle, and do the pull and tug test on the wiring harness near all the connectors. I sure hate these intermittent problems.

Be happy lf somebody had some ideas. Jim

 

[JR]

If the relay is bad in the pdc it could trigger a 1689 and cause hard starts. Easiest test is to switch relays with the horn and see if it repeats...

Any performance boxes on your truck? Edge, Quadzilla, etc.

 

[IdahoJim]

Thanks, JR. I thought that fuel relay only controlled the lift pump. I'll try that. Truck wouldn't start this morning. Checked the grounds...all good. Pulled the connector to the I.P. and put in new dialectric. Still no go.

Went right out and swapped relays, and it fired right up, JR. You're my Cummin's genius of the day, JR. usually, the first thing I check is relays, but for some reason I had it in my head that relay had nothing to do with the injection pump. One funny thing...either relay will work for the horns, but only one works for the pump. The relay was one of the originals in my truck...now 17 years old, and almost 303,000 miles. Can't say "thanks" enough! if you were close, I'd be buying the beer. Jim

 

[JR]

VP does not energize without that relay. I certainly hope that's all it was, that is by far the easiest and cheapest fix for a 1689 code.

Fingers crossed you've got it behind you!

 

[IdahoJim]

Interesting test I just did. I figured out the ASD (automatic shutdown relay) also plays a part in all this. The factory service manual has a relay diagnostic test procedure, so I ran the test on the ASD, and the old relay I replaced (fuel relay). Both showed .3 ohms of resistance where they should show zero ohms. That indicates some burning of the contacts on both relays. The relay I removed from the horn socket, and installed in the fuel relay socket showed zero...just what it should. I'm going to replace both ASD , and fuel relays with new. Looks like I need to add a bi-yearly test to these relays as a preventive maintenance step.
Thanks again, JR. Jim