I've got an 01 6 speed HO with 160k on it I bought not too long ago. Previous owner had installed a FASS and Edge Juice on it. I went to clean up some line routing/wiring and noticed what I now know to be the timing solenoid wires were completely bare at the top outside the sheath. I poked around that area a bit, looked over some fuel pump wiring/hoses and then quit for the night after I saw how much work I needed to do. 

 

Next day I fired it up (still hadn't done anything but literally poke the wire bundle around to look at it)  idling rough, p1690 pops up (no other codes) I shut it down and decided to swap the crank sensor. No change with the new crank sensor, so I went through the rest of the diagnostics I had found on here with no luck. All wiring to the ECM and Cam sensor is sound. All wiring from the vp is sound, grounds are good (less than 1 ohm on my volt meter). I don't know how to check the AC noise from the lift pump but I have a FASS so I would hope it's fine. 

 

I decided to look more at the bare wires for the timing solenoid I had poked, found that there was no evidence of ever having insulation on them (I found other pics of similar situations that seemed like they came factory like that). I wrapped them in electrical tape the best I could, started it up and wala, no codes and idling well. 5 min into the drive I heard the timing change and the CEL popped back up, no power of course, with the same one code p1690. Back to the way it was. 

 

I figured my electric tape job might have been the fix but just not done well enough, so I redid that with some liquid tape added too, and this time only got a minute or two into the drive before the issue came back. Also during this process I tried unhooking the alternator and didn't notice any difference. Tried letting it get back completely cooled off without touching the tape and still having issues so I'm not convinced it is engine temp related. 

 

Only other pertinent information I can think of is that it got below zero here last week and I'm sure the fuel gelled, but I didn't drive it until the temps were over 40 degrees. It always showed good fuel pressure (13+) and made an hour round trip the day before the issue started without a problem. Could the fuel gelling cause pump issues inside it or some residual wax floating around cause issues even after over on hour of trouble free run time since temps were below freezing?

 

Do yal have any other ideas on what this could be? Truck is undrivable at this point. 

 

Alright, so @Mopar1973Man I can tell you are real proud of your knowledge on snubber fittings and everything, but that was not my issue. The fuel pressure sensor is right on my Fass and now reads rock solid pressure. Thank you @Dieselfuture for the tip on the check ball, that ended up being the cause. The truck sat for a long time before I bought it and the ball had a nice grove worn in it all the way around and was sticking. I turned the check ball 90 degrees and haven't had a fuel pressure blip since. (I still plan to get a replacement ball/spring)

 

After looking at everything I had going on back to the beginning, I think that the jumping fuel pressure was the root cause. The truck would run fine for a few minutes and then start having issues. I think the pump was heating up due to lack of consistent fuel, the timing piston was starting to lock up and burning up the wires going to it. I fixed the check ball issue and the truck ran fine with the two bare wires going to the timing piston basically in the open, only enough electric tape to keep them from grounding out on the pump. So I know the sheathing wasn't part of it either. Before the fuel pressure would jump from maybe 12 to 18 on my edge monitor,  and you could hear the pump pulsing clearly while the issues were happening. 

 

Now FP is rock solid between 15-16.5 psi depending on throttle position and fuel temp. Pump sounds smooth and consistent.  I know that during this mess (I probly put 800 miles on the truck with the fuel pressure jumping like that, solid 200 of that towing 9k+) the injection pump had to have taken some permanent damage, and it was original with 160K on the clock so I put a reman pump in from DAP and it has been doing great for the ~500 miles since then. 

 

Thanks again for all the help gents! I hope people can use this to solve some of their problems down the line, as I know I have 100's of old threads before it. 

 

 

 

Glad you figured that out, hey needle valve before the gauge is a good idea to dampen the pulses from the vp44 so you don't destroy your gauge. And you don't really need a new spring, you can modify your old one to look like this, then get a new check ball from fass it is white plastic. And this is my T with needle valve, then another T to mechanical fuel gauge and then electric one for the quad.

 

 

My gauge senders are not even on the engine, but the driver side fender for easier testing and diagnostics. 

 

This is all I've got at my tap point. A shut off valve, then the sinstered metal snubber, and the the Push To Connector fitting. (PTC).