24 valve intermittent issue, no start

[AdanRod17]

I have a 1999 24 valve with 336,832 on the dash with an intermittent problem which led it to a no start, before the no start, the truck would fire right up, idle fine but it would start bucking at around 25 mph, it had no set schedule, whenever it felt like it, it would do it, a simple on and off would fix it until the next time I turned it off. Thinking it was injectors I ran hydraulic fluid in the tank and the problem disappeared for almost a week but then the issue came back and since then I've let it sit. And now for some reason the lift pump doesnt come on even when you bump the starter and only the 3rd and 4th injectors are getting diesel. I should mention that all 3 pumps I have are new, any help would be greatly appreciated, thank you

 

[DavidC]

A no cost thing to check. There is an elect. plug on the Drivers side near the firewall this side of the valve cover that has a lot to do with the VP and ECM. When my lift pump was intermittent I cycled that plug that has quite a few wires in and out. That was 2 years ago and still going fine. Any add ons,fueling boxes etc ?. Fuel pressure gauge ?.

 

[AdanRod17]

A no cost thing to check. There is an elect. plug on the Drivers side near the firewall this side of the valve cover that has a lot to do with the VP and ECM. When my lift pump was intermittent I cycled that plug that has quite a few wires in and out. That was 2 years ago and still going fine. Any add ons,fueling boxes etc ?. Fuel pressure gauge ?.

Thank you for getting back to me, and I have actually never heard of that plug, I've talked to a lot of mechanics and none of them really told me much, and I dont have any add ons. After this I probably am going to run gauges. Do you mind giving me a little more details on where that plug is located? Thank you very much

 

[DavidC]

With out uncovering the truck and taking a picture it is between the valve cover and fuel filter near the firewall. I will have to look it up in the FSM again. It does have quite a few wires in it.

 

[DavidC]

Ok, this is the pinout with colors and location. You can check the colors to verify.

 

[AdanRod17]

I'll have to look for it when I get off work, I've been thinking about going ahead and switching my pumps out again

 

[DavidC]

Chk that plug first. I changed out pump and pig tail to no avail. I did hardwire to a seperate switch so I could run the pump if need be.

 

[AdanRod17]

Would I be looking for signs of it going bad?

 

[DavidC]

Burn marks, seperate the two and inspect the pins, put it all together and see if the lift pump runs after bumping the starter. Sometimes connections can build a residue on plug pins and simply cycling them will make a good connection again. Hopefully it is a fix for you.

 

[AdanRod17]

Thank you sir, I will inspect it and let you know how that goes

 

[Joe Mc]

Adam, DavidC makes very good point for sure. This and other plugs, although they may have soft rubber seals between them to "deter" moisture, like a moisture "resistant" watch doesn't mean "moisture PROOF" and moisture will eventually work its way in and corrode plug pins. I've used an electronic connector spray cleaner and if there's a lot of schmutz I've sort of scrubbed the areas with a q-tip while wet with the cleaner. Blow out both plug ends dry and then dab in some dielectric grease to help ward off future intrusion.
DavidC, from my thread "funky start after injector install" (might not be actual title) I have yet to cycle the plug (same as referenced here) just been too cold for these old bones and since I have another vehicle (2011 Prius, I know eek, but can't argue with 50+/-mpg) to drive I'll eventually get to it. Hope that does the trick for both me and Adam. Thanks for your sage, keep it simple stupid before throwing parts at it, recommendations.