Anyone have a pic of the inside top of a 6.2 injection pump?

My truck developed this random not wanting to stay running condition one minute and running like a top the next. Acted like it was starving for fuel.

Fuel delivery is all good.. new filter, pump, all that good stuff. Thought i’d take the top of the IP and take a look.

Found these ground up chunks of plastic in the top.. not sure what they were, but I doubt they were sucked up through the fuel system.. so i’m guessing they were a piece that wore out.

Still poking around to see if i can find more chunks in there, but i’m not completely clear what is supposed to be doing anyway beyond the solenoid moving this linkage deal that connects to.. lets call it a “Y” shaped thing that hooks onto a cylinder looking thing. That cylinder moves forward and backward if i move it with a screwdriver, but moving the linkage as the solenoid would does not.. that Y thing just flops around. It could be that it *does* move it if the pump is running and providing pressure.

Ultimately I really have no idea what the normal behavior of the mechanism is to know what to look for.

Any ideas?

I am not a truck guy. But my generators have an IP very much like yours. Mine has a Fuel Shutoff Solenoid in the top of the IP. Item #18 in the below figure. Those bits you took a picture of, look very much like parts of that solenoid. Look in your parts TM. The solenoid is normally a part of the top of the IP cover. Any part of it broken off?

Guyfang said:

View attachment 942136

Click to expand...

Yeah, that was my first thought when i saw the chunks, and I have a new solenoid to go in with the hope that was the issue.. but the old solenoid doesn’t have any chunks missing.

The biggest of the chunks looks like it would have been round in the center but more square with rounded corners on the outside.. like maybe a sleeve or bushing of some sort.

That piece might have come off from the selenoide actuator or rod (not sure of the name of the part now) and is known for getting the pump stuck in the open position and causing some run away engines. If i find the diagram with the part, i will post it.

Check here what are you missing. This is a 12 v but similar.

Gcelevator said:

That piece might have come off from the selenoide actuator or rod (not sure of the name of the part now) and is known for getting the pump stuck in the open position and causing some run away engines. If i find the diagram with the part, i will post it.

Click to expand...

I’ve determined the plastic came from the lead that feeds the fuel return solenoid. The bigger chunk i found looked a lot like the bottom side of this lead, and with further inspection that was missing a hunk. Could be shorting to ground and that’s causing my issues. I’ll have to replace it snd see.. although running it with the front solenoid disconnected outta be basically like running it with cold advance on of I’m underatanding its function.

What about the cold advance solenoid?

Mogman said:

What about the cold advance solenoid?

Click to expand...

I finally put that together and posted it just 1 minute before you mentioned it. I'd looked at the bodies of both solenoids and they looked fine. A guy on one the the facebook groups had suggested maybe the fuel return solenoid may have shed some plastic because the way the stick out in the front they get whacked a lot. Closer examination of the bigger of the pieces I found had the same sort of shape and a little indent like the insulator of the fuel return solenoid lead. Even closer inspection I could see that the "roof side" of the insulator was missing a chunk.

Put the cap back on, fired it up with the cold advance disconnected and it idled fine for awhile then starts ruuuurrrr ---- rurrrrrr ---- rurrrrrrr like it's struggling to pull fuel in again... but when I pop the line off the fuel filter to the IP it blasts fuel and cranking the engine seems to be getting plenty of fuel.

I think I'm going to cut myself a nice access panel hole in the bed tomorrow and take a peek in the tank.. although I'm concerned some of the unfound chunks of that solenoid lead may have found their way further into the IP.

Humpty said:

I finally put that together and posted it just 1 minute before you mentioned it. I'd looked at the bodies of both solenoids and they looked fine. A guy on one the the facebook groups had suggested maybe the fuel return solenoid may have shed some plastic because the way the stick out in the front they get whacked a lot. Closer examination of the bigger of the pieces I found had the same sort of shape and a little indent like the insulator of the fuel return solenoid lead. Even closer inspection I could see that the "roof side" of the insulator was missing a chunk.

Put the cap back on, fired it up with the cold advance disconnected and it idled fine for awhile then starts ruuuurrrr ---- rurrrrrr ---- rurrrrrrr like it's struggling to pull fuel in again... but when I pop the line off the fuel filter to the IP it blasts fuel and cranking the engine seems to be getting plenty of fuel.

I think I'm going to cut myself a nice access panel hole in the bed tomorrow and take a peek in the tank.. although I'm concerned some of the unfound chunks of that solenoid lead may have found their way further into the IP.

Click to expand...

It could be a plugged return, this will starve the engine for fuel, pull the return check valve (fitting in top of the IP) and make sure none of that plastic got jammed in there.

ive had that same plastic chunks fall in the armature and cause a runaway engine while driving…it jammed the armature in full open as I was getting onto the freeway on ramp.

MY guess. Check the solenoids... Fuel and cold advance. They have plastic housing parts that could have come loose. Electrical feed thur insulators are plastic or hard fiber too.. All the other parts are metal.

And we thought HumV's were heavy metal. CAMO

Milcommoguy said:

MY guess. Check the solenoids... Fuel and cold advance. They have plastic housing parts that could have come loose. Electrical feed thur insulators are plastic or hard fiber too.. All the other parts are metal.

And we thought HumV's were heavy metal. CAMO

Click to expand...

That’s what it was.. a chunk of plastic off the fuel return solenoid insulator. I’ll have to order a replacement.

A pump rebuilder told me he suspects my pump issues are due to a sticking plunger in the pump and advised me to dump a quart of ATF in the tank for every 15 gallons and claims modern diesel fuel suffers from “low lubricity”.

I put it all back together, filled up the tank and dumped 2 quarts of Dextron in the tank. Drove it around about 25 miles today, It’s running like a swiss watch at the moment. We’ll see.

.. just because I hate finding years old posts from people who have similar symptoms and they just kinda trail off with no resolution.. here's where i'm at.

I replaced the fuel shutoff solenoid just because ya know what? The truck is 30 years old, who knows how old that solenoid is and I was gonna have the top off the IP anyway.. but that was not the issue.

I removed the check valve for the fuel return/cold advance solenoid and it was a metal valve, NOT a glass ball as some have suggested. I guess this means I have a newer check valve. Anyway, I cleaned it all out and insured it was opening and closing freely.

With an assistant turning the key from "off" to "run" I verified the cold advance solenoid was actually doing its thing. With the check valve removed from the top of the pump it's just a little needle that presses into the valve. I used the back of a screwdriver bit to simulate the valve to apply some pressure and it seemed like maybe it had been stuck. Actuated it several times and it seemed good to go. I have a new Stanadyne 24v solenoid coming because the plastic insulator for this solenoid is where the "chunks" had come from so it'll need to be replaced. The usual suspects have it for $150+ but I found a guy selling the Stanadyne part new in box for $35.. so I don't mind waiting a week to get it.

Buttoned everything up (until the new cold advance solenoid arrives) and at the suggestion of a person described as "Injection Pump Jesus", I added 2 quarts of Dextron ATF to a full tank of diesel.. 50 miles on it and an hour or so of idling and it has been running great. "Pump Jesus" or "PJ" for short believes it was a stuck "pumping plunger" and said he sees a lot of issues with these pumps in his shop as a result of low lubricating diesel fuels and recommends regular additives to prevent "metering and delivery valves as well as plungers" from sticking and keeping them lubricated.

If anything new with this develops.. i'll post more.

Seafoam is supposed to also be good for this sort of thing.

Guyfang said:

Seafoam is supposed to also be good for this sort of thing.

Click to expand...

Seafoam.. lot of guys swear by the gallon jugs of Lucas Oil.. i’m told even Stanadyne themselves market a fuel additive for $10 that treats 60 gallons.

I’ve heard old timers talk about ATF for years in the crankcase. Get a burn? Rub ATF on it. Lose a finger? Throw it in ATF fluid and try to get to the hospital within 3 days. This is the first time i’ve ever put it anywhere but the transmission. lol Seems to be purring right along tho.

Even CECOM advised soldiers to add ATF to the oil, and run the set for an hour. Drain the oil and chance the filter.