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Dead Injection Pump on '96 GMC K2500?

Stuka T

Stuka T

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Hello Truck Stop, I own a 1996 GMC Sierra K2500 with a 6.5. 235,000 miles on it. Truck has been running great since I bought it at 105,000 miles. I replaced the transmission, had the front end suspension rebuilt. Original PMD crapped out at 190,000 miles, I put a remote unit on the side of the engine compartment. No codes at the moment. Pretty sure I blew out my ignition pump a month back and I wanted to tell the saga here and see if I’m right to plunk down $1,200 for an Accurate Diesel rebuild along with a new set of glow plugs and injectors.

I had just over a quarter of a tank and felt like I was running out of fuel all of a sudden. I was on a country road with no shoulder, so I nursed it roughly a mile and a half at 3 to 5 miles an hour until I could safely pull over, with it progressively running worse and worse. I figured somehow I WAS out of diesel and the gauge was screwed up. The next day I went back with five gallons of diesel, primed the fuel pump, checked the T bar up front, both sprayed an ample amount of fuel. Truck would turn over just fine but wouldn’t start. I had it towed to my house and have been messing with it ever since, with no luck.

The front hose on the pump blows a steady stream out when I turn it over, so it seems the lift pump is working fine. FFM and t bar both still blast fuel when I jump them at the fuse box. I’ve pulled all fuel lines at the injectors, four are getting a small trickle, the other four are getting nothing at all. None of the mist I keep hearing I should be seeing. I immediately bought a new Echlin PMD from Napa to be safe. No results. I also put a new starter solenoid on the ignition pump, in a Hail Mary pass. I have an Oil Pressure Sensor on the way from Amazon, but it seems that with fuel coming out the T bar and front injector pump hose that everything at the rear is flowing fine. The fuel is grinding to a halt somewhere inside of the injector pump, and barely making it out.

I’ve checked all grounds, replaced all fuses. Both batteries are a year and a half old, I’ve kept them fully charged. I’ve plugged in the block heater. Don’t see the security theft icon on the dash console. Wait To Start light flashes during ignition, so does the Check Engine light. Recently I’ve noticed a Check Gauges light on during ignition, that seems new.

I’m a dilettante mechanic wise, though I’ve noticed modern day mechanics are not the maestros of yore. I've done OK with the repairs I've attempted. It seems all signs point to the ignition pump crapping out at 235,000 miles, which apparently is 85,000 more miles than the average. I'm baffled that my Bosch code reader isn't coming up with anything, and there has been nothing in the way of Check Engine light. Tomorrow I’ll try to pull off the Optical Sensor as some have mentioned, and see if that throws any juice into the empty lines. But that and the OPS are the last gestures I’ll make before taking The Big Plunge. I've read about ECM and vacuum lines, maybe some more advice will inspire me to dig deeper into those possibilities. I really need my truck to get back to work.

Anything I missed? Accurate Diesel seems to be a haven for 6.5 owners, are their rebuilds decent quality? Seems like everyone is out of Bosch injectors at the moment. I see there are ignition pump swap instruction vids on Youtube, and feel I’m better off chancing it myself than paying a shop $130 an hour.
 
Check that the fuel shut off solenoid is properly functioning.
I think it can be tested by unscrewing it from the top of the IP, plugging back in the wire then, without cranking over the engine, turn on the ignition key and see how far the pintle moves. If the pintle dont move then replace the shut off solenoid.
If that pintle is moving far enough, reinstall the shut off solenoid, then try unplugging the optical sensor, extended cranking time, if it starts the the op sensor needs to be replaced. if it dont start, plug in the op sensor, unplug the crankshaft position sensor, extended cranking time, if it starts replace the cps.
Those unplugging them two is recommendations fro AK Diesel Driver and He is spot on with Bis diagnosis processes.
 
Replace the 1/4” diameter 6” long fuel hose out the front of the ip (injection pump) with clear tubing. Most any hardware store sells it- it is not rated as fuel line, so will only last 3-4 years before needing replacement if you leave it there permanently as many of us do.

You are watching for air bubbles when attempting to start. The fuel
Should flow clear and leave only a small BB sized air bubble stationary in that line. Any contamination of fuel can be seen, as well as air bubbles traveling through. The air bubbles are indicating air intrusion -like fuel leak except the pump is sucking in air usually before pump, but sometimes around the ffm.

another failure point could be the extension cable you added when relocating the pmd. Which btw has a better life outside the engine compartment. Many choose back side of front bumper. Leroydiesel.com sells lifetime warranty pmd and quality extension cable.
NEVER run a pmd without it mounted to some type of heat sink. They can burn up in seconds.

the ops/cps test being mentioned above- is unplugging one and the other if good allows the engine to start after a lot of cranking. Reverse the two and again it should eventually start. Both good makes the normal start. So if this were the case for you, then Both would have to be bad currently since no start. And both going bad at same time is something I never heard of. So unless it has been hard starting for a while, I doubt this is your issue- but is theoretically possible.
 
Here are the test procedures for that. You will need a scope to test it properly.

1. Test for 10+V on the ESO solenoid while cranking, ESO connected, Pink wire.

2. Test for a 0-5 V square wave signal to the fuel solenoid module, pin A, Light Green wire, when cranking.

3. Test for a 0-12 V pulse signal to the fuel solenoid from the fuel solenoid module, pin B, Red wire, when cranking. NOTE: This pulse will appear as a 0-12 V square wave with a 20 V or higher spike, much like a gas engine fuel injector pattern.

4. Test for 12 V and ground to the fuel solenoid module, pins D and F, Pink and Black wires.

If it test good replace the pump.
 
Thank you for the answers. I will act on everything later today.

When you say a "scope", where would I find one, what model? I'm in California. Autozone, O'Reilly's, Pep Boys, they would have a scope? I'm a newb. I do wire entire houses, so I'm somewhat familiar with electricity. But there will be a learning curve.

I hear vacuum lines are another possible point of failure.
 
Its an oscilloscope, not a cheap tool and usually only repair shops have them. The average DIY mechanic doesn't have a need for one unless your diving into diagnostic work like this. We have a few here in the shop built into our Snap-on scanners. I got lucky and found a old Sun scope at a garage sale for cheap I use at home.

With modern vehicles, a scope is a must have tool for someone like myself who does this for a living
 
Sounds like the injection pump will cost as much as an oscilloscope! At 235,000 miles, I assume the IP is going to crap out at some point.

I'll try the clear tubing and shutoff solenoid check later today, along with the optical sensor and crankshaft position sensor, see if any fuel starts moving. Very much appreciate the words of wisdom
 
Amazon is saying they won't ship to my location. Is that a California issue? If you're in Fullerton Amazon has worked out for you recently? How fast is the turnaround time at Leroy Diesel?

Thanks for the shopping advice. Hard to know who to turn to. Accurate Diesel is all over the search engines, and they have some decent advice on their site. I was assuming they were a decent resource. But Leroy Diesel definitely appears to be the elite parts source.
 
Stuka T said:
Amazon is saying they won't ship to my location. Is that a California issue? If you're in Fullerton Amazon has worked out for you recently? How fast is the turnaround time at Leroy Diesel?

Thanks for the shopping advice. Hard to know who to turn to. Accurate Diesel is all over the search engines, and they have some decent advice on their site. I was assuming they were a decent resource. But Leroy Diesel definitely appears to be the elite parts source.
Click to expand...

I have residences in California and Montana. I try to have everything shipped to Montana, especially large ticket items, because there is no sales tax. I do not understand why Amazon would not ship to CA. Where are you in CA as we are back and forth.

I'm sure there will be comments ringing in on Accurate Diesel. I am not familiar with them.
 
Welcome to the forum @Stuka T Glad to have you aboard. x2 on the clear line on the IP return. also if you have a inline pressure gauge check fuel pressure at the IP inlet. you should have at least 5-8 psi when trying to crank. with 235k on the clock, if the IP is factory I'd say it's done well for it's life! usually there is a ID tag on the pump that would show if it's been updated by GM.

my rig is a 1995, I think I found a tag somewhere on mine where it had been replaced by GM in 06 iirc. the wear point in these pumps are the head and rotor, when they give up the ghost, the pump is toast. stay with GM Delco parts on anything you buy for your rig. there are no more "NEW" DS4 IP's anymore, only remans available now. Stanadyne no longer has these style pumps or any of the parts in production any longer. our 6.5's and some ford engine that use this electronic IP are a dying bread. if your truck has a manual trans you could convert to a mechanical pump without spending much more $$ than getting the replacement ds4 plus the DB2 pumps are still under contract to be in production by the military for the next decade or so.
 
Ordered a new DS 4, tune up kit and glow plugs from Accurate Diesel, ordered a set of Bosch injectors from Leroy Diesel. Amazon won't ship to anywhere in the Greater Sacramento area. Will probably have a few questions when it's time to install the new IP, but Youtube videos make it look doable if I take my time and don't rush it. I figure it's time to give the engine a new fuel landscape, seeing as how I've driven 125,000 miles with this thing without too much trouble until now. Putting a new OPS in as well.

I appreciate everyone who has chimed in. We are so lucky to have this resource, in tandem with Youtube.
 
I'm sure others will chime in on this, but with the mileage you have you might want to consider a new or upgraded timing chain while your in there. though you can r & r the IP without pulling the WP and timing area down if your careful. :) don't forget to order some new injector return lines too.

start soaking the turbo to manifold studs and nuts in some PB blaster or something to penetrate the rust. that will save you headaches !
 
If You have not done so, be a good plan to get an uprated harmonic balancer. The fluid dampener is the install it and forget it unit. Otherwise a Delco harmonic balancer will be good for about 100,000 miles.
If You can swing it, the billet belt pulley too. Those are also available through Leroy Diesel.
The Delco brand front pulley too will be good for about 100,000 miles too.
If those two components are not replaced on a regular basis there is a huge possibility of busting a crank shaft.
 
I did see the Fluid Dampener on the Leroy's site, and I definitely am going to make that a priority purchase one or two paychecks from now. Looks like he has a few other solid improvements I should be considering at this point in the truck's life.
 
Stuka T said:
I did see the Fluid Dampener on the Leroy's site, and I definitely am going to make that a priority purchase one or two paychecks from now. Looks like he has a few other solid improvements I should be considering at this point in the truck's life.
Click to expand...
Leroy is also in the process of getting more of the timing gear sets made up.
That setup removes the timing chain and in its place puts in a set of gears.
Something I definitely want to install in My truck if ever I could afford to get that.
 
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