2000 Chevrolet c3500hd 6.5 diesel stalling

I have a 2000 3500HD 6.5 diesel dually with a big service/utility bed. I’m having stalling issues. The truck sat out on the Florida coast for a while. I bought it. Changed the oil batteries and flushed coolant and put it into full time service 3 weeks ago. It has 155k miles and I was told it had the injection pump and pmd were replaced and pmd relocated. When I’m not sure.
Anyway truck ran fine for the first 3 weeks. It had a intermittent check engine light for the crankshaft position sensor, a small diesel leak around the fuel filter where it screws down, the fuel gauge floats around and the volt meter reads 17. Aside from that it ran fine. When filling up the rear tank always needs more than the front so it seems to be moving the diesel between them.
Driving home after 175 miles since last fill up it suddenly just died. I cranked it and cranked it and it started. A mile later it died again and took 10 minutes to restart and ran rough. For this entire story this is how it goes. Sometimes after a bunch of cranking it starts up and runs fine for a couple blocks and sometimes it has to sit and then runs rough and after going around the block it dies again.
So next day after doing a bunch of reading I started messing with it. Also due to the fact that parts were only at stores across town I was picking up extra stuff. I checked the grounds under the hood around the intake and they looked good. I limped it down the road and topped it off with diesel. It had plenty in it.

I replaced the fuel filter and the PMD also called FSD, which has been relocated to the drivers side. Cleared computer codes. Drove around the block and it died. same problem.

The lift pump down under near the drivers door seemed to be working fine as fuel would come out of the tee valve when opened under the hood and a amp meter said it was. I replaced it anyway. Same problem

I unplugged the optical sensor as the internet claimed unplugging it sets a check engine light off but puts the computer into a mode where the truck will still run if this is at fault. Same problem. Plugged sensor back in. Cleared codes

I replaced the crankshaft position sensor and cleared all computer codes. Same problem

I restarted and the truck and it ran fine all night. No codes. Next day it seemed to be fine but had a occasional hiccup at highway speeds. No codes. Next day seemed fine and at a light it died. It restarted right away with no issue and it has been fine all afternoon but now I have a check engine light. P0251 Injection pump fuel metering control A (Cam/Rotor/injector). I am now 160 miles from when I filled the truck right after it initially started acting up.

So basically I need to know where to go next as I have already tossed some money at it I didn’t need to. I’m leaning towards a garage with better diagnostic equipment or I need some specific spots to attack with my multi meter. Or just someone who has traveled this road already LOL.
Thanks for the help!

I’d replace that sensor and go from there.

I already replaced it. It’s noted in the post

That P0251 code seems to be telling you there may be a problem with the position sensor for the fuel injection pump

I just looked in my service manual for the 1999 P42, which uses the same 6.5 liter diesel

Anyways, check this out . . . it’s straight from the P0251 fault code description and diagnosis

“The optical sensor provides a pump cam signal to the PCM by counting the pulses on the sensor, which is a disk located inside of the injection pump. The pump cam is one of the most important inputs by the PCM for fuel control and timing. This test monitors the number of crankshaft position pulses that have occurred since the last cam pulse. The physical one to one correspondence between the pump cam and the crankshaft implies that if more crank pulses are detected than cam pulses, the cam pulses have been missed.”

Conditions for setting the DTC . . . eight consecutive cam pulses are missing or an average of eight cam pulses are missing

You may also want to check out acdelcotechconnect.com Click on shop tools, then scroll down to mode 6 data, and select your engine. Then you can further scroll down to code p0251. It gives you some more details. If I was more tech-savvy, I’d send you the wiring diagram, but I’m not, unfortunately

Grey wire from pcm to optical fuel temperature sensor 5v reference

yellow wire from pcm to sensor . . . fuel temperature signal

brown/white wire from sensor to pcm pump cam sensor signal

orange wire from sensor to pcm high resolution signal

pink/black wire from sensor to pcm sensor ground

Do you have access to a factory-level scan tool. I have a feeling that code isn’t just a coincidence. I wouldn’t be surprised if the pump cam sensor signal is indeed erratic, and possibly the cause of the engine stalling

As for that 17V . . . if that gauge is reading correctly, you’re going to fry something. That’s some serious overcharging. Use your dmm to verify

We have lots of gm 3500HDs of this vintage in our fleet, but they’re mostly gasoline. But they’re dual tank and have a fuel transfer pump located on the left frame rail. They also have a fuel balance module, which averages out the signals from the 2 senders and “decides” what it wants the gauge to read.

What’s “pmd” . . . ?

Just to be clear, your 3500HD is the old square body style, correct?

With the 225/70R19.5 tires, correct?

It seems the cam is inside the injection pump, but the optical sensor sits on top, not sure how expensive it is, but can you remove it, to check that the disks aren’t physically damaged? If everything checks out electrically, maybe the optical sensor is no good?

Concur, that’s the number one issue to address, as the other problem may well be caused by too high of voltage powering the electrical system. If you replace any electrical part, it might be damaged again if you don’t address the 17 volt problem first. The stalling, my guess is a fuel delivery problem. Likely the result of the metering control. But that probably involves electrical parts, so defer on that until the 17 volt problem is fixed. Some auto parts stores have alternator testing jigs. If you can find one to bench test your alternator, that would be a good plan.

With a meter across either battery it reads 13.7 while running. I think the reading on the dash is causes by something else.
Yes it is the old square body with the tires you listed. PMD pump mounted driver. Which seems to be the main culprit in these situations. Also called fuel solenoid driver.
I will check out that GM site. Thanks!
I wish I had better access to dealer level scan tools. I just have a $400 scanner. It’s nice but not fancy enough

That sounds correct. The 17 volt problem must be something else, like you say. Is that a digital display? i.e. digits showing “17” on a screen? Or an analog meter, with a hand that moves to correspond to the volt scale? There’s usually a voltage regulator gadget for the console display, and if that part fails it can cause this sort of meter problem. Whether it would cause other problems besides the meter dispaly, hard to say without scrutinizing the electrical schematics.

What rpo code is your engine . . . L57 or L65?

The codes are either on your sunvisor, behind the seat, or in the glove box, if you have one

glad to hear you don’t have an overcharging problem

does your scanner at least display the cam signal from that optical sensor, with the engine idling?

L65. The scanner isn’t high end enough to read the data stream from that sensor. Just intake air temp, rpm, coolant temp, volts, engine load etc.
I just started it and the check engine light is now off lol.
One forum post claimed if I unplug the optical sensor and the problem goes away then it’s at fault but I did that and it still had the problem but who knows if that is correct.
It’s a good mystery that’s for sure.

Okay, L65 is the rpo for the turbocharged engine

Here’s something you might be able to check with your dmm

“Start and idle the engine. Using a scan tool, select the RPM control and request 900rpm. With the dmm on Hertz (Hz) scale, back probe the pump CAM signal circuit at the PCM.”

The specified value is 57-63 Hz

I’m thinking if you could put a stick on the pedal, so that you’re idling at exactly 900rpm, perhaps you could perform the test.

Anyways, with any luck, that code won’t be back, and your stalling problems are over.

I did some checking, and my manual does not list a procedure for replacing the optical sensor. And online parts stores list all sorts of parts, but not that sensor. Perhaps it’s not available separately. But the pictures show a snap ring, which lead me to believe it can be removed from the injection pump assembly.

you said you’re not sure if the pmd was replaced and relocated.

The factory was is to mount it direcly on the side of the injection pump. So if it’s NOT there, then it has been relocated. Now as for having been replaced, who can say? Does the injection pump have any kind of tag or plate, which might indicate it’s a rebuilt unit, versus the original?

As for that crankshaft position sensor . . . the manual states you must perform a pcm programming procedure after replacing the sensor. To be more specific, you must perform the tdc offset procedure.

Here’s a cut and paste

“The PCM will automatically activate the TDC Offset program when the engine coolant is greater than 170 degrees fahrenheit. If the PCM is not programmed with a TDC Offset, a DTC P1214 will set.”

Considering you didn’t mention P1214, and some time has elapsed, it’s quite possible, the pcm has already performed this procedure on its own.

The pmd has been relocated. I replaced it the other day. As to when it was replaced before who knows. I will look around the injection pump for a tag but it’s pretty buried.
I will give the 900 rpm thing a try tomorrow. Thanks.
There are YouTube vids on just replacing the optical sensor. Although if I take the truck apart to that point I will be tempted to just replace the entire injection pump.
I have read threads where people have filled the fuel filter with all sorts of interesting things to clean the sensor in place. Others have even suggested that if air was mixing and causing bubbles in the diesel it does odd things.
I’m trying to get to the root of it without wasting more money and I don’t really want to try some of the hokie weird things I’ve seen in threads like acetone in the fuel filter to “clean it out” unless someone can verify results
It hasn’t given that code you mentioned. I may hit up a Catholic church and spray some Holy water on it.

Tech tip. If anyone goes to replace the crankshaft position sensor. You don’t need to loosen the power steering pump as suggested in posts. Slide the old one out until it hits the ps pump. Cut it in half with a sawzall or jigsaw. The new one will wiggle in at a angle without messing with the pump. My suggestion on the wires is to unplug the old sensor from near the injection pump and attach new sensor to it and pull it down.


Todays news. I was going to run some tests after work but it died again. Restarted once. After a mile it wouldn’t start again. Just Run for a few seconds and die. I had to have a wrecker get it and being a couple miles from a chevrolet dealer that’s where I dropped it.

I sure hope they assign the diagnosis to one of the older guys . . . who’s hopeful more patient and competent . . . versus one of the young whipper snappers

Are ya sure the fuel tank isn’t just all gunked up sitting for a while. Stuff grows in diesel and can plug things up pretty good. I only had 20K on mine and got a bad tank of fuel and finally had to drop and empty the tank to get all the organisms out. Going through about a filter a month. Just a thought.

I don’t know on the fuel gunk. That was going to be one of my next steps in the process.
Service dude wrote me up fast while I was paying the tow man. I said hold on. Let me tell you the story. He pulled another guy in pretty quick. They realized I’m not the average broken car customer and I made it clear before I spend money I need to know exactly what it is and I want to know how they came to whatever conclusion. If I drive away and 2 days later the same issue shows up I will be very displeased. I wrote on the front of the paper work parts i changed and engine codes and they stapled my business card to it.

They told me they only have a couple guys that can work on the older diesels and that it may not be done as fast as I would like. Which I told them I need the truck but I need it done correctly more than anything. Besides my dash camera is still on and recording lol.

As a mechanic, please trust me on this . . .

You’re better off if the truck sits around a few days, until the smart and experienced guy can get to it . . . versus a guy with limited experience and skills, who may very well make expensive wrong guesses

Glad they took you seriously. The service writer at the Acura dealer is a girl (nothing against that at all) but when I try to tell her what was checked etc., she just blows me off and says the technicians will check it out.

One thing though, way back, I used to use a guy that worked on diesels at the Olds dealer and still didn’t run right when he replaced the injector pump. So I went to an actual diesel shop in the big city and it never ran so good. Essentially the factory service manual was wrong and the pump had to be advanced slightly from the stamped timing mark to be correct. The Olds guy didn’t know that but the diesel service pro did. Later on there was another ancient guy in town that I found out dealers used to send their problem diesels to. He just had an old barn on a farm for a shop but fixed many a diesel, I guess. Yours might have more electronics than the old ones but still if the dealer can’t figure it out, might want call a diesel shop.

In the early 1990’s some of the Dodge truck owners also had their injection timing changed, not because the factory settings were wrong but because they preferred performance over tailpipe emissions standards.

So the dealer says I ran it out of diesel. I had 200 miles on this fill up. So does anyone know how many gallons each tank holds. It has 2. Granted the front tank foams and annoyingly clicks off a lot but I thought it was filled.
They said they put s few gallons in each tank and I put 20 gallons in after. We checked for fuel leaks and found none while running. They said both were empty so the back tank has to be pumping to the front one.