Injection Pump Failure Symptoms?

[Ms54Coupe]

I am afraid that the 97 2500 I am buying will indeed need a full injection pump rather than just a PMD...the truck was tested by a diesel tech and they named the pump as the issue. When I got to the lot to inspect the truck for myself I noticed that they had already performed some of the tests I planned to (PMD had been removed from the pump and was up above the intake mani suggesting they had clipped in a different one) one of the injector lines has been loosened to inspect fuel delivery etc.

Reading a post about a rebuilt pump going bad on this forum, one of the items tossed around is bad injectors...should I replace the injectors on my truck when I get it? I don't want to fix the pump and have it break due to injector failure (at 155,000 miles it is probably due for injectors anyway?)

[rameye]

How did they come up with that diagnosis??

Just wondering..

I have seen many a diesel mech call out the pump when it was something else..

[Ms54Coupe]

I did not have a chance to discuss with the tech who actually came up with that but I did notice the PMD had been pulled off the pump and was up sitting freely on the intake manifold and it did not say Stanadyne which suggests to me that it is not the original PMD. My guess is they turned the motor over and inspected flow (or lack there of) from the open injector line. I am not sure if they tried clipping in a different pmd or not.

What kind of flow rate should be seen when the engine is cranking and an injector line is disconnected?

[Robyn]

I would not worry so much about the flow rate at this point.

Does the truck run or is it dead ???

At 155K the IP and the injectors may be in need of some Loving.

The PMD really needs to be on a cooler at the very least.

I would not use a stanadyne PMD on a Dieing bet. Here is WHY all the way from 1994 up until about a year ago + - Stanadyne did virtually nothing to help the folks that own a GM diesel with there PMD except take their Money $$$$$$$$$$ :eek:

The D TECH PMD seems to be far and away better.

If you can get the truck running, then proceed with a diagnosis from there.

You need to get any and all codes wipped from the computer and then with the rig opperating, take into account any new ones that Pop up

I have seen fresh PMD's take a poop within a few months so age means nothing.

If the truck will not run, make sure the fuel shutoff Solenoid is working.

Tall round gizmo on top of the IP near the front. ( has a wire harness that goes into the top)

If it does not go CLICK when the key is turned to on then it may very well be bad.

Stalling issues are usually PMD related and in most instances will not set a code.

Some times if there is a Pulse width error, either too long or too short thats related to the PMD failing, it may set a code. Usually they just quit.

The only other failures related to a PMD are a burned circuit inside the PMD that results in the engine running fuel fuel and it SCREAMS until the ECM detects an overspeed and shuts it off.

This makes a spectacular amount of noise and smoke and may leave the faint of heart in need of a change of shorts.


If your cruising at highway speed and the PMD fails the engine will stay rolling and then the ECM may see and report a pulse width error.

At slow speed the engine simply dies so quickly that the ECM does not set a code due to the fact that the error was not registered long enough.

Learned this tid bit a while back when helping a friend diagnose a stalling issue.

At slow speeds just loafing along, when the PMD would fail, the engine died with no codes set.

If we got the thing up to highway speeds and the PMD failed the engine would stay turning and then after a couple seconds the ses light would pop on. The pulse width error code (short) would come up.

This short does not mean a short circuit but instead the Time factor that was read by the ECM

The ECM wants/needs to see a feedback from the internal fuel solenoid in the IP

The time that the solenoid is Open is measured and a closing signal is sent to the ECM. If the PMD fails and the engine is still turning at speed, the ECM will not get the signal it is expecting to see as the solenoid never opened due to the failed PMD


All these numbers vary with throttle position and other factors too.


Good luck and keep us posted


Missy

[Ms54Coupe]

Robyn,

The truck will not start but will turn over in a normal fashion...

I would not leave the PMD where it is for long but I think it would suffice to get the truck started at least.

I did not inspect the clunk so perhaps that is the issue??? I'll need to look specifically for it next time.

I also did not clear the codes but will do that before proceeding.

Thanks Robyn!

[DmaxMaverick]

Read the DTC's (codes) before clearing. Make a note of them, then clear.

Guessing can be expensive, and is rarely productive in a timely manner. Start over with the proper/accepted diagnostic procedures. Eliminate systems/components as you go until you find the suspect. Usually, the procedure progresses from the simple to difficult components (and less to more $$). Anything less is just guesswork, and normally leaves you frustrated and kicking yourself in the end (as well as lighter in the wallet). Most no-start problems are simple, such as a fuel filter, leak, empty tank, poor electrical connections, bad glow plugs/relay, etc. If you keep it simple and attack only one system at a time, it will usually remain simple.

Additionally, if you loosen an injector line and fuel pulses while cranking, the problem is not likely the PMD. The pump and PMD are well down on the diagnostic list.

[6.5TDTahoe]

A new PMD can be damaged immediatly if not properly mounted on a LARGE heat sink,such as a HEATH PMD mount. Mounting the PMD on a small light weight metal heat sinc under the the hood or attached to inner fenders ,core support,hood or cowl. The message to understand that PMD failure mounted on any less of a cooler than the IP is likely to start the PMD path to failure IMMEDIATELY!! DO NOT even run the engine any time with an inadequate HEAT SiNC. Just buy the HEATH system & drive happy for seven YEARS.of warranty.

[JohnC]

Without going into a lot of detail, if the PO was able to drive it in to the dealer then I doubt injection pump failure is your problem. I don't even think that the PMD is the likely cause of the no start, either. Catastrophic failure of the injection pump or the PMD at the moment the vehicle was delivered to the dealer is statistically unlikely. If it ran "one last time" then it should be possible to get it to run "one more time". It would be helpful to know what he did to get it running to bring in, if anything.

The amount off fuel you would expect to see weeping from the injector line at cranking speed is quite small.

None of this eliminates the possibility that something got damaged during the dealer's troubleshooting.

What you need is a methodical troubleshooting process. Verify the glow system. Verify fuel to the injection pump. If you cannot get any fuel to show on the loosened injector line then verify the shutoff solenoid. Verify the injection pump is in fact turning. Keep going until you find the problem.

[6.5 Detroit Diesel]

have you checked/replaced the fuel filter? just wondering on that one.

do not go throwing parts left and right at the truck. you can quickly find your self with a truck that has a lot of new (expensive) parts, and still doesn't run.

[AllThumbs]

Hang in there coupe. It has been interesting working on my truck how things just eventually sort of fell into place as I just kept plugging along. It will work.

I'm also of the opinion that if they drove it there, it can still run at least a little.

[Ms54Coupe]

Thanks guys...the truck is 200 miles away from me so I cannot give anyone the answers to some of these questions but I certainly appreciate the input and will apply the "test and move on" method as soon as the truck is in my possession. I cannot wait to have a truck again...it has been years and I have lots of work for it built up : )