My '98 suburban with 6.5L TD is having problems. Started it to let it warm up a couple of weeks ago, started fine but died after about 5 minutes. Wouldn't start right away, but tried again in about an hour and it did. A week later, repeated same thing. On Sunday, while driving down the freeway, it stalled, I thought, but as I coasted down the off ramp, I noticed it was actually still running. Ran fine the rest of the day. Yesterday morning, wouldn't start at all. Tried again in afternoon, no start. Tried again just now and was able to get it started, but it's not normal. During each of these no start incidents, the glow plugs were not coming on. Tonight they "blinked" on and off during first try, then stayed on a little longer during second try, on third try it finally started. Runs fine after it starts. I haven't had time to check anything, but here's what has me wondering. If it's a glow plug system issue, why would it die after running for 5 minutes and stall on the freeway? If it's a PMD issue, why would the glow plugs not come on? Do I have a short in my wiring? Any suggestions would be greatly appreciated!

A short or bad ground is possible, An inoperable lift pump could easily be checked, does it click away when you turn the key? and then there's the PMD.

First few lines are symptom of failing PMD/FSD.

Glow plugs will cycle less in warmer conditions (in florida, on hot day, hard to start
because glow plugs don't come on long enough )

Need to check BASIC FOOD GROUPS,

Lift PUMP operation : ( 95 and older need the " Bypasss Relay"

BATTERY CONNECTIONS , condition, amd Grouinds , etc.

FUEL SHUT OF SOLENOID

And you might as well get a remote FSD/PMD with a spare.
YOU WILL NEED IT SOONER OR LATTER

When all else fails to fix problem, New Injector Pump.

I can hear the lift pump. It's plenty cold to cycle the glow plugs, 30's and 40's. I agree that I should go ahead and buy a PMD, but that doesn't explain the glow plugs. Where is the fuel shut off solenoid, and how to check?

Glow plug relay might be a good place to look too.

More than likey that's a connection/ground issue at the batterry terminals. It tends to short cycle the plugs when it can't pull enough amps.

Battery cable....Great suggestion. It fits all of the symptoms.

Bad part is, I have had a chance to check anything yet. Glad I have 3 vehicles!

The terminal connectors GM uses are on side terminals and I've never liked keeping up with them, as they harbor oxidation on the threaded post and under the rubber boot on the connector. I cut them off went to top post with brass marine terminal connectors that havn't oxidized yet.

I never have liked them either. I will likely upgrade too.

My bet is the PMD.

Sounds like a PMD to me also. If you want to check the shutoff solenoid, it is about the same size as a roll of quarters with two wires coming out of the top. Older versions have an Allen socket and the newer ones have a hex for a standard socket to tighten or loosen it. Disconnect the wire harness and listed for a click. If you are not sure remove it and watch the plunger for movement when disconnecting the harness or turning the key off. They can be tough to get loose, and the older ones can be damaged when they are real tight by having the outer casing turn and the rest doesn’t. When that happens they will leak fuel.

I'm a new member with '96 2500 with same intermitent symptoms since new. Experience is that it will restart before a tow truck can arrive. Usually no codes show but Mr. Goodwrench has replaced lift pump, injection pump twice including PMD. All to no avail. I've checked exposed battery connections and replaced batteries and alternator over the years. If anything has helped the problem has still reappeared in a few months.
Glo plugs and fuel delivery seem to be separate systems ,but both seem to act up together.
GM has covered things pretty well but the down time is killing me I'll be watching this thread to see what comes out.

Welcome to the site maplegde! I am new to these engines as well, and in my experience if you don't have your PMD remote mounted out of the heat of things, it doesn't take but about a month for it to go bad again, is your PMD remote mounted or have a cooler? That could be why the symptoms reappear after a few months.

Hope ya don't mind me throwing in a question. Just had my IP replaced by GM. Is it possible to take the PMD off the pump without taking the intake manifold off? Since it is new, I would like to put it on a remote cooler.Thanks,
Dan

An interesting thought Duallyman. Is the remote mount a GM accessory or aftermarket? Truck is in the shop now w/ inconclusive search. I'll ask about it tomorrow but its nice to be able to sound like I know what I'm talking about.

mapledge: As far as my knowledge goes (wich isn't much lol), the remote mount is a aftermarket accessory, I went to my ...dealership and they hadn't heard of such a thing, so maybe you will have better luck with your ...dealership.

dmitch: I'm not very educated on these, so I am not sure about having to take the intake off for the PMD. What I have learned is that some people buy a remote mount kit that includes a new PMD and leave the old one in its place and just plug a jumper wire to the plug, and I have heard other people say that they took thiers off and made a plate that covers over where the old PMD was. Maybe someone in here can help you more with that that has more knowledge on these engines and components, there are alot of people on here that are very good with these engines and that have helped me tremendously.

Well she's out of the shop with a new glow plug controller,but nobody believes the demon is really vanquished. I probably will spring for a new PMD with remote mount if(when) it reappears. If anyone can point me to the source for that conversion kit I'd appreciate it. Thanks

Haven't got mine yet, but I here the best is at heathdiesel.com

Chad

kennedydiesel.com and heathdiesel.com both has them.