GMC Sierra diesel stalling

Sounds like it is time to replace the FSD/PMD (fuel solenoid driver/pump mounted driver) that is mounted on the side of the injector pump. It is a common problem with 6.5L GMC diesels with the electronic controlled pump. It is primarily a age/heat related issue.

Also, if you have less than 120,000 miles there is a service bulletin out for injector pump replacement on your truck, check with your local dealer and see if you qualify. Stalling is one of the main symptoms for the injector pump replacement program. If I recall correctly the limit is 11 years and 120,000 miles for this extended coverage.

Good luck!!

George

Chip wrote:

To add to the previous post, if you are lucky and catch it quick, you will only need to replace the fuel solenoid driver (FSD). However, if not then the excessive heat will have baked the optical sensor inside the pump and the entire pump will need to be replaced. Regardless, if your truck is not still under the waranty coverage (11 years, 120k miles) then take it to a reputable diesel shop that rebuilds its own Stanadyne pumps. You will be able to get away for around $1500.00 where the dealer would charge an out-of-waranty vehicle over $2000.00. The dealer doesn't remanufacture the pumps, so he has to pass on the cost of the new pump to you. I had a '95 Chevy C1500 with the 6.5L turbo-diesel and I had to go through this entire process myself, so I'm talking from first-hand experience.

Either way (FSD only or full pump replacement), to prevent this from happening again install a device called an "FSD Cooler". Search for it on the net and you should find several diesel supply houses that will sell it to you online, along with a new FSD if you need one. The FSD Cooler mounts the FSD away from the fuel injection pump and allows the heat it generates to be bled off into the air instead of absorbed into the pump body itself. This is one huge step towards restoring the reliability and performance of the DS4 fuel injection pump your truck uses, which is otherwise an excellent unit if it weren't for the side-mounted FSD. If all you need is an FSD and wish to install the FSD Cooler, don't bother trying to remove the old one from the side of the pump - you will have to remove the intake manifold to do so and it's not worth the trouble. Just buy a new FSD with the cooler and install both as a set. The standard mounting position for the FSD Cooler is such that you will have to fish out the wiring harness from the old one around the intake manifold, but you won't need to buy an extension. Why GM doesn't make this standard on these motors is beyond me.

Check to see if any codes have been set in your truck's computer. Depending on the code, this will be an early indication of whether you need only a new FSD or an entire pump. Post back if you have any additional questions, and I will be happy to tell you what I can.

Cheers - Jonathan

It has just a few more than 120,000 miles. Like 100k more. That's right, it has about 220,00 miles on it. Most of the time, it does not have any problem. It's been hesitating lately, but not stalling. Sometimes it exibits no trouble at all. I've printed your posts and I;m going to give them to my mom because she works for a company that does diesel truck work. I do appreciate your answers and I'll keep you posted as to what they say and what the final outcome is.

Chip

Thanks for all of your experience Johathan,

I am wondering though, This FSD is an electronic device, is it possible, however remote, that it's still doing something? If I buy the cooler, and put it on the FSD that I have, is it possible that it will fix the problem?

Yes, I'm trying to see if I have to buy the FSD and the cooler. Or just the cooler. The guy I talked to at usdieselparts.com (?) said that it's too late for me, I'll need both. I'm just trying to figure out if he was just trying to sell more parts or if I really need it. The thing does not fail all of the time and being electronic, maybe it's just too hot when it fails. Maybe that's just wishful thinking. What do you think?

Thanks,

Chip

Some of the guys over on the 62-65 Dieselpage are popping the covers off the power transisters (you will see what I mean when you remove your FSD from the pump) and retightening the mounting nuts and gaining a second life from theirs. Personally I would still carry a spare if that was my solution of choice. Long distance walking for exercise is not my first choice.

You might want to check out the 6.5L forum on

I think as a non member you will be able to search and browse the articles. And you may just want to join and get in on the fun. So yes, that may get you in motion again, but be cautious till you gain some confidence in the fix, don't start any long trips or venture into any dark alleys till you are reasonably sure you won't have to return as a pedestrian. Actually that can be checked out without buying the cooler but I strongly recommend buying the cooler anyway. It will get the FSD out where you can work with it. I made my own cooler by going to the scrap metal yard and buying an appropriate size hunk of aluminim and mounting my replacement FSD on it and then mounting the whole mess on a fabricated bracket on the top of the intake plenum where it has air all around it. One of these days I will get around to cutting the fins in it to make it a proper heat sink. The original wiring reached to the new location (just an inch or so from the original location) with no problem.

Good luck!!

George Vigner>Thanks for all of your experience Johathan,

As much as I would like to offer hope for your current FSD (and save you some $$ in the process), by the time you are experiencing the conditions you describe it is most likely too late. I will say that I am extremely impressed. If your truck has actually gone 220,000 miles and not needed either an FSD or full fuel injection pump replaced then I'm going to have to say that you have more than gotten your money's worth out of it. Typically, an FSD lasts only 75,000 miles and you've more than tripled that number. On my old truck I replaced the first FSD at around 75k miles, then the entire pump and installed an FSD cooler at 143k miles. I think that you're just going to have to bite the bullet and buy a new FSD when you get the cooler. Your biggest concern now is whether or not the excess heat has cooked the optical sensor in the FI pump or managed to thin out the fuel (reducing its lubricity) and damaged the internal components to the point where you will now need an entirely new pump (remanufactured actually). If there are any codes set in your ECM then retrieve them and I'll look them up. If any of the codes are for the optical sensor, then I'm afraid that'll be bad news for the entire pump.

As for removing the current FSD from the side of the pump, if you don't do the work yourself (and for some even if you do) the cost and aggrevation of having to remove and replace the intake manifold is greater than the cost of the new FSD you would be buying, combined with the possibility that the current FSD may be DOA even after you get it off regardless. There is no way of telling. The cooler does not fix failed FSD's, just prevents them from failing in the future. Check eBay for FSD's and you might get lucky. I sold my spare one there this past January after I sold my '95 with 175k miles and bought my current '04, and the guy who bought it got a good deal.

Cheers - Jonathan

Hi Johathan,

I checked the codes, Here's what I found out.

22 22 22 Accelorator Pedal Position 1 Circuit Low 23 23 23 Accelorator Pedal Position 1 Circuit Range Fault 35 35 35 Injection Pulse Width Error (Response Time Short) 78 78 78 Turbo Wastegate Solenoid Fault

I'll do the work myself so I'm not sure if I'll need to replace the FSD or not. For 300 dollars, I'll probably take the old FSD off. I'm going to have someone at work or the local welding shop make a heat sink for me.

Thanks,

Chip

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