Injection Pump and FSD

[M. Grogan]

(formerly grog01)

I have a 99 4 door open top with a 2003 6.5 TD & 65,000 miles on it. It is not a daily driver. Problem: It first started stalling on me at random times that did not form a pattern. Then it would occasionally not start. It would turn over fine but it acted as if it was out of fuel...it was not. Just about the time AAA shows up it starts fine. It happened 3 times in one day before I could get it to a GM Dealer (unfortunately non Hummer). They originally diagnosed it as a problem with the optic sensor in the injection pump. They told me that I needed to replace the entire pump assembly. They tell me that it shot out a code of p0251.

I remembered seeing the article that Chuck had written on this same issue at Flash Offroad which was extremely helpful. Has anyone else had the same scenario? Regardless, from what I know now, I will relocate the FSD to a cooler spot with the kit but do you really think the pump needs to be replaced or is this just another carbon copy FSD failure?

I'm asking because it's over $1500 more to replace the pump than just the fsd.

Thanks in advance.

[Planohummer]

The FSD/PMD relocate needs to happen whether the pump gets replaced or not. I'd say to get a new driver and relocate it, then see what happens. Labor goes down substantially when you're relocating the driver since the PITA is always mounting it on the pump and you sidestep that when you relocate. Worst case scenario-you end up needing a new pump. Your description of the problem leans toward a FSD/PMD anyway.
While you're at it-have the dealer ck the lift pump and ck for air in the fuel lines(typically tank selector valve). Either of those going out will get you a false optical sensor code(sensor doesn't like air bubbles) and will cause the PMD/FSD to overheat.

[audiofetish]

I would buy the harness and a new Dtech PMD. Here is a link to a place that sales both. http://www.dieselcare.net/CHEVROLETPRODUCTS.html. Also http://www.pensacoladiesel.com/index...oduct_id=30100. but they only sale the PMD and cool kit. I wouldn't sugest spending the money on a cool kit. You can add a CPU heat sink for 10 bucks at a computer store. Leave your old PMD in place so if you ever need to use it in an emergency it is still there. Like Plano said, this is a cheaper way too start. Hope this info helps!! Also check out humvee.net lots of H1 info….

[M. Grogan]

Thanks guys. I was also thinking along those lines. If it does turn out to be the optic sensor, is it replacable? I've seen a few for sale online but I'm not sure if it is a bolt-on component or if it requires adjustment.

[audiofetish]

Originally Posted by M. Grogan

Thanks guys. I was also thinking along those lines. If it does turn out to be the optic sensor, is it replacable? I've seen a few for sale online but I'm not sure if it is a bolt-on component or if it requires adjustment.

Yes it is replaceable. Here is a link to the replacement on a Chevy Truck. http://www.mamut.net/royh/newsdet9.htm

I think the sensors are very expensive. If it comes down to it and you find out yours is bad let me know. I am putting new heads on my 00 HMCS and I am replacing everything from the heads up with new parts. I have a Injector Pump that I could sell you pretty cheap. I can take it to a place downtown that will bench test it to be safe but it worked great until I tore my truck apart. It is complete and you would be able to pull the optical sensor out of it. Just let me know. Good luck!!

[HUMTECH]

I have to agree with Plano, an intermittant p0251 is very likely air entering the fuel system. You could try swapping out the inj pump feed hose with a clear plastic hose and run the engine and inspect for bubbles. also if you relocate the pmd and leave the old one in place you will need the resistor from inside the connector body, or a new one of the same value. The resistor is mated to the pump so the same value resistor is required in the new pmd. Hard to see but do able with a mirror and flashlight, not to mention a little patience.

[Jaquelyn Marilynn]

Being your glowplug light doesn't come on once you turn the
key "on" I would suspect your glowplug controller is not working.
First turn the ignition on and you will hear two things, the chatter of
the fuel pump and a clicking noise that should correspond to your
glowplug controller turning on and off.