Can any one help with issue with charging system on 1986 suburban. Already replaced batteries and multiple alternators and multiple belts. system works fine but if i turn on blower fan or lights and come to a stop the alternator stops charging and will not start charging again.

I also have 1995 dually and im wondering how the lift pump is energized. I know that on newer models it is operated through oil pressure switch located near glow plug relay but on 1995 what turns it on. I have already put new pump on but can never hear it like my other diesel and have to keep better than half tank of fuel or truck shuts down. my injection pump is farily new with low miles.

My third issue is with my 1999 suburban.first problem that i experienced was truck shutting down, I put new pmd with all better components that are supposed to with stand heat better and truck has been doing fine for several months. Started having issues when driving the engine would rev up on its own. I did have bad crankshaft sensor once. Now when the truck gets warm the engine revs up and i lose all throttle control and the truck revs up and down. my latests codes are po126 which is a coolant issue and other code po216 which is a timing circuit issue. Might this be a different pmd issue that i have never seen.

 

i would have say if shutting down at half tank some where in the pick tub in tank sucking air has hole in it


that sound like you have bad PMD you may want try PMD off the other truck see what happens


On you 86 can't help you there sorry

 

On 1995 truck it does not seem that lift pump is ever energizing, so my injection pump can only do so much up to half tank or so.

On the 1999 my first pmd issue was just shutting down now i have engine reving up then loose all throttle contrl is that typical of the pmd

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On my 1995 is the pump energized also through oil pressure switch.

 

that could be bad OPS or the LP bad best way check that is put 12V right to LP and open T-Valve and see if fuel coming out if their fuel most likey you got bad OPS

Yes it could be PMD

Yes if OBD1 OPS runs it all

 

thanks so much, these multiple different issues with the same part is so misleading. I have multiple dif pmd so will try dif one tomorrow.

 

PMD do all kind dumb things

 

I would have to agree with the pmd doing all kinds of dumb things.
I by pass the oil switch on them. I know its probably not safe but I got tired of them going out and the fuel pump not running.

Take a pmd off one of the other truck's if its mounted some were you can easily get to it(another advantage to having it on the bumper) and put it on your 99 if problem goes away you found it. My 94 was doing the same thing and it was the i/p. Had something to do with a fuel control valve inside the pump. If you unplug the os you should have throttle control it will just run like crap.

 

thanks I got multiple pmds and will try other one just stinks that this pmd is three months old, cost over 200 dollars and is supposed to withstand high temps better.

 

Where do you have the pmd mounted?

 

if it band most places back up yr it old style and 2yrs for new style