How (not) to replace a PMD

Under the bumper on a heat sink is probably a better way to go, but I'm a dyed-in-the-wool keep-it-stock sort of fellow, so I set about to replace the PMD with a D-tech, on the IP.

After about 5 hours of this, all back together, I'm admiring my workmanship, and shelving old parts, I note the calibration resistor still happily in it's happy place in the old PMD.

AAARRRRRGGGGGGgHHHHH!

So try as I might, no way to get it in the PMD through the little gaps between the intake/head/injection lines (gaps which are about half the size of my fingers), I dropped two resistors onto the valley under the intake. (I have a spare FSD which included a resistor, on a BETA cooler)

In the end, I spent far less time to R&R the intake a second time to make things right than I did trying to drop the resistors down on a wire to hopefully install them, then try various ways including a vacuum to get the stupid things out of there.

Went surprisingly quick the next time around.

So, the FSD was replaced at about 143,000 miles, but the engine never stalled or missed or anything, but there was for the last 5 years a reverse "surge" that seemed to be getting progressively more frequent (one or two times a week), this is sometimes attributed to the PMD, I don't know if the new one fixed it or not, (time will tell) and these things are a dime a dozen on e-bay, so I got one.

So, if anyone in need of the PMD described above for any purpose - to use as a spare to get you home or whatever, plus a 6 foot extension harness that came with the D-tech and which I don't need, let me know and they are yours for the price of the stamps to get them to you.

I would be happy to give it a new home. Email me please
Jim

I must tip my hat to anyone persistent enough to even entertain the idea of replacing the PMD on the IP.

I too am very anal when it comes to keeping some things stock but the PMD is just one of those items that should have never been installed where it was in the first place.

Not only is it the wrong place to even think about placing a heat sensitive electronic device but also a real PITA to change.

Good luck with the new Dtech.

Mine is happily meeting the day from a far different location I am here to tell ya :D and the old one can just rot off the pump and fall into the valley.

I have heard many excuses as to why the PMD was placed on the pump and the most probable was that GM and stanadyne were not about to share any secrets of their technology.

The components of the PMD could easily have been placed in a far different place in the vehicle as it was being built.

Always seems that when an item is one that will need service that its difficult to work on eh ? :eek:

I still totally believe that GM knew that the PMD was a POS long before these rigs ever hit the road and that a large number of them would fail.


My first one failed with the rig showing 24K on the odometer.


Best

Robyn

The right sized wire and a mirror, you can get that resistor on the PMD.

I had a rig for a short while that didn't have the resistor in the PMD due to a previous replacement. It needed the resistor in order to set the timing. The PMD on the pump was still good though. So, I installed my "spare" PMD on Beta cooler on the intake, set the timing, went on with life for awhile.

Then, about the sell the truck, so I removed the PMD/Cooler from the intake, and pulled the resistor. I then fashoned a wire tool and grabbed a small mechanics mirror and installed the resistor in the connector of the PMD while on the side of the Injection Pump.

I could have left it w/o a resistor, as the previous owner did to me, but I'm not down with that, gotta fix it right.

It wasn't easy, but it ended up taking me less than 20 minutes.

Sorry for rub it in tho :D

J

Quote:

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Originally Posted by john8662

The right sized wire and a mirror, you can get that resistor on the PMD.

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No doubt true, I was pretty sure I could do it, BUT, my problem was after dropping the tiny beggars, I could not get them back out. I couldn't even see them, I fished around with my mirror, poked around with a screwdriver with a dab of tar on the end, tried the vacuum, took off the fuel filter and pushed the hose in as far as I could, but wires and stuff were in the way.

I can laugh about it now though.

And I also believe likely the pump is not the best spot for the PMD, but the one I took off lasted there over 140,000 miles, and still worked, so, if the D-tech advertising hype is even half true, perhaps this animal may fare better, time will tell, according to their literature it needs no heat sink or anything, they sell a little bracket to put it on.

Plus, I wanted to take the intake off anyhow, good chance to return all the sockets I've dropped down there over the years back to the tool box...

Bob,
I got the PMD and harness in the mail yesterday. THANK YOU!!!!! Postage is coming back to you.
Jim

That's good to hear Jim.

It will get you out of a jam if you ever need it to I'm sure, and changing it didn't stop my reverse surging, so other than high miles, as far as I know it should be fine.