Good place to relocate PMD to

[DA BIG ONE]

My 3 units could be considered overkill but any FSD issues are short lived by simply unplugging the dummy plug from spare, and active plug from failed unit then switching them. Had to do this once when my IP was failing the unit I switched to had a #9 resistor that kept my truck running until I had replaced IP (mechanical cam ring failure).

My first thought was the FSD w/#5 resistor was bad "it wasn't". Bill Heath pointed out that the #9 had enough extra fuel to run motor and the IP would have to be replaced soon "he was right".

[Robyn]

Let me add this.
All the advice here is great stuff.
Just be sure that whatever cooler you buy is beefy and that the mounting surface is FLAT. dont pull the FSD/PMD down onto a surface thats not nice and flat.
The gasket/heat transfer pad that comes with the new FSD is good but you can also use the heat tranfer paste (White goop) that is used in computers to mount the cooler to the processor.

Coolers are what coolers are. They should be rugged with plenty of stiffness in them and have a nice compliment of fins to expose as much surface to radiate heat as possible.

All the vendors here offer good stuff
Ebay is full of heat sink stuff and cables too.

I have made them from heat sink stock that I bought at the aluminum dealer in town. The stuff is a simple extrusion.
The last one I set up for a fellow I made here and machined the back surface nice and flat on the mill.

Just take your pick of the sellers as most are very good. Just be sure the unit is flat.

The options for a PMD are limited to the Stanadyne unit and now the DTECH unit.

I dont believe there are any others but there may be as new stuff is coming on the market all the time.

Good luck and happy hollidays
Robyn

[xtrempickup]

Ordered my heat sink, now just have to wait for that to come also and pick the mouting spot where it will get the most breeze and is easiest to do with zip ties or something. thanks everyone for your input

[More Power]

replaced IP (mechanical cam ring failure).

Did you see the cam ring in the failed pump, or was this confirmed by the pump shop? Did you try the pump using a replacement FSD with a #5 or 7 resistor?

I have most of the internal parts from a failed DS4 in the shop. The rollers are badly worn, but the cam ring looks virtually untouched. See below. The new roller is there to show what they're supposed to look like. The "ceramic roller" is actually just ceramic coated.

[DA BIG ONE]

Did you see the cam ring in the failed pump, or was this confirmed by the pump shop? Did you try the pump using a replacement FSD with a #5 or 7 resistor?

I have most of the internal parts from a failed DS4 in the shop. The rollers are badly worn, but the cam ring looks virtually untouched. See below. The new roller is there to show what they're supposed to look like. The "ceramic roller" is actually just ceramic coated.

The truck would start, run awhile, stall again and generally run like cr_p, I switched to the FSD that had a #9 resistor truck ran but was using lots of fuel. I sent back to Heath the FSD w/5 resistor and he reported back to me that the parts checked out fine, and that I would more likely than not need an IP soon.

The code for mechanical cam ring failure p0251, or? was ever present, and no I did not see the damaged cam ring and have the pump sitting on a bench here. There are not a lot of miles on this unit.

[More Power]

DTC P0251 "Injection Pump Cam System" does not address and is not about the cam ring and rollers illustrated above. It's about the Optical Encoder Sensor and its ability to read an encoded disc.



The optical encoder sensor provides a "pump cam signal" to the PCM by reading through a perforated disc, allowing it to count the pulses of light that shine through. I suppose the term "pump cam signal" was carried over from other applications, but was repurposed here in the DS4 and PCM.

So, you had an optical encoder sensor problem, which is not a wear issue - more likely an opto/electronic one. This was a big problem in the 1994-95 model DS4's, which Stanadyne designed around with a new style OES (Optical Encoder Sensor) assembly. The early versions failed because of a solid potting compound, which didn't allow for adequate thermal expansion. The newer style OES was "unpotted".

I'm not sure how an OES problem could be related to or affected by the FSD or resistor value.

Incidentally, P0251 (and a few others) can be caused by air in the fuel system. Some have theorized that dyed fuel can cause this as well.

Jim

[DA BIG ONE]

DTC P0251 "Injection Pump Cam System" does not address and is not about the cam ring and rollers illustrated above. It's about the Optical Encoder Sensor and its ability to read an encoded disc.



The optical encoder sensor provides a "pump cam signal" to the PCM by reading through a perforated disc, allowing it to count the pulses of light that shine through. I suppose the term "pump cam signal" was carried over from other applications, but was repurposed here in the DS4 and PCM.

So, you had an optical encoder sensor problem, which is not a wear issue - more likely an opto/electronic one. This was a big problem in the 1994-95 model DS4's, which Stanadyne designed around with a new style OES (Optical Encoder Sensor) assembly. The early versions failed because of a solid potting compound, which didn't allow for adequate thermal expansion. The newer style OES was "unpotted".

I'm not sure how an OES problem could be related to or affected by the FSD or resistor value.

Incidentally, P0251 (and a few others) can be caused by air in the fuel system. Some have theorized that dyed fuel can cause this as well.

Jim

I'm trying to remember just who swore to me it was a mechanical failure to the cam ring? Drawing a blank, but I have asked in past postings what neg effect if any would hi-pops have on the life of the cam ring because I read somewhere that the excessive pressure required to pop the the injectors could damage the cam ring, thinking I fell for some BS along the line.

Anyway, I use a blue tinted 2 cycle oil added to my fuel and have been for awhile considering this might have been the issue then but what about now? Could this be my missed counts detected by scanner? Mechanical pump seems to be in the near future for me.

[More Power]

I'm trying to remember just who swore to me it was a mechanical failure to the cam ring? Drawing a blank, but I have asked in past postings what neg effect if any would hi-pops have on the life of the cam ring because I read somewhere that the excessive pressure required to pop the the injectors could damage the cam ring, thinking I fell for some BS along the line.

Anyway, I use a blue tinted 2 cycle oil added to my fuel and have been for awhile considering this might have been the issue then but what about now? Could this be my missed counts detected by scanner? Mechanical pump seems to be in the near future for me.

Page 6-2273 of the 1998 GM service manual discusses P0251 in more detail.

The DS4 fuel injection pump's main shaft turns at the same speed as the engine's camshaft (1/2 engine speed). So, a signal generated by the OES could be used to indicate camshaft position. The Duramax also uses a cam position sensor as part of its EFI system, but it reads a notched wheel mounted onto the face of the camshaft.

The distance is so small between the OES emitter and sensor that the fuel would have to be nearly opaque to prevent light from shining through the coded disc. So, I wouldn't necessarily agree that dyed fuel or fuel treatments could affect a typical and normally operating DS4. I wouldn't worry about dye used in the 2-cycle oil. Air in the fuel system is mentioned in the manual as a potential cause for a P0251 because a bubble could optically interfere with the light.

Also, the GM manual suggests that for a P0251, the fuel injection pump would need to be replaced once eliminating a possible wiring problem. If the problem persists, they then suggest replacing the PCM.

Some here have replaced a defective OES without removing the DS4 from the engine. There is a calibration procedure that needs to be performed at a pump reman facility when installing a replacement OES, so it would take luck, trial & error, patience, as well as a good understanding of how the OES contributes to EFI to be successful when doing it in the truck.

Jim

[More Power]

I'm trying to remember just who swore to me it was a mechanical failure to the cam ring? Drawing a blank, but I have asked in past postings what neg effect if any would hi-pops have on the life of the cam ring because I read somewhere that the excessive pressure required to pop the the injectors could damage the cam ring, thinking I fell for some BS along the line.

As far as I know it's just a theory that higher pop pressures could contribute to shortened cam ring and roller life. It kinda makes sense, if these components have a finite wear lifespan that a higher operating load would shorten that life. But, it's still just a theory... At least it is until someone runs a number of side by side bench tests using stock and uprated pop pressures to determine whether there is a difference in durability.

Another question when using higher pop pressure injectors is what effect that might have on the FSD. BETA (FSD Cooler manufacturer) found that a failed lift pump caused the FSD to generate more heat because it had to work harder. Would higher pop pressures cause the FSD to run at a higher temperature?

Jim

[Robyn]

I am wondering what Peninsular uses in their 300 HP units that are running the hig pop marine injectors???
I realize the DB2 is somewhat different but the cam ring and rollers are are still present enven in the DS4

Just currious

Robyn

[DA BIG ONE]

I am wondering what Peninsular uses in their 300 HP units that are running the hig pop marine injectors???
I realize the DB2 is somewhat different but the cam ring and rollers are are still present enven in the DS4

Just currious

Robyn

I've heard of 6.5td making 350 HP @ crank using DB4, for over the road I'm thinking some cooling mads might be needed.

[DA BIG ONE]

Page 6-2273 of the 1998 GM service manual discusses P0251 in more detail.

The DS4 fuel injection pump's main shaft turns at the same speed as the engine's camshaft (1/2 engine speed). So, a signal generated by the OES could be used to indicate camshaft position. The Duramax also uses a cam position sensor as part of its EFI system, but it reads a notched wheel mounted onto the face of the camshaft.

The distance is so small between the OES emitter and sensor that the fuel would have to be nearly opaque to prevent light from shining through the coded disc. So, I wouldn't necessarily agree that dyed fuel or fuel treatments could affect a typical and normally operating DS4. I wouldn't worry about dye used in the 2-cycle oil. Air in the fuel system is mentioned in the manual as a potential cause for a P0251 because a bubble could optically interfere with the light.

Also, the GM manual suggests that for a P0251, the fuel injection pump would need to be replaced once eliminating a possible wiring problem. If the problem persists, they then suggest replacing the PCM.

Some here have replaced a defective OES without removing the DS4 from the engine. There is a calibration procedure that needs to be performed at a pump reman facility when installing a replacement OES, so it would take luck, trial & error, patience, as well as a good understanding of how the OES contributes to EFI to be successful when doing it in the truck.

Jim

I happen to have my factory HD PCM, thinking of cutting back on boost and trying it out for awhile.

[xtrempickup]

wow well eveyrthing i thought i needed came. Cooler, new pmd and 6 ft cable. I guess i never asked how invovled getting the old one out was or the procedure. let me guess this is an all day job? i need to remove the intake manifold to do this? then i guess remove the gaskets etc and if this doesnt fix it i just spent a whole lot of time on this thing. wow i think i should have asked how much work and what was involved in changing this thing

[JohnC]

Leave the old one where it is. Use a long thin screwdriver to release the lock on the connector and pry it loose, then pull the wire up to where you can connect to it.

[xtrempickup]

my connector that is on the one thats on the IP is facing toward the rear of the truck. i dont think there is anyway to get at it. i guess i could try again. i guess isnt worth a shot since i cant even see it

[xtrempickup]

ok thanks John, was able to get the old plug off the IP mounted pmd and the new one connected and is in the front bumper nostril. just have to do something to old it there havent figured out what just yet as there isnt much to mount it to or tie it up to. my cooler is about 7in x 5 and was just able to get it in there, now comes hold to get it to stay in one place. i managed to rig something up til i can mount it better

[DA BIG ONE]

At bottom of bumper are holes to mount air dam these are good locations to mount your cooling plate too behind one of the openings. Thinking slightly longer bolts, small "L" bracket and you should be good to go........

Good luck!