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Discussion Starter #1
The low buck approach to FSD relocation





GM 6.5L FSD "connector" remote wiring harness


3M heat shrink connectors on a 42" wiring harness and the stock Fuel Solenoid Driver connector.



The 6 wires from the fsd connector must be cut and crimped into the FSD "connector" splice


and heat applied to the heat shrinks. The wires from the engine's stock harness are inserted into the corresponding letter slot on the other side of the weather pak connector.





This enables mounting of the fsd and cooler to your choice of surfaces(firewall),


as well as an OEM style connection at the engine.


FSD "Connector" Rewire harness 33


Heat sink for for FSD mount 11








Oil Pressure Switch Bypass w/ 30 amp relay,weather pak connector.





Want to make yor own?


All the parts that are required to build the wiring harness Remote Mount extension for the GM 6.5L EFI


Fuel Solenoid Driver can be aquired at an autoparts store or a home depot type store,


except the weather pak connection. It can be found online if you search for it by name.











[email protected]Edited by: quantum mechanic
 

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Hmmmmm, mighty small heat sink there..........let see wire kit and heat sink $125, then you need a new PMD/FSD which is about $300 plus either fish out your fuel resistor or buy new one for about $15-20. So thats about $440 plus shipping.


Heath PMD Issolator $379 or $374 (4 or 2 Wheel drive)plus $3 shipping includes 6 foot extension and big heat sink, new PMD, Fuel Resistor, mount kit, and just plug it in. And you get the thing out of the engine compartment from an outfit that has made these for many years. Lets see more money, poorer install, less convient. Hmm no question do the Heath Kit, thats the way I went and I have NO connection other than a buyer of their products.
 

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Heat is tha acknowledged problem so why mount a small heat sink on the firewall were it still sees engine heat. Take a look at my web page and see were I mounted my Heath in the bumper. After driving for quite some time I can not feel any heat on the heatsink or the driver. I have had 2 FSD fail on heatsinks mounted in the engine compartment.
 

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Discussion Starter #4
pmd connector


It's small and it works








This driver was rescued from the injector pump, and with the intake spyder off the die grinder has hours of porting and polishing to do.








fsd remote connector heat shrunk.
 

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Discussion Starter #5
I wanted to mention I run a #7 fuel calibration resistor and over two thousand miles later I have not had any problems related to my wiring harness(you know that long wire and connectors are resistors right?).But a friend who was running a #9 and his own wiring harness did get the trouble code for Too much resistor.
 

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quantum mechanic said:
I wanted to mention I run a #7 fuel calibration resistor and over two thousand miles later I have not had any problems related to my wiring harness(you know that long wire and connectors are resistors right?).But a friend who was running a #9 and his own wiring harness did get the trouble code for Too much resistor.

hmmmm maybe that's why Bill Heath puts #7 in his set up?
 

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Talking to Bill his contacts say the #7 gives better delivery than a #9, that said I've been running a #9 for 3 years with no problems, I originally had a #5, in all actuallity I felt no SOP difference.
 

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Discussion Starter #8
The #7 I'm running came with the truck. I felt a difference when I installed the wiring harness extension, It was like the govener was off. The Idle seemed low even( 420 rpm on the dash), but on the scantool it was 600+ rpm. I can only theorize that the added resistive value in the wiring harness along with the #7 resistor opened the fuel up a little.
 

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QM


Per JK and my own observation the value change does not appear to be recognized until TDC offset learn is run, the description in the 98 manual says the value is read at each start, I don't know for sure how the circuit really works,


I accidently swapped out a FSD without a resistor before and the truck still started but no codes, ran a offset learn to "calibrate" for the swap, had a FSD fault code, that is when I found I had forgotten the resistor. I think if you run a TDC learn it wipes the stored value and you get a code. Maybe it does reset itself after 40 cycles though, I'm not sure as this isn't the only place in the manual where the tech writers have gotten most covered but still a lot of grey in actual function, another area is OPS vs PCM lift pump control, probably worth doing some study though.
 

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On the subject of PMD heat, I was once told that the reason GM put it on the pump is that the pump is cooled by the fuel circulating through it. curiosity overcame me so after driving my truck for an hour or so I shut it off and reached down in there and touched the pump and PMD to feel how hot it was. It was difficult to get to and I pretty much burned myself on everything BUT the pump and PMD. The pump and PMD were noticeably cooler than the surrounding metals, even the intake manifold. I will say that it was a cold day, about 35 degrees so the fuel would be that temperature. I'm wondering about the necessity of the cooler mods. I think I will install one but I believe in the idea of putting it up front somewhere. It's hot anywhere in the engine compartment.
 

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Bob;


I have been around GM Diesel sites since 1996 I am no Techie or any of that. I have observed that most folks seem to get 70,000 to 120,000 miles out of a pump mounted driver. I also have observed that there seems to be failures of drivers locted on the intake on coolers from 25,000 to 50,000 miles. I'm hoping
that the remote mounting out of the engine compartment is much better. MY opinion and that and a buck will get you a up of coffee is, that either put it back on the pump or Remote mount out of the engine bay. From what I have seen the ONLY advantage of puting on the intake manifold is that it easier to change WHEN it fails again. JK likes putting them in couple of places in the engine bay, (fender wall, behind head light) That may do the job too. I think you should get it at least off the engine other wise I believe you might as well go back to a pump mount.


No your fuel was not 35 degree, because, more fuel is fed to the IP than is needed in part for cooling and returned to the tank, also there is a fuel heater built into the filter housing to help prevent Gelling of fuel. Some folks say in hot weather never let your tank go below 1/2 tank as you have more of a heat sink (fuel) to absorb the heat from the pump.


I have never had my truck Gell up and I think part of that is because of this design, the other is I use Power Service with every fueling and dose it extra heavy in cold weather.


Hope this helps, again I have no data just observations.Edited by: 16gaSxS
 

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Bob,


This is probably to most covered topic in the 6.5 world, go to any GM site and PMD/FSD is topic #1 in hits. I found out within 1 week of owning mine @ 37K when I bought used the problem(probably the reason it was turned in to the dealer). After some calls to JK he informed me of the IP extended policy, got a new GM IP&PMD, also ordered the cooler and extension from JK, mine is mounted remote on fender drvrs side just aft of batt.


Mine ran fine until about 73K mounted on remote cooler, 2 failure modes have been identified heat resulting in complete failure, or loose transistor nuts providing poor electrical contact, mine was the latter. In constraint of time I plugged in my "glovebox spare" to get home about 5 min on roadside vs forever it seems off of side of IP on a hot engine. That plus special tools always at wrong place it's much easier on remote mount.


I got home retorqued the nuts, the "bad" FSD started working no problems in last 5K miles, I know someone GMCTD over on the "page" that has recovered several "bad" PMDs with retorque, he runs his on the pump still, for me having potential of one going bad roadside, and the PITA to get off the pump makes the remote mount where ever you choose to mount it well worth it.


Heath Diesel has a remote mount kit with the FSD bonded to the plate, normally located on bumper for improved airflow many claim success with that, I don't have that but I do have some of his other "stuff" he is a good vendor well worth checking out, PMD/FSD fail in stock configuration from what I've read is not a matter of if it will fail but when.


As for gelling I've never had a problem with that but I also run additive FPPF Total Power and never had heat problems with returned fuel when below 1/2 tank, BTW just when is that?


The GM level indication is so crappy who knows where 1/2 tank is. I get 450 mi on std 26 gal tank, I did run out of fuel once while talking to GMCTD once
thought I was having FSD fail, his 1st question was how much fuel you got why it's 1/4, nope went from 1/4 to E in about 7 miles, my 1st 1/4 is good for about 140 miles.Edited by: Turbine Doc
 

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Discussion Starter #13
That's where I want my FSD, right out in front of the truck where hell and high water have a chance at it. Actually, I'm making a bracket to mount the cooler off the fire wall and I have a small 12v fan that I am thinking of mounting alongside the FSD cooler. More airflow on the driver couldn't hurt. My current mounting location(next to the hydraboost) is noticably cooler than the IP or on the block, after my morning commute, I'll pop the hood and take a temp. reading on the cooler. it runs about 150 deg. after 70 miles of highway( 70 mph+) driving. The Ip can't help running at 180 deg+ due to engine proximity and the fuel cooling the driver is a GM goof. you're heating the fuel more than cooling the PMD, that translates to increased inefficiency and lower MPG as well as the inevitable PMD failure. Maybe I should mount it on the a/c collector. It sure would stay cool there. A/c is required in Texas.
 

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QM


IIRC Howie E has had his bumper mounted for quite some time no problems with that location reported. To me cab mounted under the AC vent would probably be best location, can't get any cooler than that spot and out of the elements.
 

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Discussion Starter #15
Have you ever seen the street flooding we get here in Houston, Tx.? Some places swallow school buses and 18wheelers after a heavy rain and everywhere else it's deep enough to feel it on the fanclutch. This is the main reason I mounted mine as high on the firewall as I did. The other thing I get a lot of is mud. This pic is my gate and the bottomless mud pit of a road we have is between my gate and the highway. I dropped thirty tons of concrete breakout in march and watched it dissappear into the ooze.





I originally planned to mount it in the cab, but decided on the facility of the firewall. I also like the idea of cutting a hole in the hood and mounting the cooler under the hole and making a fiberglass scoop to force air over it, while keeping water out.
 

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Yup I've seen the rains, but you gotta remember too that ain't a submarine your driving if the H20 gets too deep, it's time to park it & wait for the floods to go away. Or you need to put a full water proofing & snorkle kit like Military HUMVees have for that kind of water, even hard core 4x4 trucks are waterproofed because they plan to go in the water & muck.


Normal rain & water should pose no problem for a bumper mount, the weatherpaks are tougher than you think; think of all the weatherpaks on the tranny, xfer case, and the frame which seem to hold up reasonably well in the muck. Granted if you are going to submerge them in the deep end of a mud hole real regular like, moving to high ground probably the best course of action.
 
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