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stalling

Yes, it does. In essence, what Leroy's pre-wired kit does is instead of having 10-15 amps of current flowing through the contacts inside the OPS to power the Lift Pump through the light wire gauge OEM harness, the OPS now energizes the coil inside the relay (< 1 amp) and the 30 amp relay takes its power directly from the battery to the Lift Pump using a lot heavier wire gauge than OEM. This reduces voltage drop to the LP, eliminates contact points failure in the OPS, and greatly extends the life of both the OPS and LP! Everything in his kit comes pre-terminated, plug and play, all you have to do is pull your power for the LP from the Aux Accessories terminal stud in the underhood fuse block.
 
Perhaps I missed it somewhere in the thread . . . In addition to a spare PMD and the OPS relay mod, consider adding a fuel pressure gauge (measuring at the IP inlet) somewhere that you can see it while driving. Reasoning is that the lift pump can 'sound' like it is working and yet still not do anything. The pressure gauge will let you know what is *really* going on. The Dodge crowd does a similar thing with a low pressure light. Point is (as noted) when the IP has to pull fuel from the tank, it will get you home and drive for a while, but this extra work is eating into its life.
 
Did it again?
Someone mentioned the PMD
Would this affect the starting the same way?

I have a spare PMD just not sure it's good.
Any way to test it?

Thanks for all the help!!.
 
Deja vu. See first sentence of first reponse.

There is only 1 test for pmd: replace with known good.
Try swapping it. If it goes away that could be it, even if different problems arise. As in: maybe pmd#1 has 1 error and #2 has a different error.

You could always buy a new lifetime pmd from Leroy and run it, then use it as known good to compare the 2 you have to see if they are ok. But again, I would just try the spare you have first...

This is why knowing the incoming fuel pressure is so important. At the glance of a guage you instantly know if the fuel supply is good and issues are ip/ ip related components. It literally cuts your diagnostic line in half.

Also when you are adding a fuel pressure gauge and spilling a little fuel already, pick up 6" long piece of clear line in 1/4" for the ip return line and replace your old one. Another piece but in 5/16 on the input side of ip never hurts. This is to watch for air bubbles. Air intrusion into a diesel casues havoc.

This is one of those things that costs a few bucks and 1/2 hour, but later down the road (or maybe now) will diagnose the problem simply by watching it.

Air bubbles on both sides of the ip means you have air getting sucked in- chase it back and fix it. If air only on he output of IP and not on the Input side try snugging case screws or time for new IP.

Keep us posted...
 
@Jerryjerry05

THe 95s are weird, even though they have a relay, I do believe it is upstream of the OPS, so the OPS is still prone to failure.


Basically, the Injection pump mounted PMD relies on excess fuel in the housing to absorb heat and then dump it back in the tank to disipate the heat.

If the LP dies, or wont run due to a bad OPS, then the IP has to suck its own fuel, and so there is little to no excess fuel to cool the PMD. PMD overheats and dies, creating a whole list of potential issues. They are both related and dependent on each other in stock form.

Just about every 1995 and older 6.5L I get in has a bad OPS and a bad LP, and a soon to be bad PMD.

I really feel that Leroy's Lift Pump Relay harness and a complete new PMD with relocation kit mounted in the bumper will take care of your current issues. While you are placing an order with leroy, you might as well check the condition of your oil cooler lines, your harmonic damper, and your thermostat. If any of them are suspect, the stuff Leroy offers is top shelf stuff that is well worth it. For mpgs and constant temp, I really like the t-stat, only one I have found that works well in the single t-stat setups.

If you plan on staying stock or near stock, then I recommend a AC Delco EP158 lift pump from a 92-93 spec 6.5L. It will fit perfectly, but pump a little more than the 94-00 spec 6.5L Lift pump. get the 2 new o-rings from the GM dealer, get the LP from site sponsor Rockauto.com along with any other maintenance goodies you need.

Leroy doesnt give me any kickbacks for my endorsements, I am just happy with his anal retentive desires for quality parts that I also share. :) I do part time hot-shotting with my 6.5Ls, routinely to California from 15-20,000 lbs combo, 1,500 miles one way, so I need to keep mine in good shape and the goodies from Leroy enhance durability and reliability so I gladly run them and recommend them.

Good luck!
 
Put in a new ops.
Runs!!
Why would it go bad so soon?

Something in the system to make it do that?

Is there any way to jump the plug the next time it goes?

I'm gonna carry a new one now.

The place the switch was plugged in was way deep down in the back of the motor.
Would it hurt to extend the brass tubing to make it easier to get to??
 
Word of advise on extesion hose, I used a regular high pressure hose and did one- it didnt carry the ground and didnt work. Buy Leroys. He carries the long term fix items like that and quality ops.

Your LP is probably drawing a Lot of current. Did you get AC Delco ops? The crap from autozone brands suck & always fail soon.

Get these parts fixed right first(like relay kit), then you need to check your system- something else is not healthy in there most likely to not even let it idle and burn out even a crappy one in a day.
 
@Jerryjerry05, I would personally just buy a new AC Delco OPS and Leroy's relay harness and be done with it for a long time. You could extend the port to make it easy to change, but IMO might as well eliminate the cause of why it needs changed so often.

Good luck!
 
Never buy AutoZone electrical parts for our 6.5 diesels. They are crap and that's putting it mildly. There are horror stories all over this forum of people's bad experiences with AutoZone electrical parts, including mine going 0 for 2 with an ECT sensor and a Glow plug relay, including new parts failing out of the box.
 
GM Guy said:
Just about every 1995 and older 6.5L I get in has a bad OPS and a bad LP, and a soon to be bad PMD.
Click to expand...
With my 95 I've changed one OPS after 11 years, two pmd's and just replaced a running LP with a Walbro a couple years ago. Funny how some trucks eat certain parts and others don't.
 
Not sure where the ops was bought that was on the truck???
Very possible A.Z. or Advance.
There was a new one(a.z.) along with a socket in the glove box.
The PO told me about them going bad.
I replaced the original a while back.
I used the one in the glove box (from A.Z.)
It worked for a week but was giving me the wrong reading on the OP gauge.
It went bad after about a week.
Replaced it with one from Napa.
That lasted less than 1 day.
Had to get another from Napa as the dealer was closed.
I bought a spare from O'Reilly's .
Gonna buy 2 from GM dealer on Monday.
Then take back all three of the bad and good cheapo's

I bought 1/4in brass tubing 4 pieces and made an L shaped extension.
I had/have a high pressure hose I could have used but thought the OPS might need a ground???
Doesn't leak and it seems to be about the same as what's on other 6.5's
 
If you make your own just make sure there is ZERO electrical resistance.
Even the junky ones should last longer than what result you got. YOU NEED the relay harness if you can build it or just buy it from Leroy.

Even with no lift pump it should start and run. It should just be low on power under acceleration. It sounds like your injector pump is not healthy. Or there is restrictions in the line somewhere.

Take the time to walk through all of it or it will leave you on the road side.
 
NVW said:
With my 95 I've changed one OPS after 11 years, two pmd's and just replaced a running LP with a Walbro a couple years ago. Funny how some trucks eat certain parts and others don't.
Click to expand...

I guess I am exaggerating a little, the 95 C2500HD has not needed anything the whole time I have owned it, but the 93 needed a OPS and LP, as did the 95 K2500HD.
 
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