fuel shut off

[Aftermath]

My 95 6.5 td just shuts off as if the classical pmd issue. Changed pmd and new ignition switch, same deal, no rhyme or reason, cold, hot, wait a bit crank it back up then same deal after a few minutes. Now it won't crank at all. I can feel the Fuel Soleniod retracting. About to check the codes and grounds, then holler back!

Thanks in advance!

[Aftermath]

Okay, codes: 31,35,36,65,84,99......cleaned all of the grounds, then cleared the codes, still no start, code 31, no egr motor. Glow plugs cycle fine. Im taking a shot in the dark thinking it's either injection pump or ecm. Don't think it would be injection pump because it never stumbled as if it was running out of gas, just shut off like a light switch. Any help is good help.

Thanks

[sctrailrider]

Sort of sounds like loose/bad wire connection somewhere.... try moving all the wires you can and see if anything happens...

[Aftermath]

Yeah, been on the wires and cables all day. Can't find any breaks and they seem to all test out right. Battery cables, anchor studs etc. All cleaned and checked. Seems like an electrical part for sure. I was for sure that it was the ignition switch because when the gremlin first started, you could switch off and crank right back up. Then got worse over a few weeks. It would die while driving then come right back on because I was driving around 55mph, so it has been off and on, now no start and scratching my head.

[Robyn]

Ok

Back to basics.

When was the fuel filter last changed ??

Do you have fuel to the IP ??

Does the lift pump operate ??

With the fuel line unhooked from the top of the IP, Connect an extension and run it to a can.

Have a helper sit in the drivers seat, and with the Tranny in D turn the key to start. (Park brake set for safety)

The lift pump should run as long as the key is held to the start position and deliver a steady stream of fuel into the can.


A plugged filter, bad lift pump

Let us know


Missy

[Aftermath]

Yeah, already checked fuel coming out of filter housing, that's good there. Lift pump is good. Not sure of its making it through the IP or not.

[Robyn]

Be sure it will come out the hose on the top of the IP.

Was the filter changed ???

It is possible that one of the wires that connect from the PMD to the rear of the IP has broken where the harness connects.

This involves yanking the intake off to get at the back of the IP

Hmmmm

Yank the fuel shut off out and test it to see if it is really working.

I have seen these fail internally and still seem like they are retracting.

Takes only a sec to unscrew the little beast.

Make sure the neoprene end has not come off and stopped the fuel inlet.

[Robyn]

OOOOOOK

Something was troubling my little brain on this one.

The fuel flow on the GM fuel manager is up through the center, through the filter then out to the engine.

The water drain comes from the center at the bottom, and the air bleed is from the center as well.

You can easily have fuel at the bleed and yet have a filter that's plugged tighter than a Bulls A$$ in fly time.

Change out the filter, Bleed it and then I'll bet she will be fine.

Stalling and relighting like you mentioned is a classic indicator of a plugged filter.

[Aftermath]

Okay, removed the fuel shut off valve, key on and is retracting back and forth fine, fuel pumping out the hole. Checked filter and hoses, all good there. I'm thinking this is electrical, just not sure where.

Thanks

[Aftermath]

Okay, key on in park position, removed the fuel hose on top of pump going to the fuel rail and fuel is trickling out with lift pump working. Not sure how much fuel is supposed to be coming out but not as much as the lift pump can pump for sure.

[DmaxMaverick]

Okay, key on in park position, removed the fuel hose on top of pump going to the fuel rail and fuel is trickling out with lift pump working. Not sure how much fuel is supposed to be coming out but not as much as the lift pump can pump for sure.

E-brake set or chocked wheels, key to RUN (not start/crank), tranny in any position OTHER than P or N, turn key to start/crank. You have a 95 model, which is unique in how the lift pump is powered during a start. It is powered any time the key is turned to start, regardless of the tranny range selection. Taking it out of P or N prevents the engine from cranking (it only powers the lift pump and most remaining electronics).

The fuel line Robyn referred to is the RETURN line. The low pressure rubber hose out of the top of the IP. Fuel flow, with LP powered and operating correctly, will be minimal (much less than at the water drain or bleed valves), but it should flow. Repeat the test with the ESS disconnected and it should not flow fuel.

As Robyn said, the fuel manager bleed valve is at the top, and will flow fuel from the inner "clean" side of the filter element. The water drain valve at the thermostat housing is from the bottom of the filter manager, but from the outer "dirty" side of the filter element (where any water and debris should accumulate).

[Robyn]

According to the cutaway and flow chart, the fuel flows from inside to outside of the filter.

If the fuel is just trickling out of the hose at the top of the IP (FUEL INLET) your filter is plugged.

The fuel should come out at a pretty good rate.

I was reffering to the larger of the two hoses on the top of the IP.

The little one is the return line to the tank.

[Robyn]

If you have a good steady flow from the large hose, then we can start chasing a different gremlin.

Once we are sure you have a good fuel supply then the next issue has got to be electrical.

Make sure the A and B ECM fuses are good.

As I mentioned before, be sure the two wires that connect to the rear of the IP from the PMD harness are not broken under the boot on the rear of the IP


Keep us in the loop

Missy

[Aftermath]

Okay, so after racking my brain on this one, and following all the advise you all gave me, I changed the pmd again and have driven approximately 100 miles with no issues. I'll give it another 100 before I claim victory with another failed pmd. I'll let you guys know soon. Thanks all !!!

[Robyn]

It can happen.

One big thing with the electronic rigs is to have good voltage and good grounds.

Poor/low voltage in the system will drive these things nuts.

Bad grounds anywhere can cause back feeding and this can destroy the delicate micro electronics.

Make sure you have the PMD ground wire fastened to the IP. Many times folks have moved the ground from the IP to the remote cooler and in doing so ended with a poor ground.

The wire that plugged into the PMD has the ground lead that goes to the top of the IP, and this is correct.
Plug in the extention cable and relocate the PMD.

Make sure the chassis grounds are good and connect the batteries to the frame, the fenders (in the engine bay)

Be sure the 2 grounds at the rear of the intake manifold on the RH side of the engine are in good shape and not broken (These are by the tranny dip stick)

Bottom line, you may have had a dud PMD
I have seen these go away in only a month or two.

CARRY A SPARE IN THE GLOVE BOX :)