Old 6.5-T strikes again !

[buddy]

The fuel shutoff solenoid in mechanical pumps is a little different and much more important, since you dont have a PCM that stops telling an electircal PMD to stop activating the elctrical fuel solenoid. It is redundant in the electrical pumps, necessary in the mechanical ones.

not that it is useless in an electrical pump since the PMD could short out while running, cause runaway RPMs and then the PCM would have to use the fuel shutoff solenoid to stop fuel flow.

I have been with no plunger in mine for the last 500 miles. I think it helped cure a cruise control momentary stutter I had every once in a while.

 

[M123KT-450]

You guys seem overly confident the PMD isn't the issue. . .So i keep chasing after other parts n peices. . .

Mikey

 

[buddy]

Im not recommending you buy a new fuel shutoff solenoid, and removing the plunger is very easy and easily put back in. Its like a 10 min free test.

It is a good idea to have a spare PMD, and would be the first thing Id try in a no start. Pensacola diesel sells the lowest price I have seen. Less than on ebay even.

 

[M123KT-450]

Ok solenoid is out !
turn IG switch on plunger is in tight .
turn IG switch off plunger is out.

With lift pump off fuel level was at bottom of the threads.
With Lift pump turned on it pours out the whole.

So LP is pushing fuel that far and solenoid is operating. . .

Now what ?

Mikey

Photos:

 

[M123KT-450]

So i am guessing with the unit opening and closing that means that the PMD is still operating ?

and

With the fuel coming out when LP is turn on that means the IP is getting fuel ?

Holy crap IP's are $2000 ! ! ! if thats bad the truck is toast simple cut n dried. . .

Mikey

 

[NVW]

So i am guessing with the unit opening and closing that means that the PMD is still operating ?

and

With the fuel coming out when LP is turn on that means the IP is getting fuel ?

Holy crap IP's are $2000 ! ! ! if thats bad the truck is toast simple cut n dried. . .

Mikey

The PMD is unrelated to the FSO, It controls injection. I'm not up on this thread but do you have fuel at the injectors?

Pensacola Diesel has IP's for $450 w/o PMD and $650 with.

 

[M123KT-450]

I do not know if there is fuel at the injectors or not. . .

I do if the IP is bad the 6.5-T is done for. . .

Mikey

 

[JiFaire]

No, the FSO tells you nothing about the PMD.

Mikey, I've forgotten - help me out here...

You say the PMD is located behind the bumper:

- Did you do the relocation, or was it there when you got the truck?
- Do you know if it was a new or used PMD (or was the stock PMD simply moved?)

Are you getting fuel at the injectors while cranking? - you can tell by cracking open an injector line and cranking the engine - if nothing comes out, you have discovered the issue.

BTW - don't worry too much about the PMD shorting out and causing a runaway; they don't work like that- the PMD provides amplification of the PCM drive signal to the Fuel solenoids and manages pulse width of said signal. It shorts out and said signal doesn't get through.

Shorting (closed or open circuit) or electrotracking PMD, on the other hand, wil cause all kinds of things - surging, stalling, stuttering, general erratic fuel flow, etc.

 

[buddy]

Now that you have the no start, a lot more checklist items come into play. PCM SES light, codes, GP/WTS light, GPs/controller. Could just be an ECM-IGN fuse. Or as JiFaire could be eluding to, a bad PMD extension cable.

If you want to test the PMD with a digital multimeter you can check the inputs and output of the PMD. Especially if anything is making it to the IP fuel solenoid (different than the fuel/engine shutoff solenoid). The wire that leaves pin B of the PMD sends the signal to the the IP to shoot fuel, that should be above 1VAC while cranking. You would have to probe through the insulation while cranking and best to ground the other meter lead to the ground on top of the IP.

Attached files have the signals...the book diagnostics are limited and usually point to IP replacement before mechanic actually does much.

 

[M123KT-450]

Yes i am the one who relocated the PMD to the bumper. . .the one on the pump is still oin the pump so this must have been replaced. . .I relocated the second one mounted on the FSD bolted to the intake manifold. . .

I had to un plug the Solenoid to get it the spin back in now i can't get fricken plugged back in to see if it send fuel to the Injectors or not. . .:mad2:

did mention i hate this truck yet ?

Mikey

 

[buddy]

yeah that harness is a pain in the ass. At least the engine isnt hot while youre trying

 

[JiFaire]

OK, so the one you put behind the bumper spent some time on the intake manifold? Have any idea how long?

(that is the death location for PMDs...)

 

[M123KT-450]

Nope not a clue. . . Long enough for you to help me diagnose it and relocate it. . .the last time this truck had an issue with bucking and stalling out. . . truck did it twice we relocated it never had another bucking stalling issue till now. . .

Yes the ses light has come on a dozen time and it shuts right back off. . . they scan it anyway and it comes back with no codes. . .The parts house said the light has to stay on for them to scan it. . .

Mikey

 

[JiFaire]

If the thing is FUBAR, moving it doesn't help... the trick is to move it before it gets screwed up. Get the FSO hooked back up and try cracking an injector line to see if you have duel getting to the injectors.

If you don't, that tells you something...

 

[M123KT-450]

LOL you make it sound so easy. . . !

What prey tell will it tell me ? yea you got fuel and it don't run ? nope you ain't got fuel so it won't run ?

Mikey

 

[buddy]

Yes the ses light has come on a dozen time and it shuts right back off. . . they scan it anyway and it comes back with no codes. . .The parts house said the light has to stay on for them to scan it. . .

Mikey

Lucky for you, you dont need the parts guys to read codes on a 95 OBD1 and they are incorrect, as the PCM stores code history, not just what is current. Just shove a paperclip across A&B of OBD1 port and put IGN to ON, never crank with paperclip in. The SES light will flash the codes. More info if needed.

And JiFaire is correct, if PMD was flaky before, relocating it may only temporarily have resolved its past issue. Fuel at the injectors could say PMD is OK, since PMD powers the fuel solenoid to shoot fuel to injectors.

 

[JiFaire]

Yep. You know your problem isn't the LP. You know it isn't the FSO or ignition switch. If you checked the input voltages at the PMD, you know it isn't the ECM-B fuse or the PCM (most likely). Now you're working on either the PMD, IP, or a concurrent failure of the CPS and IP OS (rare, but possible).

 

[M123KT-450]

You do know your making my head hurt ?

Mikey

 

[buddy]

Sorry about that, you should have brought up your old thread, where it was mentioned your relocated PMD may only last a couple months without replacing it.

 

[Matt Bachand]

I bought a brand new PMD with heatsync that was told to mount on the Intake. It lasted 3 months there before i was chasing ghosts around assuming it was good. Turned out a new one mounted underneath ( i went with heaths) fixed the problem for good.

Mikey, take that fuel line off at the lift pump and blow compressed air back into tank. THat will clear your sock out. When I had sock problems truck would start with fuel pressure, and it would drop down to zero as I was driving. Turning truck off, let pressure go on the sock, and it would start fine, and have fuel pressure / bleeder pressure / t-valve pressure, but it didn't take long for that crud to get on the sock and screw the truck up down the road.