Shut down ???

[BorJansson]

1994 k1500 with 6.5l diesel.

Following have happend to me three times within the last 2-3 days.
Engine starts fine and run great.
I put in reverse gear and go backwards 5-15 meters and engine stops as I should turn off the key. It starts again, but I have to crank it a lot in 3-4 sessions with a break in between. It hesitate when starting up and then runs OK
I have changed PMD/FSD wich is relocated on a cooler to above left fender. Third stop was with the new PMD.
It has not happend when in Drive and go forward.
I can also go fwd in drive a few meters and then reverse and go backwards without shut down ??

Have in my mind to connect a small lamp in parallell with Fuel Shut off Solenoid to check 12V.

Question is what in connection with reverse gear can cause shut off fuel ??

Regards
Borjan

[DmaxMaverick]

It could be any number of electrical connections, but it sounds more likely the ignition switch. Not unusual for earlier GMT-400 trucks, especially if it's original. Having a lot of keys or other items hanging off the ign. key can also affect weakening of the switch. The position of the column shift lever may have something to do with it.

[Robyn]

I agree with maverick on this...

Been down this road before.....

The slider type ignition switches have a habit of losing contact.......
The shifter controls the backup lights and the Neutral safety switch....

Possible loose grounds at the engine (Rear of engine on the RH side top of engine....

[a5150nut]

It could be any number of electrical connections, but it sounds more likely the ignition switch. Not unusual for earlier GMT-400 trucks, especially if it's original. Having a lot of keys or other items hanging off the ign. key can also affect weakening of the switch. The position of the column shift lever may have something to do with it.

My 94 had the ignition switch on the lower column with a rod from the tumbler running to it. Replaced it once in the 20 years I had it. Never a tumbler and I carried plenty of keys.

[DmaxMaverick]

My 94 had the ignition switch on the lower column with a rod from the tumbler running to it. Replaced it once in the 20 years I had it. Never a tumbler and I carried plenty of keys.

The physical ignition switch is lower on the column, but the Passlock sensor is at the cylinder. I don't think a Passlock sensor error would cause a shutdown, but will prevent starts or restarts. A lot of weight hanging/swinging on the cylinder can cause the tolerance to open over time, creating Passlock errors.

[Lug]

Also check remote pmd wiring harness. The new to me 95 K2500 had a bad wire in the harness that was mimicking a failing pmd. Ended up remounting the remote pmd on top of the intake manifold to get out of Beaver Creek Yukon. Unfortunately, after a week in that location seems to have heat damaged the pmd as I had an uncommanded acceleration of the engine at a stoplight last night.
Justin

[More Power]

The larger pink wire in the PMD harness is the drive circuit for the fuel solenoid in the fuel injection pump. You could monitor that as well to see if it remains powered during the time when the engine shuts off.

[BorJansson]

MorePower
All 6 wires are black.
Do You have pin-number ?

Now I had the 4:th shut down.
Started OK, put in drive, went fwd 10-15 m and shut down.
Started on the 3:rd session of cranking, hesitated like there should be lack of fuel.
I had a voltmeter across Fuel Shut off Solenoid and it showed 12 VDC during the trouble.

I have a program, GMTD ScanTech in my lap-top. When conected to the car I can shut off one injector at the time.
Can I have a malfunction in my injection pump that will shut off all injectors at the same time ?
My toughts are running wild !

[More Power]

MorePower
All 6 wires are black.
Do You have pin-number ?

Now I had the 4:th shut down.
Started OK, put in drive, went fwd 10-15 m and shut down.
Started on the 3:rd session of cranking, hesitated like there should be lack of fuel.
I had a voltmeter across Fuel Shut off Solenoid and it showed 12 VDC during the trouble.

I have a program, GMTD ScanTech in my lap-top. When conected to the car I can shut off one injector at the time.
Can I have a malfunction in my injection pump that will shut off all injectors at the same time ?
My toughts are running wild !

You must be referring to an extension harness that used the same color for all wires - not good for troubleshooting a problem. The FSD (or PMD) utilizes a 6-pin connector, identified as pin A through F.
The factory colors are:
A - Lt Green - Fuel Injection Control
B - Red - Fuel Solenoid High
C - Black - Closure Ground
D - Pink/Black stripe - Ignition Voltage
E - Red - Closure Signal
F - Black - Fuel Solenoid Low

Pin D is the main power supply pin for the module. It should be hot whenever the ignition key is on. The other pins on the PMD are either grounds (black) or digital circuits. Jim

[BorJansson]

Update and solution.
It was a faulty OPS that caused the problem.
I checked voltage on liftpump and it was between 2-3 VDC and the fuelfilter was nearly empty.
New OPS, modified circuit with aux-reley to the liftpump.
Added also a pushbutton to activate liftpump if/when I have to purge the filter.

[More Power]

Update and solution.
It was a faulty OPS that caused the problem.
I checked voltage on liftpump and it was between 2-3 VDC and the fuelfilter was nearly empty.
New OPS, modified circuit with aux-reley to the liftpump.
Added also a pushbutton to activate liftpump if/when I have to purge the filter.

Glad you discovered the problem. The relay fix for the oil pressure switch is a good one. Kennedydiesel.com offered a kit a few years ago to do what you did.

Thx for the update. Jim