95 K3500 dies,,

[94GMC2500]

OK this might get long. I bought this 95 dually a couple years ago. Its had stalling and sometimes not starting problems since I have had it. I have put new fuel tank, new sender, new fuel lines, new lift pump, now wired to run whenever key is on, relocated pump driver and cooler up behind bumper, replaced injection pump wire harness, just put new crank sensor in, replaced fuel shut off on pump, new fuel filter.

Today it started and ran about 10 seconds and quit, and would not restart. First thing I did today was unplug the fuel shut off and checked for voltage with key on, had 12.3 volts, grabbed another shut off solenoid and plugged it in and it worked fine. So I plugged that back together. Then I grabbed a spare pump driver and plugged it in up by the pump, still no start.

So then I took the fuel shut off solenoid out and turned key on and ran some fuel out the hole, put shut off back in and it started, ran rough and quit a couple times but it would restart and then ran fine again. So next I put a piece of clear hose on return out of pump and left it run a long time checking for air, not a bubble. when it does run I can wiggle on wire connections, fuses, relays and cant make it quit. also never get any codes.

It will run a week or two just fine and then the stalling starts up again.

I have no idea what else to do with it. I have another engine wire harness I thought about putting on, or maybe new ignition switch. I am getting tired of throwing stuff at it and have it act up in a week or two again.

Starting to wonder if there is water in the fuel or air getting in the injection pump some how.

Anyone have any ideas?

[cowboywildbill]

You probably have already tried these things but, Have you tried checking the fuel pressures after the pump. Also is the injector pump good? Or maybe It could be sucking air in the fuel line some where up to the pump. But it sounds like you covered that but I have had large rigs do that and couldn't find any bubbles in the pressure side. I hope you find it. I know it can drive you nuts trying to find the problem. It's probably something simple, but finding it isn't always easy. Also maybe a wire is getting hot and separating in the harness somewhere ? Sorry I couldn't be more helpful Good luck

[a5150nut]

When I got my 94 one of the first things I did was get a can of Contact cleaner and clean all electrical connectors and add dielectric grease to them. Dodged a lot of electrical problems that way. Did go thru several PMD's, set of injectors, fuel solenoid, vacuum control and an injection pump.

Might want to check all electrical grounds. Especially on the right rear head. Bad grounds will run you in circles chasing your tail for days.

[94GMC2500]

I have put a pressure gauge in the drain hose from the filter housing and opened the valve and it has 4 to 5 psi. It will squirt fuel about a foot in the air from the air bleed on top of the filter when opened.

Last year I put new ground wires from engine to body and engine to frame. I have had 3 used and one new pump driver on it. 3 different fuel shut off solenoids, all used though. No idea what shape the injection pump is in.

After I changed the injection pump wire harness it ran the best it ever had for a couple weeks then it started the stalling stuff again.

I am thinking it getting air in the system some how. I was told to put a big shop vac on the filler to the fuel tank to put some pressure in the tank and then check for fuel leaks in fuel lines with soapy water.

[Robyn]

With all that you have been through and replaced my gut feeling is ignition switch.

A poor contact in the switch can kill these quickly

Make sure the ground wire in the PMD harness is connected to the IP as it came factory.

No need to move that ground when you have a remote PMD


Replace the ign switch before you chase your tail on this any more.

12.3 volts at the fuel shut off solenoid is sketchy.


When the rig is running make sure you have 13.5 to 14 volts at each battery and at the power distribution box on the LH fender well (Large + lug)

The battery cables can fail internally in the crimps .

Battery grounds at the battery and the block can and do fail.

The battery cables can look great and be clean on the outside, but can be badly corroded internally.


Poor voltage in the system can drive the ECM nuts and cause all sorts of crap to happen.

Ign switch contacts burn and corrode over time too.

Very well may be that each time you turn things on and off you are disturbing things enough to get a different result.

If the cables are factory/factory type and several years old then they are suspect.

Factory cables use crimped ends where the wire strands are merged with the side terminals

Only soldered ends such as COPPER eyes can be trusted over the long haul.

One other thing... Have you changed the filter harness on the IP ???
This wire harness is near the top rear of the IP and has a little rectangle black box in it.
If these fail all bets are off.

http://r.search.yahoo.com/_ylt=AwrTc...1JW14Qu33SF30-

Here is a link to a picture of it.

Have you had the PMD wiring harness off of the IP
These can fail at the connections where the wires connect to the IP under the boot.


CHECK IT OUT

Good luck

[94GMC2500]

I replaced the wire harness on the injection pump, I don't think there is that noise filter harness on mine. I am not getting any trouble codes on mine.

The 12.3 volts at the shut off solenoid plug was with truck not running and batteries run down a little from trying to start it.

[Stevediesel]

OK this might get long. I bought this 95 dually a couple years ago. Its had stalling and sometimes not starting problems since I have had it. I have put new fuel tank, new sender, new fuel lines, new lift pump, now wired to run whenever key is on, relocated pump driver and cooler up behind bumper, replaced injection pump wire harness, just put new crank sensor in, replaced fuel shut off on pump, new fuel filter.

Today it started and ran about 10 seconds and quit, and would not restart. First thing I did today was unplug the fuel shut off and checked for voltage with key on, had 12.3 volts, grabbed another shut off solenoid and plugged it in and it worked fine. So I plugged that back together. Then I grabbed a spare pump driver and plugged it in up by the pump, still no start.

So then I took the fuel shut off solenoid out and turned key on and ran some fuel out the hole, put shut off back in and it started, ran rough and quit a couple times but it would restart and then ran fine again. So next I put a piece of clear hose on return out of pump and left it run a long time checking for air, not a bubble. when it does run I can wiggle on wire connections, fuses, relays and cant make it quit. also never get any codes.

It will run a week or two just fine and then the stalling starts up again.

I have no idea what else to do with it. I have another engine wire harness I thought about putting on, or maybe new ignition switch. I am getting tired of throwing stuff at it and have it act up in a week or two again.

Starting to wonder if there is water in the fuel or air getting in the injection pump some how.

Anyone have any ideas?

It's the oil pressure switch shutting off the lift pump