99 3500 Has 120,000 mi. The truck starts fine everytime as long as it is cold but everytime it gets warmed up and shut off it will not start back up again. Injection pump and lift pumps were replaced not too long ago. The problem started out intermittantly, it would only do it every once in a while. Now it does it everytime it gets shut off when warm. I was almost thinking it could be a relay somewhere. No codes are being thrown either. Anybody have any ideas on what it could be or had any similar problems?

 

Can you get it to someone that has a scan tool? The dealer's DRB is always the best, but even if you can just get any of the codes it may have stored that will get you started in the right direction.

I did have a similar problem on one of our Class 6 trucks.... When under load and at warm operating temperatures with cold outside temperatures it would trip the running light breaker and render the truck unsafe to operate at night. My guys would have to wait until the breaker (self resetting variety) cooled and then continue on their way. I wonder how much $$$ I shelled out in extra payroll hours because of that debacle. We sold that headache and consequently filed suit against the manufacturer. I only got a couple K, but my legal counsel shook out pretty well!

 

It was hooked up to a snap on scan tool just last night. No stored or pending codes.

 

heat sensor maybe?

 

Where's the heat sensor at? Is there anything else that could be doing it? Nobody else has had anything like this happen?

 

I had basically the same problem as you. Mine would start when warm but it took several cycles of the starter to start, but first thing in the morning it would start fine. I orderd the vulcan kit and while installing i changed the plastic type lines that go from the hard lines to the top of the tank and the one that was left from the return to the hard line. I do not think the vulcan is what solved my problem(although it is a great product) but it was changing the plastic lines to rubber. I nside the sleeve that covers them was diesel. I would check this it made mine start like it did before. Dave

 

I think I found the problem. If I unplug the coolant temp sensor it starts up just fine. Once it is started I can plug it in and then I have a temp gauge.

 

I would be short of amazed if that is your problem. I don't believe cts is that big of an input as to whether your truck is going to start or not. You have the scanner, what does it read at different times?

 

I have the same problem with my 97 12v. When it is warm, I need to give it throttle when I crank it, but it fires right up. If I don't give it any throttle it will fire and die right away. When it's cold I can just crank it over and it starts by itself. I am thinking it has to do with the fuel delivery, like if it sucking in air through the lines or the filter's O-rings. With air in the fuel lines it would expand when it is warm and not give the motor enough diesel to run, but I havn't fixed it yet.

 

Could be your coolant temp sensor. Without it plugged in, the engine should go into limp mode.. should run, but like crud.

If its bad, it could be telling the ECM the coolant is too hot or similar and over or underfueling the engine..

That is, if these things still work like the old 2.2/2.5 turbos...

 

Well, I changed the coolant temp sensor and it didn't fix the problem. I know that that this prob is strictly electrical/sensor problems. Once I unplug the temp sensor and put the computer in limp mode it starts everytime. So what other sensor could cause the truck to do this?

 

The Crank shaft position (CPS) is supposed to be troublesome in these years.

 

Guess I should have mentioned that I already changed it just before I changed the coolant temp sensor.

 

do you have any boxes on the truck? I know yhe timing is electronic on the 24valves but could the timing be off? It started after the new pumps were put on didn't it? Have all the filters been changed?

 

I have no boxes. Filters were just changed 2 weeks ago. Truck is compleatly stock except for 5 inch exhaust. It sounds like it is getting no fuel at all when cranking. And it started right up after new pumps were put on.