Hard to start when warmed up

[Skunk]

Lately I have had a problem starting my truck that I can't quite figure out. When it's cold in the morning it starts within a half a revolution, but once it is warmed up it will just crank. After I try to start it a couple of times (cycling the lift pump makes no difference), it'll fire off just like it does cold - almost immediately. I have tried starting it with the Comp off, and at all five settings with no difference. So my question to all of you:



What's going on, and how do I fix it?

 

[Blair]

I would try with the comp box unhooked, then you could determine if that is a cause or not for sure.

 

[jwhite1]

reply to hard hot start posted by Skunk

Skunk, you said you were having trouble with hard hot starts. Well, it sounds to me like two possible causes 1 the old vp44 has some problems. It may be in the electrical connectors. You may need to clean them and put a conductive anti oxidant grease on the pins and sockets. The problem may even be the vp44 itself. 2. A high supply pump pressure will keep it from starting because centrifugal force at cranking rpms cannot be achieved to make the shoes move out inside the injection pump. Hope this will help, but here again no guarantees. As a rule these Cummins engines fire right up hot or cold and that is one thing among many more that I like about them. They are some very capable engines and very tough. Good luck! Jwhite