5.9 Cummins problem

[Bruce Reimer]

I have a problem with the 5.9 that I put into my White tractor. It came out of a bus, has the P7100 pump. The first time I ran it I could run it at idle but as soon as I tried to rev it past about 1200 RPM it would run the pits and smoke like on a -40 day. I left it for a few days and the next time I fired it up it worked fine, no smoke and reved out nice. Today I fired it up again and it was back to the way it run the first time, smoke and all. What is going on? Any help would be much appreciated.
Bruce

 

[mkuhns]

You are either sucking air or have low fuel pressure. The return line banjo bolt on the injection pump is a fuel pressure regulator. Maybe it's sticking open? The pumps on these engines will make the engine seem to run out of time if the fuel pressure is low. I would hook up a gauge somewhere between the transfer pump and injection pump and see what you have. I can remember, but I think it should have around 30-40 psi fuel pressure.

 

[Shep VA]

Yup, Mkuhns is correct. I had a 5.9 that had dirt in the fuel tank do that. The dirt was clogging the port on the fuel tank, and sometimes it would run good and sometimes it would not. I took an air hose and blew back up into the tank to clear the blockage a few times and it helped, but always seemed to come back. I ended up taking the fuel tank off and cleaning it out and it worked good after that.

Somewhere you are starving the engine for fuel.

 

[Bruce Reimer]

Thanks guys, If I pinched the return line with a pliers it ran fine. I took the banjo bolt valve out and for some odd reason the spring was cocked to the side and the ball was loose. Put it back in the way it should be and it was nice and tight. I don't know why something like that would happen.
Bruce

 

[J.Wondergem]

Thanks for letting us know what you found.

 

[deerefanatic]

I know this thread is old, but as an FYI for future people's reference,

That bolt with the ball and spring in the return is called an Overflow Valve. It's a notorious failure item and on dodge pickups, they last about 100k miles..... when they get weak, they cause low fuel pressure and the symptoms outlined...... $40 from ebay (get a genuine Bosch part only or you'll be sorry!!) and you're back in business.