Engine/Transmission (1994 - 1998) Need Help, idle problems.

[Cummins4Life]

OK. Every once in a while when rolling off the throttle the truck wont stop at idle it'll just continue dropping off and die. Doesnt act like its trying to stay running, just flat dies. If I just crank it wont start, if I add some throttle it will start but if I take my foot off it'll die like before. If I get it running and I rev it out to 3000-3500 quickly, and let off it will idle as normal. If I try to rev it up again it'll go to about 2900 then defuel and sloooooooooowly go to 3200.



New overflow valve, new fuel shutoff solenoid, new fuel filter. Fuel pressure is 28-32 at idle, 36 at 2000rpm testing at the banjo on the pump. The governor springs are each adjusted correctly with a 50thousandth on each side.



Idle is set to 850 in gear with the AC on.



Some things I havent tryed yet are to back off each governor spring one click, and to dobulecheck the low load fuel control in the back of the AFC housing.



Anyone ever run into this before?

 

[Jeff H]

Did this start happening after the install of gov springs?

May have a problem with wiring to the fuel shut down solenoid. Vibration could be affecting the wires now. Check for good connections. Wiggle the wires with the key on. Watch the shut down to to see if it moves.

Some guys experience problems with the shut down after removing it then reinstalling it. If it dies on ya again. Check to see if the shut down is in the off position. Also misadjusted shut down can cause issues.

 

[Cummins4Life]

Yes first time it happened was the day after the spring install a month ago. Re adjusted the idle up a bit and it has worked fine until the day before yesterday when this started.



I will check the shutoff wiring tomorrow.

 

[DieselMinded]

OMG----""Fuel pressure is 28-32 at idle"""



Just throwing this out there but would it be defueling with that much pressure on the Injector pump???hard on the PUMP???



MAYBE ..... Try to Lower the Fuel Pressure and see if it runs better.



DM

 

[Cummins4Life]

I called around today. They all agreed that was high. I even bought a new gauge to double check the pressures.



Not sure if it hurts anything.



Truck runs strong, doesnt feel weak at all. Just dies sometimes.

 

[Kirwin]

Fuel pressure

My fuel pressure on the 97 varies between 24 and 30 psi depending on load and temperature. When first started cold it pegs the gauge for the first minute or so. At WOT it runs about 16 psi. I don't think high pressure will hurt a P7100. Low pressure on the other hand IMHO is bad. Ken Irwin

 

[Jeff H]

My fuel pressure at idle is around 20 psi.

At 2000 rpm I'm around 30 psi

Wich is ok according to specs.