won't shut off

[emmer]

Something strange ................ my truck will shut off till the temp gets up to about 130f, then It will not.

I have to stall it to get it to shut off.
This isn't a one time thing......... it's been doing the same thing everyday for the past 2 weeks.

any idea's ????????

Thx

 

[Jake S.]

With all the wires off the ip it still runs??? Bad FSS?

 

[franklin2]

When it won't shut off, go out under the hood and pull the wire off the injection pump. If it stops, then you must have a wiring problem.

 

[hesutton]

X 3. Next time pop the hood and remove the FSS wire. It should die then. May be a bad FSS or anything between the ignition swith to the FSS. That's a weird one.

Heath

 

[emmer]

yep, when I pull the wire off the pump it shuts off, but why not with the wire on and the key turned off?

 

[TBigLug]

Something may be shorting out and backfeeding power to the FSS wire. I had something similar happen in my Chevy once. If you hut it off with your foot on the brake the truck would keep running. Take your foot of the brake and it would shut off. Two wires melted together in the MFS and it was backfeeding through the cruise into the ignition.

 

[Jake S.]

The FSS has a red/light green striped wire. It goes a connection by the GPC and splits into more wires. One is a red/yellow the goes to the gpc. If that is on a wrong terminal on the gpc, it would do this.

 

[emmer]

I think you might have something there. About the same time that it did this, I started seeing my (unhooked) factory OP guage registering a "reverse" oil pressure.

starts at 0 psi, then the needle moves some and then down to (neg 40psi) which is weird because I unhooked it and now have a machanical OP guage.

 

[Billyisgr8]

My freinds old bobcat did this and it ended up needing a diode inline between the alt and ???. I can't remember what the part was that was next inline from the alt. Alt was sending power down one of the small secondary lines to the next part and then to the injector pump.

 

[emmer]

i noticed something else, there;s a wire (dark coloured)... (hot)..and unhooked) below my fuel filter. I don;t have a clue where it goes

 

[Jake S.]

The pic i posted is from my 1990 service manual. That wire should go to the fuel heater.

 

[emmer]

Jake is the fuel heater under the filter somehwere???? I can't find it.

 

[redneckaggie]

on mine it is on the drivers side of the filter head

 

[emmer]

I have one wire going to the top with a plug on it, but the wire looks to spilt off and one wire (the mystery one) was laying under the filter, on valve cover.

It had a metal end on the wire but it's broke. The wire is black I think.

also the mystery wire goes into a plug (water temp sensor, maybe)?

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[Jake S.]

I have the older style but, I believe the the wire on the top is for the heater. There is a also a sensor on the side by the schrader valve, and a water in fuel sensor at the bottom of the filter. My pic in the service manual must be from a 87 6.9 with the old style filter header. If you truck needs paint bad, mine needs help in the sheet metal dept.