Engine/Transmission (1994 - 1998) Fuel shut off solenoid troubleshooting

[Beast2B]

OK, so I can see the rod lift when the engine cranks and it sounds like it's running while holding the key to START for a second. It will not keep the rod up when I let the key return to RUN. Bad solenoid? Any other voltage to check?

 

[MLee]

Check and see if the boot covering the plunger has deteriated and is hanging the plunger up. You may have to remove it solenoid and give it a good cleaning. Mine started to not hold, cleaned it and seams to be OK now. If it is the boot, you can get a new one from Geno's or from foster's truck. Foster is listed in the TDR mag and on here. Do a search.

OR---- make one out of a bicycle tire. The last about 10 months-year.

 

[Beast2B]

Thanks. I thought the plunger was fine since I could lift it by hand and feel no grit or hard spots and the key in START would pull the plunger up very quickly. I did check the fuses and #9 has continuity and 12v in the RUN position. Another forum mentioned the fuse and that the FSS should have 12v to one side in RUN for holding the plunger and 12v to the other side in START for lifting. Sound right?

 

[JMcCoy]

Hold the plunger up manually while a helper starts it up. If it stays running and you have 12 volts to the solenoid, it needs replacing. Good luck.

 

[Gene Heck]

Check fuse number 9 in the left side of the dash. It's a 10 amp fuse. This is where the run side of the shutdown solenoid gets it's power from. The only other thing this fuse does is energize the coil of the fuel heater relay.



Gene

 

[Beast2B]

Thanks guys. The START position will lift the plunger, but it will not stay up and running in the RUN position. I checked fuse 9 for continuity (it's good), but I'll look for 12 volts today. Gene, is the ignition switch on the hot side of the #9 fuse or is the switch after the fuse? Do I recall correctly that someone put a switch in the cab as a theft deterrent to hold the plunger up? That may be an easy bypass...

 

[ttbird]

Blue wire on driver side battery +, fusible link going to solenoid to provide 12v to hold up, ignition switch and relay provide hold up to start, then hold up circuit is powered by fusible link. Hope this helps. Tom

 

[KSams]

Check to see if you have 2 relays on the firewall. I had this happen to my 94 Dodge and it turned out the relay was bad. Hope this might help

 

[Gene Heck]

Galen,



Yes, the fuse receives power from the ignition switch. The fuse is powered in both the start and run positions of the ignition switch. If the fuse is good then the wire to trace is the lg/bk (light green/black tracer) all the way to the plug on the shutdown solenoid. You can unplug the connector at the solenoid to check for voltage. You could possiby have a bad holding coil in the solenoid. An ohm meter will prove this. I can fax you a sheet of the circuit if you want, just send me a private message with your fax number.



I never thought about adding a toggle switch and using this as a theft deterrent but yes it would do the trick. If you added a switch in the fuse 9 circuit and had it in the off position the engine will start and run as long as you hold the key in the start position because the fuel shutdown relay is energized while the starter is engaged causing the solenoid to pull up to let the engine start but the engine will stop as soon as you let the ignition go to the run position because the shutdown relay will de-energize and the start side of the shutdown solenoid goes off. The circuit from fuse 9 is on the holding side and keeps the plunger up after the engine starts if all is normal. But if the fuse 9 circuit is messed up or intentionally interupted with a switch then there isn't any current to hold the plunger up and the solenoid releases the plunger and the engine stops. Once you see the wiring diagram it's really simple.





Gene

 

[Gene Heck]

Correction

I made a statement in my post number 5 that the only other thing that fuse 9 does is energize the coil of the fuel heater relay.



That was incorrect.



It provides power to the ac compressor clutch relay, the fuel pump relay, the automatic shutdown relay, the fuel shutdown solenoid, the heated intake air system relays 1 and 2, the engine diagnostic connector, the fuel heater relay and the egr solenoid if you have an egr equipped truck.



Sorry for the misinformation.



Gene

 

[hsmith]

As ttbird says, the blue wire at + terminal drivers battery. TAKE IT COMPLETELY OFF, make sure it is not broken at the crimp or corroded.

 

[Gene Heck]

hsmith,



In the first sentence of the first post Galen says that while he cranks the engine the fuel shutdown solenoid pulls up and the engine "sounds like its running" until he releases the ignition to the run position and then, "It will not keep the rod up when I let the key return to RUN. " This proves the blue wire from the battery is okay. The blue wire goes from the + battery post to the common contact of the fuel shutdown relay. When you turn the ignition to the start position and the starter pulls in it sends power up to the coil of the fuel shutdown relay closing the contact and providing power to "B" terminal on the shutdown solenoid. This is the high current coil in the fuel shutdown solenoid that first pulls it up to enable the engine to start. When you let go of the ignition switch and it goes to the run position the starter drops out, the coil of the fuel shutdown relay de-energizes opening the contact that provides power to the start side "B" of the fuel shutdown solenoid. The run side of the fuel shutdown solenoid is powered from fuse 9 which is powered from both the start and run positions of the ignition switch. If fuse 9 is good and you have power to the "A" side of the fuel shutdown solenoid the engine at this point will stay running unless the fuel shutdown solenoid has a bad run coil. You can check this with an ohm meter. A & C are the running coil. B & C are the start coil. C is the ground. It's that simple. If you don't have a FSM send me a private message with a fax number and I will gladly send you these pages of how the circuit for the fuel shutdown solenoid actually works. Or any others you might need as well.



As you said though it would not hurt to check the battery post where the blue and orange wires are landed just for preventitive maintenance. Winter is coming.



Gene

 

[Missouri Mule]

Beast2B,you can always tie the rod in the up position if you need to go some where.

Pull your connector and check for power when key is in run position if you have power then the solenoid hold up coil is bad, if no power go to the fuse no. 9 and start from there and work forward.



Yes you can set up a hidden switch inside the cab to keep truck from starting or running.

 

[BlameCandida]

I am not finding a blue wire coming from the driver's side battery. I have two large red wires (one coming from the other battery, and one going beneath the engine), a medium red wire going to the engine fuse box, and two smaller black wires, plunging down beneath the battery. When I open the engine fuse box, I see the connection for the medium red wire. There is a second smaller wire connected to the terminal. It extends about 4 inches out of the fuse box, and is then just cut off. Is this wire supposed to go somewhere, or is this something that a previous owner had installed to power lights/trailer?

 

[GAmes]

I am not finding a blue wire coming from the driver's side battery. I have two large red wires (one coming from the other battery, and one going beneath the engine), a medium red wire going to the engine fuse box, and two smaller black wires, plunging down beneath the battery. When I open the engine fuse box, I see the connection for the medium red wire. There is a second smaller wire connected to the terminal. It extends about 4 inches out of the fuse box, and is then just cut off. Is this wire supposed to go somewhere, or is this something that a previous owner had installed to power lights/trailer?

There are 4 fusable links attached to the drivers side battery. The blue one (with a clothes pin attached) is so dark it looks black. It is attached to a fairly heavy gauge wire that is red with a black tracer. The orange fusable link is attached to a smaller gauged red wire, IIRC it is for the fuel pre-heater. The two black fusable links are for the grid heaters and go to relays.