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Ronbstewart · 08-19-2014, 07:40 PM

120 miles into a recent 900 mile trip engine just shut down in my 1994 Monaco Executive (Cummins 300 8.3 C) Gages and dash lights all worked normal, but nothing when key was turned to the start position. After an hour of trouble shooting at night and in the rain I found no power was being supplied to the start solenoid. I connected jumper wire to the fuel shut off solenoid and used a screw driver at starter solenoid to start and get off I70 to park for the night (those old 300 mechanical Cummins are pretty simple) next morning went to Walmart got a switch and some wire and rigged it so I could start and shut down from the bed room 1800 mile trip went great from that point. Got back home and went to start it several days later engine would start and then die, fuel shut off solenoid would pull in on start but wouldn't lock in when starter was released, but would latch if I pushed plunger in by hand. Pulled it off coach and hooked it directly to 12V battery (just a positive and negative for the magnet and a wire used momentary to draw in the plunger) with positive and negative connected plunger will suck in but won't lock in unless pushed in by hand. I ordered a new solenoid and low and behold when hooked up in coach or battery it does the same thing. Do I have 2 bad solenoids or is there something I'm missing here. I want to be sure before I return the new solenoid.

DonL · 08-19-2014, 08:06 PM

According to the electrical drawings for my 1995 Spartan Chassis with 8.3 Cummins, the fuel shutoff solenoid has three terminals. Terminal B is the pull-in terminal and is powered from the starter side of the starter solenoid. Termina A is the holding power and it comes from circuit breaker on the rear run panel. The C terminal, of course, is the ground terminal. Which terminals are you using for your battery test?

pwhittle · 08-19-2014, 08:50 PM

The fact that it stays pulled in if you push it manually sounds like the ignition signal is good.

It could be the wire from the starter that is marginal and is not pulling it in all the way. Try pushing the battery boost switch while cranking to see if it pulls in all the way. You can check the terminations on the wire as well as the wire itself.

Paul

DieselTech39 · 08-19-2014, 09:06 PM

FWIW...My experience with FL chassis on the route trucks I worked on was that there are two relays that operate the fuel shut off solenoid. Not sure if that's the case for you, but if the relay that charges the pull in circuit is weak the shut down solenoid will not stay engaged. You probably need the shut down solenoid and possibly, if equipped, a new relay.

pwhittle · 08-20-2014, 04:43 AM

If it is like my 1994 Signature, the pull in coil is a direct red wire from the starter.

Paul

NHRA225 · 08-20-2014, 06:19 AM

Quote:

Originally Posted by DonL

According to the electrical drawings for my 1995 Spartan Chassis with 8.3 Cummins, the fuel shutoff solenoid has three terminals. Terminal B is the pull-in terminal and is powered from the starter side of the starter solenoid. Termina A is the holding power and it comes from circuit breaker on the rear run panel. The C terminal, of course, is the ground terminal. Which terminals are you using for your battery test?

On my 92 there is a Remote Starter Solenoid mounted to the frame rail in the Eng compartment which activates the Shutoff Solenoid from the key on switch

Ronbstewart · 08-20-2014, 10:35 AM

Both old and new solenoids have 3 wires (red, white and black) I take the red and white to be the positive and negative when connected in the coach or to a 12V battery create the magnet. Black wire is only powered in start position from starter solenoid to cause the plunger to pull in and held in by magnet (red and white wires until connection is opened between the 2. What puzzles me is why the plunger won't lock in even on the new solenoid. a strong 12V supply is not the issue as I've tried 3 different sources of 12V power. Plunger pulls in rapidly each time power is applied to the black wire and pops back out when power is removed (won't lock in), but I can push plunger in with my hand and it will remain in until connection is broken by either the red or white wire. I ordered the new solenoid because of that problem with the old solenoid. I decided to test the new solenoid before I installed it and was thrown for a loop when it done the same thing, so I'm trying to determine if the new one is bad also. I know the fuel solenoid is powered by another relay on bulk head in engine compartment, but I need to figure out this problem first. I have made calls to several shops in my area, none so far have the equipment or knowledge to bench check a solenoid. My question a new solenoid connected to a strong battery, shouldn't the plunger just pull in and stay in when power is momentary supplied to the black wire (red and white wires connected to positive and negative) thanks for all the replies and open to suggestions.

C-PHartley · 08-20-2014, 01:23 PM

I have a similar vehicle ('95 Newmar / Spartan Chassis / Cummins C 8.3) My Fuel Solenoid also has three wires - Ground, Start, and Hold (run). You should be able to find the ground terminal by checking for continuity to the frame (Terminal C). This is the white wire on my solenoid. The other two are not latching solenoid connections. The plunger will pull as long as 12 volts is applied to one of the other connections. Terminal A is the Run and Terminal B is activated from the start relay. When the 12 volts is disconnected, the solenoid returns to the off position due to the spring pressure of the solenoid. I can send you the wiring diagram from Spartan if it would help. You should see a strong snap of the solenoid when 12 volts and ground are applied when bench testing.

Phil R · 08-20-2014, 02:47 PM

I had the same problem. It was a wire coming from the relay inside the engine compartment
to what I call a bus bar (strip that supplies power). I stumbled across it by getting a good grip on each wire and giving a good tug. The wire had a terminal crimped on the end and it was positioned so that it was holding water and whatever else gets in there.It slowly corroded strand by strand. When it was cold I think the wire would draw away and break contact. When it was warm it seemed ok. This would be a long shot but give all the wires you can reach a good tug.

Good luck.........

NHRA225 · 08-21-2014, 06:27 AM

Spartan Wiring Diagram

Ronbstewart · 08-21-2014, 08:51 AM

Thanks for all the good replies, my problem is now fixed I was a bit stuck on stupid, in a lot of theses older coaches when wiring mods are done the wiring color codes go out the window and in some cases a relay or 2 might even be eliminated, such was my case. Wiring bundle leading up to my fuel shut off solenoid has 4 wires, 2 red, 1 yellow and 1 white. Solenoid only requires 3 to function. After numerous trial and error test I was able to get the correct wires matched. Thanks again to all.