Loss of Power - Stranded

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Loss of Power - Stranded

March 16, 2023, 12:04:35 pm

1996 U295; we lost power to the dash, engine stalled so we drifted off the road and parked. For a few minutes there was no dash lights, no power, no nothing and then it all came on and we started back down the road only to lose power again after 1 mile. This time nothing would come on again, so we had a tow to Kingman, AZ.
So far, I have replaced the ignition solenoid with a heavy duty ($75) one from O'Reilly's and also the ignition switch but to no avail.

I have 12v coming in on the battery side of the ignition solenoid. On the first small lug I have ground (green 233), next lug white wires 103,19,21 then out going large lug not power going through when key is in first position. Only solenoid clicking and only have around 8 volts when clicking. I believe this should be good 12 volts. Where does these white wires get their power?

Re: Loss of Power - Stranded

Reply #1 – March 16, 2023, 01:14:31 pm

Yes, the solenoid needs 12 VDC to work. Unlikely to work on 8 VDC.

Short term work around is to use a small gauge wire from the "always hot" large lug to the small positive "signal" terminal.

Worse case, if failed solenoid is to remove the wires from one large lug and JOIN THEM to the other large lug. Same electrically as solenoid working properly with ignition on.

And assume that the new ignition solenoid IS rated for constant not just intermittent duty.

Re: Loss of Power - Stranded

Reply #2 – March 16, 2023, 01:39:10 pm

Did you try starting the generator and using the boost solenoid? Have you pulled and cleaned the engine battery terminals? The engine solenoid should have the same voltage on the hot side as the batteries. What are your house batteries doing voltage wise? Generator start OK? Engine battery voltage with the engine running?

Pierce

Re: Loss of Power - Stranded

Reply #3 – March 16, 2023, 01:47:22 pm

Yes, generator starts and runs fine.
Starter battery is approximately12.8 volts.
White wire 103 has 12v when not hooked up to small lug.
2 other white wires, 19 & 21, unhooked from lug have no power.
When 19 & 21 are unhooked from and 103 (12v) hooked up to small stud only, relay engages and dash power comes on, engine starts for 3 seconds then shuts off.
When 19 & 21 are hooked up there are 8v.

Re: Loss of Power - Stranded

Reply #4 – March 16, 2023, 02:06:40 pm

When testing fuel shut-off solenoid on engine for 12v, what wires is it between? Red, black or white?
While holding open engine fuel solenoid, the engine stays running.

Re: Loss of Power - Stranded

Reply #5 – March 16, 2023, 02:32:09 pm

Make sure your fuel shutoff is opening,it is on the engine passenger side above the lift pump,if you have the 8.3 mechanical engine,all you need 12 volts for is to hold the fuel shutoff open and to start,you could start the engine and manually open the fuel shutoff to get you going.

Re: Loss of Power - Stranded

Reply #6 – March 16, 2023, 02:59:59 pm

Yes, engine runs while I hold open the fuel shutoff but dies as soon as I let go. There is no power going through the red wire coming down to the fuel solenoid.

Re: Loss of Power - Stranded

Reply #7 – March 16, 2023, 03:27:44 pm

Im not familiar with your coach but Im confident there is a circuit breaker for the fuel Solenoid or some sort of protection. I would go to that point. If it's good then you have a wiring problem or a control issue. Starter switch ignition position powered up? Control solenoid? Is the buss for the power source powered up? This will give direction on which way to look. No power go towards battery. Got power keep checking towards fuel solenoid

Re: Loss of Power - Stranded

Reply #8 – March 16, 2023, 03:29:03 pm

Quote from: Ahb867 – March 16, 2023, 02:59:59 pm

Yes, engine runs while I hold open the fuel shutoff but dies as soon as I let go. There is no power going through the red wire coming down to the fuel solenoid.

As I recall, the fuel shutoff solenoid has two stages of operation. The initial stage is a "higher" amperage signal that pulls the solenoid rod up. The second stage is a lower amperage signal that "holds" the solenoid rod in the up position, until the ignition switch is turned off. Then the rod drops and the fuel shuts off.

Sounds like your solenoid might be pulling up, but not holding. Should be 3 wires going to solenoid. One is ground, one is "high" amperage signal (only when starter is energized), other is "low" amperage signal (when ignition switch is in "START" and "RUN" position). Video in Reply #13 (below) shows how to determine which lead is which.

Re: Loss of Power - Stranded

Reply #9 – March 16, 2023, 03:44:09 pm

The 8 volts is the clue.
Check battery grounds
Dash grounds
Engine grounds

Re: Loss of Power - Stranded

Reply #10 – March 16, 2023, 05:07:16 pm

As Chuck said, that fuel shutoff solenoid has two relays...the pull and the hold. It sounds like your pull is working and the hold is not. Worst case, you can manually lift the solenoid and ty-rap or bailing wire it up to keep the engine running.

Re: Loss of Power - Stranded

Reply #11 – March 16, 2023, 07:23:45 pm

The fuel solenoid has two sets windings. The pull in winding has a wire from the starter so when the
starter is engaged that winding gets powered. It is a heavier than the other winding which is the hold
in winding which gets power from the ignition. To get by you can tie up the solenoid until you can find
the problem.

Re: Loss of Power - Stranded

Reply #12 – March 16, 2023, 09:06:13 pm

The fuel solenoid requires 12 volt for pull in, activated by starter circuit, and 12 volts hold in signal from ignition (run) circuit.

Re: Loss of Power - Stranded

Reply #13 – March 16, 2023, 11:12:25 pm

Quote from: Realmccoy – March 16, 2023, 09:06:13 pm

The fuel solenoid requires 12 volt for pull in, activated by starter circuit, and 12 volts hold in signal from ignition (run) circuit.

Thanx for the clarification of terminology. I changed my earlier comments (Reply #8} from talking about "higher" and "lower" voltage to the correct term amperage. As you state, inside the fuel shutoff solenoid, both pull up and hold coils are 12V powered. It is the amperage that is different. Higher amperage is initially required to pull up the rod - lower amperage is sufficient to hold the rod in the up position.

The video linked below includes a simple demonstration of how to identify which wire powers which coil. Using a 12 volt battery for bench test, connect the fuel shutoff solenoid black wire to negative terminal on the battery. Then, one at a time, connect the battery positive terminal to each of the other solenoid wires (white and red).

One of those wires when powered will cause the solenoid rod to pull up (retract). That wire is the "high" amperage lead and should be connected direct to a power source that is ONLY hot when the starter is activated. (For example: the starter post on the AUX START solenoid).

The remaining wire is the "low" amperage lead that holds the rod in the up (retracted) position after the ignition key is released from the START position and goes to the RUN position. The guy in the video makes the point that the "low" amperage lead should see 12V power when the ignition key is in both the START and the RUN position. If not, he says the engine will start but as soon as you let the key move from the start position to the running position the engine will die. The B-2037 12V wiring diagram for my coach shows a wire (19 BK) running from the activation terminal on the ignition solenoid to the fuel shutoff solenoid. Since it would be hot with the ignition key in both START and RUN position, I believe this wire must supply power to the "low" amperage lead on the solenoid.

Anyway, for those who, like me, weren't clear about how the fuel shutoff solenoid works, the video may help clarify.

http://www.youtube.com/watch?v=x3UN9s_8T8s

Re: Loss of Power - Stranded

Reply #14 – March 17, 2023, 07:25:48 am

Good explanation Chuck, thanks for posting and the video.

Re: Loss of Power - Stranded

Reply #15 – March 17, 2023, 08:50:01 am

Would get a spare coming whether you need it or not,good to have one on hand,check the net for Larry B's.

Re: Loss of Power - Stranded

Reply #16 – March 17, 2023, 09:20:29 am

FWIW the continuous duty solenoids under the dash work the same way but have internal contacts. Once the solenoid is pulled in, the contacts open leaving the finer wire, more turns, low current hold coil running. That's the difference between a cheap "starter" relay and the continuous duty power relay, and additional coil and pair of contacts.

Re: Loss of Power - Stranded

Reply #17 – March 17, 2023, 09:40:02 am

When I had my last coach the pull in winding was iffy sometimes it would pull in and other times
I would have to manually pull it in. When it finally quit I got a new one and that quit while driving,
so I wired it up to get going and as I was away on a trip I got a spring and that put it into the driving
position and then to shut off the engine I had string to pull that shut the engine off. I ran the string
to the bedroom so I didn't have to lift the bed. I ran it that way until I got home.

Re: Loss of Power - Stranded

Reply #18 – March 17, 2023, 09:56:17 am

When I was researching online info, I saw a couple "trucker" videos describing how to remove the fuel shutoff solenoid and replace it with a permanent push-pull knob in the truck cab. Kinda like a manual choke control cable on a car, but connected to the fuel lever on the injection pump. I guess that would work OK in a conventional or cabover truck, but not too practical in our "pusher" coaches.

Re: Loss of Power - Stranded

Reply #19 – March 17, 2023, 11:07:47 am

Mercedes and others have for decades, used a vacuum or electric shutoff for the fuel. The Detroit in my old bus also had a solenoid to shut down, otherwise, the engine would run until it ran out of fuel. Seems easy to adapt this kind of arrangement to a Cummins. Once fitted, the otherwise mechanical engine would not need any electricity once it was started.

Pierce

Re: Loss of Power - Stranded

Reply #20 – March 17, 2023, 01:27:12 pm

We want to thank you all very much for all your information. After replacing the ignition solenoid with heavy duty we believe our fuel solenoid is probably going bad. Good news we have some large cable ties if need to tie it up. And we know which two white wires on the ignition solenoid to unhook to keep the dash power on. Thanks to plan. We have 1200 miles to get home to Montana so we are asking for prayers. When we are home then I can replace fuel solenoid. We have the original one I believe which is no longer made. So now we have to order the new style, but does anybody know where we can get the older style so we don't have to change all of the brackets are?

Thanks again

James and Suzi

Re: Loss of Power - Stranded

Reply #21 – March 17, 2023, 02:45:08 pm

Go to Cummins Quickserve website and sign up for free. Put in your engine SN and it will give you the parts lookup online.

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Re: Loss of Power - Stranded

Reply #22 – March 17, 2023, 03:00:24 pm

Quote from: Ahb867 – March 17, 2023, 01:27:12 pm

When we are home then I can replace fuel solenoid. We have the original one I believe which is no longer made. So now we have to order the new style, but does anybody know where we can get the older style so we don't have to change all of the brackets?

James and Suzi,

To match your fuel shutoff solenoid, you need to look at the mounting bolt spacing on the old solenoid, and the shape of the 3 pins inside the electrical connector, and the rod end design. Your old solenoid should be either 2.5" bolt spacing OR 3.0" bolt spacing. The pins inside the connector can be either flat or round. The rod end can be plain or Heim joint.

Whichever type solenoid you need, Larry B's probably has you covered. They sell quality parts! If you have any questions, call them and ask. They are good people. Check out their selection:

Fuel Solenoids - LarryB's

When you go shopping for parts for your coach, be wary of buying of cheap knockoff parts. Read the cautionary tale linked below:

C8.3 Fuel Shut Off Solenoid Troubles Part II

Re: Loss of Power - Stranded

Reply #23 – March 17, 2023, 04:34:03 pm

That video in post 13 really helped me put it all together. The Larry B part is working great for me and he actually answered his phone and promptly responded to texts. He also shipped quickly.

Re: Loss of Power - Stranded

Reply #24 – March 17, 2023, 10:55:10 pm

James and Suzi, I have the same year coach and although mine is a 270 I would think the fuel solenoid would be the same...Larry B's solenoid came with a new bracket but it fit my old bracket just fine.

Contact him with your coach/engine info and he will fix you up.

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