Thanks guys......I feel better already.
Yes, I am very fortunate to have a "keeper". She is my biggest fan and assistant in our Barth adventures.
I think she was worried that I would drop that starter on my face! Going to use a couple of small ropes ran around the bottom of the starter to lower it down this time.

You guys are great! Hope to meet you all some day(maybe a GTG next year). I hope you and your families have a very safe and enjoyable Christmas.

Depending on what type of starter you have you may be able to replace it with a lighter one. On my bus that i had with a Detroit Diesel 8v71, i was able to change over from a MT42 starter to a MT39 starter. Big difference in weight, no difference in cranking!

Hello All,
Installed a new starter(solenoid was toast and decided to go with a remanufactured instead of just replacing the solenoid).
Anyway, turned the ignition key and the engine turned over smartly but would not run. Fuel related? I cable tied the fuel solenoid up and tried again. Engine turned over and ran.
So at this point I'm thinking the fuel solenoid has crapped-out but why? Is this at all related to the ignition switch replacement, or the starter issue?
As the engine is running I knew that once I cut the ties, the engine would shut-down because the solenoid is bad...right? Well I snipped the ties and the plunger stayed up and the engine kept running.
So the hold-up winding of the solenoid appears to function but the pull-up function is not for starting. I verified that I am getting 12.6 on the wire attached to the starter relay when the ignition is engaged. The current is momentary. Guess it is designed that way to energize the pull-up function of the fuel solenoid. And there is continuity on the wire from the relay to the solenoid. On Allison World Transmissions(this is one), there is not a neutral safety switch(states that on a print I have that came with the coach). The starter relay at some point has been jumped from the post that has a wire routed off to what is depicted on the print as a neutral safety switch. The jumped post to ground is essentially what the neutral safety switch does (closes to ground according to a print I have from Gillig.
Can a fuel solenoid partially fail? And are the symptoms pointing to a faulty fuel solenoid? I did go directly from the battery to the wire that is momentarily energized to the fuel solenoid and the solenoid plunger did not move. I would think this would be the same as taking the solenoid out to bench-test. I do have a good ground to the fuel solenoid.
All suggestions appreciated. Wife is losing faith in the time and expense getting this engine back up to speed again.
Told her I could rig a wire to pull-up the solenoid plunger during starting, but would rather fix the problem with a new solenoid if needed.

Mike, Try going back to this post by Mwrench and it might help you understand what is going with your Cummings starting issue.

Mike my link was not function properly, so I quoted Ed below.

quote:

Originally posted by MWrench:
YES jumping the two large posts on the starter should confirm starter motor is OK If the engine turns over, BUT it may not start. The fuel shut off solenoid on the injection pump may not pull in with just turning on the ignition switch.

The fuel shut off solenoid has a high current winding used only during starting and is engaged only when the ignition is turned to the start position. Once the engine has started and the ignition switch is released to the run position, the main coil of the fuel shut off solenoid will hold the fuel shut off to run.

As Steve suggested, try to jump the large starter terminal, the one from the battery, to the smaller terminal, from the ignition to verify that the starter and the starter solenoid is OK. If the solenoid does not click or engage the starter from this test then the starter solenoid is defective. This is assuming you have battery power from the battery to the starter. Jumped into the smaller terminal to the larger terminal will also pull in the fuel shut off solenoid as the start circuit drives both the starter and the fuel shut off solenoids

If the starter does not engage, then jump the two large terminals on the starter solenoid, if the starter does then spin and/or engage that will confirm the starter solenoid is indeed defective. By prepared to loose a screw driver if you do these tests using one to jumper the big terminals. You must use a tool big enough to allow high current to flow, do not hold a wire by hand to do this test, severe burns may result.

If the starter is tested to work OK then proceed to trace back toward the ignition. This may require someone to turn on and off the ignition while measuring voltage.

HTH

There are two windings on the fuel solenoid, as Ed suggested. The pull in winding is momentary high current (ie 50 amps!)
The hold winding is like 5 amps. Sounds like you have a bad pull in winding.

I still don't have diagrams yet for specific pin/colors, but if you pull the connector to the solenoid (I think it is 3 wires) you should have continuity between the pins if the solenoid coils are good. Chances are you will find one pair that is open.

You are doing well.

Consider this: the things you are finding are common to older coaches. Better to find them and take care of them now than later on the road.

Thanks Kevin and Steve as always for your quick responses.
I have reassured my wife with your very words Steve...better to replace this stuff now than out on the road.

My fuel solenoid has the wires plumbed directly into the top of the solenoid housing. I'll prick the insulation on the red wire(run) and the white wire(pull) to check for continuity Steve. I'll also check the black wire for a good ground(didn't know that was a ground wire at the time, but process of elimination...).
Thanks for the encouragement! Will keep you posted.

I remember now Steve that I saw a connector in the vicinity of the solenoid. That's the pins you're referring to.

Yep, there is a cable coming out of the solenoid. Plug is close by.

If I get the chance I will pull my connector and measure ohms for you. (It will be a balmy 28 tomorrow!)

There should be a three pin plug about a foot down the cable from the fuel shut off solenoid. If you turn the ignition switch to the start position and the fuel shut off solenoid does not move then YES the fuel shut off solenoid is defective. And YES this does happen. it can happen either from and electrical problem internally or a mechanical problem externally.

I had a solenoid break the mechanical linkage to the injection pump and drove 1000 miles home with a coat hanger holding the shut off lever on the pump up! From the sound of it, yours is an internal electrical problem of the fuel shut off solenoid. It is possible that the ignition switch or other external electrical problems caused the fuel shut off solenoid to fail as well as the starter solenoid to fail (they are both activated by the same electrical source) BUT if that were the case the starter would also have been running after ther start sequence was finished, and continue to run. These are all intermittent running devices and as the starter seems to be OK I doubt that happened.

The fuel shut off solenoid is easily replaced. On line you can find them for about $30.00-$50.00 but at Cummins they are listed for over $300.00. I bought both and the $30.00 units are exactly the same as the expensive ones. I tested both, same pull-in force, same current draw, both pull-in and holding current, same temperature rise during holding coil operation, tests were performed on the bench. You may find the replacement unit has a different style connector and require changing your mating connector from the coach wiring.

Solenoid

Setting up the linkage is important, you want to make sure when the holding current is applied the solenoid is fully retracted and the fuel linkage has just a tiny amount of looseness. The solenoid has to be FULLY seated in the run position as well as the shut off lever on the pump to be fully moved to the on position but not to the point where the pump linkage prevents the solenoid from full seating.

Good luck, you will be motoring down the road shortly!

Here are Michael's pictures. His problem is similar, and I will post his email with these pictures.

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"Would like to know what the function is. I can hear it "click" when turning the ignition key. Also discovered that the "run coil" on the fuel shut-off solenoid is powered from one of the small posts on top of this relay. Started the Barth today and it ran fine for 10 minutes and then shut down. I turned the ignition switch and took the multimeter to the relay and discovered a very quick 9.0 volts to ground at the small post that the run coil of the fuel shut-off solenoid is powered from. The relay would connect(click) off and on repeatedly, but would not stay "connected" internally. The engine would start and run momentarily, but then shut-down because the run coil would not be getting 12 V from the relay.


Tried it again later and the engine started and ran without shutting down. The electrical diagram from Gillig has the "run" coil of the fuel shut-off solenoid powered from the rear "starter-box". For some reason the power for the run coil was rerouted from the top of the mystery relay.


Need some guidance on this one. Don't want to take it out for an exercise run only to have the engine shut-down on me. Would like to get these posted in the Tech Forum as soon as possible."

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Read through the above information and links Michael and you may find your answers to solve your issues.

We see some issues like these from time to time. Someone likes to treat the starter solenoid like it is a 12v buss! Connecting all kinds of 12v loads to terminals that individually draw power from the single battery cable. In audio, radar and airplanes a 12v buss is somewhere else from a high current load device so I would build myself a true 12v heavy buss and take everything but the battery cable off the solenoid. Then the battery can provide full power to the starter. If the ignition wire is one of those small posts and it ties to the fuel solenoid as well you have to get a drop in voltage when all those things get energized. Most times we find that isolating the starting curcuit from other loads improves voltages throughout the coach.

I'm confused on this one guys.

A few weeks ago I replaced what I thought was the "starter relay" mounted near the rear of the engine adjacent to the coach batteries. This relay had a wire routed to the starter solenoid(mounted on the starter) It tested faulty and once replaced the starter spun-up great. Also installed a new Delco-Remy starter...solenoid on the starter was bad.

The relay in question is located just inside the bed box. It has voltage on both large posts all the time. It makes an audible "click" when the ignition key is turned, and the smaller gray wire coming off one of the smaller posts goes to the run coil of the fuel shut-off solenoid. After the engine shut-down, I measured voltage from one of the larger posts to the post with the gray wire(routed to run coil). Meter would show an instantaneous 9.2V then "0". The relay kept clicking on and off.

I replaced the fuel shut-off solenoid two weeks ago as the pull coil was defective(wanted $450.00 from Cummins...bought one off EBay for $40.00). So the old girl started and shut-down great last week.

I thought a relay's function was to transfer power from one side of the pot to the other when prompted to do so by another source...say the turning of the ignition key.
With the ignition key "on", the relay pictured was cycling on and off repeatedly(clicking), so I figured that was why the run coil was not staying open to allow operation of the engine.

On the relay pictured, You mention the gray wire goes to the fuel shut off solenoid, I see a purple wire there also. Where does that go?

When the key is off, measure that gray/purple connection to ground. I think it should be "0" volts. Keep the meter to the same point (gray/purple) and turn on the key. It should read 12 volts steady, don't worry if it is 11.8-13.5 but what ever it is it should be steady.

If the relay is clicking, and you see the voltage at the gray/purple connection cycling and it goes to ground or "0" volts with the clicking then you have an issue up stream from that relay to the ignition key source.

I would bet that purple wire comes from the ignition key path either another relay driven by the ignition key or the ignition key itself. The two small terminals of the pictured relay is the coil of the relay and is what pulls in the higher current contacts that controls things that require a lot of running current while the ignition switch is on.

That relay shown I do not believe is in the run circuit that controls the fuel shut of solenoid. I think it is parallel with the run circuit so if the relay is turning on and off, so is the the fuel solenoid but that is not the root cause of the problem.

Go to the ignition key and measure the voltage there when on and off. If it cycles to zero and back on the run side of the ignition switch while on, measure the other side of the ignition switch to make sure it is steady all the time. if not your switch is defective. If the run side of the switch is OK, then your problem is be between the ignition switch and the relay and fuel solenoid in the back.

You didn't mention how fast this relay is clicking. If it is clicking with seconds in between the clicks, that would be a thermal circuit breaker turning on and off probably because of an overload or short somewhere. As the run time seems to vary I would suspect something is shorting out at random.

I KNOW, all Barth are different-----On mine the only thing the ignition drives is a large relay in the front electrical compartment. Anything that the ignition switch controls goes thru this large relay. It is a continuous duty relay and gets rather warm when on for long periods of time and I have replaced two. When one of them went bad, the engine would start but immediately shut down when I released the key to run. The start position of the key should only drive the starter solenoid and the pull-in coil of the fuel shut off solenoid.

It is hard to "Monday morning quarterback" issues particularly when intermittent. Best I can do with the information provided. PM me and I could call you today sometime.

Will call tomorrow if that is ok(will be at the Barth working on it tomorrow).

My Barth is set-up like yours in that a continuous duty relay(located in the electrical bay behind the drivers tire),is controlled by the ignition switch. It was replaced by the PO sometime in 2016.

Yes, the relay in question would click on and off every couple of seconds. I guess I need to find the ignition controlled wire in the rear start box and feed the shut-off solenoid(run coil) from there as was originally dictated by the Gillig prints.

Stopped by this morning, started and ran the Barth(20 minutes run time) with no issues. Had replaced the ignition switch just a month or so ago after it was testing faulty.

Will meter the switch as suggested along with the smaller coil posts on the relay as suggested. Thanks for your insight!