Cummins ISL400 runs and quits... questions

[MarcW]

I'm currently stuck in a RV campground with a engine that won't run.
I called and talked with the nearest Cummins service center and the tech on the phone says he thinks it's the lift pump.

The problem goes like this... After getting parked after a normal 250 mile day driving, I started the engine again later and it ran for about a minute and then quit. That was a first. I started it again and did the same thing. I got a "engine comm error" on the dash.

It repeated the same thing several times so I took a break to go on line to search the engine comm error thing to see what I could find out.

One person said that they had a similar event that was caused by a "WIF sensor", another said to disconnect the chassis batts and reset.

That was easy so I did it and the engine started and ran. I let it run long enough to come up to temp and it ran perfectly but I had to shut it down because it was getting late and I didn't want to make everybody mad.
The next morning I restarted and once again it quit, so what exactly caused it to run normally on the previous start and now go back to the problem again is unknown.

When I turn it on the lift pump runs for 30 seconds. Same amount of time every time I do it. The tech said it should run for a couple minutes.

At this point we're waiting on the lift pump and then they will make the 45 mile drive out to diagnose and hopefully fix the problem.

Anyone have any thoughts on what else might be going on? It acts like it is simply running out of fuel after it starts but the "engine communications error" sounds electrical to me.

The coach is a '07 Monaco Dynasty.

Thanks in advance for any insight you might be able to give me..... Marc

[Ivylog]

Interesting that your problem had nothing to do with the engine side of things.
You will find that turning the engine battery disconnect off does NOT disconnect the engine starter from the batteries. That switch is not capable of 1800 amps. I only learned recently that Monaco puts both of the starters on the same batteries so if the generator will not start... you are in trouble even holding the boost switch down for 10 minutes. Instead of running a large battery cable to the back and the house batteries, they tap into the large engine battery cable in the front left compartment for the generator. With dead engine batteries the BigBoy and wiring will not pass enough amps (200 amps) to overcome the dead batteries and start the generator. Instead of unhooking the engine batteries (hard to get to because of "How I tow", I cranked up the toad and turned on the parking lights and let it and the boost switch charge the engine batteries enough to finally get the generator to start and then the converter would charger the engine batteries enough to finally get the engine started.
The Big Boy has replaceable contacts so no reason to buy a new one unless the electromagnet does not pull the round disk into the contacts. Any good starter repair place should have these contacts that bolt into the solenoid and are what the large copper straps bolt to. A simple test is to see if you have any voltage between these two large studs when someone hold the boost switch on. You should not have any voltage as it's just a on/off switch. Another indication would be that your house batteries are not being charged when going down the road.
A friend with a 06 Exe could not boost his engine start and by removing these studs/contacts and taking a file to the corrosion on them we had him running in less than an hour.

[MarcW]

Thanks YC 1... interesting reading. The tech was voltage testing the two sides on mine while I watched and when it clicked he said it was trying to transfer to the house side but wasn't doing it because there was no charge going to that side.
What do you think about that being able to put a heavy enough load on the chassis side to pull the voltage to the ECM down enough momentarily to cause an engine shut down? Obviously that is not a common occurrence or there would be lots being said about it.
I think that my problem has been the ECM is getting some kind of electrical signal or drop in voltage that is causing it to shut down and the question is where and what is doing it. And... why would disconnecting the batteries reset anything and cause it to stop happening?
At this point the relay being bad is clear and needs to be replaced but whether it could be a factor with the more serious problem is just a guess.
Also... one other thing that was done while I was there and the computer was hooked up was he down loaded a updated software program.

[YC_1]

Mark, how do you know your solenoid is working properly?? It can be very tricky trying to test it. They can work but poorly. For example, they may not work if you need to boost your batteries when starting. The contacts become contaminated and resistive. As a comparison think of it as a fuel filter that is dirty but still allows you to roll down the road under normal conditions. Now you try to go up a steep hill and the fuel filter cannot deliver the extra load need and you have issues. The same can happen with relay contacts. They may not be able to deliver the load.

I just thought of a way to test them. We should be able to turn the engine battery off and then try to start it through the aux start function. That would put a huge load through it. If it turns over and starts normally then the solenoid is fine.

[YC_1]

Scroll down to YC1 #28 response for pics

I can put you on to 33 threads concerning the BIRD if you are interested is some fine reading. There are some excellent pictures of many different variations available.

[MarcW]

Mr.Mark wrote:

YC 1 wrote:
The large relay can run very hot to the touch. Mine draws 1.5 amps so is like having a 20 watt bulb running. The contacts inside are notorious for failing. I am on my third relay in five years. I am beginning to believe the relay should be changed out like a fuel filter as part of regular maintenance.

YC 1, just for future reference since we have similar coaches, where is this 'Big Boy' relay? I will want to keep an eye on it as we have had no problem in 6 yrs. of ownership.

MM.

It's behind the removable panel in the engine compartment on the right side with all the wires, lights and fuses. It's the biggest thing in there and says " BIG BOY" on it.

[Mr_Mark1]

YC 1 wrote:
The large relay can run very hot to the touch. Mine draws 1.5 amps so is like having a 20 watt bulb running. The contacts inside are notorious for failing. I am on my third relay in five years. I am beginning to believe the relay should be changed out like a fuel filter as part of regular maintenance.

YC 1, just for future reference since we have similar coaches, where is this 'Big Boy' relay? I will want to keep an eye on it as we have had no problem in 6 yrs. of ownership.

MM.

[YC_1]

The large relay can run very hot to the touch. Mine draws 1.5 amps so is like having a 20 watt bulb running. The contacts inside are notorious for failing. I am on my third relay in five years. I am beginning to believe the relay should be changed out like a fuel filter as part of regular maintenance.

[MarcW]

Ivylog wrote:
Marc, how did you figure this out? Did you call Monaco? Another reason for not wanting a monoplex system.

I didn't exactly figure it out. I was guessing.

You are right, the Intelletec Monoplex system is very complex. There are a lot of neat things about the way it works but if you get a gremlin... good luck. The whole coach is controlled by this monster.

The house switches were acting glichy. They were flashing lights in the wall panels that didn't make any sense.

The house and the chassis electrical interface with each other so I thought maybe there was a short or bad ground somewhere in the house system that was feeding over into the chassis.
That's why I disconnected the house side just to see if that might do anything. It was my last guess.

It appears that disconnecting the batteries for the 40 mile drive to the service center has reset everything (at least for the time being). The house system is now acting normally and the engine runs with the house turned on.

I spent all day with a tech going over everything and the only thing he found was the battery isolator relay is bad. It is a part of the Intellitec system that basically allows both house and chassis batteries to charge when the engine is running.

The House side isn't charging and the "Big Boy" relay (yes that's what it's called) was humming and clicking and got very hot while the engine was running.
He said that it could possibly be pulling the EMS down below 10 volts which would shut the engine down.
He's just guessing though because it wouldn't repeat the problem and throw a code that would identify where the problem was.

So.. that bad boy will get replaced and we'll see if that's it.

[Ivylog]

Marc, how did you figure this out? Did you call Monaco? Another reason for not wanting a monoplex system.

[djedgar]

Glad you can drive into the repair facility. Hope you get there before your refrigerator loses it's cool.

[wny_pat1]

MarcW wrote:
I just had another long talk with the service tech at SW Cummins and he is thinking that it is probably electric now but will be bringing the lift pump anyway.
One thing that I failed to mention (too much to think about) is when the engine stops it displays a check engine light and the needles swing back and forth and don't stop until I turn it off. The light resets and does not come back on until I repeat the restart/stop.
I hate this kind of guess what's wrong kind of thing. I would rather just have something break.

The thing is that your engine, including lift pump, is computer (electric) controlled. That is what I love about the old mechanical engines. No sensors or cables to mess up.

[MarcW]

Thanks everybody for your responses. I found the source of the problem. It is in the house electrical system. The Intellitec Monoplex system is acting strange and has a red light blinking in one of the modules about every 30 seconds or so. The light is labeled comm fault. I turned off the house system at the batt disconnect, leaving just the chassis side on and the engine fired right up and runs without problems.
The tech I've been talking to at South West Diesel in St George Utah is experienced with this Intellitec system and says it sounds like a low voltage/faulty 12v power supply to the system due to a bad connection. He doesn't know why it would interfering with the chassis side and be shutting the engine down, but they do interface with each other so I guess it's one of the mysteries of electricity.
Anyway... I'll be able to drive it to him and he'll trouble shoot it and see if he can find what the problem is with the power to the house side.

Obviously a big relief that no towing will be necessary and it looks like our trip can proceed even if the house system doesn't get fixed due to a bad module or whatever. Running with the house 12v off only shuts down the lights and water pump. Everything else is on the inverter so it's not really much of an inconvenience.

Thank again for taking the time to help..... Marc

[Blaster_Man]

Whenever there is a running/stop/start problem, it's a good idea to change the two fuel filters.

[YC_1]

With guages acting strange it would seem to be electrical.
Check out this thread about some electrical splices. I will do some more searching to see if there are a couple of other links.

Jiffy-Splice