Class A diesel help

[noswad]

Hello, I have a 2001 Damon Ultrasport with a 24 valve 5.9 ISB. I have run into a problem. When driving home from the campground sunday it was raining. I had the generator running so the kids could watch TV. Every so often the check engine light would come on and the tach would get real jumpy and I would loose power. If I was pulling a hill then it would not downshift. Then the light would go out and the power was back. No other gauges would be affected. So then I turned the generator off and the check engine light would not come on. In my regular maint. I changed all filters, oil and etc. Even the generator fuel filter. which was less than 150 miles ago. Does anybody have any clue what this could be??? Maybe a ground wire loose? Fuse?? Please let me know what you think I should check.
Thanks, Chris

[prism]

txhandgunner wrote:
I would echo those who say "electrical short" and/or water into the intake. Although, I'll offer that the latter is unlikely: diesel's don't care for ingesting water AT ALL! If you got enough in there to choke the engine, you'd most likely have some additional damage.

I'd look for a short caused by water seepage.

But how do U then relate this to "only when he runs the generater while driving down the road" to your theory of water in the main engine intake?

[noswad]

I don't have a computer to check for codes. Is there a way to do it without a computer??

Chris

[vegasfoodguy]

DryCamper11 wrote:

noswad wrote:
I turned the generator off and the check engine light would not come on.

There weren't many comments about this symptom, which seems pretty relevant. It's worth checking how the gen (I assume it's diesel) is connected to the fuel line/fuel tank. I've seen them wired into a "T" in the main feed line. This reduces fuel pressure when the gen is running and can cause air to get pulled into the line.

The gen should be connected to a separate feed from the tank - not the same feed that supplies the engine. This would be unusual(a "T" install), but occasionally it's done if the second tank feed has been damaged, or if multiple fuel tanks are installed and it's not necessary to prevent the gen from pulling all the fuel from the aux tank, which would leave you stranded if all fuel was pulled by the gen from a single main tank.

Did you check for codes?

Terry

[DryCamper11]

noswad wrote:
I turned the generator off and the check engine light would not come on.

There weren't many comments about this symptom, which seems pretty relevant. It's worth checking how the gen (I assume it's diesel) is connected to the fuel line/fuel tank. I've seen them wired into a "T" in the main feed line. This reduces fuel pressure when the gen is running and can cause air to get pulled into the line.

The gen should be connected to a separate feed from the tank - not the same feed that supplies the engine. This would be unusual(a "T" install), but occasionally it's done if the second tank feed has been damaged, or if multiple fuel tanks are installed and it's not necessary to prevent the gen from pulling all the fuel from the aux tank, which would leave you stranded if all fuel was pulled by the gen from a single main tank.

[fcooper]

noswad wrote:
Every so often the check engine light would come on and the tach would get real jumpy and I would loose power.

I'm fairly sure your coach is built on a Freightliner chassis. The symptoms may indicate water intrusion into circuits that originate in the VDC (vehicle data computer) and that drive the dash guages among other things. There are some relays in some of these circuits that can behave in a strange manner if water soaked (I've had a transmission problem caused by a wet relay.)

I suggest you call the Freightliner Help Desk 1 800 FTL HELP and have your last 6 digits of the coach VIN number available. This is a free service, and they really know their product.

You may also want to look at Freightliner SB 54-12 for info on how your instrument system works. See the link below:


Freightliner SB 54-12

When you solve the problem, please post the solution as some of us may also encounter the same thing someday.

Fred

[noswad]

I had a cam sensor go out on one of my work trucks and it was doing the same thing, so I was kind of thinking that. Is that something I can do myself or do I need to take it somewhere?? I live in southern Indiana just wonder if the cummins dealer would be able to do that??

Chris

[Whaler]

I have the same engine and had the same problem. It was the crankshaft position sensor which was a common problem in the 99 - 2001
engines. The other common problem is the VP44 fuel injector pump failure. The VP44 is ultra-sensitive to water in your fuel. Your issue does not sound like the pump. The oil pressure sending unit is a known issue in this time frame too. And yes, I know all diesels have problems handling water in the fuel system for all who want to reply to what I said.

[txhandgunner]

I would echo those who say "electrical short" and/or water into the intake. Although, I'll offer that the latter is unlikely: diesel's don't care for ingesting water AT ALL! If you got enough in there to choke the engine, you'd most likely have some additional damage.

I'd look for a short caused by water seepage.

[wolfe10]

Yes, I would start by checking battery connections as well as ground connections at the engine.

If everything clean and tight, I would rig a volt meter to the OUT side of the ignition solenoid. See if it is dropping power when this happens.

If so, see if the signal wire from ignition switch to the ignition solenoid is dropping, of if it is a problem with the solenoid.

BTW, other symptoms of this would be for other things like the dash HVAC fan to cease working when power out of the ignition solenoid is failing. Is that happening?

[wilpower]

If the check engine light comes on, it usually does put you in "limp" mode. It may be a fuel problem, since when you turned the genny off, the problem didn't occur.

[noswad]

I don't know where to really start looking because it is intendment. The loss of power and not downshifting thing has be stumped. Its almost like it goes into limp mode, but when the check engine light goes off the power is back. The other thing is the tach bouncing around while all this is going on. I guess I will start at the fuse block and check my fuses.

Thanks, Chris

[JimM68]

I also have no experience with your particular rig, but my (and may other) monaco's tend to turn on the ALT light on the dash if the genny is run at the same time as the main engine.

Sounds like something similar, tho also more severe.

[naturist]

I know nothing about that particular rig, but from general info, I can suggest a couple things. Since it was raining, it is possible that you have a pending short somewhere in the electrical system, and the water caused arcing. Obviously, the higher the voltage, the more easily this occurs, so I'd start looking at the generator 120 volt lines first. Obviously you have no spark plug wires to worry about, but 12 volt wires could be the problem, too.

The other possibility is the engine air intake sucking in water. I don't know that this rig is prone to the problem, but I have known of people with OTHER diesels that did suffer it until the fixed it. It had to do with the air filter getting soaked with water, thus not passing air and temporarily choking the engine. The fix involved relocating the airbox intake so the wheels didn't splash water into the intake.

Best of luck tracking it down.