engine ignition won't turn off

winniehaha · 01-15-2012, 02:42 PM

Would like to know if anyone has had this problem, and what they did to fix it:
the ignition switch (or relays) on our 99 Adventurer 34V (Cummins 5.9 pusher) sometimes won't turn off. When we pull in to a Wal-Mart parking lot in the middle of the day, usually no problem - turns right off. But if we pull in to a park at night, with other RVs all around, and they would appreciate quiet, the engine WON'T TURN OFF! It usually will after 10-30 minutes of messing with the key, and mostly just waiting, after we turn the ignition off. DH has sprayed electronics cleaner in the ignition, checked the wiring at the ignition, cleaned the contacts at the relays/solenoid...
Don't think the ignition switch would be worn out, because the rig doesn't have a lot of miles on it... suggestions would be appreciated.

Poke a Long · 01-15-2012, 03:50 PM

I'm betting it's your ignition switch, mileage nor age may not be the issue. We had way tooooo many keys and do-dads on our ring and it caused a wear on the switch. Good luck

Elkhartjim · 01-15-2012, 04:05 PM

I'm betting its a shot in the dark finding the cause. I've had it happen four times. Once two years ago and then three times this past summer. Turn the ignition of and it just keeps chugging. I spent literally hours on the phone with Freightliners help desk. I pulled relays, fuses, jiggled wires, etc. The only way I finally killed it was pulling the negative cable from the chassis battery. After the last time doing it it hasn't happened again in several trips. KNOCK WOOD! I called Pat at the Freightliner service center in Gaffney and she said they had had a couple mh's in with the same problem and never found the cause. FL believes its electric feedback from something.

timex · 01-15-2012, 04:40 PM

I have seen on other diesels that the linkage on and or the fuel pump shutoff solenoid is bound up (rust) not allowing it to operate the shutoff on the fuel pump. If the linkage is free have someone check (with a test light) for power at the fuel pump shutoff solenoid when you cycle the ign switch on then off. That will tell you the switch is okay. If that's okay have them check the solenoid with an ohm meter to see if it is open. Good luck

Elkhartjim · 01-15-2012, 05:13 PM

Quote:

Originally Posted by timex

I have seen on other diesels that the linkage on and or the fuel pump shutoff solenoid is bound up (rust) not allowing it to operate the shutoff on the fuel pump. If the linkage is free have someone check (with a test light) for power at the fuel pump shutoff solenoid when you cycle the ign switch on then off. That will tell you the switch is okay. If that's okay have them check the solenoid with an ohm meter to see if it is open. Good luck

You're the second person to mention the fuel pump solenoid, timex. As you can imagine, intermittent problems are a bear to find/fix.

AFChap · 01-16-2012, 09:37 AM

When a diesel won't shut down by the ignition, my very first suspect would be the fuel pump shut-off soleniod.

Luckiest Dreamer · 01-16-2012, 10:22 AM

A diesel needs fuel and air to run! So the only way to stop them is to starve them of one of those two items. You can unhook the battery and it will still continue, unless when you unhook it a solenoid closes off the fuel by resetting.
So chances are that either a fuel solenoid is bad or the switch is bad. When I was driving 18 wheelers they always had a button or a lever to push or pull mounted somewhere on the frame near the engine that bypassed the switch in the case it failed. I have not checked to see if my MH has one. Because of this post I suspect that I will. Intermitten problems are no fun!

Elkhartjim · 01-16-2012, 10:29 AM

I failed to mention there were two idiot lights on and the air pressure gauges registered pressure also. I was having electrical feedback somewhere, somehow...I think. Thats why FL had me pulling relays and fuses to maybe isolate the cause.

I appreciate all the replies.

winniehaha · 01-16-2012, 12:15 PM

Many thanks for all the responses - we are in Yuma today at a large park that only has free wifi in the office. I put up the message yesterday, and walked back to the rig. This morning, I was surprised by all the suggestions. Thanks!

We are parked next to a farmer/custom cutter, who is familiar with diesel rigs and their foibles. He said right off, fuel solenoid. DH has decided to take the rig to a diesel repair place in town (not the big RV dealer), but now we have good info on what to tell the mechanic. He's a little tired of working on the rig...

DH just replaced the leaking heater core - I checked the forums and, of course, found much info on the subject! The local RV dealer where we were in New Mexico needed $320 to order the direct replacement - not to mention how much a shop would charge to put one in - yikes! So, I routed around the forum and found the link for Mill Supply. On pg. 165 of their step-van parts catalog (sub-heading: heaters) is model #50-573 - fits Utilimaster. The dimensions are 14 1/8" x 6" x 2 1/2", 5/8" inlet/outlet. It's a little shorter, but will fit - $94.21 plus shipping. It's not quite as stout a unit, but the dash heat works again. (DH had to do some retrofitting - "alter" the plastic shroud a little, and deal with the curved inlet/outlet - but he made it work). There was enough room where the core is for him to be able to work without taking the front off. It wasn't rocket science, but it did take a whole day. If anyone's interested I can put up a pic. It's not pretty, but it heats, and no more leaks.

Before that, he rebuilt the genset - it had thrown magnets...again, I got good info from the forum. Two parts - $1500 - but he did the work, and now the generator runs fine.

Now, we'll see if replacing the fuel solenoid solves this problem - then we'll start working on why the slide doesn't want to go in (if I push from the outside while he's running the switch, it will eventually, but that's getting old).