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Tinstar's avatar
Tinstar
Explorer
Dec 11, 2016

Start problem

I'm going to throw this out there and see if anyone has suggestions.

I bought a newer, larger motorhome a few months ago and I need to sell my old one. I'm having a problem with the old one.

We're talking about a 1994 Tiffin Allegro Bus diesel pusher with the B-5.9 Cummins Turbo Diesel (mechanical engine) and it has had problems starting for years. What happens about 1/2 of the time is when I turn the key to the on position the dash lights up like it's ready to go BUT when I turn it to the start position I get nothing. Lights on the dash go out and there is no power to the starter. I hit the starter again and it might crank and run or it might take another 5 - 10 tries before the starter will engage and it will run fine, until the next shut down and restart. Next time it might engage on the first try or I might have to turn the key to the start position another few times. It always cranked up and like I said, this has been going on for a few years. It's never been a big problem until today.

I went out to start it and as usual, the starter wouldn't engage. I hit it another half dozen times and it finally started BUT as soon as I released the key, it would die. It's never done this before and it previously always stayed running. I tried it several more times and each time it will crank and runs fine as long as I've got the key in the start position but as soon as I release the key back to the run position it dies. Just FYI, I don't leave the key in the start position more than a couple or three seconds after it starts as I know that is not good.

I've got a couple of ideas but don't want to taint the thoughts of anyone that might have some ideas. I almost positive it's not fuel pump related as it doesn't die like a fuel starvation problem. Any help will be appreciated.
Class A

7 Replies

  • Tinstar's avatar
    Tinstar
    Explorer
    Dec 12, 2016
    Ava wrote:
    On my 5.9 cummins the signal from the key switch goes to one solenoid inside the engine compartment which has to activate before the current goes to the starter solenoid. The terminal had come loose on the first solenoid on mine and gave starting problems. I also replaced the wire from the steering column to the solenoid as it was shakey. No problems since. After 20+ years of bouncing around on the road, we need to keep vigilant of electrical connections and wires.


    Ava, I sent you a private message. I'm almost sure this is what is wrong with mine and had a couple of questions on the work you did.
  • Ava's avatar
    Ava
    Explorer
    Dec 11, 2016
    On my 5.9 cummins the signal from the key switch goes to one solenoid inside the engine compartment which has to activate before the current goes to the starter solenoid. The terminal had come loose on the first solenoid on mine and gave starting problems. I also replaced the wire from the steering column to the solenoid as it was shakey. No problems since. After 20+ years of bouncing around on the road, we need to keep vigilant of electrical connections and wires.
  • Sam_Spade's avatar
    Sam_Spade
    Explorer
    Dec 11, 2016
    Ivylog wrote:
    I would have said your starter solenoid needed rebuilding until you said it dies so now I'd say ignition switch is your problem. I would put a test light on the contacts of the ignition switch and see what happens.


    Good suggestions so far BUT......

    This can also be a sign of a corroded or loose connection, even INSIDE the battery.

    Since the problem is reproducible, a meter and a second person should be able to find something fairly quickly I would think.

    And yes, a corroded connection certainly can pass current when the demand is high (starter) but then fail when the demand goes back down (keeping the engine running).
  • Ivylog's avatar
    Ivylog
    Explorer III
    Dec 11, 2016
    I would have said your starter solenoid needed rebuilding until you said it dies so now I'd say ignition switch is your problem. I would put a test light on the contacts of the ignition switch and see what happens.
  • wolfe10's avatar
    wolfe10
    Explorer
    Dec 11, 2016
    Since lights on dash go out as well as a no start:

    1. Check battery voltage at the battery side lug of the ignition solenoid up front when key engaged. That will tell you whether you have a problem with battery and/or wiring to it OR if this is an issue "up front".

    2. If voltage at the ignition solenoid good, it could be either the ignition solenoid or the ignition switch. To determine which one check for 12+ VDC at the small signal terminal of the ignition solenoid when you turn the key on. If you have voltage there, check for voltage at the OUT lug of the ignition solenoid. If you have power to the signal terminal and no power out, you have a bad ignition solenoid. If no power to the signal terminal you have either a bad ignition switch or wiring from switch to solenoid.

    You can temporarily remove the small wire from the signal terminal of the solenoid and use a small jumper wire from battery-side lug of ignition solenoid to the signal terminal. This should give you all dash lights and allow you to start and would confirm a problem with the ignition switch or wiring.
  • shepfly's avatar
    shepfly
    Explorer
    Dec 11, 2016
    Check your ignition switch,sounds like progressively burned it's contacts. Check at the starter solenoid for voltage when someone turns the key to start position. Should get voltage on small start terminal then.
  • WILDEBILL308's avatar
    WILDEBILL308
    Explorer II
    Dec 11, 2016
    Have you tried holding your battery switch down to tie the batteries together.
    Bill

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