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 > Cummins 8.3 won't start - then finally did, what's up?

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Ozarkwoods

Highways, and Byways

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Posted: 05/10/10 08:50pm Link  |  Print  |  Notify Moderator

I had an issue that my coach would run but then if I went to shut it off and then try to start it again it would not start until it cooled somewhat. My issue was the fuel shutoff solenoid. Changed it out and have not had a problem since.


Full timing since June 2013
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Steve S.

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Posted: 05/10/10 12:05am Link  |  Print  |  Notify Moderator

The Shadow Nos wrote:

I got a 1996 Allegro Bus it would not restart when I wanted to move it at a campground 15 min later it did no more problems rest of the year. Next spring sometimes it would not start right a way or when I shut it off it would stay running for 1 to 2 min. Had new start/run solenoid installed no problems. By the way the new solenoid was twice the size as the old one.


Was the problem initially a "hot engine - won't start" problem? If so, yes the solenoid going makes total sense. Every single solenoid I have personally had fail on me has always "started" to fail when hot (I seem to have bad luck with solenoids...). Eventually (if I don't change it), it gets bad enough where it won't work when cold either (unless I tap it with a hammer) or it starts sticking in the "on" position when it should be "off". Most of the solenoids I've had fail have been starter solenoids, but the same principal and failure mechanism applies.

Actually staying running with the key off is a dead giveaway - almost guaranteed that the solenoid is sticking (or power staying applied to the solenoid for some bizarre reason).

There is actually a linkage for the fuel solenoid that could possibly also get seized up; making it "appear" that the solenoid has failed. I have no idea how common this is with these engines, but when a fuel solenoid starts acting up it might be worth lubing the linkage first and seeing if this fixes the problem.


1996 40' Monaco Dynasty, Princess floorplan, Bunkbed Conversion
C8.3, 300hp@2200, 820ft-lbs@1300,
2000 Saturn SW2 in tow

2002 Jayco Qwest 10X, Penguin 13,500 BTU A/C LP, Monroe RV shocks, Dexter 7" brakes, Carlisle 145R12, Dual Deep Cycle

Steve S.

Ottawa, Ontario, Canada

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Posted: 05/09/10 11:52pm Link  |  Print  |  Notify Moderator

larry barnhart wrote:

the start run solenoid was what the problem was on a friends Monaco doing the same thing but it didn't start.
chevman


Are you sure the symptoms were the same? After sitting for some time, it would start, run for a short while, then stall, and then after cranking quite a lot eventually start "rough" with the throttle down?

If so, I very much doubt the solenoid was really the problem.

Did your friend have the fuel filters changed at the same time as fixing the solenoid? If so I suspect he fixed a fuel leak when the filters were changed and that was the real problem.

On the other hand if it just wouldn't start at all one day or sometimes wouldn't start when hot and would when it cooled down, then the solenoid makes sense.

* This post was edited 05/10/10 12:07am by Steve S. *

Steve S.

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Posted: 05/09/10 06:22pm Link  |  Print  |  Notify Moderator

TominTampa wrote:

Great info. - After my fuel chase I'll probably go ahead and replace the start/run solenoid just for insurance. - Tom


You may not have to if you think about the way it stopped running, what it is doing now and the fact you can easily override it manually at any time.

The fuel solenoid is essentially a pair of solenoids in one. One solenoid, the high power high current one, is designed to pull (or push) the fuel lever into the run position. The second solenoid is actually just a small electromagnet that holds it in the run position.

If it was running and then quit (as it was) and the problem was the solenoid, the small electromagnet would have failed or the power to it would have been removed. Now when you try to start it, it should fire initially, but then stall when the key is released since the "hold" solenoid has failed. I believe it is more common for the large "pull" solenoid to fail, making it so you can't start the engine but it will run if you turn on the key and then manually move the solenoid to the run position (allowing the magnet to hold it in position).

One great thing about the fuel solenoid is if it fails you can always manually override it and hold it in the run position. This can be done with any small piece of wire by manually moving it to the run position and wiring it there. I don't know about yours, but my owners manual tells you how to do this.

BTW, when my coach stalled the first time (after running perfectly for 10-15 seconds at high idle) the first thing I checked was the fuel solenoid and I discovered it was working perfectly.

Based on the way it stalled and the fact it started hard later, it really does not make sense that the solenoid is the culprit. For example, if the solenoid won't move, it will never start. If the solenoid is stiff or "sticky", once it does start it won't stall. After stalling, not wantint to start and running the air purge, yours cranked, eventually firing now and then with the throttle down a little, eventually started. I can't think of anyway for the solenoid to do this, especially if everything is working fine now. On the other hand since you did run the air purge using the Winn system and then it was hard to start, this perfectly maps to the symptoms you would get if there was air in the line initially and after running for 30 seconds it got into the injection system. The expected behaviour after this and running the air purge would be that it would be difficult to start (due to air in the injector lines) and after some cranking and throttle it would start. Again a perfect fit so most likely the problem is a leak in the fuel system somewhere (and due to the particular coach and fuel system in use, the most likely culprit is the o-rings at the pre-filter).

In my opinion, the best thing to do is to learn where the solenoid is and make sure you know how to manually override it - just in case it ever does fail. Also lean how to turn the ignition to the on position and manually pull the fuel lever against the magnet (in the solenoid) in case the main "pull" solenoid fails at any point.

* This post was edited 05/09/10 11:25pm by Steve S. *

Steve S.

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Posted: 05/09/10 06:55pm Link  |  Print  |  Notify Moderator

I guess I should mention where to find that fuel solenoid...

It is located underneath the large round air filter. If you reach down you can feel it and if you get someone to crank the engine and start it up while watching you can see it move. It won't move just by turning the key on, but if you turn the key on and then manually move it, it will lock in the up position. It will move as soon as the starter is engaged though.

jwmII

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Posted: 05/09/10 07:55pm Link  |  Print  |  Notify Moderator

This entire thread up to this point is very informative. Those who have this setup on their coaches should study the information here carefully.


jwmII

TominTampa

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Posted: 05/06/10 03:46pm Link  |  Print  |  Notify Moderator

Gentlemen,
Thanks so much for the responses! I'm going to dig into my fuel system this weekend and see what I can find. First stop - Orings on the pre-filter! - Tom


1996 Monaco Dynasty 36', Cummins C8.3 with Banks Stinger kit, Allison 6 speed.


larry barnhart

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Posted: 05/08/10 08:57pm Link  |  Print  |  Notify Moderator

sepisllib wrote:

TominTampa wrote:

Gents,
Something kind of weird happened today, I started the Monaco with the intent of taking it up to the gas station, (it was about 3/4 of a tank so I figured I'd go top it off). I began warming it up using the high idle/ cruise control feature like normal, after about 30 seconds it stalls. So immediately I think "that's not normal" and try to restart it, no luck, she just turns over. So I figured, "well maybe it's because my driveway has a 3% downgrade". Who knows! Was it starving for fuel? It had over 3/4 a tank! So I went to the rear and activated the "Wynn" fuel system air purge feature, still nothing. So I sat in the drivers seat and pressed in the throttle about 1/2 of an inch. Finally after 3 more tries she starts, grumpy at first, but starts nonetheless. I let off the throttle and she idles with no problem. I went to the gas station, topped off the diesel and drove back home with no problems. Does anyone have any idea what I did to make her mad? She hasn't done this before! - Tom


Most likely is the "start/run" solenoid was the cause. Over time these things begin to become sticky and sometimes, without warning, just drop out.

No - it was not jelling

God Bless

Bill





the start run solenoid was what the problem was on a friends Monaco doing the same thing but it didn't start.
chevman


chevman
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TominTampa

Bellevue Nebraska

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Posted: 05/08/10 09:05pm Link  |  Print  |  Notify Moderator

Great info. - After my fuel chase I'll probably go ahead and replace the start/run solenoid just for insurance. - Tom

The Shadow Nos

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Posted: 05/08/10 08:29pm Link  |  Print  |  Notify Moderator

I got a 1996 Allegro Bus it would not restart when I wanted to move it at a campground 15 min later it did no more problems rest of the year. Next spring sometimes it would not start right a way or when I shut it off it would stay running for 1 to 2 min. Had new start/run solenoid installed no problems. By the way the new solenoid was twice the size as the old one.


2005 Allegro Bus
400 HP Cummins
2005 Jeep Liberty CRD

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