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Another Starting Issue

Once again (more about the first time later) I went to start the coach after it had sat for a couple of weeks and was not successful.

The engine (8.3 mech) turned over and it initially began to fire but then would only turn over.
I left the ignition on and went back to frown at the beast.

Two years ago It acted similarly. I fiddled with the fuel shutoff solenoid. The rubber boot had just about disintegrated and after removing the pieces the solenoid would pop up and down like it is supposed to. After a few gingerly trys to coax fuel back up it fired and all was well.
I bought a new solenoid and kept in on the shelf where all replacement parts are stored :P .

This time I knew right where to look!!
I'll inspect the solenoid and be prepared to replace it. :thumbsup:


(Significant diagnostic information follows I think)

The spring was compressed (since sans boot I could see and feel it) and the body of the solenoid was warm.
I could pull the solenoid rod down with a twist if a screwdriver but it popped back tight when engaging the starter.
After  reading a couple of old posts and revisiting what I remember of the theory I have come to the conclusion that it is probably doing exactly what it is supposed to do.

So now what??

I did have a similar occurrence when I got ready to leave MI but after initially trying to start and dying it started right up and did every day on the road.

I inspected the plastic bowl at the bottom of the Racor when we got into the storage facility in Hutto (near Austin) and fuel looked fine but I didn't look this time.

Suggestions :help:

thanks
Elliott & Mary Bray
ex. 1996 36' U295 - Build 4879
ex. 2018 Coachmen Leprechaun 319MB
 

Re: Another Starting Issue

Reply #1 –
Hi Elliot,
  Do you have any white smoke when first starting? If so, you may want to check your fuel lines for small cracking.
Raymond
Raymond & Babette Jordan
1997 U 320
1998 Ford Explorer XLT

Re: Another Starting Issue

Reply #2 –
FYI....The p-7100 injection pump on your 8.3 engine has a ball valve on the side of the pump going to the return line...This "Check valve" is a common issue on the Cummins 5.9 and 8.3 12 valve engines due to use and age. you can find the check valve on line for around 30 bucks...

Google ''Cummins Overflow valve'' And you can read up on it. Also look up Tork Teknology, They have a very good replacement and its easy to change out yourself...When one starts to go you will first notice delayed or long starts and some times once the engine is running you will sometimes notice loss of power, this is due to the Weak spring in the ball valve allowing the fuel to return back to the tank and starving the P-7100 injection pump of fuel....If you would like more info just call me 361-244-0665, My name is Matthew, I own a 96 with the same engine 
1996 U270 36'

Re: Another Starting Issue

Reply #3 –
I dont have that engine, but on my Cat. I have a similar issue and it is from fuel starvation.  I guess the Cat is infamous for that and they put in a priming pump to mediate the situation.  Lots of ways to get there and am sorry I cant be more specific.  Just have to eliminate possibilities until you find it.  Have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Another Starting Issue

Reply #4 –
A temporary fix is to remove the overflow valve and open it up. It has a spring and a tiny steel ball. Measure the length of the spring, should be about 1/2" long, if not stretch it out and reinstall it. This should get you going if this is the problem, but by all means get a new one or it is going to fail again soon.
Ron & Donna Brunson
1997 U320 40 ft.
Honda CR-V toad
Tangent, Oregon
Build #5032

Re: Another Starting Issue

Reply #5 –
Quote from: fkjohns6083 –
I dont have that engine, but on my Cat. I have a similar issue and it is from fuel starvation.  I guess the Cat is infamous for that and they put in a priming pump to mediate the situation.  Lots of ways to get there and am sorry I cant be more specific.  Just have to eliminate possibilities until you find it.  Have a great day  ----  Fritz

No, the manual priming pump is there to allow you to fit the filters dry and use the manual pump to prime.  Nothing to do with fuel starvation. 

Said another way, unless you are pumping the manual pump while driving (a real ergonomic feat!) the manual pump is NOT pumping.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Another Starting Issue

Reply #6 –
When we had a similar fuel flow problem, we used plastic cable tie to fully open solenoid, then start engine and drive to where we were going, than cut wire tie and pull down solenoid to shut off full to stop engine. We repeated this for over a week until we could replace solenoid with the new larger style Cummins solenoid.

Re: Another Starting Issue

Reply #7 –
Yes a Ty-Rap or a good spring works great on the Bosch type pump for a temporary get you up and running, Howsomever, be aware you have ZERO safeties, over temp, low oil pressure etc, it will just keep running until it comes to an expensive stop if un monitored.

Re: Another Starting Issue

Reply #8 –
Clarification  ----  On my Cat engine, I have to prime it if the coach sits for more than about a month regardless of filter replacement or not.  I'm not sure why, but the manual talks about it and I assume that it is because the fuel leaks back to some point and it doesn't self prime.  I once loosened the piping at the injectors and cranked until fuel was present at the loosened connections and after re-tightening, it fired up easily.  Fuel starvation??  Any way you slice it, it's not getting fuel.  Have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Another Starting Issue

Reply #9 –
Yes, diesels (any brand) can leak down fuel if the check valve (in fuel return  line) or an injector is leaking. 

If the primer pump started out easy to pump and then got firm, it does indicate that fuel is leaking back or into the engine.  Not an uncommon issue, particularly if the rig has been sitting for awhile.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Another Starting Issue

Reply #10 –
On our Cummins C8.3 engine we have zero safety devices built-in. The only electrical wires to the engine are the fuel shutoff held open when ignition is on, and engine pre-heat. Keeping fuel shutoff solenoid open with cable ties will keep engine running until removed. On our engine, over temp, low oil pressure, etc only displays a dash light and sounds an audible alarm.

Re: Another Starting Issue

Reply #11 –
And that again is why these old school mechanical Cummins diesels are so Reliable....If the thing fails to start or just will not run it's 99% chance you have a fuel issue
 
1996 U270 36'
 

Re: Another Starting Issue

Reply #12 –
If it starts every day it would be interesting to know how may days go by before it won't start.  Might give a clue as to problem area.  Check valve, line leak, injector, etc.  Have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'