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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: RandallBrink on May 15, 2018, 07:56:46 pm

Title: Detroit Diesel Fuel/Starting
Post by: RandallBrink on May 15, 2018, 07:56:46 pm
An urgent request for input from Detroit operators:

A week ago I was in a hurry to move my coach from storage to a shop. I had been running my genset and don't trust my fuel guage. I added 5 gal of fuel from a can that I filled at a station with a mismarked fuel pump. In haste, I put about four gallins of regular gasoline in the tank which I estimated to be at or below 1/3.

I drove to the shop, no problems; picked up the coach today and drove home—15-mile roundtrip. Engine started and ran fine. I ran my genset for perhaps 2.0 hours this afternoon charging new house batteries. Two main engine start attempts failed, i.e., engine fired then quit. I stopped to troubleshoot and that is when I noticed the gasoline in my gerry can.

Could this acct. for non-start problem?

It is also possible that main tank fuel is low, but I discount this because gen was still running, and it is the engine that is on the low-fuel switch.

Any advice greatly appreciated.


Title: Re: Detroit Diesel Fuel/Starting
Post by: Pamela & Mike on May 15, 2018, 08:28:28 pm
It is also possible that main tank fuel is low, but I discount this because gen was still running, and it is the engine that is on the low-fuel switch.

That is the way it is supposed to work but needs to be verified as I have seen more than one coach that was hooked up with the generator on the low point pick up.

Mike
Title: Re: Detroit Diesel Fuel/Starting
Post by: RandallBrink on May 15, 2018, 08:35:09 pm
Ah, well in this case I hope you're right about the low-fuel part of it.

As to restarting, I'm tempted to add diesel and try again. As I said, it ran fine when I parked just two hours earlier.

Thanks very much!
Title: Re: Detroit Diesel Fuel/Starting
Post by: oldguy on May 15, 2018, 09:28:29 pm
Change your fuel filters. The filters are suppose to stop gas. You may want to drain your tank and start over with fresh diesel.
I had this problem when the separation panel of a fuel truck broke and we got gas in the diesel. We drained all the fuel out of the equipment replaced all the filters and that solve the problem. If you don't want to drain your fuel get extra filters. There is also
fuel polishing which will clean the fuel. Good luck
Title: Re: Detroit Diesel Fuel/Starting
Post by: RandallBrink on May 15, 2018, 10:07:52 pm
Thank you. I will start with the filter change, as I only got about 3 - 4 gal of gasoline into the tank. I'm now inclined to think its low fuel and unlevel toward the tank.
Title: Re: Detroit Diesel Fuel/Starting
Post by: JohnFitz on May 15, 2018, 10:14:15 pm
I think the gas mixture is messing up the ignition flash point for the engine for a cold start.  In the 70's I remember a fuel supplier putting gas into the underground tank for diesel. The fix was to just add motor oil to the mixture for the amount of gas added.  No issues back then with any of the diesel equipment.
Here's link of someone else doing this more recently: UNLEADED GAS INTO DIESEL TANK -- THE FIX??? - General Discussion - Antique... (http://forums.aaca.org/topic/176669-unleaded-gas-into-diesel-tank-the-fix/)
Title: Re: Detroit Diesel Fuel/Starting
Post by: FourTravelers on May 15, 2018, 10:15:40 pm
DD 2 cycles may be different, maybe Pierce will chime in on this, but if it were a cummins (mine) I would fill the tank with diesel and run with it. Only 3 or 4 gal in a 148 gal tank......... About a 40:1 ratio?
Title: Re: Detroit Diesel Fuel/Starting
Post by: RandallBrink on May 15, 2018, 10:46:26 pm
Thanks to all—I believe the panic was premature and caused by a series of coincidences. 1. The first was using a previously-designated diesel fuel pump that was still marked in green despite now being a gasoline pump; 2. Miscalculating fuel level and then running the genset with low fuel—never again; 3. The coach was parked laterally level but with an approximate 2-3 degree longitudinal list at the curb, to the right and away from the fuel pickup. I believe it was just enough to briefly cavitate at the fuel delivery pickup, thus causing the start failures.

I manually added 10 gal diesel and it fired right up. I will add more fuel manually in the morning, then off to the truck stop for full fuel.

Thanks again to all who answered the anguished call.
Title: Re: Detroit Diesel Fuel/Starting
Post by: Pamela & Mike on May 16, 2018, 06:50:38 am
 As you have found out due to tank size, angle of how the coach is setting, and fuel gauge being inaccurate can leave you in the walk mode. Glad you got this part figured out. A good rule of thumb is never play the low fuel guessing game with one of these coaches. This is the reason we always fuel at the truck fuel deck. Now days even there you have to make sure that you don't use the DEF hose.

Mike
Title: Re: Detroit Diesel Fuel/Starting
Post by: John44 on May 16, 2018, 07:22:29 am
If I was going to use that fuel with the gas I would definitely put in a double dose of fuel treatment to lubricate the fuel injection
pump.
Title: Re: Detroit Diesel Fuel/Starting
Post by: Pierce & Gaylie Stewart on May 16, 2018, 10:30:44 am
Back when I imported diesels, Mercedes allowed up to 25% gasoline to be added to the diesel in very cold weather. It won't hurt anything.  The tank hoses could be backwards or a low tank might introduce air into the system from fuel hoses that are starting to go south.

Detroits 2 cycles don't have a main fuel injection pump like other diesels but rather have a pump and injector combination (unit injector) at each cylinder. This is what the extra lobe on the camshafts is for.

Pierce
Title: Re: Detroit Diesel Fuel/Starting
Post by: RandallBrink on May 16, 2018, 12:03:33 pm
I will certainly add the additional fuel treatment. Thank you.
Title: Re: Detroit Diesel Fuel/Starting
Post by: RandallBrink on May 16, 2018, 12:05:01 pm
Thanks Pierce, I am greatly relieved to hear that this will pass with the refueling.