Engine shut off while idling... now wont start

topfrog007 · April 22, 2012, 08:32:11 PM

Guys,

86 MCI 102A3. 6V92TA

I had the bus Idling on our driveway for a few minutes today when the engine shut off, sounded like it ran out of fuel. I've done this a few times over the past few months to let the air build up and check some various fixes/functionality. Before it finished airing up the engine slowly died, it would not restart, it was turning over but never firing.

My first thought was that it sounded like it ran out of fuel, our driveway is a fairly steep incline and the bus is parked facing down the incline (engine at the highest point). The fuel gauge is about 1/3 full and I estimate it should have at least 30 gallons in there.

Is it possible the fuel got below a certain point for the fuel pump to suck it up because of the incline? Doesn't seem likely but who knows... Other ideas?

Thanks a bunch!

Busted Knuckle · April 22, 2012, 09:20:05 PM

Yes it could have run out of fuel.
But it could also be other things too!
The most likely one is the rear engine stop switch.
Sounds to me like it built up enough air and shut down.
Have you tried starting it after the air bled off?

BK

Dave5Cs · April 22, 2012, 09:56:12 PM

how old is your fuel, did you put conditioner in it over the winter.

RJ · April 22, 2012, 10:09:50 PM

Frog -

Only 1/3rd showing on gauge (notoriously innaccurate) plus parked on a slope = Go buy about 20 > 40 gallons of fuel, and get out your priming pump.

FWIW & HTH. . .

Carbone · April 23, 2012, 03:30:48 AM

I chased the EXACT same thing for hours before I realized it was the solenoid for the shut off lever on my 8V71. I felt silly but hey, I got it fixed.

Scott & Heather · April 23, 2012, 04:32:09 AM

Ditto on the engine stop shutoff. Don't move the coach (oh wait, you can't haha) and bleed off the air and then try to start again. Or you could manually pull the lever back into "start" position. I honestly think it's that...but could be fuel level too..

bevans6 · April 23, 2012, 05:20:31 AM

And while we are speaking of engine shut offs - there are often two of them. The normal engine stop lever on the top of the governor, activated by an air cylinder controlled by a Skinner valve, and the emergency stop flap valve on top of the air intake manifold, activated by a electric solenoid and the emergency stop switches. That one is known to randomly apply itself and have to be manually reset, that happened to me twice. Sadly, it took just as long to figure out the second time as the first... Symptom is the engine cranks and lots of white smoke comes out.

Reading your original post again, engine starting and running fine and slowly dying as the air builds up is classic engine stop lever problem. What happens is the air supply to the Skinner valve that controls the engine stop air cylinder is fed from the accessory system, which is after the Pressure Protection valve. The engine must run long enough to build up 65 psi of pressure before the PPV opens, then must run long enough to build up pressure in the accessory system to move the engine stop air cylinder and the effect is the engine stop lever is very slowly activated and the engine just slowly dies.

What smoke appears as you crank is a good clue. If lots of white smoke pours out the exhaust, that means there is fuel and no air. If no smoke at all comes out, that means there is no fuel. That can be either no fuel (duh!

), or the engine stop lever activated.

Brian

Busted Knuckle · April 23, 2012, 05:53:38 AM

Brian while you are correct about both shut offs on the 71 series. The 92 series doesn't have the air flapper. (OK let me be more specific, none of the ones I have ever worked on did!)

But still good info to share with those who don't know about them.

BK

Scott & Heather · April 23, 2012, 06:05:26 AM

my 92 series does not have the emergency flap either. And as if to remind me every day, it says so on a bid red tag on my dash. Should I lose sleep over that?

Busted Knuckle · April 23, 2012, 06:11:52 AM

Quote from: Scott Bennett on April 23, 2012, 06:05:26 AM
my 92 series does not have the emergency flap either. And as if to remind me every day, it says so on a bid red tag on my dash. Should I lose sleep over that?

Only if you have absolutely nothing else in the world to worry about!

BK

Scott & Heather · April 23, 2012, 06:13:44 AM

thanks Bryce

good. in that case, I'll worry about topfrog's coach not running

let us know what your result is!

bevans6 · April 23, 2012, 06:29:48 AM

Sorry about the air flap flap - I had in my mind that this was an 8V71. DD went to spring loaded injector control levers and did away with the emergency flap. The spring loaded levers allow the injectors to go to no-fuel if one injector sticks open.

Brian