Need Suggestions..Bus will not start/stay running

[Kmon]

Hi all, 

    A little background.   I have a '89 102A3 with a mechanical 8V92, never any problems in the 4 years I have had it.  I went out to start it a few weeks ago to take it on a business trip, at first, all was well, started right up, air started building, and I was putting loose things in cabinets, etc.  After a couple of minutes, the engine started losing rpms and eventually died.   I could not restart it that morning, just seemed like it wasn't getting enough fuel, the engine would fire but not start.  So, not having the time to mess with it, I figured I would try changing the filters when I returned from my trip(I had to stay in a hotel for 3 weeks, YUCK). 
     Fast forward to this morning, I replaced the fuel filters(filled both with fuel), primary looked a little cloudy, the other was fine.   Hit the starter, the engine fired right up, ran for maybe 15 seconds, then died a slow death and would not restart. 
     I know there is at least 100 gallons in the tank, and the genset is running fine off the same fuel.  Fuel is relatively fresh, as we drove the bus 1700 miles in early July.

So...any suggestions for fixes would be great! 

Thanks in advance,

Keith

[Nick Badame Refrig/ACC]

Hi Keith,

I still wouldn't rule out algea.. This is the time of year that it grows the most.

It's possible that the fuel lines are clogged or collapsed.

More expierenced members have to chime in here.

Good Luck
Nick-

[Busted Knuckle]

Have you checked the shut down solenoid? It is a small cylinder that is about an inch or so round that has a air hose going to it. When it has air it has a small rod that comes out and pushes the fuel shut down lever in! My guess is either the rear shut off switch has accidentally be flipped or the skinner valve that controls it's air is hung up! It is located on the engine right about center of the thermostat housings. BK
If ya need more info feel free to call! 270.705.1139

[Kmon]

Nick and BK,

Thanks for the suggestions,  I really hate not knowing enough about these 2 stroke beasts. 

Nick, I will check the fuel lines in the morning.

BK, I think the rod is out...I remember looking at it and thinking....should that be out or in....I will look for sure tommorow. 


Thanks again,

Keith

[Busted Knuckle]

BK, I think the rod is out...I remember looking at it and thinking....should that be out or in....I will look for sure tommorow. 
Thanks again,

Keith

Keith,
It sticks out 1/2 to a whole inch normally, but when it's fully out it'll be 2"s or more depending on adjustments. But you can easily test it, by seeing if you can push the lever any farther with a screwdriver or finger. If you can't not the cylinder is all the way out, and doing what it is supposed to do. Now the problem is to find out why it is staying out. First start by checking the emergency shut off switch, next to the rear start switch. If it is on it will shut the bus off as soon as it has enough air. If it is off we'll check farther.   BK 

[Sammy]

Rod on engine stop shrader valve should be "IN" - when starting and running.
Will be "OUT" when bus is shut off..... 

[Kmon]

BK and Sammy,

Thanks!  I am pretty sure it the shut-off valve was out, if so, that would seem to be the problem.  I am heading sown to Pueblo to the bus now to check.

Keith

[gus]

The shutoff valve is at all times normally in the run position except momentarily when the engine stop switch is turned to the off position. You can easily see this by turning it back on just before the engine stops completely-it will start right back up.

If the rear engine compartment shut off switch is accidentallybumped and/or left in the off position the engine will start and run for a short time until enough air pressure is built up then it will shut off. If there is enough air pressure it won't start.

In other words, anytime the starter will operate the engine will start no matter what position the switches are in as long as there is no/low air pressure.

[gumpy]

Well I was originally going to suggest he'd lost prime, but then I recalled that he said it was "building up pressure" and then slowly
died.

This is a common symptom of the safety shutdown system being active and kicks in as the air builds enough to activate the
shutdown cylinder, as Gus said.

First, check the run switch on the remote panel in the engine compartment. Make sure it's in the run position.

Then, with the switch in the proper position, try starting again. If it starts and does the same thing as air builds, it's the safety
system being engaged.
So, in that case, remove the wires from your temperature alarmstats and try again. If it starts and stays running, attach one at a
time to see which one is the culprit.

It could also be low oil pressure sender, or if equiped, low water sender. Test these in the same manner.

craig

[Kmon]

Hey All,

Just returned from the bus.   Shutoff valve is in, and the switch is in the run position...still won't start.  It acts as if it wants to, and fires but will not run. 

Craig, looks like you could be correct, I will run out there tomorrow evening and disconnect the safety stats and see if that may be the problem. 

Thanks again for everyones suggestions.  My bus would still have the seats in it if I hadn't discovered this awesome group of people.

[Busted Knuckle]

Keith if the shut down rod is in, then it will not be the shut down stats. More likely lost fuel prime or bad fuel lines (collapsed). FWIW   BK 

[Sammy]

Keith, does your bus have an emergency shut down switch in the operator's compartment?
If it does, it might have been activated accidentally.
Go to the engine compartment again, look at the top center housing on the engine (non-turbo engines). It's an air intake housing - pipe from air filter housing attaches to this .There will be a big solenoid mounted on one side of this housing with a rod that attaches to a lever on the side of the same housing.There is a large, sping loaded metal flap or door that will cover the airbox under this air intake housing in an emergency,cutting off the air supply to the engine,causing it to stall.
Maybe you hit the switch by accident, now your engine cannot get air into the airbox to fire up.
Diesel engine needs air and fuel to run. The heat from compression ignites the fuel. Good luck.
Sammy 

[Kmon]

BK, Thanks, that makes sense, looks like I'll be blocking the girl up and having a look at the fuel lines.  I'll also check and make sure I have a prime still.

Sammy, There isn't an emergency shutoff in the operators compartment, and I've got the 8V92TA, thanks for the suggestion though,

[gus]

Craig and a few others have mentioned losing prime and this got me to thinking along those lines.

It could start and run a short time on the fuel in the filter housings. When that is used up air in the lines would put out the fire.

Keith's first post fits this situation.  He didn't say so but it sounds as if it was sitting a while before he started it the first time.

Same thing happened to me when my fuel supply line check valve just before the primary filter failed, the fuel slowly drained back into the tank over a week or so. It turned out that my primary filter gasket had a very slight leak, just enough to allow air seepage into the filter top and check valve. There was some slight fuel wetness on the primary filter but not easily noticeable.

[Kmon]

Gus,

It's looking more and more like losing prime might be the first thing I check.  Thanks for the post.