Engine started, then died

[Iceni John]

This evening I started my 6V92TA (DDEC II) for the first time since early June  -  it started within two or three seconds as normal, idled smoothly for about twenty or thirty seconds while building air, then it slowly sputtered to a stop.   No amount of cranking will restart it, and after about five tries I stopped.   Luckily I have two good 8Ds, but I do not want to burn out the starter or drain the batteries.   As it died it made some black exhaust smoke, and when I tried restarting it makes white smoke.   There is about 70 gallons of fresh diesel in the tank.

Have I lost prime?   If so, why, and how best for a newbie like me to reprime it?   I don't have compressed air to pressurize the tank, so it may be either the garden sprayer trick or buying an electric fuel pump to put between the tank and the primary filter.   A few weeks ago I drained a small amount of crud and water out the bowl of my Racor 900F filter, but would that have introduced air into the fuel system?   Where is the check valve located  -  betwen the tank and primary filter, or further downstream?

Any other reason an apparently-healthy 6V92 that has always started and run well would behave this way?   If the DDEC were bad, surely it wouldn't have started at all.   All I did this evening was change out the high-pressure hydraulic hose from the pump to the fan, and when the engine started the fan was turning OK  -  could that have done anything to kill the engine?

John, depressed in Orange County CA   

[gmbusguy1]

John,  I have made it my practice to always run the engine before and after touching anything fuel system related IE draining or changing filters or tightening any fuel line etc and I like to use a sharpie and put the date of a filter change along with the hub miles just for reference.

with that said I am no expert on DDEC's but am with you on it losing it's prime so if it were me I would get a bug sprayer and install a fitting for future use and re prime her I'll bet she fires right off

oh yea keep the sprayer in the bus for next time

Chris

[luvrbus]

John, blowing white smoke you lost your prime
I carry a electric pump with me to help guys sometime I have 2 hoses 1 for the suction and 1 for the filter.
I just take out a plug on the filter housing install a barb fitting for the hose drop the hose in the fuel tank(or a 2 gal can) connect power to the pump run it for a few minutes and off they go.    good luck

[NewbeeMC9]

you wouldn't happen to have one of those run switches in the back where you can start the engine from ythe back would you?

[Iceni John]

NewbeeMC9,

Nope, the previous owner removed all the switches from my engineroom start panel, and cut back the wiring as well.   That was going to be another project to restore the wiring (I recently obtained an original complete wiring diagram from West Coach) and replace the switches, but for now there's no chance of accidentally killing the engine that way!   Thanks for thinking about that possibility.

John, feeling much less depressed in The OC.

[Buffalo SpaceShip]

John, I'm pretty sure that white smoke generally means she's getting fuel. It's unburnt fuel... should smell like diesel. I would think that NO smoke at all would indicate a lost fuel prime. Back in the old days of trying to crank an ailing and cold 8v71, white smoke was the indicator that the mill was getting close to firing off. And the fumes would burn your eyes. Clouds and clouds of white smoke when she finally did fire off... until the mill warmed up and the crappy compression rings expanded.

I know almost zero about DDEC, unfortunately. Always had mechanical injectors on my buses. But air, fuel, and compression (and reasonably warm temps) should be all that's required to start a two-stroke. Is there any chance that there's an air restriction?  Any kind of flapper/ shutdown?  I'm pretty sure those were only on the old mech. injector DDs.

Otherwise, maybe it's either a fuel quality issue or a compression problem.

Keep us posted,
Brian

[Don4107]

Something had to replace the stuff you drained out of the filter, I'm betting on air. 

While the garden sprayer works and is great for helping out another bnut, why not plumb in an electric pump?  Makes a filter change a snap, or a flip as it were.  Change the filters, flip the switch, bleed the air, fire her up! Wait until she is humming like normal and flip the pump off.  No fuss no muss and no smelly diesel container in the bay.

Mine hangs on the right hand engine cradle upright.  A switch and fuse to the alternator, a couple hoses and you are set.  It either needs to be a pump that will allow flow when not powered, on all the time when engine is 'on', or plumbed with a bypass setup. I vote for a pump that allows flow when not powered.  Fewer parts and places to leak.  That's the way mine is.

Good luck
Don 4107

[John316]

Check your coolant level. Ours has a low coolant shutdown. It really stumped us for a while.

God bless,

John

[NJT 5573]

John,

I agree with the air deal. DDEC 2 is a real problem to reprime if you don't use a pump. I never break the seal on my fuel system unless the engine is at running temperature. When I restart the engine, I go to wide open throttle until it hits the governor. Thats the only way I know of to reprime it without a pump. You may have had enough fuel to reach governored RPM, but if you use it to idle, then it loses its prime.

DDEC also has a sensor at the filters that stops the fuel to the injectors if air is present that will stop you from reaching governed speed. When I change filters, I have to unhook the wire on this sensor to get it spinning fast enough to reprime. Then it will act like a mechanical engine and usually reprime its self.

If you have other issues like water or oil they should show up on your check engine light.

[Iceni John]

I bought a Facet-Purolator Posi-Flo EFP-3 fuel pump (made in USA!!!) from the brothers Pep:  it's rated at 1.5 - 4 PSI, and 25 gal./hour  -  is this OK?   Tomorrow I will install it between the tank and the first filter, so it should push fuel all the way through both filters and back to the tank.   It seems to be a full-flow type (I can blow through it when it is off), but I will bypass the main fuel line with a shut-off there  -  this way it won't impede the flow when it's not running.   Does this sound practical?

Let's hope this works.   I had been thinking about installing a priming pump, but not quite so soon!   Thanks for your good advice and support.   I'll let everyone know if it succeeds.
John, feeling much more hopeful in muggy SoCal 

[gus]

John,

Anything will work, I used a very small electric auto fuel pump.

Be sure to mount it as close to the tank as possible. Since it is a suction pump it won't work well a long distance from the tank.

All you have to do is fill the fuel lines and primary filter with fuel, the engine pump will do the rest.

I plan to permanently install mine also and make it bypass the fuel line using shut off valves just in case the pump line is too small.

One big advantage of using the electric pump is that it will show you if you have a leak anywhere in the line. The engine pump is suction so leaks won't show up when using it, however, you will be sucking air. Not good.

[Iceni John]

It starts!   It runs!!   IT'S ALIVE!!!

On the recommendation of so many of you good folk I installed an electric fuel pump that bypasses the main fuel line.   I had wanted to put it before the Racor fuel strainer/filter so it would push fuel through both filters and the engine's pump, but there wasn't enough space for that.   Instead I put it after the Racor and before the engine, put a shut-off valve on the main fuel line so the electric pump will push everything forward without bleeding back to the Racor, ran the pump for a few minutes, cranked the engine, cough cough no start, squirted one second of ether, cranked again, cough splutter cough hicup vrooom!!   There is no sweeter sound than a Detroit coming to life and then idling smoothly, especially after this episode.

Now I have a permanent repriming setup for anytime I have to change filters.   Close valve, turn on pump, start engine, turn off pump, open valve.   Why don't all buses come with such a setup?   It cost me about $150 and a few hours of work  -  nothing in the grand scheme of things.

So, another project done.   I've now replaced two of the high-pressure hydraulic hoses;  next I'll replace the air compressor's coolant lines that are really crusty, then I'll run new hose up to the power steering.   One thing at a time.

Thanks for your encouragement and wisdom,
John, happy once more

[buswarrior]

I have seen priming pumps already installed from the factory on the new MCI J model coaches for the last few years.

Another switch back in the engine room.

With today's high pressure fuel systems and really fine injector spray patterns, the manufacturers don't want any fuel put into the fuel filters before install, as un-filtered fuel goes into half of it.

Spin them on dry, run the priming pump to fill them.

happy coaching!
buswarrior

[John316]

BW, Our 95 DL3 has a priming pump....I love it

Good bless,

John

[gus]

John,

Glad things worked out.

It appears you lost prime  was because of your filter draining. Unfortunately, with a stock suction system you can't drain the filter very much at a time because you introduce air.

With your new primer pump you don't have to worry about that anymore!