Alright, the last time we all spoke I was having starter issues...that's mostly fixed (more on that later). Right now our issue not staying running.
So here's a list of symptoms for the Dr to deduce from.
When starting cold, the 8v71 NA (MCI MC-7) will only run for a few seconds.
After a few starts it'll run for about a min or so... Before it dies it sounds like its taking on a load (or starving for fuel) and then quit.
Once it's warmed up it will run for about 5 min... But if it ever gets put on fast idle, it dies within a few seconds... Lots if dark smoke and a labored sound, then a shakey death...
When I apply the accelerator from the back, it can hold it in place and the engine will rev up accordingly, but slows down despite me holding the accelerator rod stationary.
Starter issue, I purchased a starter for the bus from a a fellow bus nut who was very helpful, but the starter he wanted to sell me for a 8v71 wasn't up to his standard, so he sold me one of his 8v92 starters. Believe me when I say the fit was tight, it was tight. As a matter of fact, it's so tight that the starter may be a little off center. Because of that I think the starter shaft isn't disengaging, which means the starter is still spinning after the engine gets going. That's neither here nor there though, I can fix that... I believe.
I just purchased a pump to feed diesel into the fuel line to remove air, I think that is a good place for me to start trouble shooting. Any helpful tips on how to go about that with minimal fuss would he appreciated, as would any other thoughts on what my issue might be.
Thanks in advance for your remarks!
Blowing the black smoke it is losing the prime or you have a bad air filter restriction
Okay, kinda what I was preparing for with the pump... Is there a right/wrong way to get my prime back?
I would get a fuel pressure gauge (can be any pressure gauge 0 - 100 psi) and put it in one of the unused ports on the secondary filter head and see what the running fuel pressure is. That will tell you instantly if you are losing prime, fuel pressure will drop quickly. If you have a bad pump fuel pressure should stay kind of stable but low.
Brian
Excellent idea! Why didn't I think of that?!?!
What is a normal pressure range? 20psi?
I would think 20 psi at idle to 55 psi at 1500 rpm is probably a good range. I never checked mine, though.
Brian
On my (1991) 8V92TA, it started doing the same thing in early summer. Start and run for a few and die. Finally checked fluid reservoir and water (anti freeze) was low. Sensors picking it up and stopping engine. After starting a few times I guess fluid would heat up and hit sensors. Don't know if yours has any of the safety shutdowns but mine does.
Interesting point, I'll check my coolant levels...time to fish out a ladder.
Yeah, Done it twice and after a try or two it would take off and run for a 250 mile trip to beach and back down here in Texas. After second time and looking up to tank glass and see no fluid, filled up and no more problems. I'm glad my Prevost is smarter than I am (which don't take a lot).
I doubt he has a DDEC 8V71
True enough, I don't have a DDEC 8v71, but topping off the tanks has been on my list, until yesterday... I'm off to the store to see if I can find a gauge on a Sunday in Killeen... Wish me luck.
It is starving for fuel or air.
Have you reset the emergency shutdown?
Is it sucking air through a fuel line?
Is there enough fuel in the tanks to submerge the bottom of the standpipe?
Does the standpipe have a hole rubbed in it from a baffle?
Is the air filter or a fuel filter plugged?
Diesels are pretty simple. If they have enough air and fuel they will run.
If you have checked all these things and still don't have joy, let us know.
Yeah, what Cliff and Joe said.
Also, you did not indicate if the engine is shutting off with the air shutdown cylinder or if it's just dying. If it's shutting down because
the air cylinder is pushing the shutdown lever, then you have an issue with your safety shutdown system (over temp, low oil pressure,
low coolant level) or with the stop/run switch or just with the shutdown solenoid system in general.
Craig reminded of something.
Check every thing you have been offered. If they don't fix it try the below.
Carefully label, then remove the wires from the shutterstat. That should eliminate the auto shutdowns.
If it starts and runs then, you must figure out which system to troubleshoot.
There are some other places to look. If all the suggestions you have recieved don't fix the problem, let us know.
Okay, problem all fixed.
I tightened all the fuel fittings, installed a fuel pressure gauge on the secondary filter, topped off the coolant and added fuel to the tank.
It works now, I don't know which solved the problem, but who cares!
Thanks all for your help.
Good to hear you have it fixed!
Thanks for the post. Many do not post their fix. It leaves us hanging.
YOU'LL care when it does it again.