| Author |
Message |
JR
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 19, 2005 - 9:25 pm: | |
Need help from DD knowledgeable! Got an 87 MC9 with a 6V92T DDEC 1 that I pulled and replaced the rear main seal. Back in the bus and it starts right up. And quits after 10 or so minutes of running. Water's low and I add water. Clear codes for low water. Starts right up again...about 10 minutes later quits after dropping one and then eventually all six cylinders. Not a "shutdown" like the DDEC will do. The thing seems out of fuel...but the tank isn't. The primer pump will pump fuel thru until it drops into the tank. No DDEC codes other than the "25" which means no codes. Batteries are up.
Any ideas? Could it be so full of air that for some reason the primer is not purging sufficient to start? Would the DDEC injectors complicate the situation? Engine did not smoke on startup, or shutdown. Just sounded like it ran out of fuel. The engine fuel system was not drained while out of the coach...ball valve was closed and is now open. No great loss of fuel when disconnected..although it may well have drained the lines back into the tank.
Any ideas would be helpful...looked at the archives and didn't see much that would explain what I have here...or maybe it is and I'm not smart enough to grasp the concept! I'm assuming that if the factory primer will pump up, the thing cannot be a fuel pickup related problem. Ran out of time today to dx, but I'm going to pull the return line at the engine and see what I get. Seems to be a lot of air in the secondary filter purge fitting....still, hear fuel returning to the tank when using the primer????
Ran out of fuel once 3 years ago and it pumped right back up and took off...no issues. I have issues now. Have relatively new fuel filters and very clean fuel tank...new tank in '01.
Thanks, JR |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 20, 2005 - 12:01 am: | |
Could your fuel pump be going out/ gone out OR somehow not connected back up OR not getting the proper "trigger" from DDEC?
Assuming it's a separate primer system (and not the fuel pump) that fills up the filters after every shutdown, maybe the 10 minutes runtime is the capacity of the filters and your fuel pump's not working at all.
Just a thought,
bb |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 20, 2005 - 8:05 am: | |
My guess is that it is your cooling system that is air locked. If you have to add water every time it shuts down, that indicates that it is slowly displacing the air with water. If you don't have bleed valves at the various high points in the system, you may have to keep running it and adding water as the air comes back to the radiator. |
JR
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 20, 2005 - 10:04 pm: | |
DDEC fuel pumps are similar to MUI pumps...just delivers fuel to electronic fuel injectors. They are working..no codes. Had a low water but added just about a gallon of water and solved that. I "burped" the cooling system at the crossover and both rad elbows where they enter the thermo housings. A low water shutdown is immediate...like the switch is turned off. It didn't do this the second time..just started running out of fuel one cylinder at a time. I knew it was doing something funny for several minutes before it quit. No heat problem. I believe it's full of air..ran off the filters. Anyone have any idea about how long it would take a priming pump to pump fuel thru a static fuel pump assuming all the fuel in the supply line drained back into the tank? Have a fuel primer pump in the supply line with a ball valve to prevent pumping back into the tank. Should eventually force fuel through the system...unsure how long this may take. Looks like about 30' x 3/4" line full of air? Sure ran good for a few minutes. I had the rear of the bus jacked up almost a foot, and lost very little fuel when the engine supply line was disconnected. Probably all ran back into the tank. Thanks for the input!
JR |
airless in jacksonville
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 21, 2005 - 12:15 am: | |
JR I have found with our style bus that I lose prime on occasion. Mainly when My fuel level is low. This last time I pulled the lever at the pump ran the pump for just a moment till changed tones. Then I cut off the pump turned the valve back and turned the pump back on. Started right up I forgot that I had it on went back and turned off the pump all was fine. You may try to see if you leave the pump on if the bus continues to run, if so then it may be the mechanical pump. |
JR
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 24, 2005 - 9:16 pm: | |
Bus started. Ran primer for an extended time. Also FYI, I connected a clear line into the bleeder on the secondary filter to see how fast fuel can pump through the static fuel pump. It ain't very fast at all. In about 15 minutes, it pumped about a quarter gallon of fuel. Also bled the air, but it took about that to get clear fuel. Left the pump running, ball valve closed, and started the bus, it was slow to start, but fired off....cleaned out pretty quick once started. I immediately turned the primer off and the ball valve (prevents pumping fuel back into tank) on. Relief to hear it run again!
Thanks for the ideas! Add this event to my knowledge base. |