Hi all,
I have what looks like a fuel leak under the pass. side fuel filter area under engine area.
The area on the ground is about 2'x4'.
It got down to 17 last night here in Alabama, but my wife had the bus plugged in. It's definetly diesel fuel.
Where do you think it's coming from? I can't find any drips, and the diesel has spread so far it's difficult to tell the exact drippoint. It looks as if it is coming out of the right side slobber tube.
I haven't started the bus yet, in case I ruptured something. wouldn't it then suck air?
I need ideas of where to look, or a test to try.
Thanks,
Devin
Check to see if you didn't crack your filter(probably at the bottom) - that would explain the one-time discharge - HTH
I doubt if it's coming out of slobber tube get some cardboard ans slip under it for a bit and check for drips and where it's coming from.
LarryH
Devin,
Where in Alabama are you? I'm currently in Mobile.
Bill Williamson
MCI-9
Bill,
We're in Demopolis. We stay at a place called Foscue Creek Park(Corps Park).
Cell (479)970-8337
Devin
I had a leak at a similar location on my 8
It turned out to be the fuel sensor that was leaking it had a cracked plastic body
It had been bypassed so it served no function
I just removed it and plugged the hole
Just a thought from my experience
Melbo
Put a piece of cardboard under it. Run the engine a bit to make sure all the fuel lines are full. Then watch for drips.
Found it. It's a fuel sending unit, but what for?
Can't find my D**N book, so I don't know how I should proceed.
Still haven't fired it up. would rather fix it first. will take it off tonight and take it with me to town tomorrow.
Devin
Devin,
Probably the fuel pressure sensor.
Is it on the secondary filter?
Mine was leaking also and had to replace.
Little trick, if it should fail, sender part, just ground out to keep going.
Get yourself a little 1/4 plug(if I remember right) at the hardware, quick fix in a pinch.
Kind of a funny sensor as you will know rather quickly if you lose pressure, of course could save a reprime. ???
Cliff
The fuel pressure sensor on a MCI is part of the starter interlock system. When the fuel pressure switch is activated, you cannot engage the starter solenoid.. It is a normal;ly closed switch to ground so Floridacracker is correct about putting the sensor wire to ground. This will allow the starter to work but you will not have the safety interlock.
Devin,
I sent you a message regarding this.
Stan is correct. This is part of the safety shutdown system. If your shutdown system is activated due to low oil, high temp, or low water, you can override it by holding down the start button to get the bus off the road. This pressure sensor disconnects the starter solenoid ground once fuel pressure is detected, so the starter won't continue to spin while holding the button in.
It'll need to be replaced, but you can remove it for the time being and plug the hole.
And, as Cliff says, if the switch fails, you can ground the output and start the bus. I keep an alligator clip next to mine. Have had a lot of problems with this switch. I'm on the third one. So far, it's working better than the last two. One leaked. One failed. This one's still working ok.
craig
Quote from: gumpy on December 10, 2006, 07:14:49 PM
you can override it by holding down the start button to get the bus off the road. This pressure sensor disconnects the starter solenoid ground once fuel pressure is detected, so the starter won't continue to spin while holding the button in.
craig
Mine leaked too. Never been functional since I bought the bus. It was jumped. I removed it when it started leaking. One thing regarding this switch that I wish to run by ya'll...do you have to hold the starter button down when the "override" switch is held on?
Does this apply to DDECs? I was under the impression (however mistaken it may be) that the override switch would keep the bus running for several minutes as long as it was held in the on position. Is wrong? May be that the shutdown system on an MUI operates differently?
JR
I'm not familiar with the NJT configuration, or DDEC, so I can't comment on either.
On a standard, non-DDEC, non-NJT configuration, the starter button on the dash is the override switch. If the safety system is engaged due to one of the sensors, you can hold the button in, and the engine will start and continue to run while button is held. The pressure switch is there to disconnect the starter so it won't keep spinning while the engine is running and the button is being held. Without it, the starter will continue to spin while the button is held and could result in severe damage to the starter and possibly the flywheel.
One other point, if your safety shutdown system is functional, you typically have to hold the button in upon startup until the low oil light goes out on the dash. If you don't hold it, the safety system will cause the engine to shutdown. This pressure switch is needed here, also, as the engine is running during that extra few seconds of hold time.
It's not unusual for the safety shutdown system to have been disabled, though. You should test it to make sure it is functional.
craig
That switch was leaking diesel when we bought our bus. I went to a local truck parts store and bought a replacement switch. It failed electrically in a few months. I then ordered a replacement switch From Luke. This switch was much larger than the first replacement. 6 years later it is still working. Jack
Bit of trivia: Prior to the late MC-7s, MCI had a switch marked 'Overrule' which was an option on bus purchase. This switch overrode the safety shutdown circuit and let the bus be started and moved to the side of the road. With an overheat shutdown you could run the bus at high idle to get the temperature down more quickly. If the switch was not ordered with the bus you had no way to restart a hot engine without removing the wire from the shutdown sensor. This system was replaced by the fuel pressure switch interlock on later models with MUI engines.
I have no idea what sytem they use on DDEC engines. NJT5047 mentions an 'Override' switch which may duplicate the old 'Overrule' switch by fooling the computer.
Quote from: NJT5047 on December 10, 2006, 08:08:40 PM
Does this apply to DDECs? I was under the impression (however mistaken it may be) that the override switch would keep the bus running for several minutes as long as it was held in the on position. Is wrong? May be that the shutdown system on an MUI operates differently?
JR
JR you are correct with the DDEC unit you should be able to just hold the overide button in and get it off the road, if my memory serves me right it gives you like 30-60 seconds. Then it dies & you'll have to turn it off and restart it while holding the overide again! (but it's been a long time since I've dealt with it and maybe only partially right about this! (especially with a NJT as they did some different things on their own! BK ;D
Hello all.
I might suggest a busnut with an older mechanical motor should get rid of the auto shut down system.
Here's why:
The shut down system was there to protect the coach from uncaring employees. If the motor shut itself off, the driver couldn't keep driving it.
Busnuts, since we pay the bills, won't keep driving it until it seizes, and we would prefer to choose the place to pull off and park, rather than the coach choosing for us.
And try to hold your starter button in against that spring to bypass the shut down and steer.....
happy coaching!
buswarrior
Quote from: buswarrior on December 11, 2006, 06:06:27 PM
I might suggest a busnut with an older mechanical motor should get rid of the auto shut down system.
Here's why:
The shut down system was there to protect the coach from uncaring employees. If the motor shut itself off, the driver couldn't keep driving it.
Busnuts, since we pay the bills, won't keep driving it until it seizes, and we would prefer to choose the place to pull off and park, rather than the coach choosing for us.
And try to hold your starter button in against that spring to bypass the shut down and steer.....
happy coaching!
buswarrior
Well, to each their own. Personally, I hooked mine back up and made sure it's working properly.
Why?
Well, I don't have $10K to spend on a new engine, and if for some reason I miss the temp rise due to loss of water or otherwise, I'd prefer not to have to say, "well, I'll be more careful next time."
If I have to hold down the button and steer to get to a safe place to figure out what's happening, well, so be it.
BK, you got it right....hold the switch under the bomber door and you have 60 seconds to start the bus and get off the railroad tracks. Then the ignition switch must be turned off and on to reset the override and go another 60 seconds.
Unless one has alarmastats or something to announce a low oil or overheat issue, the shutdown feature is probably best maintained...IMHO. A major fault with early MCIs is the crap dash with the guages buried in holes. No one can read the guages without gettiing forward and looking down into the holes the guages are residing (hidey holes) in.
Even Terri, who's generally a tightwad when it comes to the bus, wants a new dash. That reminds me, gotta call Luke and get some of those dash light bulbs....both center guages are quite dark at night. The dash is a fine reason to have a 102A or later. They have nice, easy to read dashes.
Regarding the starter limit fuel pressure sensor...since the starter isn't necessary for operation of the emergency override with a DDEC, no replacement is necessary. On DDEC units, this is all a function of the ECM. MUIs have a Robertshaw control sytem?? A sort of mechanical gizmo that will shutdown on overheat, low oil, or hot oil.
Thanks, JR
JR,
Remind me to show you the R&M dash in our MC-8 when you get to Arcadia. When we rewired our bus, I did away with the auto shutdown. HOWEVER, each alarm system has a flashing red LED in the dash and it's own audible alarm (Each alarm is a different sound (ie. Low Air=buzzer, Hot Engine=constant high pitched tone, Low Oil=beeper). The audible alarms are only on the situations that require immediate action. Alarms that do not require immediate action such as No Charge, Low Tag, and Low Fuel have flashing LEDs only (I can still drive with these conditions and don't want to hear an alarm sound). Because Hot Engine and Low Fuel alarm senders only function when a hot engine or low fuel condition exist, I added a test switch on the left panel to check operation of these each time the engine is started. Just our way, YMMV Jack
Thanks Jack, I saw your dash at T'ville...great work. All that wiring is beyond my simple skills....plus the DDEC cannot be easily defeated, nor do I wish to defeat the the 3 shutdown codes. So I reckon I'll stick with the factory settings.
Your dash is an item that we could easily deal with...the only problem is my steering column is flat and will not fit into the R&M dash that's designed for an MCI. Wonder what factory made dash would be available without the notch for the OEM steering column? May end up building a dash...have to see what I can find.
See you soon, JR