| Author |
Message |
phil potter (216.109.196.189)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 28, 2002 - 3:46 pm: | |
My 8V 71 shut down on a cross country trip. Sitting at a fuel station, she just slowed to a stop. restarted for a few seconds and then would not start. Radiator fluids were fine. Had a road service call. I happened to have a mechanic show up that was the "real deal" - had been around for years working on these things. He checked out the rack, a rod in the blower, everything looked fine, looked like fuel starvation. He found a flexable fuel line with a spot rubbed and worn. Must have had a small pin hole in the line that finally let air in the fuel line and lost the prime. He got it fixed and up and running.
two weeks past.
I'm home and started it up today. It sat running for 5 min. and shut down the same way. What is going on? |
Geoff (64.1.0.153)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 29, 2002 - 9:42 am: | |
Unless one of them is loose you have another bad fuel line, and probably a clogged fuel check valve. I would change all the flexible fuel lines in the engine compartment and take the check valve off for cleaning or replacement. |
bobm (152.163.188.227)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 29, 2002 - 10:01 am: | |
get a small hand vaccum pump and see if you can prime the fuel system through the fitting on the fuel filter housing just ahead of the check valve. if you can and it stays running you have either a bad check valve or a bad line between tank and check valve |
Chuck MC8 (207.69.79.161)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 30, 2002 - 7:21 am: | |
My MC8 is doing the same thing....When I prime with an electric fuel pump, Runs fine, but when I switch back to bus fuel, runs a few minutes
and quits.Also, It pumps the fuel out of my priming bucket quickly, so I think I have check valve problems also. The only thing That I see that looks like a check valve is on the return line up on the firewall.
Would that be my culprit or another suggestion pleeze?
It's sitting in the middle of my driveway...... |
Geoff (64.1.0.14)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 30, 2002 - 8:49 am: | |
The check valve is usually in the line coming from the tank to the primary filter, although some buses have the check vavle on the return line to the tank. Either way, the idea is to keep the fuel from draining out of the engine and back into the tank. If you have a bad fuel hose(s), it allows air to get in the fuel line, and if you have a bad check valve, the process is speeded up. So I give you the same advice as for Phil-- first make sure all the lines are tight, remove the check valve and blow through it to make sure it is working, and finally replace any and all old fuel hoses in your engine compartment. This should solve your problem. BTW, of course your priming bucket is going to empty-- you are pumping the fuel back into the tank!
--Geoff
'82 RS CA |
Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 30, 2002 - 5:14 pm: | |
My best guess for whatever it is worth would be that some of your fuel hoses are getting rather old and they are swelling up on the inside, thus restricting the fuel flow.
They can look brand new on the outside but still may not be passing enough juice. Testing them with pressure does not help because they will just expand out and seem fine.
Then under normal operating conditions just swell shut again and not pass the fuel. Kinda like our old tired heart arteries. The solution is also kinda the same.
Just replace ALL of your rubber fuel lines with one size larger and the problem should (may?) go away. It just may be a fuel starvation caused by old fuel hoses. Good luck. |
Rick (12.251.212.175)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 30, 2002 - 11:14 pm: | |
You might check this url it's for old trucks but very informative of deisels go to features
http://www.atca-inc.net/ |
Ron R. (152.163.188.227)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 31, 2002 - 6:51 pm: | |
Phil:
I had the same problem when I first drove my bus. I changed all of the lines, filters and steamed the tanks(not in that order). I almost got the gun out and shot it to end my misery, BUT!, it turn out to be the skinner valve. That is the rare valve that shuts off the fuel to the motor when you turn it off. It is named skinner because Mr. Skinner invented it. It is a small round electric switch with a air line that goes to the shut off piston on top of the motor. The skinner valve will not shut off the motor until it gets over 60PSI. If the skinner valve is bad, it will shut off the fuel when it gets past 60PSI whether you turn it off or not. If you have a skinner valve, test it by starting the engine and unplug the two lead wire from the valve. If it is bad, then the engine should keep running. You will have to use the emergency shut down to stop it.
This is another idea for you to check. I spent alot of $$ before I found this out. Hope this helps.
Ron |
Bradd B. Smith (208.26.165.165)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 02, 2002 - 1:16 am: | |
Hi Guys, do yourselves a favor and click on Rick's link above. Go to the features, in the shop-its. 4 excellent articles on fuel systems, and then thank Rick for bringing them to our attention, Bradd |
Buswarrior (Buswarrior) (64.229.213.188)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 13, 2002 - 10:07 pm: | |
Hello all.
Just to add a bit to Ron's advice, if your skinner valve for the fuel shut off isn't working, due to low air pressure or failure, you only need to manually pull on the fuel rack arm that the skinner acts on. Always nice to avoid the stresses on the blower seals that choking the engine with the emergency stop creates.
Go ahead and practice one day, you never know when you might want to shut it down in a hurry before the air is built up.
On the older mechanical engines, this is the only thing that the master switch up front does to stop the motor. Pretty simple, huh?
So, it is easy to watch the solenoid as the air builds up to see if it starts closing the fuel rack shut off. If so, one can just remove a couple of fasteners, head down the road, and just shut it down manually in the engine room instead of up front via the switch.
As a note of warning, don't have someone else messing around up the front while you mess around down the back. The little air solenoid will pinch if it is activated with your fingers in there.
Don't we have enough reasons to holler at the spouse without adding more?
happy coaching!
buswarrior |
Ron G. Vandegrift (207.222.255.242)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 06, 2003 - 5:36 pm: | |
As long as the subject of skinner valves was brought up, I have had my '81 mod 10 Eagle for two years doing the conversion. While messing around under the dash, I must have disconnected something because the engine won't shut down now with the key (I shut it off my covering the air intake). The wiring diagram in the fuse panel compartment says that there is a skinner valve for shut down. I can not find what wiring I disconnected. Does this skinner valve shut down the engine when 12 volt is applied or does it have to have 12 volt to let the engine run and shut it down when 12 volt is removed. Does the skinner valve have wire(s) to it. I cant see anything on the top of my engine that has wires connected. The engine is a 6-71 turbo with a 3 speed Allison. |