:'( I got a 1989 MCI 102C3. I had not ran it for about a month. Yesterday I started it and it started normal. After it ran for approx. 5 - 10 minutes it shut itself off. When I tried to restart it, it would only crank and not fire. Sounded like it tried a couple of times with no success. I pulled both fuel filters and found them to be 1/4 full or lees with fuel. I filled them with diesel and put them back on. No change. Any Ideas. Im wondering if I might have a bad fuel pump.
Sounds like your fuel tank is empty. The empty filters is a sign of this. However, it's possible that you have an air leak in the fuel line which has allowed the
fuel to drain back to the tank and suck air into the line. In this case, the engine would start and run on what was in the filters and pump, but when the air
got to the pump, it would airlock and die. The pump
is not self priming.
It's probably not the pump, or it would not have started in the first place.
You will need to reprime the fuel system and remove all the air between the tank and the fuel pump. Suggest you search the archives on how to do this. The
electric pump is the best way, though not necessarily the cheapest way.
Thank you for that. The fuel tank is approx 1/4 to 1/2 full so I dont think im out of fuel. How do I track down an air leak in the fuel system.
Probably the simplest way is to buy yourself a 12 volt inline fuel pump and plumb in it at the tank. It will solve your priming problem and keep the engine running while you track down your air leak which will turn into a fuel leak when you put the pump in. Pressure wash everything until it looks nice and then use the bus for a while - the leak will be the place that gets dirty first.
This comes up regularly so the search function should turn up lots of threads for you - this one came up near the top of my search:
http://www.busconversions.com/bbs/index.php?topic=18135.0 (http://www.busconversions.com/bbs/index.php?topic=18135.0)
course in my case is paper in the check valve
I had to ask this board this very same question. Check to make sure your engine shut off switch in the back is on. If it is off you will be able to start engine until air pressure builds and then the shut off will shut you down. I am not sure this is you buses problem but it sound like my situation.
John
interesting, I did notice that the air pressure was around 60psi when it shut down. Where is the shut off valve and how do u move it manually
Mine is in the back as you face the engine on the left side.
John
His is probably a DDEC 6v92 or 8v92 his problem is it lost prime the pump is good or the filters would not be low
Thanks, Its a 8V92. Not sure if it has a DDEC but im guessing it does. I will try again tomorrow
how would it have lost prime. It was running for a good 5 to 10 minutes before it died. After it died I was unable to restart it.
You may have a cracked fuel hose allowing air into the system. That would cause a loss of prime in some cases.
Or... you could have a collapsed fuel line, in which case not enough fuel as was in my case.
Quote from: viking1 on May 29, 2011, 06:43:42 PM
how would it have lost prime. It was running for a good 5 to 10 minutes before it died. After it died I was unable to restart it.
I dont believe there is enough fuel in the filters to run it that long without any fuel flow, but regardless, its lost prime. Could be a loose fitting, even a loose filter, anywhere it can suck air rather than fuel will cause the problem, and running time depends on quantity of air to fuel. IOW, it was pulling air in with the fuel which allowed it to run longer than it would have without any fuel flow.
Is there some work youve done previously, fuel filters? Lines? tank? Anything with the fuel system you have taken apart and put back together? The filters need to tight like an oil filter, 3/4 turn after contact. They do not need to be tightened past that point
Lost prime is going to be the problem.
Reason? Could be many reasons such as the cracked line, hole in a line or whatever. Usually (not always) it's a worn out, or comprimised check valve that allows fuel to back flow when it's not supposed too!
Quote from: chev49
course in my case is paper in the check valve
As chv49 mentioned in his case it was paper in the check valve.
Now one would ask how would paper get in there? Hmm what is inside a fuel filter? Paper! So my guess would be old or defective fuel filter!
AT any rate viking1 if it were me I'd REPLACE the filters with new full filters and either add a primer pump or use an old school solution and supply fuel & pressure to the engine long enough to get it up and running on it's own!
And yes an engine can run on the fuel in the pump and filters about 5 mins before running out if it's lost prime!
;D BK ;D
Another piece of advice.
If you get low on fuel,never fuel up with the engine running. It gets very expensive to fix.
Call a road tech that knows nothing about a Detroit.
he will try to prime with starter fluid.
putting it straight in the blower breaks heads.
learn things the hard way for a few years.
Either a electic pump or a old oil pump oil can with diesel into the secondary filter till it runs.
evening BK
uncle ned
First thing i would do is double check your fuel level. Seems like a while back this happened to somebody else and they finally found out that even though they had a quarter tank of fuel, that the bus was tipped a little and their pickup tube was on the high side so it was sucking air. :)
actually i have a check valve in line just before the primary filter... i think maybe some kids at one time put paper in the fuel tank ...
I had problems with my MC8 loosing prime when I parked on a slight incline. It would only happen when the engine was higher than the fuel tank and it would lose prime regardless of how much fuel I had. It would be fine for a day or two but if I did not start it for a month I always lost prime. I installed an electric fuel pump at the tank to re-prime. I started parking with the engine lower than the tank and never had any more prime problems. I'm sure I had some sort of leak that allowed air in the system, but I could not find a fuel leak.
Good luck,
John
Guys, Thanks for all the input. Im thinking it might be a combination of a air leak and possibly the fact that I drove the inner rear tire and tag up on blocks to change the outer wheel and its been sitting like that for 3 weeks. Maybe a combination of that and a posible air leak led to it loosing its prime. I have not been able to prime it yet. Still trying to get a local Detroit guy to help me with that.
By the way I live in the Antelope Valley in the High Desert in Southern California. Any local bus nuts in my neighberhood?
Quote from: viking1 on May 31, 2011, 04:46:33 PM
Guys, Thanks for all the input. Im thinking it might be a combination of a air leak and possibly the fact that I drove the inner rear tire and tag up on blocks to change the outer wheel and its been sitting like that for 3 weeks. Maybe a combination of that and a posible air leak led to it loosing its prime. I have not been able to prime it yet. Still trying to get a local Detroit guy to help me with that.
Hmmm, the plot thickens....
Are you sure you are not low enough on fuel that putting it on the blocks and slanting it to the driver's side has not caused the fuel to run to the driver's side and away
from the fuel pickup tube?
I mention this only because I know it's possible for this to happen. Can't say how I know this, but trust me, I know it.
I suggest you get a 1/4" hardwood dowel and stick it down in the tank through the filler neck and see how much fuel is in the tank on that side.
BTW, is your fuel pickup line on the top or bottom of the tank?
OK. So today we disconected the fuel line and stuck it in a can of diesel and pressurized the can with air, doing this we got the motor primed and started. When we stoped pressurizing the can the engine died. So my take on that would be that the fuel pump must have gone bad. Any ideas. I talked to a tech at ABC Bus and he said my pick up tube in the tank might be cracked. So what do I do now, disasemle the tank or replace the fuel pump?????? ??? ???
I'd start with the easiest one. For me that would be the fuel pump.
Brian
We need Clifford to chime in on this one but I think he told me that there is a little drive key on the fuel pump that is a known failure point. The pickup tube is a red herring - get the engine running off your outside tank first before you worry about anything else.
transfer pump? looking from back of bus thru doors center of motor towards top center Just above crank pulley; follow the lines. about a 100/150$ dollar item easy change. if it is just weak I have run a hose to it from a 5 gal bucket to back bus in shop-just remember it also returns fuel to tank so it empties bucket quick.
Easiest is to dump 20 more gallons of fuel in your tank and see if it runs.
I often look around car lots for "back lot specials". Most often its real junk, but occasionally I find something interesting. One time the owner pointed me at this almost new Dodge station wagon, said the motor was bad I could have it for $75. I got it home and before yanking the motor started checking it out. It cranked, had spark, so I doused the carb with fuel and it fired. I put a couple gallons of gas in and it ran like a top. It was simply out of gas. I later found out the car had been past three mechanics and none ever thought of putting more gas in it.
Just because you pumped fuel into it externally, doesnt mean it will stay running if its out of fuel after you stop pumping. Your obviously going to drive it, and its going to need fuel anyway, I would add 10 gallons and see what happens.
IOW, I wouldnt spend 5 minutes looking anywhere else until I put some in it.
The DD pumps gives very few problems sometimes the drive yoke will round out remove the 1/4 plug and see if the pump is turning it will turn to the left if turning check for air leaks they will not pump with any air leaks on the system or no fuel.
I thought the C3 had a electric lift pump at the tank or inside the tank also ? I know the ones with L10 Cummins or the Cat C12 engines do
good luck
Definitely ck to see if it has a elect pump. I wasn't aware it might have. Just assumed it had mechanical like older models. My mistake! sorry. Could be blown fuse or tripped breaker in that case. Bob could you add a electric in line fuel pump if one in tank is bad???
Again Clifford good catch! I forgot that this was a C3 and yes ALL C3's I have ever been around have had the lift pump! The switch for it is on the same panel as the rear start/stop and engine compartment light switches!
;D BK ;D
Viking,
Find that switch and start the bus while holding the switch on and have someone accelerate the engine RPM's up at about 13-1500 RPM for a few mins while you hold that switch on. It takes a little time to suck that fuel back up from the tank after losing prime and you need it at a fast idle for a short period to make sure it's drawing it and not just sucking your filters dry!
Did you figure out what the problem was? :)
I have a new pump on order, should have it in a day or two. 95 bucks from Iron Man in LA. Hope to have it in over the weekend. Will let you know as soon as its in.
Is there a fuel shut off valve near your filters? One time some idiot shut off the valve. The bus started and ran then shut off. I asked for help with it and the forum pointed to everything but the problem ::)
No matter where I go that same idiot shows up and causes me problems.
JIm
Ok! Now I am just more frustrated and confused. I put the new pump on. Primed it and it ran for about 5 min and then died. I then put 20 gallons in the tank just because and I am now showing a half tank. Primed it and again it started and ran for about 5 min.
I wonder if I am priming it right,
I filled both fuel filters with diesel and got myself a 12 volt fuel pump that I connected to the first fuel filter (also tried the #2 filter, runs both ways). I then pumped fuel while cranking the engine with a valve open on the 2nd fuel filter until fuel started coming out, at that point the bus starts and i close the valve. I ran approx 1 to 2 gallons through it this way before disconecting the 12 volt fuel pump. After i remove the 12 volt fuel pump she will run in high idle for approx 5 min and then she dies. I have also diconected the fuel line just before the fuel filter and put it in a can and it runs fine this way. So as some one suggested in an earlier post, it must have a leak, must be sucking air somewhere between the tank and the fuel line to the fuel filter. "SO" how the heck do you trace down this kind of air leak. Any suggestions.
I was even considering taking a tank out of my boat and riging it up with a 12 volt pump and mounting it in the rear so I would be able to drive it to ABC Bus in Orange County.
Any help or ideas would be greatly appreciated. And I did check the shut of valve and it is open.
Regards,
ONE FRUSTRATED BUS NUT
As fore mention that bus has a lift pump
good luck
Lift Pump? please explain
Read BK's post at top of page. he has hands on experience with your problem. Or PM him he will prob give you a call and walk you thru it. I don't know enough about it myself to help. Sound like to me like a pump like a car has inside a gas tank is what they are talking about. Look around fuel tank area and see if you have a couple power wires running into tank around area where hoses run into tank. or a external pump/electric
Is it shutting off when air pressure reaches 70lb or does it do it at any air pressure above or below that? Is air after 5 minutes over 110 lbs?
No, It does not matter what the air is at. I aired it all the way up when I had it running.I looked at the tank, I have a few electrical wires at the top of the tank but Im thinking thats for the fuel gauge. I called ABC Bus and the guy there said I dont have a lift up pump and I could not find a switch for it either. getting very frustrated. So much for the weekend trip.
Get use to being frustrated sometimes. This will happen periodically. One real drag is that the rebuilt fuel pumps are sometimes bad too. When mine was changed, it took 2 to get one that worked. If you rig it so the fuel pump pulls from an external can of diesel, you should be able to see if the pump is good. Even a small crack in a fuel line will let the pump suck air. Can you hook up your electric pump in line and see if it runs that way to try to disqualify the leak theory.
I have a 89 prevost with a 8-V92 ddecII about same set up as yours. Leaving tank check valve first then line goes to inside engine compartment behind right rear tag wheel to 1st fuel filter then to primary& secondary then to transfer pump.( I have put on two transferr pumps) Next it goes thru the ddec module where it acts as a coolant for the module. Be careful with these fittings easy to break the housing they screw into. thru injectors to return line to tank. If you use your boat tank you will be returning a large amount of the fuel to the tank in the bus so you cannot depend on using all of it(maybe 1/2) Possibly disconnect primary supply line from tank and attach temporary spliced in extension pickup piece of line in thru fuel gauge port to eliminate possible damaged pick up. Could add a in line ck valve if that test doesn't work to test to see condition of ck valve that is suppose to be in the system(prevents fuel from flowing back into tank and draining filters etc) You said it was definitely fuel! The only other real problem I have had with a similar set of symptoms was a bad low coolant sensor. ( Would not leave fuel filters half full.) Would spin but would not start.
Did you actually, physically, measure the amount of fuel in your tank, or are you just going by the gauge? When mine is full to the brim it only reads 3/4 full. Yours could be the opposite and read 1/2 full when really it is empty. If it was me i would completely fill the tank to the top and see if it runs before i started tearing things apart. I have only lost prime one time and it took about 10 tries before i got it to keep running.
Question???? why would a electric pump work drawing out of tank and the mechanical pump not work? Did you put the electric pump in line drawing out of the tank? Just trying to solve problem long distance here. Could be crud in tank or something a simple as a rag sucked over intake;strange things get in tanks. Do need to verify fuel level physically. take a piece of rubber hose and stick thru filler and ck level. Gauges can and do lie and get off with age 20 gal will only make a couple inches difference in a big tank if it's level. and if tilted away from pick up,you get picture. Let's hope in the end it will be something simple and a How did I miss that! Keep checking possibilities.
Called ABC? Shoot they don't have a clue they sell & service Van Hools!
Seriously I bet it has the lift pump. Every c3 I've ever been around has.
OK. I had to go to work for a while so I didn't have a chance to play with the bus. Got home a couple of days ago and started tackling the bus wont run issue again. It has no lift pump. It runs just great if I have a 12 volt fuel pump hooked up to the #2 filter. So today I removed the fuel line where it goes to the # 1 filter and hooked the 12 volt fuel pump in line and it pulls fuel from the fuel tank, no problem. I disconnected the pump put the fuel line back on and hooked the pump up to the # 2 fuel filter for prime. Fires right up and runs great. when I unhook the fuel pump it runs the filters half down and dies. I have replaced the fuel pump. I wonder if I might have gotten a bad rebuild or if i needed a right hand pump instead of a left hand pump. The pump that came of didn't have any markings on it, but the guy I bought the new pump from was sure it was a left hand. Any ideas. its a 1989 102c3 8V92. >:( >:(
It has marking has a tiny arrow under the bottom fitting all fuel pumps running of the blower in the front turn to the left,I still think you have a lift pump in the tank on that model bus but I could be wrong
good luck
how would I find the lift pump. There is nothing on the rear start panel
the lift pump, if so equipped, would most likely be in the tank or really close to it.
......Priming a Bus is an artform, I have learned!!!!!!!.........
Finally....... I think I got it.
So to figure out whether it was my pick up tube in the tank or the fuel line, i disconnected the fuel lines on both ends and blew air through it to make sure I had the right one. Then I put the line going to the #1 fuel filter in an empty bucket and hooked up a 12V fuel pump on the other end. It took several minutes for the fuel to make the journey. Once I had fuel coming out I hooked it up to the fuel filter and unhooked my pump and put my line in a bucket. And wouldn't you know it, the bus ran like a champ sucking the fuel from the bucket. I shut the bus of and carefully hooked the line back up to the tank thinking I had just eliminated the fuel line being my problem. I figured it had to be in the pick up in the tank. But guess what? I hooked it all back together and wouldn't you know it. PROBLEM SOLVED. It needed to be primed but I guess priming it in the back as I had been doing just didn't cut it. I had to prime it from the front at the tank.
SO what was my problem, was it the fuel pump? I replaced it. Or was it pilot error. I had forgotten that I took fuel out of my tank to put in my tractor (about 5 gallons) the old fashion way, hose in tank and suck and let gravity flow due the rest. Now I wonder if maybe that was my problem. All along I was doing all this trouble shooting when actually I may have created the problem myself. ::) ::). I will never know I guess, but just in case I don't think I will be siphoning any more diesel out of the bus for the tractor......
I am one happy bus Nut. At least until the next problem comes along.
Probably the latter you just never got it primed sometimes they can be a bear be sure and hang on to your pump they are priceless
good luck