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Author Topic: MCI wont start  (Read 8879 times)
uncle ned
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« Reply #15 on: May 30, 2011, 12:05:15 PM »



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

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Ed Hackenbruch
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« Reply #16 on: May 30, 2011, 07:32:09 PM »

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. Smiley
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
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« Reply #17 on: May 30, 2011, 08:27:23 PM »

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 ...
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« Reply #18 on: May 31, 2011, 08:59:26 AM »

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
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viking1
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« Reply #19 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.
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« Reply #20 on: May 31, 2011, 04:49:22 PM »

By the way I live in the Antelope Valley in the High Desert in Southern California. Any local bus nuts in my neighberhood?
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gumpy
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« Reply #21 on: May 31, 2011, 06:24:31 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?


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« Reply #22 on: June 01, 2011, 01:22:05 PM »

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?Huh?? Huh Huh
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« Reply #23 on: June 01, 2011, 01:38:48 PM »

I'd start with the easiest one.  For me that would be the fuel pump.

Brian
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« Reply #24 on: June 01, 2011, 03:02:14 PM »

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.
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robertglines1
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« Reply #25 on: June 01, 2011, 03:07:32 PM »

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.
« Last Edit: June 01, 2011, 05:04:59 PM by robertglines1 » Logged

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Ed Hackenbruch
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« Reply #26 on: June 01, 2011, 05:05:48 PM »

Easiest is to dump 20 more gallons of fuel in your tank and see if it runs.
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1968 MCI 5A with 8V71 and Allison MT644 transmission.  Western USA
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« Reply #27 on: June 01, 2011, 09:00:50 PM »

  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.
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luvrbus
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« Reply #28 on: June 02, 2011, 06:30:42 AM »

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
« Last Edit: June 02, 2011, 06:42:45 AM by luvrbus » Logged

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robertglines1
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« Reply #29 on: June 02, 2011, 11:13:25 AM »

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???
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