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Author Topic: Help. No fuel from the pump 8v71  (Read 2003 times)
gears80
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« on: September 10, 2007, 05:09:43 PM »

I tried to start my mc5a after two months. Ran fine before. Won't start. I started checking for fuel problems. I found out there isn't any fuel leaving the pump. I am new to these diesel engines so I looked it up in the maintenance manual and all it shows is a circuit diagram. Does anyone have an idea where to start looking? thanks
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Utahclaimjumper
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« Reply #1 on: September 10, 2007, 05:54:50 PM »

To get fuel FROM the pump you need to get fuel TO the pump, its probably sucking air, thats where I'd start.>>>Dan
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« Reply #2 on: September 10, 2007, 05:55:55 PM »

Have you tried to bleed the pump?  That's probably why it won't start.  Depending on what you've disconnected, it may be loaded with air.
I'm not sufficiently versed on MC5s to tell you how to bleed it, but you may find a pump or other valving has been installed that will bleed the system.  
You may want to call the previous owner for info on bleeding the DD fuel system.
It shouldn't have air in it from sitting for 2 months.  You may want to check for an air leak or crack in the fuel supply line.  
Since the pump won't pump with air in it, you'll have to add fuel under low pressure ahead of the fuel filter until you have fuel coming out of the the pump....or from the bypass line.  
I'd recommend installing a bleed pump if you don't have one.  
If you've done any maintenance on the coach, you may wish to look back over what has been done.
Time to get a manual for your engine.  If it was running well when it was shutdown the last time, it will likely run well again with minor fix.
Keep in mind that the coach may be out of fuel.  The tanks sit crossways and if the bus is parked with the driver's side low, the fuel goes to the wrong end of the tank.  You can run out of fuel with a quarter tank of fuel.  
Install a ball valve in main fuel supply line and tee off on both sides of the ball valve.  Then install an electric low pressure fuel pump between the "Ts".   Shut the ball valve off, and turn the fuel pump on...it'll force fuel thru the pump.  
You can install the pump in the engine compartment, or near the fuel tank.   Wherever you can gain easy access to the fuel supply line.  
Don't mix up the return for the supply line.  The supply line is the larger of the two.
This gives you something to think about...others with MC5 knowledge will get you going.
There are other issues that will prevent starting...emergency shutdown, skinner valve, or electrical solenoid issues.  However, the fuel pump would be pumping in these situations...until a fuel line was opened and air got in??   Could be that the fuel pump is a problem, but not your primary problem.   I'd add a fuel pressure guage to the fuel system so that you don't open the system to check for fuel.  Unlike a gasoline engine, you cannot do this with a diesel.  
While you're bleeding...go ahead and change the fuel filter(s).
Good luck, JR

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

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FloridaCliff
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« Reply #3 on: September 10, 2007, 06:02:48 PM »

.  The tanks sit crossways and if the bus is parked with the driver's side low, the fuel goes to the wrong end of the tank.  You can run out of fuel with a quarter tank of fuel.

JR,

Good call!

This happened to me on the way home from the first Timmonsville rally.

Luckily I had only stopped for Julie to run into a store and had enough air to release the brakes, push in the clutch and roll down to the bottom of the parking lot. and then restart.  Lesson learned as I knew I had a 1/4 tank.

Flatlanders need additional parking info!  Grin

Cliff
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« Reply #4 on: September 10, 2007, 06:18:49 PM »

Hi Cliff,
Yeah...BTDT.   And I did it when the air starter was on the bus.
BUMMER!  Anyway, I had no idea why the thing wouldn't start.  Knew it had a good bit of fuel. 
Actually, I didn't do it...the guys that installed the caps and AC holes did it.  Parked it out in their lot with the wrong side downhill.  It then became my problem.  Had to drive 2 hours over there and get it running... or pay them to do so.  They shoulda known better.   I hauled my cheap butt over there and fixed it.  And used a lot of their air doing so.  Spent all day with that thing.  Cannot do that with an electric starter. 
A phone call to Sawyer's and viola...understood the problem.  And learned a valuable lesson.  I've learned a lot of lessons. 
Luke bailed me out once too.  Good to have knowledgable nice guys around! 
See ya'll soon!  JR

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
gears80
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« Reply #5 on: September 10, 2007, 06:28:12 PM »

Thanks for the information. I loosened the fitting on the out going side of the pump to see if it would leak while cranking. I didn't get a dribble so went ahead and disconnected the line. It was dry. We live in the woods so maybe a critter chewed on the line. I will start checking lines and change the filters. I like the idea of adding an electric fuel pump for bleeding.
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Stan
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« Reply #6 on: September 10, 2007, 06:36:35 PM »

gears80: The fuel circuit is from a fitting on the top of the tank to a check valve at the inlet to the fuel strainer (the one closest to the starter) then to the fuel pump and back down to the fuel filter which should have two outlet hoses (one to each head fuel rail).

It definitely sounds like you have air getting into the system somewhere. The fuel pump will not pull fuel all the way from the tank (maybe sometimes if the tank is full). The fuel pump is a gear pump so you cannot push fuel through it (only up to it with a priming pump).

If you fill both the strainer and filter right to the top with fuel and put them back on, you may be able to start it if you are not sucking air in the system. There are many threads on the board about priming a Detroit using a pump (manual or electric) or some use a garden sprayer to pump fuel into the filter. Even a can of fuel held higher than the engine with a hose connected to the strainer will get you running. HTH
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cody
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« Reply #7 on: September 10, 2007, 08:44:26 PM »

not sure if this will help or not but I watched an old logger with a DD take the plug out of the top of the filter houseing and use an old time oil can the type you would use with the thumb pump, filled with fuel to top off the filter area, he said it was to keep from loosing prime.
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jhaggerty
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« Reply #8 on: September 11, 2007, 04:50:07 AM »

I just finished getting a detroit started that had run the fuel line dry. We applied some air pressure to the fuel tank and the line filled in a few seconds. If you have an air supply- compressor or an air pig, just put the hose in the fuel fill opening and rap a rag around it to keep the air in the tank. It still needed to spin the engine for a while. I found that you run out of battery fairly quickly and will probably need a booster of some sort.

Jim
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jjrbus
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« Reply #9 on: September 11, 2007, 05:16:13 AM »

On my 5C there is a shut off valve at the fuel filters. You close this when changeing filters so as to not lose prime. Did this accidentally get closed? When you change filters, were both filters full? Was there any black looking stuff in the fuel in filter?
 If filters are not full of fuel you can prime by closing valve, filling filter with fuel usually just the primary or rear filter, open valve try to start. May take several tries, but it works. If useing air to prime system, use low pressure like 5 lbs so as to not damage system.
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Don4107
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« Reply #10 on: September 11, 2007, 10:46:56 AM »

As jjrbus said, you need to use very low pressure to avoid damage to the tank. A little pressure for a longer time is much better than bursts of higher pressure for a short time.   May only work if you have the line open someplace like the filter to purge air.  Other wise you have the same pressure on the return line.  Depends on where/if there is a check valve.

Don't crank for minutes at a time or you will burn up the starter.  I don't know if there is a rule, but I would not crank for more than about one minute out of ten to allow the starter to cool.  No more than 15 seconds at a time.

The built in electric priming pump is the way to go.  One valve, a couple tees and a pump can make your life a bunch easier.  It will cost a fraction of a new starter, a service call to get you going, or a tow ect.

Don 4107
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Don 4107 Eastern Washington
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jlaney
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« Reply #11 on: September 11, 2007, 05:21:53 PM »

hello
i had the same problem with my old cruiser. would not get fuel. i went  to  the tank and removed the check valve. and found it was leaking the fuel back into the tank when i let it set for awhile. problem solved. thanks jt.
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j.t. laney  tyler texas 1980 prevost lemirage
gears80
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« Reply #12 on: September 12, 2007, 02:20:47 PM »

I want to thank everyone for these inputs. I now know I should be able to fix this problem this week end. I will let you know what happens next week. Thanks again
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Fredward
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« Reply #13 on: September 12, 2007, 06:38:29 PM »

As others have suggested, I installed a 24v in-line fuel pump in a bypass circuit with a ball valve on my -5a. It makes any fuel related issue easy to handle; like changing filters or, in my case, removing and re-installing the fuel tank. Just close the ball valve and energize the pump (I just use an alligator clamp and attache it to the hot side of the starter solenoid) I may have attached a picture to this reply but its pretty low resolution. If you want something better, let me know and I'll send it to your email account. This works great.

Fred

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Fred Thomson
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« Reply #14 on: September 12, 2007, 07:01:44 PM »

Regarding electric primers...use a low pressure pump designed for carburetors.  High pressure automotive fuel injection pumps may result in the DD mechanical pump seal passing fuel into the engine. 
Run the pump until it begins to "bog" due to pressure buildup (only 5 or 6 lbs), and start the engine while the pump is running.  On an MUI, hold the throttle WFO.  Once it starts, keep the engine running at a high idle or better until it smooths out.  If the engine is allowed to drop back to an idle, it may quit.  That wastes batteries and is rough on electric starters.   It may take a bit to purge all of the air bubbles from the injectors lines and filters.
Don't forget to shut off the electric pump and open the ball valve once the engine is running smoothly. 
Fred's pix show a good resolution for your primer. 
JR   

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
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