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MBE4000 Prime Issue

Discussion in 'Trucks [ Eighteen Wheelers ]' started by underpsi, Feb 28, 2014.

Page 1 of 2
  1. Feb 28, 2014 #1
    underpsi

    underpsi Road Train Member

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    Sep 18, 2008
    Toronto, Ont
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    It's a 2004 Western Star with a non egr MBE4000 @ 450hp with dual 150 gal tanks

    Don't even know where to look anymore. When the truck is running it idles, drives and pulls fine. If you shut it off and let it sit for more than a couple minutes you have to prime it to get it running again. Only way I've been able to get it running without ether is to crack the high pressure lines to bleed it. It does not have a hand primer.

    Heres what I've done/looked at:
    I've changed all three check valves and pressure regulators I know of, one on the filter housing return, one going into the ecm cooler and one coming out of the high pressure return from the unit pumps at the back of the block.

    I've taken the fuel pump off and checked the torque on the pump drive to see if it was slipping (22ft/lbs) and it check out good so I put a new pump on.

    I've pressurized the tanks to try to find any lines that may have been sucking air and nothing visible I can find.

    The fuel filters are both new and seals are good.

    Any suggestions on what else I could check? or maybe a better way to test for a line sucking air?
     
    underpsi, Feb 28, 2014
    underpsi, Feb 28, 2014
    #1
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  3. Feb 28, 2014 #2
    leftlanetruckin

    leftlanetruckin Road Train Member

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    Mo Via Blackpool,Lancs.
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    Tried pulling the return line off and putting it into a bucket etc, to see if air is in the return line?
    Also, you can make an adapter out of clear plastic tube, to fit onto the feed side of the Davco filter if it has one.
    Checked for fuel in oil? Maybe a high pressure fuel line leaking at the nozzle fitting in the head?
    The only times my old one lost prime was if I changed filters or had a high pressure line leak.
    Do the unit pumps themselves have a check valve in them? I have spares still, but never tore one apart.
    If you need any spares, shoot me a message, I tore down the engine that went boom and kept all the good parts.
    If need be, the guys at Interstate Detroit in Altoona,Ia are very good with the MBE motors. If you called after 4pm Central time, you could talk to Jack in the shop there.

    Martin
     
    leftlanetruckin, Feb 28, 2014
    leftlanetruckin, Feb 28, 2014
    #2
  4. Feb 28, 2014 #3
    underpsi

    underpsi Road Train Member

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    Sep 18, 2008
    Toronto, Ont
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    We pulled the line off the filter housing and put it in a bucket to elimiate the lines from the tank forward to the ecm. It still does the same thing.

    I pulled all the valve cover just to get a good look at the high pressure lines and they all looked good. The covers on the driver side are all off we took them off and kept them off long ago. Everything looks good there. You'd think if any thing infront of the fuel pump was leaking you'd easily see it since its high pressure.

    Theres no fuel in the oil.

    I don't know if the unit pumps have check valves built into them.

    I also put my laptop on it with DDDL and its putting out a pretty steady 200rpm while cranking so I can't see the cam or crank sensor being bad.
     
    underpsi, Feb 28, 2014
    underpsi, Feb 28, 2014
    #3
  5. Feb 28, 2014 #4
    Pablo-UA

    Pablo-UA Road Train Member

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    Borispol, Ukraine
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    try to check simple things
    1. intake lines
    2. fittings
    3. tank level equalizer valve
     
    Pablo-UA, Feb 28, 2014
    Pablo-UA, Feb 28, 2014
    #4
  7. Feb 28, 2014 #5
    JPenn

    JPenn Road Train Member

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    Northern Tier PA
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    Do you have a shutoff valve in the incoming fuel lines anywhere? I had one go bad and suck air around the packing for the handle. Similar symptoms to what you're describing.
     
    JPenn, Feb 28, 2014
    JPenn, Feb 28, 2014
    #5
  8. Feb 28, 2014 #6
    JohnP3

    JohnP3 Road Train Member

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    Feb 21, 2010
    Rock Creek B.C. Canada
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    With a flashlight you can look into the fuel tank and see the return line after it is running look if the return fuel is clear, It is posible the return line is allowing air into the system and the fuel drains out. There is a preasure limiting valve at the back of the head. Also if the pass thru connector cracks it is posible air could get into the system. Usually when the pass thru connector is cracked there is a fuel leak at the connector .
    Just a thought!
     
    JohnP3, Feb 28, 2014
    JohnP3, Feb 28, 2014
    #6
  9. Feb 28, 2014 #7
    leftlanetruckin

    leftlanetruckin Road Train Member

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    Mo Via Blackpool,Lancs.
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    He said he can get it going by loosening up a HP fuel line to allow it to prime, so I would think fuel supply is good.
    Try to remove a return line from the head (IIRC), or the one that goes directly to the tanks, and check for bubbles. I also had a plastic tube made, threaded for pipe fittings, to go inline on the feed side too.
    See if there are check valves on the unit pumps too.
    Give Jack a call at Interstate Detroit, 407 Adventureland Dr Ne · Altoona, Ia. (515) 957-3300
    He comes in at @4:30PM M-F, after picking his daughter up at school. There till @11pm.

    Martin
     
    leftlanetruckin, Feb 28, 2014
    leftlanetruckin, Feb 28, 2014
    #7
  10. Mar 1, 2014 #8
    Pablo-UA

    Pablo-UA Road Train Member

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    Borispol, Ukraine
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    mercedes does not use shut off valves on PLD engines
     
    Pablo-UA, Mar 1, 2014
    Pablo-UA, Mar 1, 2014
    #8
  11. Mar 2, 2014 #9
    underpsi

    underpsi Road Train Member

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    Sep 18, 2008
    Toronto, Ont
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    No shut off valve. No equalizer on the feed line side.

    Seems we never ran it long enough in a seperate jug of fuel. With the line going into the ecm ran straight to a jug of fuel it will fire right up. What doesn't make sense to me is if the issue is with one of the lines before the ecm going to the fuel tanks why wouldn't the truck fire up right away and then die once air was brought into the system since all the check valves are after that point anyways?
     
    underpsi, Mar 2, 2014
    underpsi, Mar 2, 2014
    #9
  12. Mar 2, 2014 #10
    Tobytob

    Tobytob Light Load Member

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    Aug 17, 2013
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    Had a similar problem, My injector rings were bad even had one missing. replaced all rings and cleaned injector cups. truck fires right up!
     
    Tobytob, Mar 2, 2014
    Tobytob, Mar 2, 2014
    #10
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