Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 28

Thread: M109A3 Idling bad

  1. #1
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default M109A3 Idling bad

    Truck has all new filters, new HH O rings, FDC bypassed, injectors have been tested. I just cant win with this truck I got taken to the cleaners with....Got it running for the first time in a while (just got my tank back on from having new bottom put in it). Has a surging Idle when cold and somewhat clears up when warmer. I can hit the throttle and It will throw black smoke and clear up real quick to a really good sounding motor and exhaust. I let off the throttle and it just about goes dead. Everything I am reading I THINK points to a IP issue. I do not think it is anything to do with the droop screw since the rpm's are fine at idle, just surging and of course just about shutting off when I let off throttle. I can not put it under a load due to having the cab still mostly torn town, etc. etc...

    It is a 1988 rebuild.
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  2. #2
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default

    In tank pump is fine also.
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  3. #3
    4 Star General Floridianson's Avatar
    Join Date
    Dec 2006
    Location
    Interlachen Fl.
    Posts
    5,913
    Thanks
    2,649
    Thanked 3,058 Times in 1,561 Posts

    Default

    Yep now that your FDC is bypassed the droop screw does not act the same because the FDC wedge plate is no longer moving. Now every change comes through the twin nut main fuel adjustment. If you did change the setting on the droop now you are just changing where the main is set to. Did you read the other thread that is having the same problem?
    Last edited by Floridianson; 06-23-2019 at 01:06.
    James

  4. The Following User Says Thank You to Floridianson For This Useful Post:

    frank8003 (06-23-2019)

  5. #4
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default

    Quote Originally Posted by Floridianson View Post
    Yep now that your FDC is bypassed the droop screw does not act the same because the FDC wedge plate is no longer moving. Now every change comes through the twin nut main fuel adjustment. If you did change the setting on the droop now you are just changing where the main is set to. Did you read the other thread that is having the same problem?
    Yea I think so. It is what led me to think it is the IP. Just can't find anything else wrong. It has a small leak at an injector line but as the other posts state it is unlikely for that to cause this.

    Sent from my SM-G955U using Tapatalk
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  6. #5
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default

    I have no oil in the transmission. I want to crank it and let it sit there and run for an extended period to see if this may change something. If the truck is in neutral and clutch is not pressed, is there anything freespinning in the transmission? I don't think so but I have to ask.

    Sent from my SM-G955U using Tapatalk
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  7. #6
    4 Star General frank8003's Avatar
    Join Date
    May 2012
    Location
    Ft. Lauderdale, Florida
    Posts
    3,603
    Thanks
    2,516
    Thanked 5,528 Times in 1,890 Posts

    Default Deuce jackshaft moving

    and I have the question of How much fuel have you put thru her since you been working on it?

    About all the gears and such...............It is all moving
    Put some straight 40 W motor oil in the transfer and transmission cases.

    Study your jackshaft

    Last edited by frank8003; 06-23-2019 at 10:10. Reason: confusing myself
    I was here, had a good time.

  8. #7
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default

    Quote Originally Posted by frank8003 View Post
    and I have the question of How much fuel have you put thru her since you been working on it?

    About all the gears and such...............It is all moving
    Put some straight 40 W motor oil in the transfer and transmission cases.

    Study your jackshaft

    Not much fuel at all since it has had alot done to it. . Will go ahead and get the oil back in transmission and let it run for a good while.

    Sent from my SM-G955U using Tapatalk
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  9. #8
    4 Star General Floridianson's Avatar
    Join Date
    Dec 2006
    Location
    Interlachen Fl.
    Posts
    5,913
    Thanks
    2,649
    Thanked 3,058 Times in 1,561 Posts

    Default

    Oil good fire bad. If you can get it running I like the LDS troubleshooting manual. Seems like most of the time it's said to check pressures at the bleed screw. That might be a nice place to start if she will run.
    James

  10. #9
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default

    I let it get up to operating temp. Released throttle and it shut down and would not crank back up. Will see if it fires up after cools down completely. Still have pressure at bleed valve.

    Sent from my SM-G955U using Tapatalk
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  11. #10
    General fpchief's Avatar
    Join Date
    Aug 2014
    Location
    Bay Minette, Al.
    Posts
    564
    Thanks
    43
    Thanked 343 Times in 150 Posts

    Default

    Replaced my in tank pump with a Parker. Had it a while and decided to go ahead and do it. The original one is getting louder so I am sure it is on its way out the door. The in tank pump was not the problem but now I know it is a good pump.
    After sitting back and thinking what I have done, I decided to check to make sure the two screws holding the little U shaped bracket for the fuel shutdown were not too tight. Read somewhere that if they are even just a tad too tight, they can impede free movement. Took the cover off (only oil in there best I could tell) loosed each screw maybe one turn...fired it up and no more surging.

    Sent from my SM-G955U using Tapatalk
    1972 M109A3
    1970 M35A2
    1971 M35A2 (sold)
    1991 M998 w/6.5 (sold)
    1995 Field Kitchen
    2013 HDT Nordic Air 18k BTU
    2011 Fremont MEP-803A

  12. The Following 4 Users Say Thank You to fpchief For This Useful Post:

    Floridianson (06-24-2019), frank8003 (06-24-2019), pjwest03 (06-25-2019), SCSG-G4 (06-26-2019)

Page 1 of 3 1 2 3 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •