1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Truck is surging, mostly at idle, what's up?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by nelstomlinson, Nov 22, 2020.

  1. IDIBRONCO

    IDIBRONCO IDIBRONCO

    Posts:
    6,933
    Likes Received:
    5,142
    Joined:
    Feb 5, 2010
    Location:
    edmond, ks
    You may have to hold a little bit of down pressure to get the bolts started. I like to use a shallow socket on a short (3" or so) extension to help with this too. I also like to start the one toward the rear of the engine first simce the other one seems easier to start to me.
     
    The_Josh_Bear likes this.
  2. IDIBRONCO

    IDIBRONCO IDIBRONCO

    Posts:
    6,933
    Likes Received:
    5,142
    Joined:
    Feb 5, 2010
    Location:
    edmond, ks
    To help with this, I like to tip the pump up so that the arm points down, away from the cam.
     
    riphip likes this.
  3. nelstomlinson

    nelstomlinson Full Access Member

    Posts:
    804
    Likes Received:
    433
    Joined:
    Oct 21, 2015
    Location:
    Delta Junction AK
    Done! Details to follow.
    Edited to add:
    I did bar the engine over a bit, and that seemed to help.

    I removed the pump, got out my thread chasers and chased the bolts and the holes in the block. That made some difference, I think.

    I could tell from looking at the engine on the stand that the pump arm needed to go under the cam, so I made a point of pointing the arm down as I put it in the hole. I'm optimistic that it's underneath the cam.

    I finally took some 3/8NC allthread and made a stud, threaded that into the back bolt hole, and slide the pump into place on it. I was able to get a nut started on it and used that to suck it down into position, then got the front bolt on. Finally I tightened them both down.
     
    Last edited: Nov 28, 2020
    The_Josh_Bear and IDIBRONCO like this.
  4. The_Josh_Bear

    The_Josh_Bear Full Access Member

    Posts:
    979
    Likes Received:
    597
    Joined:
    Jun 1, 2016
    Location:
    Western WA
    Nice work, I just saw this now but would have suggested making a stud for the back bolt. One of my favorite hidden mods!
     
  5. nelstomlinson

    nelstomlinson Full Access Member

    Posts:
    804
    Likes Received:
    433
    Joined:
    Oct 21, 2015
    Location:
    Delta Junction AK
    Next trip to Fairbanks I'll get some grade 8 allthread for this kind of thing.
     
  6. nelstomlinson

    nelstomlinson Full Access Member

    Posts:
    804
    Likes Received:
    433
    Joined:
    Oct 21, 2015
    Location:
    Delta Junction AK
    This afternoon I fired it up and the new pump solved the problem.

    What is a good, US made fuel pump? I want to get an OEM or better mechanical fuel pump.
     
  7. IDIBRONCO

    IDIBRONCO IDIBRONCO

    Posts:
    6,933
    Likes Received:
    5,142
    Joined:
    Feb 5, 2010
    Location:
    edmond, ks
    I'm glad to hear that the new pump worked. I think that the electric pump was a Band Aid fix in the beginning. I still think that having one on a toggle switch is a good idea for emergencies. I've had good luck with mechanical lift pumps so far so I don't really have any brand recommendations. The one that I'm running now is whatever I got from Auto Zone 4 1/2 years ago. I can't remember what brand it was.
     
  8. nelstomlinson

    nelstomlinson Full Access Member

    Posts:
    804
    Likes Received:
    433
    Joined:
    Oct 21, 2015
    Location:
    Delta Junction AK
    Pretty sure the e-pump was to bandaid air leaks in the return system.

    I've found a Motorcraft e3tz9350b pump on fleabay. It's a little spendy, but if it's better than the aftermarket one I just pulled off, it would be worthwhile to put on the new engine for the '94.

    Edited to add: the fact that the e-pump couldn't keep up when the engine was running and the old mech pump was failing suggests that it's not pushing hard enough to cause problems when the engine is running. It's probably still worth turning it off and seeing what happens. I may not need the bandaid.
     
    Last edited: Nov 30, 2020
  9. riphip

    riphip Supporting Member Supporting Member

    Posts:
    980
    Likes Received:
    363
    Joined:
    Nov 16, 2005
    Location:
    Memphis, TN.
    Airtex was good for me, when I used mechanical pumps. You were probably sucking air from damaged diaphragm but electric didn't push hard enough for a good noticeable leak.
     
  10. nelstomlinson

    nelstomlinson Full Access Member

    Posts:
    804
    Likes Received:
    433
    Joined:
    Oct 21, 2015
    Location:
    Delta Junction AK
    This is turning into the never-ending story!

    Today the truck wouldn't start after work. Turns out the olive at the top of the hard line from mech pump to filter was damaged, and leaking. A quick ride home to get a spare olive and a 3/4" stubby wrench, and I was back in business. I probably dribbled about a 1/4 tank of diesel on the road on the way to work this morning.

    I'm glad it had warmed up to a little above 0F.

    Hopefully that's the end of this saga.

    Edited to add:
    Just so I'll have the info handy, the e-pump is a
    FACET 60302 POSI-FLO PUMP

    12 inches minimum dry lift
    23 – 40 GPH
    1.5 – 10 PSI
    ESD compliant
    1.5 amp average
    Diesel Priming and Self Regulating
    Light-Weight – Compact
    Internal 3.5 amp fuse
    Quiet valve – 65Db
     
    Last edited: Dec 1, 2020
    riphip likes this.

Share This Page