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Hard/no start when sitting/cold - 2000 F250 7.3

Discussion in '7.3L Powerstroke Diesels' started by Macrobb, Sep 12, 2019.

  1. Macrobb

    Macrobb Full Access Member

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    So... I, the IDI guy, finally bought a Powerstroke. This truck, a white 2000 F-250 4x4 CCSB 4R100 truck, marked as "crank no start" came up at auction. 226K Miles. It all looked intact, so I decided to take a chance on it. $1800 later(2K after taxes and fees), it was mine!

    Now... Get it home, put new batteries in it(both were at 5V), cycle the glow plugs and... she cranks fine, sounds like she's trying to start on one cylinder... but won't pickup and go. No clouds of smoke.

    So, I grab my handy can of Engine Destroyer(ether) and... she fires up for a few seconds sounding "normal", before dropping down below idle and dying as she runs out of ether, with loud clacking as she does so(If you've ever heard a 7.3 running on 4 cylinders, you understand what I mean by loud clacking).

    A few more tries, checking a bunch of stuff and... nothing. Wait for a bit, figure on taking a video of it cranking to post online... we crank and she fires up! This attempt didn't even use any ether.
    Now, she's running, but on 7 cylinders and no power. Back it off the trailer, take it out for a short drive... floor it and as soon as the RPMs hit about 2100 it... takes off. Turbo spools and it just goes! Back to idle and it's running great.
    It runs good throughout the evening, warm starts happen without issue.

    That was two days ago.

    Yesterday morning, she was very hard to start but finally started(no ether). Rough and no power until I hit the road and floor it... get it up to 2K and... off she goes! Drive it to work, park, starting it after work was a little loud, and again stuck on 7... get it under load at 2K and working fine again.

    This morning was colder. Above freezing, but cold. She... did not want to start at all. Bring out the ether and as I'm giving her a thin spray while cranking, she lights off, revs up... and back down and dead. Repeat twice until I actually just sit there feeding it ether to keep it running(Note: my friend was in the driver's seat with the pedal floored the whole time) until it finally "catches". Repeat the 'running on 7 until loaded above 2K rpm'.

    So... I'm trying to troubleshoot this problem now. Once she's been started for the day(and "unlocked" by hitting 2K under load), she runs quite nicely.

    Oh, and I'm not seeing any codes. I'll have to check again, though, but I didn't see any codes(aside from KAM code due to batteries being disconnected) two days ago, and that didn't come back.

    I've checked:
    1. Fuel filter looks clean, don't think that's the problem. (especially as it has plenty of power when warmed up)
    2. Oil was recently changed - was still clean enough on the dipstick to see through. Changed by PO back in May, according to writing on oil filter.
    3. Glow plug /relay/ was replaced, and seems to be clicking. Not sure on the glow plugs themselves(could well be dead).

    What other tests should I do?
     
  2. 79jasper

    79jasper Chickenhawk

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    Imo, sounds like the fuel or oil is draining back.
    After it sits overnight, pull out the hpop reservoir plug. Should be about a inch from the top max. Any lower and it is draining back. Between early vs late engines, one has a anti drainback valve in the hpop itself, the other is in the front cover. Sounds likely to be your problem.

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  3. greenskeeper

    greenskeeper Full Access Member

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    Start simple...see what I did there? :Thumbs Up

    Put down the ether can...you will damage the engine soon enough with that.

    Since you have no service history, I would remove the valve covers and replace all 8 glow plugs as well as the GPR with the larger stancor unit.

    While the valve covers are off you can look for any burnt wiring or loose connections under the valve cover.

    I'm betting on a glow plug system problem as the cause for the no/rough start and ok hot starts.
     
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  4. Macrobb

    Macrobb Full Access Member

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    Finally found my allen wrenches... Not this(thank goodness!). It's a little more than an inch from the top when measured from the outside surface of the HPOP(shoved a screwdriver in there till the handle hit).

    I'm thinking you are right. One working GP, which is why it sounds like 1 cylinder is firing.
    I did check the GP relay, and it seems to be working(about .2V voltage drop across it when the GPs are on).

    We shall see tomorrow - I found out the block heater works, so I shall plug it in first thing tomorrow and give it a couple of hours, then crank and see if she fires right up.
     
  5. u2slow

    u2slow Plan B

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    Use a DC clamp meter to see the total current draw when the GP relay pulls in. Should be in the 130-150A range. You can meter out individual GPs at the valve cover connector (without taking covers off.) Being down 1 or 2 plugs isn't a show-stopper.

    No smoke after it catches suggests fuel has not been delivered during cranking. When I had cold start problems, the cylinders would pile up with fuel and the van became a fog machine for a few minutes after it started. (My problems ended up being hpop-related)

    Other tricks I used on my cold-start diagnosis:
    - mechanical oil pressure gauge (lube oil)
    - hydraulic oil pressure gauge (hpop)
    - mechanical fuel pressure gauge
    - removed check-valves in hpop ports (balance pressure between outputs to each bank)
    - porta-power ram and adapter fittings to press up and leak-down test the hpop rails
     
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  6. Macrobb

    Macrobb Full Access Member

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    So... it's pretty clear it's an engine heat issue. Plug her in for a few hours and she fires right up. Drive her to work, fire her up after 6 hours and she fires a little rough but is fine.
    Wait 8.5 hours instead at slightly colder temps and... barely starts with several cycles of GPs.

    Glow plug check/change time. Hopefully tomorrow.
     
  7. u2slow

    u2slow Plan B

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    Maybe, maybe not. I had 7 of 8 GPs working and the block heater was still the recipe for reliable starts. My hpop basically could/would not make pressure on a cold engine. And that's with 'tight' oil rails that held 1500psi cold with the porta-power.

    Do test the GPs (i.e. meter them out through the harness) but don't tear into it assuming they're all bad.
     
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  8. 79jasper

    79jasper Chickenhawk

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    I've seen worn injectors cause hard start. You could reset the armature clearance, but may be time for a new set.
    Could try a heavy dose of stiction eliminator to try to clean them.

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  9. greenskeeper

    greenskeeper Full Access Member

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    HPO pump, injectors, LOL !

    the OP has no idea the condition of the glow plugs or relay but lets throw expensive parts at the problem. A new set of glow plugs and relay would be around $150 and would be first on my list if it was my truck.
     
  10. u2slow

    u2slow Plan B

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    That's why I said meter the GP's first. It proves the UVC wiring then too. Why get up to your elbows in a job that doesn't need to be done?
     
  11. greenskeeper

    greenskeeper Full Access Member

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    Because glow plugs can meter "good" but hardly glow at all. The only way to truly test unknown glow plugs is to pull them and apply 12v....the entire length of the plug should glow cherry red within 10 seconds
     
  12. 79jasper

    79jasper Chickenhawk

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    Yep. Cheap enough to throw a new set in as well.

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  13. u2slow

    u2slow Plan B

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    I forgot they can 'ghost' like that. use a DC clamp meter to see that I'm pulling corresponding amperage.
     
  14. 79jasper

    79jasper Chickenhawk

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    The glowplug solenoids like to go out as well.
    But again, without any real testing, it's a waste to guess.
    Just fyi, the glowplugs will stay on for 2 minutes each time. Even though the light goes off, they are still on. Just leave the key on and watch for the voltmeter to come up, or hear the solenoid kick off.
    IMO, a 2v dropped across the solenoid is fairly substantial. I would say it's toast. You could try jumping across it with a screwdriver.
    On my 94, it always started great until the one time it didn't. Wasn't even cold out, maybe 60's at night. (Same thing when the solenoid went out) Went to replace them, only one would glow when hooked straight to the battery.
    Also, for the hpop reservoir oil level, maybe a tad on the lower side, but isn't your problem.

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  15. DaveBen

    DaveBen Supporting Member Supporting Member

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    If you change glow plugs use ONLY Beru or Motorcraft glow plugs (Beru makes them for Motorcraft). ALL of the others will cause problems like swelling, making them damn near impossible to remove.
     

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