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Rough Cold Start - Runs Fine Warm

Discussion in '1st Gen 4Runners (1984-1989)' started by dgodrummer, Dec 5, 2017.

  1. Dec 5, 2017 at 6:22 AM
    #1
    dgodrummer

    dgodrummer [OP] New Member

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    Durango CO
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    1988 4runner
    got my '88 4runner from brother in law (finally). low miles... 120,000. Since it really has only been driven 2x a year (if that) for last 25 years, I've found myself dealing with some unexpected issues. Here's the latest one that maybe someone can advise me on.

    Since this is my 2nd '88 3.0, I feel I am constantly comparing the "feel" of this one to my last one. Old one, started just fine, even on a cold Colorado morning. This one doesn't. It will always start, just gotta turn it over a few times, and baby it. Once it starts it' coughs /chugs for about 10 -15 seconds, then BAMMO rpms come up to about 1000 and it's purring. But that ain't all.
    Until the truck is warmed up, I can't even pull out of the driveway (slight up hill) to save my life. When not moving, I can rev RPMS up just fine, as soon as I let out clutch, the power dies, and RPMS fall... i.e. NO POWER. This has been going since I brought this vehicle to Colorado from California in Summer of 2016.

    Heres' what I have replaced and checked as I pick away at this issue.
    - new plugs/wires
    - O2 sensor
    - fuel filter
    - checked fuel pump pressure at a banjo fitting (about 35-40 psi)

    and other repairs that we're done to truck for other reasons:
    - timing belt/ water pump
    - flush and replaced radiator fluid
    - new thermostat

    removed (2) 6mm bolts on COLD START INJECTOR mount; to clean and test it: it wasn't horribly dirty.
    - sprayed it / wiped it with rag to remove build up (did not remove it - I was concerned about breaking the plastic clip on the wire that was already showing signs of weakness).
    - put it back on, when engine was running shot it carb cleaner to see about leaks, there was a leak as engine would slightly decrease RPMS as carb cleaner made it's way in. I fixed the leak using high temp gasket sealant all around gasket, as one bolt was about to strip out and I didn't want to make a gasket and have to tighten it down more than I had to. Let it sit over night to allow gasket sealant to dry. in AM started engine, sprayed outside of CSI with carb cleaner, NO LEAK. Engine remained at a constant RPM during idle.

    BUT, weak power issue remained, when engine was cold. still couldn't pull that sucker out of driveway w/o much effort.

    Next day I decided to observe cold start injector on a cold start (had a buddy inside vehicle to turn key):
    - removed CSI and plugged holes where it mounted (so no vacuum leak)
    - upon turning key to ON (but not turning over engine) I saw nothing from the cold start injector
    - upon starting engine it sprayed only once for about 1/2 second; an even misty spray in two directions. nothing from cold start injector other than the initial 1/2 second shot of gas. Friend revved engine up and down a few times, I allowed engine to run for about 1 minute; observed nothing else from cold start injector. IS THIS THE NORMAL BEHAVIOR for a CSI?

    If I can't figure this out soon, I'll deal with it, as once she warms up, she'll drive just fine.
    and then next summer, I'll remove gas tank, clean it good, and replace fuel pump. Found a great post on this elsewhere:
    https://forum.ih8mud.com/threads/1988-4runner-gas-tank-restoration-saga.995930/page-2

    Maybe it's a weak fuel pump? though fuel pump pressure at idle was fine.

    scratching head on this one. My mechanic is doing same. Only thing I have not check it EVER SINGLE vacuum hose on the engine. I've checked what I can easily access and see, but plastic and rubber is old on this engine, so cannot rule out a vacuum leak somewhere.

    also read that the electronic sending unit to the cold start injector can fail.

    any ideas?
     
    Bob likes this.
  2. Dec 5, 2017 at 7:29 AM
    #2
    RonT4R

    RonT4R New Member

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    Virginia Beach
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    Sounds like you covered a lot of the common issues.
     
    Bob likes this.
  3. Dec 5, 2017 at 8:46 AM
    #3
    RonT4R

    RonT4R New Member

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    Does sound like a vacuum issue....:notsure:
     
  4. Dec 9, 2017 at 9:27 AM
    #4
    xcuzzi

    xcuzzi New Member

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    I know it's not the same but my 22RE had a cold start injector that went bad. When replaced all I had to do was touch the key and it starts and runs strong. No idea if your 3.0 even has one but that was the cure for my '85.
     
  5. Dec 9, 2017 at 9:40 AM
    #5
    dgodrummer

    dgodrummer [OP] New Member

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    Durango CO
    Vehicle:
    1988 4runner
    yeah, it has a CSI. I'm was able to test it somewhat while out; one short spray upon starting engine, then nada. not sure how the CSI is supposed to behave, not finding info not that. I read it could also be the electronic unit controlling the CSI causing issues. my mechanic will see this vehicle tuesday... too many irons in the fire right now. so will leave it up to him. hopefully he'll find the issue.
     
  6. Dec 9, 2017 at 9:41 AM
    #6
    xcuzzi

    xcuzzi New Member

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    to many to list
    Good luck !
     
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