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Can anyone help diagnose this problem?

Discussion in 'Pacific Region' started by TrcksR4ME, Mar 23, 2004.

  1. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Well I need a work vehicle asap, so I am thinking about using this old 84 Chevy Van my parents have. I can basically have it for free, but it needs a few things. It has a reman. 350 in it with about 80,000 miles on it, and a 700r4 that was rebuilt with all the good stuff about 75,000 ago.

    The problem is that the thing will start and idle ok, but when you put it in gear it starts doing some funny stuff. It's hard to describe but it is like it basically loses a lot of power and when you push on the gas it doesn't respond very well. Again it will idle and rev up in park, but not in gear. So I am thinking it could be three things: Vacuum line/ modulator deal on tranny, fuel pump, or maybe the carb. I know the fuel pump was replaced when the engine was done, but that was a while ago-the carb was also rebuilt then, but again it was a while ago. The tranny stuff I don't know on.

    Do these sounds like good things to check? When we were driving it regularly the problem basically happened rapidly, no slow decline or anything. /forums/images/graemlins/1zhelp.gif & TIA
     
  2. jakeslim

    jakeslim 1/2 ton status

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    i would agree with the fuel pump being suspect. Actually all of the above including the vacuum are right on. Also, have you tuned her up yet(new plugs wires etc)? Since it idles good, i am sure it is one the minor things you listed.
     
  3. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    I haven't done much to it yet. It has sat for about 8 months but prior to that was maintained regularly and I am sure my parents had it tuned up. We use to use it to tow and take family vacations so it has had a lot of work put into it over the years. I will probably go ahead and do a tune up soon, but its not like its been 5-10 years since the last one.
     
  4. jakeslim

    jakeslim 1/2 ton status

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    if its been sitting, i would def change the plugs. Also, i would change the fuel pump if its the mech kind since its cheap. Not sure if it is though in that vehicle.
     
  5. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Yeah, its a mechanical pump. Like you said, its cheap so I will probably go ahead and do it. Most of the stuff needed to be done is cheap, but even so money is tight so I can't do it all right away. Well I might have to, but if it will run ok I will wait on the tune up and stuff til I have a few extra bucks.
     
  6. jakeslim

    jakeslim 1/2 ton status

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    [ QUOTE ]
    have a few extra bucks

    [/ QUOTE ]
    i hear ya. Thats what ebay is for. gather some junk and sell it. you'd be amazed at what will sell.
     
  7. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Ok, update kinda...

    I went to the ole schmucks and got a new battery and popped that in. Check oil and tranny fluid, both fine and the ATF was red and non burnt smelling. Turned it over and it started right up, and after it warmed up a few minutes it sounded pretty smooth and idled/ rev'd up fine.

    But as before, almost as soon as it was in drive it started to kind of hesitate and it almost seemed like maybe it was missing...but put it back in neutral and again it ran smooth and rev'd fine.

    So far I cannot locate a vacuum line going to the tranny, so I am thinking 700r4's don't have them? or maybe I am not seeing it. While I was looking I pulled the air cleaner off and checked the carb a little, it seems to be ok, the accelerator pump works like a champ anyways. So thats where I am at.

    Damn these 84's have so many hoses and emissions related crap, I just want to pull it all off /forums/images/graemlins/rotfl.gif I should take a pic, its a nightmare.
     
  8. shane74

    shane74 1/2 ton status

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    [ QUOTE ]
    So far I cannot locate a vacuum line going to the tranny

    [/ QUOTE ]
    That's 'cause there isn't one!

    Ok, first, you need to pull the codes. If you have and there's nothing stored, then you need to check the fuel pump first. Pull it off and compress the lever. It should make a loud sqwishing sound and move at least 1/2" or so. If it doesn't, it's junk. If it's working right, then check all the basic junk like cap, rotor, EGR valve, PCV valve, all the basic stuff like that. Last thing check the ign. control module and eng. control module. Chances are it's something simple. On my bro-inlaw's burb, it was the EGR valve that was all wacked out. You can check it by manually closing it. You should be able to stick your finger underneath it and push the plunger up to close it. If the plunger won't move, it's junk. With a bad EGR valve, it'll run fine at idle, but as soon as you put it in gear it'll stumble like it's missing. Also, check the plug wires, are they good? Have they melted through anywhere? Like I said, check ALL the simple stuff first.
     
  9. POWERMAD

    POWERMAD 1/2 ton status

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    Is there a Feedback carb and an EST distibutor on it?
    If so that could the problem.
    If that's the case then swap out the carb for a regular ol Q-jet and either modify the distibutor or toss it over yer shoulder and get a regular HEI.
    An ESC system will have a plug in the carb and more than the usual wires than a regular HEI distributor.
    One thing to think about... it's in a van, everything is a PITA to do. I wouldn't go tossin parts at it to see if it cures it. A $10 Vac/fuel pressure gage can rule out alot of aggrivation.
    I would start with the easiest/cheapest thing first to begin with.
    That would be the air and fuel filter.
    Idles and reves fine in park or nuetral, guttless when a load is applied.
    Since it sits for a while and has been sitting check those two 1st.
    Q-jets don't have very big filters and if the fuel has varnished it it will restrict fuel flow.
    Air filters are paper elements that will draw moisture when they sit to long, that's a problem here in the PNW.
    And if the filter was full to begin with that kinda makes concrete.
    At any rate always start with the easiest things first.
    A fuel filter is only a few $$ and while you are changing it the fuel line will be disconnected and with a $10 Vac/ fuel pressure gage you can rule out the fuel pump.
    Unless you are on a fuel pump R & R in a Van Olimpic team and need the practice or happen to be extremly bored and enjoy going through alot of hassel just for the sheer joy of it.
     
  10. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Ok, this will sound dumb, but what does the egr valve look like? I haven't worked on anything with all the neat 1980's emissions gadgets on it before, but it sounds like a good candidate. The van has over 200,000 miles on it and I am guessing when the engine was replaced all the small parts such as the egr were not. It seems to have endless vacuum lines and little vacuum diaphrams everywhere.

    Also it does have a plug going to the carb. The distributor looks pretty normal from what I can tell. The only nice thing about vans is once you take the hump off inside, the distributor is right there /forums/images/graemlins/laugh.gif Also, it had the problem before it sat, so I don't believe it is anything related to sitting. All the suggestions are good things to replace though and I will replace as many as I can.
     
  11. shane74

    shane74 1/2 ton status

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    The EGR valve will be sitting just in front of the distributor on the left side of the engine. It looks like a little round suacer shaped thing with a vaccum line connected either on top of it or into the side of it. Did I make any sense?
     
  12. POWERMAD

    POWERMAD 1/2 ton status

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    Common engine problems assosiated with the EGR...
    Rough idling.
    Stalling at idle after deceleration.
    Surging at cruising speeds.
    and stalling after cold starts.
    Doesn't sound like your gremlin.
    I would check the fuel and air filter and see what the fuel pressure is, it should be around 9psi and be able to pump about 8 ozs in 15 seconds.
    You have GM's first attempt at electronicly controling the engine (ESC)Electronic Spark Control
    That system is designed to retard the timing up to 20 degrees. Very common for them to fail and cause all sorts of problems.
    They are not even worth the time or money to try and fix.
    Modify the distributor and install a regular Q-jet.
    With out actualy being able to look at it first hand that would be my best guess.
    Being that old it is most likely the culprit.
     
  13. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    Loose plug wire maybe /forums/images/graemlins/histerical.gifYup it was a loose wire on number 2 plug that made the motor run rough /forums/images/graemlins/waytogo.gif,next why is tranny in gear and motor loads up? Soon to find out!Hopefully! /forums/images/graemlins/waytogo.gifCome on guys help him out I don't know shiznit about 700r4's! /forums/images/graemlins/dunno.gif
    Bill
     
  14. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    -check the tran module vacume line for fluid, any at all, made mine load up.fact, it had all those symptoms, so check it.
    -incorrect air/fuel ratio without rpm's to handle the load will do it
    -also check the throttle plate bushings, if it sukkin air itll load up and puke under low rpms with load.
     
  15. POWERMAD

    POWERMAD 1/2 ton status

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    [ QUOTE ]
    The problem is that the thing will start and idle ok, but when you put it in gear it starts doing some funny stuff. It's hard to describe but it is like it basically loses a lot of power and when you push on the gas it doesn't respond very well. Again it will idle and rev up in park, but not in gear.

    [/ QUOTE ]
    No auto tranny I know of will do that.
    Usualy will rev like hell and not go anywhere.
    Attach a timing light to the engine and see if the timing is advancing when you increase throttle.
    If the distrubutor is not advancing the engine will be a pig under a load.
    From his descripion of the gripe it sounds like a timing issue.
    And with that obsolete crap set up it is most likely the problem.
    It's amazing it has lasted this long.
    That has got to be be GM's most famous screw up.
     
  16. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    [ QUOTE ]

    No auto tranny I know of will do that.

    [/ QUOTE ]
    /forums/images/graemlins/rotfl.gifIm willing to bet 1 year of my life and $ 1400.00 it will, and many other member will vouch for the same problem /forums/images/graemlins/wink.gif
     
  17. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    [ QUOTE ]
    Loose plug wire maybe /forums/images/graemlins/histerical.gifYup it was a loose wire on number 2 plug that made the motor run rough /forums/images/graemlins/waytogo.gif,next why is tranny in gear and motor loads up? Soon to find out!Hopefully! /forums/images/graemlins/waytogo.gifCome on guys help him out I don't know shiznit about 700r4's! /forums/images/graemlins/dunno.gif
    Bill

    [/ QUOTE ]

    LOL, funny how those little things don't help a motor run correctly. Good thing Bill came by and caught that /forums/images/graemlins/blush.gif /forums/images/graemlins/bow.gif /forums/images/graemlins/peace.gif

    It still doesn't run right and I haven't had a chance to really look it over and check vacuum lines and the egr etc. And there is not vacuum line to the tranny, or modulator hooked to said non-existent line, so no need to have a pissing match over that /forums/images/graemlins/deal.gif

    I am sure its gonna end up being related to the emissions related garbage and distributor. Hopefully I will get a day to work on it soon and figure it out. Thanks for the help so far /forums/images/graemlins/thumb.gif
     
  18. Tweetysuarus

    Tweetysuarus 1/2 ton status

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    If you need the distributor I have your more than welcome to it.
    Bill
     

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