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H**p question edit:fixed, explanation in first post.

Discussion in 'The Garage' started by rick88blaze, Oct 14, 2005.

  1. rick88blaze

    rick88blaze 1/2 ton status

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    My daily driver is an '88 Cherokee with the 4.0 I-6 and auto tranny. This past weekend on Saturday I changed out the sending unit assembly on the gas tank because the old one was leaking where the wires went in. Starting on Tuesday or Wednesday it started running like total crap. I thought I had water in the gas so I added a couple bottles of heet to it. That helped a little bit. Now it just runs like crap when it warms up. It's fine when I first start it when it's cold. The engine will start idling really rough, and when I give it gas it will back fire through the TBI and spit and sputter has no power when I give it gas until I get the RPM's up. I changed the distributor cap and rotor back in March, I just put in a new fuel filter and plugs 2 days ago. There was some pretty crappy fuel that came out of the old fuel filter, which is only 6 months old too. I checked the new one tonight and it's still clean. If anyone has any ideas please post them up because I am out of them. :crazy:

    Thanks in advance,
    Rick

    I finally got this thing running right. I checked everything under the hood that I could think of. Luckily I didn't have to spend any major $$$ on new parts. Anyways, I pulled the sending unit back out of the tank yesterday. :doah: :doah: It's running like a champ now. :D :D
     
    Last edited: Nov 20, 2005
  2. blazerguy 90

    blazerguy 90 1/2 ton status

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    It sounds like you have a bad CTS sensor (coolant temperature sensor), it will cause the problems your having.
     
  3. rick88blaze

    rick88blaze 1/2 ton status

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    I thougth that too, but it doesn't have one. Any other ideas? :confused:

    Rick
     
  4. 88sub4x4

    88sub4x4 1/2 ton status

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    Check to make sure the injectors aren't leaking, causing it to run too rich.
     
  5. 3 on the tree

    3 on the tree 1/2 ton status

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    Backfiring is usually caused by a vac leak or some other lean condition, or a burnt valve. I think you can rule out a burnt valve. Could you have kinked or twisted the fuel supply line when you changed the sending unit? Does it have an in tank fuel pump? Try plumbing in a fuel pressue gauge in the engine comp, see what it is reading. I don't know what it is supposed to be, but a Chiltons or Haynes Manual will have that info.It is idling cold allright cause it is programmed to run rich when idling cold, but when the system reverts to normal operating temp, the fuel mixture is too lean.
     
  6. rick88blaze

    rick88blaze 1/2 ton status

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    88sub4x4: What do you mean leaking? They aren't leaking onto the intake manifold or anything.

    3 on the tree: It does have an in tank fuel pump. I doubled checked the lines yesterday and they are all straight. I'll try to get a gauge and plumb it in and see what pressure I'm getting.

    I'll keep messing with it. I'll let you guys know what I find out on it. If anyone else has any suggestions, I'm open for all of them. :thumb:

    Thanks,

    Rick

    Oh yeah, I forgot to mention that sometimes when it acts like it's getting ready to die, it will "catch" itself and the RPM's will shoot up pretty high, then it will come back down to idle. That tells me that it's probably a vacuum problem. Please correct me if I'm wrong.
     
    Last edited: Oct 15, 2005
  7. rick88blaze

    rick88blaze 1/2 ton status

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    TTT Trying to get this fixed this weekend!!! :bow: :bow:
     
  8. diesel4me

    diesel4me 1 ton status Premium Member

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    maybe...

    EGR valve??...sticking open?? :dunno: ..could be a vacuum leak too..I've seen a lot of crank sensors crap out on those 4.0's too..but diagnose,don't buy a lot of costly parts for nothing.. :crazy:
     
  9. kick

    kick 1/2 ton status

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    sounds like a bad plug. Could you have cracked the ceramic part on the install ? Also you may have knocked loose or cracked a vacumn line on the plug change.
     
  10. rick88blaze

    rick88blaze 1/2 ton status

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    I am pretty sure that you are dead on. I just got done messing with the Jeep and it was running just fine until I messed with the EGR valve. As soon as I moved it by hand, the engine started doing the same crap it was before. Now I just have to shell out $118 when I get it to get it fixed. :D

    Thanks to everyone for their help!!! :bow: :bow:

    Rick
     
  11. 88sub4x4

    88sub4x4 1/2 ton status

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    Glad to hear you fugured it out.
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    EGR== Expensive Godamm Valve!!

    My friend works on lots of those 4.0 's in Cherokees--they are extremely popular around here...he said those 3 things are the most common parts to fail on those motors..other than that,they seem to run a long time without too many problems..

    He goes to the boneyard if he needs a "cheap" alternative,when the customer can't afford a brand new part..he's lucky in the fact there are 3 of them close by,and will gaurantee it to work for at least 30 days--they usually charge 20-30 bucks for something like an EGR valve that would go for 100 or more new..nothing wrong with "good used" parts!..(might want to be sure its the valve itself,and not the vacuum switch or electric solenoid that tells it when to open first!--maybe taking it off and cleaning out the carbon build up might cure it too--you might get lucky!)... :crazy:
     
  13. rick88blaze

    rick88blaze 1/2 ton status

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    No sh!t they're expensive. I'll try cleaning mine out to see if that helps. The parts stores around here want $120 for them. I'm going to the local U-pull it next weekend and pulling one off with the valve. Now I've got a problem with my wife's van. I'll put that in another thread though. :D :D

    Rick
     
  14. rick88blaze

    rick88blaze 1/2 ton status

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