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Tbi Update!!!

Discussion in 'The Garage' started by southernspeed, Sep 13, 2005.

  1. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    UPDATE. ...Thoughts?
    I've just checked the fuel filter...clean as a whistle.
    My crappy Summit fuel guage in-line just before the throttle body was reading 11 psi until i reved it up and it dropped to 3psi. Not trusting it I put a Snap On gauge on it and it reads 12 all the time idle or 5000rpm. When hot after 5 mins of hard driving it still read 12psi but was 'fluttering' a bit but still constant. I gave it quite a hard drive and all seems well! Which is a PIA as I haven't done anything so it could come back at any time :mad: .
    So was I just unlucky and the FPR stuck for a bit? TPS or MAP had a mad moment? I wouldn't have thought they have 'off' moments....thought that was just women!! :rolleyes:
    Any thoughts gratefully recieved!

    The '90 tbi motor in my '78 has just starting acting like it's getting real bad fuel starvasion. I just had to drive it home on a very light throttle and low revs. Try to open it up a bit and it just dies and bogs down, sounds like the motor actually cuts for a moment. As soon as the revs drop it picks up again. No popping or banging so it seems very fuel related rather than electical.
    Too busy at work to look right now but I'll check the fuel filter and lines as soon as poss but has anyone else had this or can suggest other sensors that might make it do this?
    Everything is new inc. in-line pump, filter, hoses and a rebuilt TB unit.
    Maybe my tank is just so rotten inside it's fouled up the new filter already!!
    Any suggestions? Thanks.
     
    Last edited: Sep 17, 2005
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    Sounds like similar problems that a friend of mine was having with his 97 Tahoe. Ended up being a fuel pump. Actually he is on his 3rd new pump! The last time he thoroughly cleaned out his tank and found a ton of junk in the bottom. Even plastic shavings from when the tank was made!

    His truck ran great from idle to about 2k rpm. Then it had no power and wanted to die until he let off.
     
  3. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I'd also say fuel pump :)

    They can be a real pain in the butt!
     
  4. HarryH3

    HarryH3 1 ton status Author

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    I had that happen once from a crap tank of gas. Truck wouldn't even keep up with traffic on the highway. I was on a long road trip, so I just stopped and swapped in a new fuel filter, but no help. When it got down to about 1/3 of a tank I filled up again and the problem was gone within half a mile. :doah:

    Don't throw an expensive fuel pump at it unless you're sure that's the problem... :cool1:
     
  5. 4xcrazy

    4xcrazy 3/4 ton status

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    ditto, sounds EXACTLY like what mine did when the pump died, kept throwing false codes too,,,really sucked, i drove it home from San Diego,CA to Phoenix like that. :crazy:
     
  6. jekquistk5

    jekquistk5 Weld nekid Premium Member GMOTM Winner

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    My car did this but it was the spark plugs and wires. I thought it was gas, but just wires and plugs
     
  7. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    OK thanks guys. I'm kinda leaning toward a fuel delivery problem of some sort. It's a Turbo City external pump with an aluminum bodied filter inline just before it. I'll check out the filter first. Not sure how I can check the pump really as checking FP at the TB unit could indicate a bad FPR if it's low. The FPR is a new Jet adjustable one so that should be ok anyway, mind you, the pump and filter are new so hopefully it'll be a clogged filter. I'll check it out this weekend if I can get some of this work cleared out before I go on holiday! :doah:
     
  8. Thunder

    Thunder 3/4 ton status

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    If the filter dosn't fix it. Check the TPS. It could have gone bad. Check for trouble codes. Do you have a scanner?
     
  9. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I've got Winaldl and EFIlive so I can use those. It didn't throw any codes at the time but I haven't put a scanner on it yet. TPS...good idea, thanks.
     
  10. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    UPDATE. ...Thoughts?
    I've just checked the fuel filter...clean as a whistle.
    My crappy Summit fuel guage in-line just before the throttle body was reading 11 psi until i reved it up and it dropped to 3psi. Not trusting it I put a Snap On gauge on it and it reads 12 all the time idle or 5000rpm. When hot after 5 mins of hard driving it still read 12psi but was 'fluttering' a bit but still constant. I gave it quite a hard drive and all seems well! Which is a PIA as I haven't done anything so it could come back at any time :mad: .
    So was I just unlucky and the FPR stuck for a bit? TPS or MAP had a mad moment? I wouldn't have thought they have 'off' moments....thought that was just women!! :rolleyes:
    Any thoughts gratefully recieved!
     
  11. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    what regulator are you running?
     
  12. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Jet adjustable.
     
  13. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    i wonder if it was sticking...
     
  14. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I was thinking that too but it would seem unusual. There's not much to stick really. It's all new and the fuel filter was clean so no dirt could have gotten thru there. Odd. Can't think of anything else though. I've been considering getting a vaccum ref FPR (just surfing for one now) so I may change it anyway. I'm going away for a week in my '91 so hopefully I can get one ordered and it'll be here for when I return (as long as I can find someone who sells overseas! GMPartsdirect have them but won't ship overseas or take my c/card!)
     
  15. blazerguy 90

    blazerguy 90 1/2 ton status

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    It could be the coolant temperature sensor, that would cause the problems your having.
     
  16. mouse

    mouse 1/2 ton status

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    Any possibility of fuel starvation from low fuel level in an un-baffeled tank?
     
  17. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    LOL....no, I put £90 worth of gas in shortly before it went really bad, but it did it a bit before I put the gas in.
     
  18. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Checked that, it's fine thanks.
     
  19. 1979jimmy350

    1979jimmy350 1/2 ton status

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    do you have enough chip for the cam. I put i TBI setup on my friends blazer which had a bigger stock cam and it would pop and cut out like crazy
     
  20. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I've got about 450 miles on this set up now and it's been fine. And it's fine again now. It shift so hard at 5000rpm I'm worried I'm going to break something!!! No, this is some kind of fuel delivery glitch.
     

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