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1985 GMC Jimmy Fuel injection?

Discussion in 'The Garage' started by mnstrbetle, Jul 14, 2005.

  1. mnstrbetle

    mnstrbetle Registered Member

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    Hello everyone, great website that you all have here, I'm proud to be a member!! :bow:

    Here's my dilema, I have a 1985 Full Size GMC Jimmy. I just changed the fuel tank and now about a week or two later the Jimmy has decided to start acting up on me. It quit three times on my way home from work yesterday and this morning it quit twice and then left me stranded along side of the road and wouldn't start back up. It started right back up every time it quit, except for the last time it quit on me. I was going to change the fuel pump that is inside the tank when I changed the tank but decided to 'roll the dice' and never changed the fuel pump that is in the tank...I know, I know, I broke a cardinal rule when changing a fuel tank, always install a new pump when changing the fuel tank, but I didn't. So now, I'm at work and I'm calling around for a new fuel pump for my fuel injected 1985 GMC Jimmy and I've had two parts stores tell me that they never made a fuel injected Jimmy in 1985?!?! Does anyone know if there was infact a fuel injected Jimmy in 1985 or do I have some sort of rare Jimmy? What do I do? Where do I go from here?

    Thanks for your help, I really appreciate it!!
     
  2. 6.2Blazer

    6.2Blazer 1/2 ton status

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    From my understanding FI was introduced until '87.
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Someone has done some mods to your Jimmy. Fuel injection wasn't available until 1987. Your truck left the factory with a 305 or 350 and a 4 barrel carb. Unless it was a diesel... ;)
     
  4. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    i just junked a 1985 gmc jimmy..... stipped it of course for what I neede...
    and it had a carb.. knew I forgot something.. to take that, alt, starter :doah:
     
  5. mnstrbetle

    mnstrbetle Registered Member

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    Wow, I guess I'll have to get a fuel pump for a 1987 then. I know that when I bought this Jimmy the owner told me that the original owner changed the motor from a 305 to a 350, he also had a new tranny installed and a new rear end. As far as I can tell the transmission is the 700r automatic four speed with overdrive and the rear end is definately a limited slip, but he never mentioned anything about a fuel injection swap?!?! :doah:

    Why on earth would someone go through all the hasle of putting fuel injection on a vehicle that wasn't originally intended for it? Just seems like alot of work. Wouldn't all the lines to the tank have to be changed? Wouldn't a brain/computer need to be installed? Wouldn't the sending unit need to be changed?

    Does the carbureted Jimmy have the fuel pump in the tank as well?

    Can I get away with just installing a universal electric fuel pump somewhere in the line without having to remove the gas tank?

    OMG!! So many questions!! Sorry guys!
     
  6. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    Alot of us have installed fuel injection on our older K5s. It takes about a day to do if you have all the parts. I like FI for offroading, better angles and throttle response. A new tank sender from advance, checkers, etc. will run you around $220 IIRC. You can run an inline factory pump that came on the camaros, I think the napa # was 5001 and about $150 but you don't have to drop the tank.

    Are you sure you haven't kinked one of the lines at the tank. I know I did this when I replaced a tank once.
     
  7. gone huntin

    gone huntin 1/2 ton status Premium Member

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    Carb'd fuel pumps were mechanical and mounted on the passenger front of the engine. They were driven by the camshaft. Just curious, is your engine TBI, or MPFI? Also, what did your donor tank come out of (year)?
     
  8. mnstrbetle

    mnstrbetle Registered Member

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    Well, I got the darn thing running. After towing it home I started and ran for just a minute. I got to looking around the fuel tank and tapped on the side of it with a small rock and it sounded awful empty...so I put about two gallons of gas in it and it seemed to run fine. I put 5 more gallons in it and drove it around my road for a little while untill I gianed the courage to drive it all the way to the gas station. Aparently this was just an expensive way to find out that the darn thing had run out of gas!! :mad: If I had known that it was just out of gas I would have never paid 62 bucks to have it towed home! Aparently the sending unit is readin incorectly now and I will have to start filling it up at around a quarter tank. Oh well, it could have been worse.

    This still doesn't explain why my 85 is fuel injected though. I've been all over everything oin this Jimmy and everything looks factory right down to the black zip ties and the black fabric tape on the wire harness. I can only assume that the truck was totalled and re-titled as a 1985. Just seems funny that someone would re-title it as an older vehicle. I know that it has been in a fron end accident at one time because there isn't a panel or fender that matches in color and nothing lines up so someone just slapped it together at one point.

    I did replace the fuel filter this last weekend and I ordered the new one for a 1987 and it fit just perfectly...so I guess I'll just have to order my fuel parts for a 1987 or take them off first and have them matched up at the parts store. :doah:

    Thanks alot for the help!! Someone had asked about the fuel injection system and the donor tank. The fuel injection is a throttle body, and the fuel tank that I just put in it a few weeks ago was brand new. I don't like to use used parts if I can get away with it and if i'm going to go through all the hassle to drop a fuel tank the replacement will be new!!
    Thanks guys!!
     
  9. RootBreaker

    RootBreaker 3/4 ton status Premium Member

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    glad you got it working...

    I am a true redneck... used parts is my middle name.... used eldorado calipers for rear disc swap (then traded them in due to pistons rusty but mainly needed the springs and levers), radiators, d60 front (try pricing a new one of them!!!! some parts are good used and some arent...

    also chevy tanks are known to be inaccurate... hell my 1996 camaro.. I can drive 120miles then the gauge reads 3/4 full... drive t0 250 and it is on 1/2... then she drops like a rock....!!!!!!

    I think the way it works is that it reads from the bottom of the tank to the top so e to f... but doesnt take in consideration any thickness differences..

    think of it this way.. if you look at a triangle... the top is pointier and would hold less gas than the bottom.... this has always been my pet peeve... why can they get the tanks accurate... if I have 1/2 tank left I should be able to say.. ok 15.5 gallon tank - 7 3/4 gallons left... but no :doah:
     
  10. mnstrbetle

    mnstrbetle Registered Member

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    Well, the truck ran out of gas and the guage on my dash read over an eighth of a tank. When I got it home I put the two gallons in it, ran it for a little bit then i put five more gallons in it and it read just a hair over a half of a tank. That's when I started getting that fishy feeling about what goes on inside my new tank becuase seven gallons doesn't make a 31 gallon tank half full! But the real kicker was when I decided that it was safe to venture away from the house...I took it to the gas station and the fuel guage read just over a half a tank. Once I got it full the gas pump said that it took 24 gallons to fill it. So now I'm sure that my problem lies within the sending unit...I doubt that I will fix it though, I'll just fill it when it hits a quarter tank :D

    I'm starting to think that a trap door in the floor right above the fuel tank may prove beneficial!!
     
  11. mnstrbetle

    mnstrbetle Registered Member

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    I know what ya mean abou the used parts theory. There are some things that ya just can't get away from. But when it comes to brakes and fuel related stuff I really like to use new parts. I had to replace the upper left shock mount on my Jimmy last month and I contacted a local Chevy dealer and he told me that he can't get that part anymore because they no longer carry it :eek1: I had to call a local salvage yard and they said that it was only going to be like five bucks for the mount...so that's all cool right? After that was all said and done it cost me 25 dollars for them to torch off my five dollar part!
     

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