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93 4.3 Want Run. Need Help.

This is a discussion on 93 4.3 Want Run. Need Help. within the General Help forums, part of the LSx Technical Help Section category; I have a 93 4.3 gmc Jimmy that will idle, but want let you open the thottle up on it.last ...

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    Question 93 4.3 Want Run. Need Help.

    I have a 93 4.3 gmc Jimmy that will idle, but want let you open the thottle up on it.last year I changed the tuneport injector under the intake and it has ran good up until now.only the problem was there was too much gas being dumped and it had the plugs foul with gas.now I have not enough gas feeding the engine.I changed the fuel filter thinking that was the problem but it wasn't.I checked the fuel pressure and it had 55lbs of pressure, but was I told that wasn't enough,so I installed another pump and it to have about 58lbs, still the same problem.Do anyone know anything about these engines? I can spray gas or carb cleaner in the thottle while opening the thottle and it will run, but once the spray stops it goes back to straving for gas when you open the thottle on it. can it be the tunesport again only going something different this time? I am leaning toward the tunesport. what do you all think.

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    Moderator Cutlass's Avatar
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    Hey I'm familiar with this setup. Its a 4.3 'W' isn't it? Its called a CPI or central port injector or the spider. They like to leak gas into the engine as you experienced. Yes this setup is extremely sensitive to fuel pressure, but I think you are ok with 58 at idle. The pressure should increase when you open the throttle quickly. Its should go up into the 60 to 61 psi range. If it doesn't then the fuel pressure regulator is bad. It can be replaced seperate from the CPI.

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    Quote Originally Posted by Cutlass View Post
    Hey I'm familiar with this setup. Its a 4.3 'W' isn't it? Its called a CPI or central port injector or the spider. They like to leak gas into the engine as you experienced. Yes this setup is extremely sensitive to fuel pressure, but I think you are ok with 58 at idle. The pressure should increase when you open the throttle quickly. Its should go up into the 60 to 61 psi range. If it doesn't then the fuel pressure regulator is bad. It can be replaced seperate from the CPI.
    Thank you for the info,I tried to find a regulator for this engine but everyone tells me there isn't one on this engine, I have the intake off now and I have a free replacemet on the setup, so I will be getting the whole thing.Yes this is a Wcode engine. Seems to me you have had some dealings with this setup also.Once again thanks for the help,I fell better now about putting it back together with some good results.

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    Quote Originally Posted by Cutlass View Post
    Hey I'm familiar with this setup. Its a 4.3 'W' isn't it? Its called a CPI or central port injector or the spider. They like to leak gas into the engine as you experienced. Yes this setup is extremely sensitive to fuel pressure, but I think you are ok with 58 at idle. The pressure should increase when you open the throttle quickly. Its should go up into the 60 to 61 psi range. If it doesn't then the fuel pressure regulator is bad. It can be replaced seperate from the CPI.
    I agree.....I have a 4.3 in my zr2 truck. Usually if that spider starts leaking it'll wash the inside of the intake walls down in gas. Those spiders are notorious for leaking. Was the first one you put in a new unit or a junkyard unit? Let us know what you find out. Another thing to watch for on those trucks is the distributor cap mounting points. Everything is plastic and the distributor cracks really easy if you overtighten the cap when putting it on then it'll let moisture in and develope a miss when it's wet out. Ran into that a few years ago.....ruined 2 of them and they're pretty damn expensive if I remember correctly.
    Last edited by 0rion; 05-10-2008 at 12:46 PM.

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    Thanks to all that helped me get the the truck back running right.It was the regulator, but like I stated I had a free replacement on the tunesport setup so I replaced the hold thing and now it's back to it's old self. Once again thanks.

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    Veteran 0rion's Avatar
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    Quote Originally Posted by Street Fighter View Post
    Thanks to all that helped me get the the truck back running right.It was the regulator, but like I stated I had a free replacement on the tunesport setup so I replaced the hold thing and now it's back to it's old self. Once again thanks.
    glad to hear it..... have you had the lower intake coolant leak yet? 4.3's are known for that too. I pulled my intake and did that gasket last year.

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    Quote Originally Posted by 0rion View Post
    glad to hear it..... have you had the lower intake coolant leak yet? 4.3's are known for that too. I pulled my intake and did that gasket last year.
    Did it last year when I did the tunesport.From what I see all of the newer GM cars and trucks have the same problem with the intake leaking coolant. Have a nice day.

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