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Thread: Jet Valve elimination kit

  1. #1

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    Jet Valve elimination kit

    I can see 'in theory' why this is recommended by the users here. But how would this benefit me in particular?

    My truck is my daily driver, has been for 24 years. So (hopefully) there is someone here who has done this and I can determine if the 50.00 kit is worth it. So what I'm looking for is someone who can give me the "before and after" so to speak.

    There are three things that I hope to eliminate as a result of this operation. (In order of importance to me.)

    1) Excessive run on or dieseling after it is warmed up and then shut off. As it stands right now, I have to pop the clutch to fully kill the motor. I use 5th gear to lessen the shock on the drive train. But dang it I just want to turn the key off like any other car.

    2) Not as important, is an elimination of the surging that can turn up at times at very low vehicle speeds in 1st or 2nd gear. The vehicle is in a correct state of tune, so throwing parts at it will probably not change a thing. Some instances are worse than others, but in the heat of the driving moment, the only way to stop it is to engage the clutch or floor it.

    3) Of lesser importance still, is the elimination of spark knocking. It has done this since day one, best I can remember. (The Weber install did not affect this phenomenum at all.) At 344,000 miles on the original engine, I'm not worried about engine damage, but none the less, I'd would rather it didn't do it. Retarding the timing really doesn't change anything.

    Part II-

    I read a lot of talk about retrofitting an electric pump with a Weber carb retrofit. I never did that when I went to a Weber. I am still running the mechanical factory pump that is mounted to the cylinder head. The Weber does not require more fuel volume or pressure than the factory pump can provide, so what's the point? Thinking out loud here, but could that be part of the problem on the surging? I also "get" why folks go to electric pumps, but if the mechanical factory pumps are up to the task...???...???

    Background information-

    I bought this truck brand new. I had never planned on keeping it this long, but the way it all played out in my life, I ended up still having it. At this point, I look at it as an exercise in "automotive longevity".

    In general, the longevity of the factory components has spoiled me so to speak. The factory parts are extremely slow in wearing out, and that has led to me having a strong "if it ain't broke, don't fix it" attitude on my part. This is why last year was the first time the valve stem seals were replaced. The oil consumption was cut in half and the tailpipe smoking was eliminated altogether. (It will use a quart of oil every 1000-1200 miles now and I believe approximately half of that consumption is due to an oil leak at the rear main seal caused by age/mileage.)

    All of the smog shit is gone with the exception of the cat. Truck is old enough to be emissions exempt in my state.

    I am not interested in increasing the performance on it. Never was, and never will be. It won't pull a greasy string out of a cat's ass, and I'm OK with that. I am on disability due to health reasons, don't work, and now drive no more than about 3000 miles per year. If money was no object or fell out of the sky, I would make a hot rod out of it with a motor swap, but that prolly won't happen.

    The vehicle is a 1988 Mitsubishi MM SPX. 2.6L 5 speed 344,000 miles. See the pics that were taken last week. Any input is always appreciated.




  2. #2



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    I'm thinking your run on and surging are atleast partially related to the fuel pump. The stock pump puts out 5-6psi I think it is and the weber only wants ~3psi so that's why people go to an electric with a pressure regulator.
    Josh
    09 BMW 335i E92 Twin turbo
    89 Macrocab 4g63 Turbo swapped & Bagged: Build Thread

  3. #3

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    Quote Originally Posted by DroppedMitsu View Post
    I'm thinking your run on and surging are atleast partially related to the fuel pump. The stock pump puts out 5-6psi I think it is and the weber only wants ~3psi so that's why people go to an electric with a pressure regulator.
    I get what your saying, but the run on problem only started right after the Weber install. It never did it until the the Weber was on. I understood it was because the factory setup had mechanisms in place (in the carb mainly) that completely shut off fuel delivery to the intake when the key was turned off. Automatic fuel shut off when the key was turned off in other words.

    But you may be on to something. So is the factory fuel pump delivering too much pressure?

    I was not aware that the factory mechanical pump could be delivering too much fuel pressure. Is that what you are saying?

  4. #4



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    Yes it is putting out too much pressure. 5-6 psi instead of the recommended 3 for a Weber
    Josh
    09 BMW 335i E92 Twin turbo
    89 Macrocab 4g63 Turbo swapped & Bagged: Build Thread

  5. #5

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    I have an 84 power ram 50 2.6 and have the weber install with an aftermarket mechanical fuel pump. It deiseled until I put a 5 dollar fuel regulator set to 2 1/2 pounds as the weber instructions called for 2. The deiseling dropped a good 60% and now only happens after I sit in tacoma WA traffic and then shut it off at school. MIght just be caused from the extra fuel in the motor.

  6. #6



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    the stock pump is more like 9-13 psi and putting a regulator inline with it now will kill the pump due to excessive back pressure. There are 2 ways to deal with it - 1 is to go electric or 2 is to use a regulator. However, there are 2 ways to run a regulator - inline or in a t configuration. If you put a t in the line to the carb, then put the reg off the center of the t and install a 2nd t in the fuel tank return line, it will bleed off the excess fuel pressure without backpressuring the pump and also won't act as a restriction to fuel flow at WOT. its the same as a fancy reg with bleed off without the price
    Pennyman1
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    Living the D-50 lifestyle since 1980

  7. #7

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    I'm sure glad you told me that!

  8. #8

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    Quote Originally Posted by pennyman1 View Post
    the stock pump is more like 9-13 psi and putting a regulator inline with it now will kill the pump due to excessive back pressure. There are 2 ways to deal with it - 1 is to go electric or 2 is to use a regulator. However, there are 2 ways to run a regulator - inline or in a t configuration. If you put a t in the line to the carb, then put the reg off the center of the t and install a 2nd t in the fuel tank return line, it will bleed off the excess fuel pressure without backpressuring the pump and also won't act as a restriction to fuel flow at WOT. its the same as a fancy reg with bleed off without the price
    Hmmm...reading all this has convinced me I should have an electric pump with a regulator. Now I have to decide if I want to spend the money on it. Is there a way to do it w/o spending more than a hundred bucks or so? Bear in mind I don't half-ass shit. (But I may have back in the day)...LOL

    I had just blocked off the vapor hose to the canister and as far as I can remember there is no return line to the tank anymore either. I think I just blocked that one off too...*self face palm*

    Hmmmmmm......

  9. #9


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    There is also an idle cut off available from Weber. Runs off 12 volts, screws into the side of the carb in place of a jet. Don't have apart number handy but a Weber shop should be able to find it.

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