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Discussion Starter · #1 ·
I've read the threads on hard to start, but not 100% sure where to mount it and in which direction. Will someone post a picture for me? Thanks...
 

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Attached is a couple pics of how I have mine.

I still haven't ordered the aluminum check valve. I drive my Jeep most days so the hard start isn't an issue for me.

The arrow points in the direction of flow (toward the gas tank).

Hopefully this helps.

Good Luck, L.M.
 

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Discussion Starter · #3 ·
LM,

Really appreciate the pictures. Here is where I'm struggling a bit on this one. If the fuel is running back from the carb bowl into the filter and back to tank causing the issue, why would we not put the check valve between the filter and carb as a one way in with arrow toward carb? I haven't grasp this one yet. Maybe I'm just being thick headed, thanks again.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Great Question, I would like to know same thing.

Since L.M. did the research on the valve and it requires some amount of pressure to open, his model was like .3 psi,. My guess would be that in essence the valve acts as a pressure regulator of sorts and would hinder the flow into the bowl?

I'm actually having an opposite issue mine starts right up cold with the choke, but stutters and stumbles until I put my foot into the pedal or upshift to increase the load on the motor, Just started when the temps went from 70 to 100 outside. Gonna start a new thread on that before I start tweaking anything.
 

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What started the check valve thing was that one forum member (I don't remember who) noticed that in the exploded view of the fuel filter system, that there is a check valve between the fuel filter vent hose and the metal line that runs back to the gas tank.
Look close at the diagram.

We surmised that through the years, when a PO changed the fuel filter and fuel filter hoses, that the check valve inadvertently was discarded.
The question was "Why did the engineers place a check valve there"?

I don't know the mechanics or the engineering behind why the check valve was/is supposed to be there. Once I installed the check valve the problem of hard start after a few days went away for a long time.

The fuel filter diagram shows the vent tube on the bottom. The text says to have it at the top. The general wisdom is that the vent should be at the top. I took the pics in post #2 prior to turning my vent to the top.

What I think happens is that if there is no check valve that gravity starts a siphoning action that sucks the fuel from the filter and then from the carburetor bowl until the fuel bowl is empty. Even the .3 lbs. of resistance of the check valve prevents the siphoning from starting.
If the check valve was between the fuel filter and the carb, the siphoning action could still drain the fuel filter, causing an interruption in fuel flow as the engine starts and the fuel pump has to fill the filter.

DISCLAIMER!!! I'm not an engineer nor a mechanic. I haven't even ever played one on TV. The advice I give on this forum is from what I have heard from other forum members or from my own experience. I always try to be as clear as possible when making any statements and as accurate as possible when offering advice.
I've been proven wrong at times, so take what you can use and ignore what seems foolish.

Good Luck to all, L.M.

P.S. Got it at last....What is your timing set at and are you sure that the vacuum hose to your distributor advance is operational?
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Good Luck to all, L.M.

P.S. Got it at last....What is your timing set at and are you sure that the vacuum hose to your distributor advance is operational?

Holiday weekends keep me working 7/24 so I haven't had time to investigate fully. I usually try to have a little more info handy.

I just threw the light on it right now and cold it is at 7* at 600 rpm's Haven't adjusted it since I did the HEI and Carb in Dec. Vacuum advance seems to be working fine. Timing mark rolls right up the balancer when I bump the accelerator over 1000 rpm. I broke the vacuum line going into the cab for the vent door, but capped it off, almost all other vacuum lines are gone. Not a whole lot left to play with.
 

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A new thread is a good idea. FYI, I'm running a non-stepper carb and HEI.

I have my timing set at 10* (or 12*, I don't remember exactly).

Good Luck, L.M.
 
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