CJ-7, 4.2L. Ran Out of Gas and Now Won't Run?!?!... - Page 2 - JeepForum.com

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post #16 of 34 Old 01-27-2013, 08:54 PM
86cj74.2L
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It's called "2/3 carb better then none" by John Strenk.

Those were his fingers in the pictures.

If your taking it apart blow out all passages with carb cleaner. Remove the fuel screws and blow through them also.

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post #17 of 34 Old 01-27-2013, 09:03 PM Thread Starter
dvzant
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Quote:
Originally Posted by 86cj74.2L View Post
It's called "2/3 carb better then none" by John Strenk.

Those were his fingers in the pictures.

If your taking it apart blow out all passages with carb cleaner. Remove the fuel screws and blow through them also.
Found it, not sure why I didn't see it earlier... I'd like to think it's something other than user error.

That's pretty impressive.
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post #18 of 34 Old 01-27-2013, 09:50 PM
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Your fuel level similar to John's?
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post #19 of 34 Old 01-27-2013, 10:15 PM Thread Starter
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Originally Posted by 86cj74.2L View Post
Your fuel level similar to John's?
It was similar, a little lower. I'll check that a bit better tomorrow. I couldn't say if mine was actually lower as I probably squirted some of the fuel when I removed the upper half of the carb.
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post #20 of 34 Old 02-03-2013, 12:54 PM Thread Starter
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Ok, I finally had some time to tear down the carb. I cleaned everything but still won't run/idle.

Same as before, it will start and stay running as long as I'm pumping the gas to keep the RPMs above 2500'ish. Also, if I continually spray a small amount of starting fluid into the carb it will idle (1500'ish RPM) without me pumping the gas.

Are there any parts in the carb that could have failed to create this problem? All of the mechanical parts looked fine but I'm wondering about the electronic parts. Any suggestions?
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post #21 of 34 Old 02-03-2013, 03:51 PM
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Open your fuel screws 1 turn and see if idle improves.
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post #22 of 34 Old 02-03-2013, 04:05 PM Thread Starter
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Open your fuel screws 1 turn and see if idle improves.
I tried those at the very beginning (you mean the set screws on the outside of the carb, correct?)

When I have the pedal pressed and keep the RPMs well above the 2500 mark it will keep running. As I let off and the RPMs fall it will sputter and then die if I don't pump the gas to get the RPMs back up.
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post #23 of 34 Old 02-03-2013, 05:49 PM
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I mean the two idle mixture screws under the fuel inlet facing front of engine.
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post #24 of 34 Old 02-03-2013, 06:55 PM
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I've never run into this on my jeep, but my dad's truck (79 Chevy 305 with a Quadrajet) did something very similar one time. Out of the blue, it would not idle, had no power, and generally ran like, well, you know...

Anyway, we finally ruled out the carb and adjusted the timing, everything has been hunky-dory ever since.
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post #25 of 34 Old 02-03-2013, 08:48 PM
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On a BBD the fuel mixture screws should end up being between 2 1/2 and 3 1/2 turns out from all the way in with out any vacuum leaks.

Did you set the throttle needles correctly when you assembled the carb to ensure the needles track the throttle plates?

It's worth checking timing.
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post #26 of 34 Old 02-03-2013, 10:19 PM Thread Starter
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It was timed great but I can't even keep it running to check the timing now. I know I'll have to re-time it as I've moved the distributor to check to see if advancing it or retarding it might help.

I re-set the mixture screws and it didn't help. However, when I tore apart the carb I didn't remove the mixture screws. I will take the carb off again tomorrow and make sure there aren't any problems there.

I would have taken it to a mechanic by now if I wasn't so stubborn but I'm getting really close.
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post #27 of 34 Old 02-03-2013, 10:33 PM
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And you shot carb cleaner through the brass tubes in the Venturi cluster.

This is a odd problem.
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post #28 of 34 Old 02-04-2013, 04:14 AM
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I had this issue. it was the fuel pump. Had some flow but not enough at higher rpm and sometimes would work and sometimes starve the engine. Replaced it, engine idled perfectly
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post #29 of 34 Old 02-04-2013, 07:29 AM Thread Starter
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Quote:
Originally Posted by 86cj74.2L View Post
And you shot carb cleaner through the brass tubes in the Venturi cluster.

This is a odd problem.
I cleaned out the tubes with a thin wire and shot carb cleaner though them.


Quote:
Originally Posted by VooDoo2 View Post
I had this issue. it was the fuel pump. Had some flow but not enough at higher rpm and sometimes would work and sometimes starve the engine. Replaced it, engine idled perfectly
Within the past month or so I've replaced the fuel sending unit in the tank, the fuel pump (mechanical one), the fuel filter, and all of the flexible fuel lines from the tank to the carb. The carb itself was even completely rebuilt.

When I stand over the carb and pump the gas lever I can see the fuel coming out of the jets and there's never a lack of fuel when I'm doing that... It's only when it's trying to idle or even run at lower RPMs.
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post #30 of 34 Old 02-04-2013, 07:51 AM
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I like being able to monitor my fuel pressure, so I installed a cheap pressure gauge in-line to the carb. You should have at least 4 psi at idle.

Don't rule out a faulty fuel pump, even if it's new. I had a replacement pump from NAPA that was bad right out of the box.

Good luck,

Matt
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