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Unread 05-18-2012, 09:05 AM   #1
bluedaffy
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1989 YJ Wrangler 
 
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Location: Stevens Point, Wisconsin
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Ways to restrict fuel pressure?

I have a weber 32/36 that is showing all the signs of running rich from gas bypassing the needle and seat. I have checked the needle (rubber type) and seat many times and the function appears to be clean and promising, but yet the bowl overfills.

I have the return line hooked up on my fuel filter (12 o'clock position) and the return line is clear, but I'm still getting too much pressure at the carb.

Can I drill out the return line to allow more flow back to the tank?
Is there a way to use two fuel filters to reduce the pressure?
Is there a replacement fuel filter that has a larger return opening?


I know that I could probably get a fpr, but I don't want to add another thing that can go bad, when I could plumb something manually.

Evan

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Unread 05-18-2012, 09:16 AM   #2
skyj
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Quote:
Originally Posted by bluedaffy
I have a weber 32/36 that is showing all the signs of running rich from gas bypassing the needle and seat. I have checked the needle (rubber type) and seat many times and the function appears to be clean and promising, but yet the bowl overfills.

I have the return line hooked up on my fuel filter (12 o'clock position) and the return line is clear, but I'm still getting too much pressure at the carb.

Can I drill out the return line to allow more flow back to the tank?
Is there a way to use two fuel filters to reduce the pressure?
Is there a replacement fuel filter that has a larger return opening?

I know that I could probably get a fpr, but I don't want to add another thing that can go bad, when I could plumb something manually.

Evan
I just use a fuel pressure regulator. I've had it for 3 years and no problems. It works great, and its just a cheapo Mr gasket one.
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Unread 05-18-2012, 09:24 AM   #3
superj
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Have you put a gauge to actually see what pressure is at the carb?
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Unread 05-18-2012, 09:52 AM   #4
bluedaffy
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No I haven't superj. I have a vacuum tester that says was advertised to be a vacuum and fuel gauge. I suppose this would work, I'm just not sure how to safely do that.
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Unread 05-18-2012, 09:58 AM   #5
bluedaffy
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The only reason I'm blaming fuel pressure at this point is because I don't know of anything else that can overfill the bowl other than needle/seat operation, but I am a newbie with carbs and I'm all ears if you have any ideas.
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Unread 05-18-2012, 10:23 AM   #6
Jeepsr4me
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Quote:
Originally Posted by superj View Post
Have you put a gauge to actually see what pressure is at the carb?
This 1st... Stop not knowing. Know what pressure you got.
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Unread 05-18-2012, 10:24 AM   #7
Jeepsr4me
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Quote:
Originally Posted by bluedaffy View Post
The only reason I'm blaming fuel pressure at this point is because I don't know of anything else that can overfill the bowl other than needle/seat operation, but I am a newbie with carbs and I'm all ears if you have any ideas.
A bad float can do it............
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Unread 05-18-2012, 10:38 AM   #8
Jax89Jeeper
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If tou are still on the mech pump, you should be running at 4 or 5 psi at the carb inlet... This is too much for the Weber which doesn't like more than 3 psi. If your float is all good, try a fuel pres. reg and that should fix the issue.
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Unread 05-18-2012, 10:47 AM   #9
bluedaffy
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If by "bad float you are referring to a cracked one, or one that is somehow allowing fuel into the float, then no, the float is fine.

Jax89Jeeper, I have read that the weber likes anything up to 3.5 psi. Could 4 or 5 really be enough to overpower the needle/seat? And no, that wasn't sarcastic, I'm actually quite curious.

For a quick test to see if too much pressure is the problem could I just use a pair of pliers and pinch the fuel line going into the inlet of the carb and see if my idle smoothes out? Would that give me an accurate idea?

Thanks all!
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Unread 05-18-2012, 10:55 AM   #10
Jax89Jeeper
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Quote:
Originally Posted by bluedaffy
If by "bad float you are referring to a cracked one, or one that is somehow allowing fuel into the float, then no, the float is fine.

Jax89Jeeper, I have read that the weber likes anything up to 3.5 psi. Could 4 or 5 really be enough to overpower the needle/seat? And no, that wasn't sarcastic, I'm actually quite curious.

For a quick test to see if too much pressure is the problem could I just use a pair of pliers and pinch the fuel line going into the inlet of the carb and see if my idle smoothes out? Would that give me an accurate idea?

Thanks all!
A bad float could be cracked or sticking or out of adjustment... And yes 4 or 5 could really over power the carb inlet to the bowl. You are 30-50% over the spec the carb was designed to handle. This is a common issue when installing a Weber. If you already have the fuel pres./vac gage it is perfectly safe to follow the instructions and hook the gage up to the fuel line. Again, a good mech pump will read 4-5 psi.
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Unread 05-18-2012, 10:59 AM   #11
Jeepsr4me
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Floats need adjustment, they also can be bad as in cracked. All that will cause a raise in the needle and allow too much fuel in.
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Unread 05-18-2012, 11:06 AM   #12
bluedaffy
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Good to know! I don't know why, but I thought a little bit over 3.5 wouldn't affect things.

Now to test the fuel pressure with my gauge... How exactly would I go about doing that safely?
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Unread 05-18-2012, 11:07 AM   #13
bluedaffy
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I thought when the needle "raises" that is when it seats and does NOT let fuel in. Am I wrong on that?
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Unread 05-18-2012, 11:31 AM   #14
bluedaffy
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Okay, so I figured out how to measure the fuel pressure by doing some internet searches. You guys were right about making sure that was all in line, because it was bouncing between 1-2 psi which I think is normal because it's a mechanical pump. I measured after the fuel filter, basically taking the fuel line off the carb inlet and hooking the gauge up to that line.

Well then what could it be? The float isn't letting fuel in, and the needle and seat are absolutely clean...
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Unread 05-18-2012, 11:50 AM   #15
Jax89Jeeper
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What brand is the vac gage? Are you sure it is accurate? The results don't match the problem you are having with the carb, but could point back to the needle not seating on the carb showing a float or seal issue.
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fuel filler , fuel pressure , fuel pressure regulator , weber
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