| [ Total Views: 629 | Total Replies: 11 | Thread Id: 85002 ] |
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 lauzboy
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| posted on July 25th, 2010 at 03:53 PM |
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aux venturis at idle
Ive got a Weber 32/36 DFEV and i cant get it to idle properly. Its been surging high and low on idle. When i look down the throats at idle, i can see
the aux venturi is spraying fuel out. Ive adjusted my float levels higher and lower but it doesnt seem to be affecting this. Ive now reset it to the
original
What else would be causing this to happen? Suggestions on how to fix this
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vlad01
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| posted on July 25th, 2010 at 05:33 PM |
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yeah that can be to high float or leaking float valve/seat.
fuel is no suppose to come out of there at idle. Also idle air set to high will do that, to high fuel pressure.
about all I can think of? I got more experience with EFI though.
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Sides
A.k.a.: Dave Sidery
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| posted on July 25th, 2010 at 05:38 PM |
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What fuel pressure are you running ???
Don't know about 32/36 DFEV specifically, but in generall Weber's don't like more than about 3.5 PSI.
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 matberry
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| posted on July 25th, 2010 at 06:10 PM |
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Yep, check fuel pressure.
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General_Failure
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| posted on July 25th, 2010 at 07:26 PM |
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I don't remember having an alternate username  I'm having the exact
same problem, but have been chiseling away at it.
My rough progression was like this:
Fuel regulator malfunctioned.
I took the top off the carb.
needle and seat malfunctioned.
discovered jetting was wrong.
Checked all the jets but the inside of teh carb is squeaky clean.
replaced needle and seat.
checked runner manifold flanges for trueness.
flattened manifold flanges.
Now I'm up to replacing a couple of the jets. Removed most of the over rich condition, but the hunting idle remains which is a bummer. I haven't
looked down the top of the carb while it's running yet.
The hunting idle didn't happen before the regulator issue. the power valve diaphragm seems to be fine. If the jetting doesn't fix it I'm officially
stumped. There is nothing left.
I have mine running a lot better as a result, but the idle is still wrong. If you make progress OP, say what you did!
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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lauzboy
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| posted on July 25th, 2010 at 11:52 PM |
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im using a stock mechanical type fuel pump. without a gauge, i guess the only thing i can do is check the max pushrod height. any other suggestions?
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Sides
A.k.a.: Dave Sidery
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| posted on July 26th, 2010 at 09:45 AM |
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Yeah, even tho mechanical pump I'm still thinking fuel pressure... AFAIK fuel squirting out of there can really only be fuel pressure.
From memory a stock pump does around 3-3.5 PSI when the pushrod height is correct... so presumably they can go over the 3.5 PSI if the max height is
higher.
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General_Failure
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| posted on July 26th, 2010 at 12:04 PM |
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3.5PSI is still a little too high for a Weber. Mine is set to a shade over 2.5PSI.
When it is ran over the max pressure which is 3PSI I think, they can misbehave pretty badly and intermittently.making faultfinding hard.
Your problem haunted my dreams last night so feel privileged.
You shouldn't be seeing any spray from the secondary jet. The secondary throat should be closed at idle, therefore no vacuum to suck fuel out.
Either your secondary throttle plate is incorrectly adjusted or your float bowl is overflowing.
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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lauzboy
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| posted on July 26th, 2010 at 08:59 PM |
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i think u might have misunderstood. Its dribbling from the auxiliary venturi of the primary throat. Nothing is coming out of the aux venturi of the
secondary.
just checked my fuel pump pushrod. it seems all ok but have put a few more gaskets underneath. fuel seems to be coming out at a reduced rate. anyway
borrowing a gauge tomorrow to see whats what
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General_Failure
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| posted on July 27th, 2010 at 07:35 AM |
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I see. I did misunderstand. Sorry about that.
I found / have some nice cutaway diagrams of the weber. Will try to dig them up later today if i didn't save them I need to visualise this a little
better.
Are you saying that your main is putting fuel down the primary throat at idle instead of just the idle on the main?
If at first you don't succeed. Build, build again.
Vehicle: 1975 Special order delivery walkthrough panel based LCA pop-top camper. Motor: Nippon 1.8L Single port Wasserboxer, Transmission: 3 rib 002.
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lauzboy
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| posted on July 27th, 2010 at 09:49 AM |
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bingo
just to clarify, on the primary and secondary venturis, there its a smaller venturi at the top of the carb (when u look down into it). This is called
the auxilary venturi. The main jet feeds fuel through the piping into the aux venturi and hence you have your main circuit running.
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lauzboy
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| posted on July 28th, 2010 at 11:53 PM |
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so checked the fuel pressure. its about 2- 2.5psi so all good
called a carbie specialist and explained the problem. they immediately said that ive most likely got a blocked idle jet. so blew took out all the jets
and the idle mixture screw and blew thru all the passages with compressed air.
and guess what... its all good! now just got to dial in the jetting properly
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