Fueling issue (tune has gone very very rich all of the sudden) 48IDAs on pump ga

[Jim Ratto]

40mm venturi
160 Main
F2 tube
185 air
60F10 x 110 idle
Float tab .955” below carb body lip
Needle valve 2.00 (25mm from carb top)
3.0psi checked w/ two different pressure gauges
New intake gaskets @ carbs/heads
New plugs
New wires
Tried 2 different coils (one Bosch high KV and one MSD)
Valve lash @ .005 cold
30 degrees advance

What would cause the tune to all of the sudden go very very rich? I mean REALLY rich. On AFR I’m seeing low 9.00’s in transition from idle to main. Before the “problem” I was seeing 12.5-12.8-13.00 @ same rpm and car ran flawlessly. I can usually nail this stuff down, but obviously I'm missing something. Any ideas? Ready to push the car off a cliff and collect stamps instead.

 No settings have changed.

[Taylor]

leaking or dripping needle and seat?   have you looked down the throat when running? 

[Jim Ratto]

looked @ idle and butterflies are dry. Forgot to mention, tried my spare needle valves too. It idles ok. It is when you put a load on it and bring rpm up around 2000-2500 then it bucks and gargles and pukes black smoke. Steady state cruise @ 3000 is awful. 
I used to be able to soft shoe it around, shifting @ 2700 or so, which is how I would drive it until oil temp came up, just to be nice to it.
Now it sucks, but nothing changed.

[Taylor]

I had "A" car (read: not vw) do that to me once,  heavy load it would seem fine, Idle... nothing special but when driving at a constant speed it would buck.  I tracked it down to bad spark plug wires. 

[Jim Ratto]

I'm going to strip all down to the bone again this week and see if I can find it. I had a Bosch 215 rotor cut one cylinder out, I thought it was a vacuum leak until my friend said "try a new cap and rotor" and bingo.
thanks Taylor,
Jim

[TexasTom]

Have you pulled the plugs to inspect and compare all?
It does sound as if you're losing a cylinder ... When did it start, before or after you replaced plugs & wires?
I assume you've checked that jet stacks are tight ... it's got to be ignition ... what's your setup?
TxT

[Bill Schwimmer]

Have you tried putting a timing light on it & making sure of the advance? I agree w/ everybody else re: checking the ignition. For some reason our immediate instinct is to go for the carbs. & usually it is the ignition.  Hope you get it sorted out.  Bill

[Bruce]

Float tab .955” below carb body lip
Needle valve 2.00 (25mm from carb top)

Although these are the Weber specs, they are an indirect measure of the float height.  As you know, it's the fuel level that counts.  The confirmation I use is to take a short piece of coat hanger wire and stick it down the vent hole between the jets until it touches the floats.  Compare side-to-side.  When you have the carbs apart, check for fuel inside the floats.

When I was daily driving my 48s, I had something similar happen.  Over about 2 weeks it got really rough running, obviously rich.  Eventually I tracked it down to corrosion in the idle jet wells.  The bottom where the idle jets seat against the aluminum was badly corroded so that fuel was bypassing the jets.
If you're taking them off and apart, have a look down all the jet wells.  Look for a contact ring.  You could even paint the taper of all your jets with a Sharpie, then screw them in and take them out to look for a continuous ring.

[lawrence]

I would double check timing and make sure wires are hooked correctly to plugs and cap. I had a similar issue once when I did not tighten a main jet stack completely. The car would idle fine, but as soon the carbs transitioned it ran terrible. Good luck.

[kingsburgphil]

FUEL QUALITY ??  You wouldn't be the first person to get load of Diesel mixed with your gas. Other than that if the problem
effects all four cyls. perhaps it's a fuel pressure issue.  If its gas contaminated with Diesel, just drain/purge and refill with gas.

[Jim Ratto]

Have you tried putting a timing light on it & making sure of the advance? I agree w/ everybody else re: checking the ignition. For some reason our immediate instinct is to go for the carbs. & usually it is the ignition.  Hope you get it sorted out.  Bill

yeah Sunday morning before I came down to Orange I was out back checking advance @ 3K, enough to get death look from old lady down the way.

thanks again everybody

[DKK Ted]

Hey Jim, don't give up, with all the knowledge you have, you'll get it. Besides, stamp collecting is boring.... But here is a one, check the squirters, maybe loose? Pumping more gas in? The check valve at the bottom of float bowl?

Ted

[Jim Ratto]

Have you pulled the plugs to inspect and compare all?
It does sound as if you're losing a cylinder ... When did it start, before or after you replaced plugs & wires?
I assume you've checked that jet stacks are tight ... it's got to be ignition ... what's your setup?
TxT

yeah I've had idle jet stack back out while driving, which felt like IDF plugged idle jet, but this is different feel... like idle circuit to main circuit is getting no air. It hits on all four, then slogs down and gargles and nosedives, you can clear it out, unlike a lean condition.
Ignition is MSD 6A box, MSD distributor (old- from 1995), locked advance set @ 30 BTDC, Bosch-Mercedes W123 coil or MSD coil, new wires, X5DC plugs

[Jim Ratto]

Hey Jim, don't give up, with all the knowledge you have, you'll get it. Besides, stamp collecting is boring.... But here is a one, check the squirters, maybe loose? Pumping more gas in? The check valve at the bottom of float bowl?

Ted

Hey Ted thanks.

I had carbs off and stripped down twice last week and went through it all, with no luck. I always double check the squirters and "aim" them anytime I'm in there. Good call though, same of check valve in bowl.

what's interesting is I was talking to a friend Sunday about it and it was like he had ESP, as he mention he noticed a drastic change in way his car is running lately too. Fuel companies just can't leave things alone? Not only is it $4.45 gallon now but runs like piss too? Who knows.

[kingsburgphil]

FUEL QUALITY ??  You wouldn't be the first person to get load of Diesel mixed with your gas. Other than that if the problem
effects all four cyls. perhaps it's a fuel pressure issue.  If its gas contaminated with Diesel, just drain/purge and refill with gas.

This gross rich/misfire condition, is it on one cyl., one bank  or all four?. Circumstances prior to noticing the problem ? and
the last thing you fixed (service history) 

[BeetleBug]

Permanent solution: get rid of those old, pesky carbs and install EFi.

[Jim Ratto]

hi Phil,
judging by plugs, it's a;; 4 affected the same (plugs look all the same) so it's hard to isolate one hole. I know, hard to blame carbs if it isn't one throat causing it all. History is, mid March drive car up to Goleta and back ran tip top, few days later it got warbly. Figured it was time for plugs/check intake gakets/vlave adjust. Did all that like I usually do and no improvement. Oh oil change too.

[Fastbrit]

Do you have a mag you can throw on it? I'm inclined to think ignition like the rest – getting to hate (sorry, 'mistrust') MSD...

[Jim Ratto]

No mag to try. I do have the usual 009/Bosch coil. If it makes any difference subbing it in for MSD at least I know it's spark related.

[Harry/FDK]

Jim, i'm just talking. The last thing you changed was the fuel-pressure regulator. (Diaphragm?).

Figment.

[Jim Ratto]

Jim, i'm just talking. The last thing you changed was the fuel-pressure regulator. (Diaphragm?).

Figment.

No that has been on car since 2008, since then the motor was gone through, and I think I've ruled it out (regulator) becuase I can turn it up and watch the fuel bleed over, checked psi with 2 gauges.

[Taylor]

My Dad has a mag you could throw on there.    But try that 009 first  how old is the MSD box? and where is it located?

[kingsburgphil]

Any progress yet?  If I read you right it's not spitting back thru the carbs or shooting ducks out the exhaust? You changed the plug wires....
including the coil wire?  We're assuming at this point that whatever has malfunctioned has effected both banks. Therefore the failed part/system
is shared by all four cyl's.,ie  valve timing, fuel etc., ignition,  exhaust? (don't laugh mufflers do fail).  By the way we learned the hard way in the
early days of Lambda Sond, not to rely/lean too heavily on the O2 sensor as a diagnostic tool. I think interpretation is the key here.     

Again assuming all the 19th. century parts are functioning, a process of verify/elimination should narrow your possibilities.


On a personal note Jim, I applaud you for reaching out, even the best techs get stumped. The smart one's ask their peers for advice.
The cool part of asking is even if the responses are way wrong, they stimulate your/our brain(s) to as to why they aren't correct.   

[Rick Meredith]

On a personal note Jim, I applaud you for reaching out, even the best techs get stumped. The smart one's ask their peers for advice.
The cool part of asking is even if the responses are way wrong, they stimulate your/our brain(s) to as to why they aren't correct.   

Agreed.. also usually find that when I'm stumped it's usually something simple that I overlooked. 

[Fastbrit]

On a personal note Jim, I applaud you for reaching out, even the best techs get stumped. The smart one's ask their peers for advice.
The cool part of asking is even if the responses are way wrong, they stimulate your/our brain(s) to as to why they aren't correct.   

Agreed.. also usually find that when I'm stumped it's usually something simple that I overlooked. 

To quote once more Dave Kawell's great advice to me when I apologised for asking him a "dumb question"

There's no such thing as a dumb question, only dumb people who don't ask questions.

Best advice I ever had.

[javabug]

Do you have a mag you can throw on it?

This sounds familiar ...

http://cal-look.no/lounge/index.php/topic,5983.0.html

[Fastbrit]

There you go! A mag solves everything!

[Jim Ratto]

hi KBPhil, thanks for the note it's appreciated and thanks for checking in. No, no breakthroughs yet, but I did gather some more interesting evidence.

a) all 4 plugs look the same (on the fat side of normal, like a briquet just beginning to turn grey)
b) one carb base gasket (cyl # 2) was saturated in fuel (other 3 were dry)
c) carb top-to-body gasket on #1 & 2 carbs was "wet" (they're normally dry when I pull carbs down)

That's as far as I have gotten. Weeknights are tough for finding free time. Dug out an old 009 and wires that work with it, maybe this weekend I can test it and put this all back together.

[Jim Ratto]

009 with 6A box in, better but curve difference needs jetting now 

I have to say- I found another 800 rpm up top (time for springs?)
Forgot how good the good ol 009 runs.

more later

thanks to all

[stealth67vw]

Forgot how good the good ol 009 runs.

You obviously don't read the Samba forums.