weber flooding problem

[Tooth911]

Hi everone last time out at the track had alot of popping out driver side tailpipe (dual in out) on decel. Carbs were cleaned out had the usual setiment. recent rebuild. Now wont start and is flooding on driverside.What gives? or what does a possible stuck float look like. Thanks Chuck. 77 911s

[dd74]

Subscribing. Not that I know, but I wonder if it could be the Webers' jetting and the exhaust (2/2). I've read here and there that sometimes Webers need to be jetted specifically for a single out or dual-out muffler.

The flooding you have throws me off though...

[Tooth911]

Has run great in the past this is a recent problem i would like to solve ASP thanks

[john walker's workshop]

fuel pressure limit 3.5# street, 5# on the track if it feels like you're running out of gas, dirt in the float valves, fuel level in the bowls too high, imploded floats from using an air gun to blow out jet passages, maybe just a defective float valve.

[Steve@Rennsport]

FWIW,..I run 3.5 psi regulated fuel pressure on everything. High-HP engines get fuel pumps with lots of volume and the carb plumbing gets a crossover to ensure consistent volume & pressure to each flow chamber.

If you have some flooding, here are some things to check:

1) Fuel pressure (as above)

2) Stuck float needle (these do not last forever and are a wear item)

3) One MUST have perfect float levels

4) Leaking float that has "sunk". If you pull the floats, make sure none of them has fuel sloshing around inside from a pinhole leak. If so, replace it.

[911pcars]

"Now wont start and is flooding on driverside.What gives?"

Have you confirmed it's flooding? Do you see raw fuel spilling into the throttle bore during idle/off idle?

If so, follow the suggestions previously posted. Did you check the active float/fuel level with the PMO gauge?

Popping on decel might indicate a lean mixture.

Sherwood

[jwetering]

Originally posted by 911pcars
"Now wont start and is flooding on driverside.What gives?"

Have you confirmed it's flooding? Do you see raw fuel spilling into the throttle bore during idle/off idle?

If so, follow the suggestions previously posted. Did you check the active float/fuel level with the PMO gauge?

Popping on decel might indicate a lean mixture.

Sherwood

Just a question on checking float levels with the PMO gauge....is there an elegant way to do this? Right now I take out the bowl plug, which drains fuel all over the place, then install the gauge, and fill it, and then remove the gauge when I get another big fat drain event. When I repeat this process four times I get the better part of a half litre of fuel all over the place. Any tips?

[911K]

Originally posted by jwetering
Just a question on checking float levels with the PMO gauge....is there an elegant way to do this? Right now I take out the bowl plug, which drains fuel all over the place, then install the gauge, and fill it, and then remove the gauge when I get another big fat drain event. When I repeat this process four times I get the better part of a half litre of fuel all over the place. Any tips?

I use the plastic top off of an aerosol can to catch the fuel along with a couple of shop rags underneath to catch the little bit the cap misses. Works great- give it a try.

[RoninLB]

was it running ok after the rebuild ?

[shbop]

Steve: What are your thoughts on checking, setting, float level on the bench, before installation? Is there any reason a gravity fed fuel supply would have a different effect than 3.5-5 psi?

[Tooth911]

How encouraging! thanks everyone for the replies .Here is some more background info rebuild was done about a year ago. Car ran great after rebuild . Last time I clean them out floats did not seem to be defective as far as pin holes and such.Fuel pressure is 2psi which is to low but like I said car ran good for some time up till recently. Iam running aMSD 6 ignition could this be a intermittent problem as one bank gets spark and the other does not?. The plan is to get a better fuel pump and check things out again as suggested Keep the replies comming Most appreiated Chuck

[RoninLB]

IMO.. the car must be on very level ground and idling for a good float setting to happen.

Bench setting is just to make the carb doable.

After adjustments remove plugs and clean them.

[john70t]

I went through this as well recently, and am now trying to sort out the smoothness issues.

My method (tips repeated):
#1. Take out spare tire and unhook the carbon canister so that taking the batteries out and recharging them on the bench is easier after the testing. Never leave batteries on concrete.

#2. Disconnect the CDI connections so only the pump is running.

#3. Make sure tank flows gas freely(the screen fills with rust) by cracking the lines for a second.
-Fuel pressure should be limited to 3.5 lbs for street or the extra pressure may push past the needle valves. I bought a Holly(it's kinda cheap but o.k.) regulator with a delivery pressure gauge on it.
-Use fresh gas and change the filter if it hasen't been done in a while.

#4. Have a little cross-ventilation in the garage, and put a fan blowing over the engine so you don't suffocate from the gas fumes. Blow all dust out beforehand with a leaf blower/etc.. and work clean!

#5. Remove both carburators(6-13mm nuts ea.) and place them in plastic pan. Run the pump to see which bowls are overflowing.

#6. Check the four(4) float levels by: unscrewing the bowl drains(10mm) and draining into paint caps (with rags under and have a gas can to empty that into), screw on the PMO external gauge, and run the pump. This is supposed to be done with the engine running, but it is a ballpark start.
-The fuel level should be between the top lines on Webers and the bottom lines on Zeniths(I believe).
-Turn off the pump and wait a few minutes while watching fuel pressure and gauge levels. If they go down, there is a leak somewhere.

The fuel height is raised by adding shims under the needle valves(use 14mm deepwell socket) under the covers(16mm).
The fuel height is lowered by installing a thinner shim. If not, the top section has to be removed, the floats removed, and the tab bent slightly. This is tricky, so check others first and take measurments.

VERY IMPORTANT- make sure the needle valves operate smoothly. I previously bought a rebuild kit (I have heard there is only one manufacturer of these), and the new needle valves stuck open/shut, which flooded the oil with gas and nearly caused a roadside fire!!!! No telling what kind of damage was done to the engine. I reused the old ones.

#7. Reinstall drain screw and repeat. You will start a rythim going.
-Don't overtighten. The carburators are not made of hardened steel.

[Tooth911]

Looks Like first thing is to get a PMO float gauge !! .Seems like the starting issue is more difficult if the car sits a few days or weeks when starting it acts like its only running on a few cylinders coughs and spits till warmed up smooths out and holds an idel.I realise some of this is tipical for webers but the extreams are baffling. motor is a 2.8L heads ported 37mm on intake E cams by the doc. dizzy curved 9.5cr.Would love to get this finicky bad boy under control thanks Guys!

[jwetering]

Nice written procedure.

I have been using aerosol lids and rags, but I was hoping that I was too stoopid to figure out the clean way of doing it. No such luck I guess.

shbop - that avatar CRACKS me up ! I laughed out loud. I'm going to show it to the wife.

[Tooth911]

Just tried a little starting flued to see if she would start no luck just a momentary cylinder fire then nothing. was hoping it would start and begin above procedures

[Tooth911]

Also whats the best after market fuel pump I checked with our host and didnt find a rce type application

[shbop]

my 2 cents on fuel pumps. I went through a couple before realizing that most are pusher type. The Hardi and Facet didn't last long, having to pull from the tank before being able to push. I ended-up with a Holley. I also found out, after opening the box, that the Holley is also a pusher style. The pushers all like to be gravity fed. I mounted it as low as possible in the smugglers box. So far all has gone well, but I'd like to hear what others have done.

I can't take credit for the avatar. I saw it somewhere and grabbed it.

[Tooth911]

I had a facet then to a purolator was rated 4 to 6psi but I only get 2psi with pump running and about 1.5psi with engine runnig and can peg 0 when first hit WOT

[RoninLB]

Originally posted by shbop

but I'd like to hear what others have done.

the '81 SC fuel pump and the PMO regulatur, which uses the stock return line, is a nice carb feed.