Fuel Issues

[sfdon]

Nicely stated...

"If fuel starvation is the actual problem, you could have a good idle or low speed operation, only to buck and stutter at larger throttle openings."

 

[David]

Ive been on the road for the past month, but I finally replaced the fuel pump and the pressure is now up to just north of 2psi. Looks like that was the culprit. Thanks to all for the help.

 

[David]

Well, not done yet.

Car seemed fine for the first 40 miles or so after the fuel pump was replaced. However very quickly the car's performance degraded to the point where I wasn't sure if I could get it home. Pulled the plugs today to find this. Note plugs 4, 5 and 6, the crap shooting out the tail and pretty strong gas smell.



Sorry. The photos are now long gone.

 

[cartoonz]

your rear carb is running rich, likely stuck float?

I suspect your issue lies not with fuel pump but with the carbs themselves... have you cracked them open?

 

[61porsche]

Carb tricks and tips continued.....

Yes, your rear carb is running rich or flooding.

Replace with new plugs.( just the rear three)

Before you crack the carbs open.... try this...


Pinch off or disconnect and cap the fuel line to the rear carb..

Run the engine till it runs rougher.... using up the fuel in bowl.. so the float drops all the way.

Hook the fuel line back up... start it up...

Sometimes floats just hang up... a light rapping with a screwdriver handle sometimes works too.( Easy big fella)


Find your idle mixture screws..... carefully count how many turns it takes to gently close. Write it down... check the good carb for the same and compare. Chances are the rear is open more.

Always write down your adjustments... it's easy to reference what worked or didn't.

p.s. the front carb idle mixture ( the spark plug color) seems a little on the lean side.... slightly turn out the screw 1/4 turn.

Good luck and keep the cards and letters coming!

 

[David]

Thanks for the the tips. I'm pretty sure the fuel pump was part of the old problem as it was putting out a very low PSI. Now, I think I'm finding a new problem.

I pulled the fuel line from the suspect carb, let it run to sputter, and reconnected the fuel line. It seems to have helped. Ill get to the mixture settings next weekend.

I really appreciate all the help guys!

 

[David]

In our latest installment....

Replaced plugs, cap, rotor, and vacuum lines (one was missing), did the timing (two spark plug wires were loose at the plug end) and ran through the lean setting instructions from Redline. Car runs 80% better and doesn't smell like gas anymore.

Now, the car runs great above 2500 RPM, but below it struggles. And on cold start I don't think the chokes are working correctly.

Does anyone have a link to a site which documents stet-by-step instructions for troubleshooting the carbs ? (including how to synch--I bought the Synch tool from Mesa last weekend)

Thanks again for all the help.

-David

 

[61porsche]

here's a synch site-http://www.aircooled.net/gnrlsite/resource/articles/dualcarb.htm

The bluebook is pretty much the same-- you just have to figure out which screws work for what operation.

Weber has a site for trouble shooting. Redline...

After you sync what you've got or before... you're going to have to check the jetss- clean and the fuel level/ float to.

It's mathematically difficult to have both carbs acting up, unless you're lean now. Pull a plug again for color check.

If it's hard to start- you're probably lean or clogged jets causing lean.

Get a can of air or use a compressor...... find the air bleeds on top.... a short shot might blow it out. Short... not long.

take the top off a carb- see if there's junk. filters don't catch small junk.

 

[David]

Well, I'm getting closer. Synched the carbs, resolved a binding problem with the linkage, replaced the choke diaphragm and figured out how to set the choke. Car has never run better. But,....

The outer choke housing has melded to the bi-metal housing making it impossible to set the choke without forcing the water lines into all sorts of strange bends. I cannot get the two pieces apart. Since I need to replace the choke housing, why not just convert to electric chokes ? Jim at Mesa tells me it's going to cost me the same either way.

 

[61porsche]

Picture pls.

The choke spins the whole assembly by loosening the three screws. I take those off to get to the carbs without cracking the lines. I don't touch the bolt/ o-ring etc.

Back carb- put longer lines on or they're crossed. that's the usual problem. It hits the linkage or block or short and won't turn.

But the chokes are both water and electric.

Just one?

 

[David]

http://www.carburetion.com/diags/3236DGAVDiaginfo.asp

Loosening the three 7mm screws (#42) allows me to spin the choke. However, #45 and #48 spin together (which I think is wrong). I cant get the two apart to allow the correct setting of #45 without #48 being at a funky angle. The 11mm bolt (#44) won't budge on either carb.

 

[61porsche]

#11 must be loosened. Very light tapping on the wrench, back and forth. Once that's loose, only the o-ring is between the two parts.

 

[David]

I'm guessing you mean the 11mm bolt, not part #11 in the diagram.

That bolt simply will not budge on either carb and so I'm getting a new housing for an electric choke (DGEV?). I hope plugging the coolant lines won't be a big deal.