R67/2 Left cylinder starving

[norrisk66]

Hi-

I have been trying to get my R67/2 tuned up.

Runs very poorly. I had to clean the fuel tank, resealed inside, rebuilt fuel petcock.

Only runs on right cylinder. I installed some clear glass fuel filters right before the float bowl inlets. The right fuel filter stays nice and full of fuel. The left fuel filter is nearly empty at all times. You can see a faint trickle of fuel, but this causes the left cylinder to run very lean.

It seem like the "Y" banjo fitting at the petcock is not letting equal fuel enter the left fuel inlet hose.

I have taken the lines apart several times, no obstructions.

Seems like it is almost "vapor locking" to where air is getting trapped in the left fuel line, not allowing fuel to pass?

Help!

Keith

[schrader7032]

Keith -

I would try swapping the fuel lines after the Y adapter...see if the problem switches sides. You could also rotate the Y adapter and try various combinations of fuel lines to see if you can figure out what the issue might be.

[oligee7275]

Keith,
The problem is most likely in the carb itself. The float, needle or seat are likely the culprit. Something is not letting fuel enter the carb.
Start at the carb and work back to the tank.
If fuel cannot get into the carb it won't fill the line or the filter. The fuel has to have somewhere to go.
Take the fuel line off from the carb with the filter in place and turn on the petcock to see if fuel runs out. If it does, the problem is not in the line from the tank to the carb, but in the carb itself.
You say it only runs on the right cylinder. Is the left cylinder getting spark? Is it timed correctly? Is the spark plug good? Are the valves adjusted correctly? Is the ignition system timed or gapped correctly?
Just throwing things out there.
Hope this helps, Let us know how it goes.
Dean

[norrisk66]

Cylinder is getting spark. I checked compression-both cylinders are comparable.

I can blow through the fuel line easily.

I've cleaned both carbs, and float is set correctly.

Pulled line off at left carb- no fuel flow. I "blew" into the fuel tank filler-fuel will begin to flow with pressure.

Thanks for the input- i'm still stumped...

[miller6997]

Pardon me if I missed it, but have you taken the petcock apart? It could have debris blocking the fuel flow on one side. You said that one of the fuel filters stays nearly empty.

[Slash2]

The devil's in the details you generally take for granted.

As I understand it, vapor lock requires pretty high heat and I doubt that's likely in this situation.

What type petcock are you using? I'd be inclined to disassemble, clean, and take a high pressure air chuck to all the ports. I wouldn't reinstall the fuel lines until you can visually test that both sides of the Y fitting flow equally.

Good luck!

[Darryl.Richman]

Is the fuel line kinked at all, when installed? Some fuel line will collapse and block the flow, especially if it is susceptible to the ethanol in the gas.