Series III petrol stalling when pulling away

Morning,

I have a Series III lightweight 2.25 petrol, 24v with a 24v to 12v dropper supplying a 12v ignition system.

I have had problems from the start with poor running, initially it would kangaroo at speed, then the kangarooing became progressively worse and now the it will not pull away without stalling. However my lightweight will start from cold (although it is difficult to start once the kangarooing starts and it stalls).

I have replaced the coil, checked the timing and the general condition of the carburetor. I have swapped the Weder carb already fitted with a Zenith pattern carb from Christian Autos (with no improvement) and cleaned out the Weber carb, which has then been refitted (with no improvement).

The lighweight has dual tanks, I have checked the fuel (one tank was dirty), cleaned out the dirty tank, cut a new gasket for the fuel switching tap, checked clean fuel is being drawn through and replaced a dirty in line filter.

I have checked the fuel pump, which looks like it has been recently replaced. Although this is working, the fuel is not being pumped through particularly strongly at the connection into the carb (after passing through the in-line filter). However I'm not sure how powerful the fuel pump is supposed to be and the flow rate I should see from the pump.

Anyone have any ideas why my lightweight is stalling as I try to pull away?

Thanks,

Richard

If you search for "vapour lock" on this forum you'll find a few replies from me. The routing of the fuel pipes can cause problems with the fuel boiling in warm weather. Also, I gave up and got an electric pump as I was finding that when the pump gets warm the vapour sits in the valves and causes bother. Since fitting an electric pump I don't get any bother.

D

Check the seal on the fuel bowl on the fuel pump for a bad or hard gasket - if you're sucking air there that can cause difficulty keeping the fuel bowl full. Also check the lines back to the tank for air leaks, and lift the fuel pickup from the tank and check the screen on that for clogging - blow out the fuel pickup line and make sure it's clear, too.

Do you have an inline filter in the feed to the carb? If so check or replace it.

Low fuel level in the carb can cause all the issues you document.

Worth checking the air pipe to the filter (if you've got one). They sometimes delaminate and the lining can collapse. You should get a decent spurt from the fuel pipe at the carb. Blow through the pipes and check the filter in the tank at the end of the pickup pipe.

Check the ht leads by pulling each one off and seeing if the engine changes, i am guessing its more fuel related though?
Do a compression check, check all cylinders fire then look at fuel. You can pick up compression testers on ebay cheap, they just need to read similar readings, forget comparing with the manual.
Oh, valve lash? that can sod up a good engine easily! good luck.

I would be checking the fuel lines for blockages, sounds like a restriction with the problem starting at speed and steadily getting worse as the pipe got more blocked and as you say you did have muck in the tank.

Thanks for the pointers, not sure vapour lock or blocked fuel lines are the issue, but I'll keep you posted.

Cheers,

Richard

As a test try dousing the fuel line over the engine and the pump with plenty of cold water and see if it perks up...

I have the exact same problem with my S111, was wondering RichardPinchin did you manage to fix the problem. Will start working on my problem soon now that the snow has gone and the temp is getting above 0 up here in Norway.