TheSamba.com :: View topic - Suddenly

Mon Sep 23, 2013 1:26 pm

I should clarify - it will only idle!. Car was running fine until I tried to pick up my son from school today. It started right up and idles fine, but if I touch the accelerator, even slightly, it dies.

It will resume idling - its as if it "cuts out" on acceleration. Throttle cable, linkage, vacuum lines, everything looks fine.

Ideas? I'm thinking it's not likely spark-related. Maybe a clogged jet? Thanks in advance.

Mon Sep 23, 2013 1:53 pm

ccihon wrote: I should clarify - it will only idle!. Car was running fine until I tried to pick up my son from school today. It started right up and idles fine, but if I touch the accelerator, even slightly, it dies.

It will resume idling - its as if it "cuts out" on acceleration. Throttle cable, linkage, vacuum lines, everything looks fine.

Ideas? I'm thinking it's not likely spark-related. Maybe a clogged jet? Thanks in advance.
Accelerator pump not working, or a clogged jet, but not the idle jet. If you have a can of carb cleaner with the plastic straw, then there are three passages that are visible from the top of the carb that you can spray out. If it's the main jet, then you should pull the top of the carb off to inspect and clean out the bowl. Also note the fuel level when you take the top of the carb off. The accelerator pump should squirt a shot when you blip the throttle, and you'll be able to see it by looking down in the carb.

Paul

Mon Sep 23, 2013 3:12 pm

Accel pump seems to work - took carb top off and was fuel to nearly the top. Remove two jets on carb right side and one in the center....cleaned each with carb cleaner and reinstalled - no improvement.

I did not remove the float and clean the bowl...and there could still be some blocked passage? It sure seems fuel. starved, but I am ruling out the fuel pump as the bowl is full.

When re-started, it putters and seems to cut out and finally arrive at an idle, but will die with any acceleration. Should I have ruled out an ignition fault? Or still likely something in the carb?

Mon Sep 23, 2013 3:42 pm

I'm leaning more to ignition problems , like points ,condenser or coil .

Mon Sep 23, 2013 7:18 pm

Get a spray bottle and fill it with gas, let it idle and hit the throttle as you spray some gas down the throat. It should rev up a bit as you increase the air being drawn in. It sounds like the accelerator pump to me. Check the linkage, there are different points you can set the pump shaft at to get more of a squirt. If it idles it is generally not a spark issue. I guess one could throw a timing light on ty at idle and see if it jumps around much but other than that if you have enuf spark to start and idle you should have enough to run on load, unless you are short on battery juice from a non charging condition, but even that would affect idle.

Mon Sep 23, 2013 8:47 pm

I was trying to get an old motor running that had baby dells on it same problem as you it was a thing called the emulsion tube gas was going through just not in the proper amount as the emulsion tube was totally plugged

Tue Sep 24, 2013 5:17 am

ccihon wrote: I did not remove the float and clean the bowl...and there could still be some blocked passage? It sure seems fuel. starved, but I am ruling out the fuel pump as the bowl is full.
Your main jet is in the bottom of the bowl. To remove it, take out the float, then the 13mm acces plug on the left side of the carb. The jet comes out with a straight edge screwdriver. If you take out the float and see a lot of debris in the bottom of the fuel bowl, then clean it out before removing the main jet. With the access plug removed for drainage, you can spray out the bowl, then remove the jet and check and/or clean it.

Paul

Tue Sep 24, 2013 5:19 am

djway3474 wrote: I was trying to get an old motor running that had baby dells on it same problem as you it was a thing called the emulsion tube gas was going through just not in the proper amount as the emulsion tube was totally plugged
That's a possibility too. The emulsion tube is the one in the middle when looking down into the carb. Always a good idea to pull it and check in situations like this...

Tue Sep 24, 2013 5:23 am

I did clean the emulsion tube, but not the bottom of the bowl or main jet. I've got two fuel filters on this thing, but there was likely crud already in the carb when I put these on a few months back. Is there a pin/hinge that releases the float? Searching for a diagram someplace - its an H30/31

Meanwhile I think I'll do the points and condensor as those are overdue anyway.

Tue Sep 24, 2013 1:15 pm

While I'm glad I figured out how to clean the carb, turns out that wasn't the issue.

Pulled the cap and rotor to discover the connecting wire from the points to the condenser was severed, or nearly so, where the wire is crimped to the points.

My guess is a faulty condenser may have cause that wire to heat up. It would idle, but when the vacuum advance pulled the points, the wire would disconnect - and so forth.

New Bosch points and condenser....so all is good again....

Except that the condenser and points I have seem a "near" fit. The plug passing the two green wires through the bottom of the distributor housing is indeed round, as is the hole, but the diameter was smaller and I had to engineer a friction fit. Also, the points set had the central conductor wire exiting to the car front, rather than to the rear, and needed extended with a bit of soldered on wire and heat shrink to get it to the condenser spade terminal. There must be many variations of these, but next time I will look for the set better matched to this distributor.

Thanks all for the help - you're never alone with a problem here!

Wed Sep 25, 2013 8:44 pm

Glad you got it figured out. Idling fine but not accepting any throttle threw me. With the increased resistance of the damaged lead lowering the total current going to the coil, there simply was not enough time to charge the coil when the points were closed, except at idle. Lesson learned for me!

I had a weird problem once where the engine ran fine if the decklid was open, then stalled when I closed it. Turns out the tach sending wire had gotten caught in the decklid hinge spring... :lol:

Paul

Thu Sep 26, 2013 3:45 pm

Good detective work, makes sense. Glad you figured it out!