Technical Fueling issue? advice required please.

[MOD500]

My 500 has developed an intermittent fault.
Occasionally it loses power revs drop off and if the accelerator pedal is pressed the revs wont pick up. although it doesn't cut out. This lasts for about 10 - 15 seconds then it returns to normal.
This has happened at low revs and at idle.


This started on the way home from work after about 4 miles and repeated every day at the part of the journey.


I have swapped the carb with a recent rebuilt one and I have swapped the fuel pump with a known working spare. The issue is no better and no worse.


I will swap the distributer next. Maybe the bob weights are playing up.


I'm inclined to think it's carb or distributor as they are the only components that have a separate idle and fast running function.


If anyone has experienced anything similar or has any suggestions please let me know.

 

[looigi]

Reading this from the comfort of my couch halfway around the world, it sounds to me as if you have a fuel starvation issue.

I would look there if it were me.

Fuel issues tend to cause the engine to 'fade' whereas ignition problems generally cause a sudden cut.

My two cents
Chris

 

[MOD500]

Thanks Chris,
That sounds like fair logic.


The only nuisance with it being intermittent is I can't replicate it in the garage and if it does happen on the road, by the time I get out to have a look at it, the problem has gone!


Fuel line and fuel filter next!


Thanks,


Michael

 

[Duffys Dad]

After the swaps you have made already it has to be something with the fuel supply between tank and carb. Easiest thing to try is the fuel filter. Perhaps also try disconnecting fuel pipes at tank and pump. Empty of fuel and blow through with an airline.