Fuel problem?

Hello,

My mk1 cabriolet has suddenly started to feel like it wants to cut out when foot down going up hills, almost feels like it's kangarooing if that makes sense?

It has a brand new Weber carb which has been tuned and had been running well for months. Typically it's started on one of nicest days of year!

Any ideas welcome, thank you,

Rachel

fuel filters? mechanical  pump? evaporator pot thingy  sadly not got much experience on carbs

With Covid 19 how long has your fuel been in the tank and how low has it been. Are you running normal or super unleaded at the moment. If you have an inline fuel filter check to make sure its clear. Mine tends to pick what looks to be like fatty deposits. If you've got one try rotating it 180 degrees for the minute to see if it improves. When you say about the hot weather I have now re routed my inlet pipe around behind the headlight to the pump prior to this. It keeps it away from the heat shield by the cam cover as well.

Many thanks both that's all really helpful

Rachel

Who tuned the Weber carb and how did they do it? Also do you know what they altered, eg was it just the mixture screw and idle, or did they fit different jets or comment that the existing jets are the right size for the engine etc?

Hi,


Thanks for your response. It was Jim Parks in South Yorkshire. Not sure about what he did but it's been running fine for months until today. Was a daily driver until Covid-19 then weekly…

Rachel

Ok no worries - I'd say the fact it was running fine before, then not now, means its not a setup issue.

I'd say its either a partial blockage in the fuel system, or (unlikely though) the mechanical pump not working properly any more.

Typically on carb cars they have an inline filter, normally in the engine bay right hand side near the carb itself. Also there will (should) be a fine gauze in the fuel inlet of the carb itself. Either of these could be blocked with something. If not, then its possible a particle has made it into a jet in the carb, eg if something got into the main jet but didn't affect the idle or progressive, then it would affect 3/4 to full throttle. Similarly if the accel pump jet was blocked, the car would start hesitating on initially pressing the throttle but run normally in other situations.

Mech pump is easy to test - they normally pump far more fuel than is needed, and internally regulate according to the demand of the carb (float pin controls it). Take the fuel line off the carb, put in a jam jar and turn it over a few times on the starter, you'll get a good idea if its working okay.

If the fuel filter is 12 months or older fit a new fuel filter and check the air filter.
Do you have a standard air box or air filter stuck on the carb type set up?

Many thanks, I'll check the pump and buy a new filter as current one definitely over 12 months old.

Check the fuel lines and clips at the same time and replace if need be. Also get a barbed fuel filter. I've had the smooth type come loose uphill and on a blind bend, not funny.

Many thanks just ordered a barbed one and will do checks. Definitely don't want anything similar happening!

Hello again,

Well, after (I thought) finally having this problem fixed around 6 months ago (yes it took that long), it's back! I could go into all the ins and outs and what's been done but it would be War and Peace.

So, could anyone recommend an expert in fuel systems so I can hopefully solve this once and for all? Based in Sheffield but happy to ship the damn thing off somewhere if confident they would sort it.

Many thanks,

Rachel