Volkszone Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
825 Posts
Discussion Starter · #1 ·
When the float chamber in the carb fills and the needle valve operates is the fuel pump meant to stop pumping in reaction to the back pressure?

My car is a 1303, 1973.
 

·
Registered
Joined
·
18,482 Posts
Essentially, yes.

When the pushrod rises, it compresses a spring in the pump.
As the rod lowers, the spring is free to drive the pump diaphragm
and create pressure. If there is nowhere for the fuel to go,
the spring/diaphragm merely keeps pressure against the static fuel
and no real "pumping" occurs.
 

·
Registered
Joined
·
825 Posts
Discussion Starter · #3 ·
Speedy Jim said:
Essentially, yes.

When the pushrod rises, it compresses a spring in the pump.
As the rod lowers, the spring is free to drive the pump diaphragm
and create pressure. If there is nowhere for the fuel to go,
the spring/diaphragm merely keeps pressure against the static fuel
and no real "pumping" occurs.
Thanks for the reply - the reason I asked is that fuel is pouring out of my carb at the inlet and I wondered if a faulty fuel pump would cause too much pressure and cause this?
 

·
Registered
Joined
·
18,482 Posts
No, the spring-driven design deliberately limits the
pressure that the pump can produce.

The brass inlet pipe is merely press-fitted into
the carb casting; often they loosen and can cause
major engine bay fires.

Various fixes:
Knurl the pipe to expand it.
Loctite.
Compress casting metal around the pipe.

More info on fire prevention:
http://www.type2.com/
Click on Library
Click on "F" for FIRE
 

·
Registered
Joined
·
825 Posts
Discussion Starter · #5 ·
Thanks for that, I will have a check of the inlet pipe but I am fairly sure that it is okay. I will replace the hose too. I was sure that my carb was flooding even though the needle valve is working, hence my thoughts of the fuel pump. Thanks I'll investigate some more
 

·
Registered
Joined
·
10,675 Posts
Hi Des , not seen you on the forum for a while , hows it going ? :)

Just a random thought but could the float valve be jammed open (in the carb) causing it to overflow externally ? :)
 

·
Registered
Joined
·
825 Posts
Discussion Starter · #8 ·
yellow_spider said:
Hi Des , not seen you on the forum for a while , hows it going ? :)

Just a random thought but could the float valve be jammed open (in the carb) causing it to overflow externally ? :)
Hi, I haven't been doing much work on the beetle recently and so haven't been on much. Things are okay though.
 

·
Registered
Joined
·
825 Posts
Discussion Starter · #9 ·
Moby5153 said:
Don't forget you have some cash on the slate Des.
Yeah and I've noticed you're selling the very stuff I need. I have replaced the fuel hose now but just the bit from the fuel pump to the carb. This seemed to solve the problem. The car is booked into the garage for a full service on Tuesday - I have been using it everyday and don't have the time to do anything with it myself at the moment. When it comes out of the garage I'll mail you if I am changing the rest of the fuel hose - it would seem wise to since this has happened.
Thanks
 
1 - 9 of 9 Posts
Top