TheSamba.com :: View topic - engine won't idle on the flat or under braking...

Wed Jul 16, 2014 8:24 am

Alight guys.

So I have a very od issue as the title would suggest.
Its a VW 1500 SP totally stock.

If I am facing uphill (even a small incline) the car will idle fine, however once the car is level it just cuts out. It does the same thing if I brake hard too.

Now Originally I thought Fuel likes, however i have cleaned out my tank and ran brand new fuel lines and it made no difference(fuel flows very easily thought the system)

I had a local garage (MAC VW) set my carb up and the timing. But the car still conks on idle.

Any ideas guys?

Wed Jul 16, 2014 9:22 am

Just trying to think of this from a physics side. When you're braking, the fuel (in the lines and tank) is being pushed towards the front of the car, so the pressure before the pump is lower. When you're on an incline, the elevated tank means a higher pressure in the lines and at the pump. In the middle is idling on a flat, or neutral pressure. I'm guessing it won't idle if you park it facing down an incline, right?

I wonder if you have a fuel pump that's bad, and needs a slightly higher pressure before the pump to work. A small tear in the diaphragm perhaps? That would be the first place I'd look.

Wed Jul 16, 2014 9:27 am

Dwayne_71SB wrote: Just trying to think of this from a physics side. When you're braking, the fuel (in the lines and tank) is being pushed towards the front of the car, so the pressure before the pump is lower. When you're on an incline, the elevated tank means a higher pressure in the lines and at the pump. In the middle is idling on a flat, or neutral pressure. I'm guessing it won't idle if you park it facing down an incline, right?

I wonder if you have a fuel pump that's bad, and needs a slightly higher pressure before the pump to work. A small tear in the diaphragm perhaps? That would be the first place I'd look.

Thanks for the quick reply. I tried an electronic fuel pump with no joy too.

However i just cleaned out the idle jets and seems to be a bit better now

Thu Jul 17, 2014 2:49 am

check your float