[Mini] Fueling issue

Tom Parker tom at carrott.org
Fri Jan 4 02:23:17 MST 2013


On 04/01/13 17:30, Anne wrote:

> The Van has the tank in the back with a fuel line running under the car,
> coming up along the bulkhead connecting to a fuel filter and then to a
> (new) facet pump mounted on the bulkhead.

The pump is above the fuel tank?

> Another thing I noticed is that in all cases the fuel filter is empty.
> When it fills again the engine starts and runs no problem.
> But that also is not a tell-all; at time the egnine will run (idle) just
> fine while there does not seem to be any fuel in the filter.

Where is the inlet in relation to the outlet on the filter? If the inlet 
is such that air cannot exit the filter, it won't fill up with fuel.

> As I also suspected the tank creating a vacuum, I removed part of the
> inner workings of a fuelcap and drilled a (small) hole through it, which
> should make sure it always can get air in.

The fuel system should be pressurised by the vapour pressure of the 
petrol. When you open the fuel cap on a modern Japanese car a 
significant amount of gas exits.

> 4. Disable the power to the facet fuel pump to see how long the engine
> keeps running when no new fuel is coming.

Yes, do this. I found with a delorto carb the car would drive 
surprisingly far with the fuel pump switched off.

> I've had a similar issue before which turned out to be an air leak in an
> old fuel line. But these lines are new and most are not of the old black
> cracking, but of the flexible PVC(?) see through type.

Hopefully nylon, not pvc! I've not heard of plastic or see through fuel 
hoses on cars. Are you sure they're designed for petrol?

I don't know how the facet pump works, if it's above the tank it might 
stop working if it fills with air. Are you sure you don't have any air 
leaks? Does the fuel ever get hot on it's way to the pump? That can 
cause vapour in the line which doesn't pump well.

Get a small pressure gauge and connect it to the fuel system between the 
pump and the carb. If the pressure drops, then you have a problem with 
the pump, filter or pipes.

Could the engine be flooding? I had somewhat similar symptoms once, I 
stopped at some lights and the engine faltered and stopped. The smell of 
fuel was strong and it eventually started with wide open throttle. I 
pulled the fuel pump fuse and was able to drive the rest of the way by 
inserting it every now and again. I believe the float valve jammed open, 
after disassembly I never found the reason and it never repeated.


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