Back on road and confusing fuel system problem

[DDS]

Hi All,

Its been years.... five I think.

Finally got my 914 back on the road with a 160 hp turn-key FAT performance 2258cc engine. Engine starts and idles beautifully from cold, then after running awhile (like a 5 mile drive) it stumbles and spits and stalls at idle. Fuel pressure on gauge drops from an intial 3 psi down to 1.5, 1 and less. Car still seems to run fine above idle, oddly enough.

Tank is clean, fuel screen in tank looks OK, fuel filter is new, fuel pump is good. I have not removed the regulator/gauge yet. I have drained and flushed the lines up to that point.

Still, won't idle after warm up, and fuel pressure appears to drop. Any thoughts?

TIA!

Dave

[John Rogers]

I imagine you have carbs, probably Webers? If they do not have any heat spacers between the carb and the intake they can get hot enough to start the fuel inside boiling and the floats can then stick open which would cause a drop in fuel pressure. This can be worse if there is no engine tin and the rubber seal so things get really hot on top.

I'd say pull the plugs when this happens and see what they look like. If they are very black and sooty then the carbs are flooding but if they are white then the engine is starving.

[DDS]

Thanks John and sorry guys, in effect I have double posted, as the problem became clearer. Thread is here:


Gradual fuel pressure decrease.... Why?

[Jared at Pelican Parts]

You mentioned it's a FAT motor. Does it have one of those 911 style shrouds?

[DDS]

Nope, stock tin. So far (when fuel supply is fine) oil temp sits around 190 on my vintage bosch gauge. Haven't sat in traffic on a hot day yet.

[Jared at Pelican Parts]

Get a picture of the carbs.