Help with solex PI 40 fuel pump set up

[lars1965]

I am startnig to figure out , how to fit my solex, so

Can anybody possible help with a drawing or know someone who can help with konfiguration on the pump + hoses, what goes where..?

NB! I will not use the mecanical pump, and I have a 1965 911 with original engine
with ca. 185 HP

I know duel in holland use one Bendix/facet fuel pump in the front( where the gasheater normaly was) + 2 pierburg cylindric fuel pump in the engine area, one for for each side tribbel solex.

But.... how is it set up? does they remove float + float valve in flotbowl on mainfold or?
and is it nesseray with return hose to gastank?
your help is much apriciated

Lars

[1QuickS]

The pump in the smuggler's box delivers fuel to the engine compartment where a "T" is used to divide the flow to the fuel inlet lines that supply the spill tubes (fuel delivered to the fuel lines with the banjo fittings.) The fuel that drains into the float bowl on each intake manifold drains out the bottom of the bowl and a Pierburg pump sends this fuel back to tank (one pump per maniflod); the floats are removed from the bowls. The rate of flow must be regulated so that there isn't too much flow delivered to the spill tubes; when I recently test ran a set of Solexes I used an adjustible pressure regulator after the main supply fuel pump to adjust rate of delivery to the carbs.

[lars1965]

Thanks Paul

the 2 return pump, are the joined together i one hose back to the tank? or ?

does the hose run where? in the tunnel where the stel fuel line runs ?
does you connect it to the fitting on the tank, where the gasheater normaly were?

rg.Lars

rg.

[Scotty]

Paul,

Is the routing described above the stock set up or the reverse set up?

Scotty

[chris_seven]

This is the standard fuel circuit.
.

[Scotty]

A picture is worth a 1000 words. Thanks for that diagram Chris_seven! Can you tell me where you found it? I'm a new 65 owner and need to get some workshop manuals.

[lars1965]

thanks

the 2 return pump, are the joined together i one hose back to the tank? or ?
I dont use the mecanical fuelpump, so It would be super if I could get a dreawing that shows the routing with the 2
ekstra perburg pump

does the hose run where? in the tunnel where the stel fuel line runs ?
does you connect it to the fitting on the tank, where the gasheater normaly were?

rg.Lars

[1QuickS]

The two Pierburg pumps would have their output hoses joined with a "T"-fitting and the fuel would then return to the tank either at the fuel nipple for the auxiliary heater or into the top of the tank via a vent pipe. If the return is routed through the tunnel then a rigid line would be best for safety purposes. This is what I think would be best subject to input from others.

[chris_seven]

The standard set up doen't have any fuel return- the fuel is simply re-circulated into the manifold the Pieberg pump takes fuel from the reservoir and into the fuel rail which in tuurn fills up the spill tube. The fuel falls through the spill tube and back into the reservoir. though a fuel rail in the manifold.

There is a comment in Ludvigsens book that this 'was to aid fuel vapourisation'. I think that this comment expains some of the issues with this set up.

If you try to return the fuel to the auxiliary heater outlet then the pump will need to overcome the head of fuel in the tank and this may be an issue depending on the pump capability.

If you ise the recirculating pumps to pump the fuel back to the tank then you will have to decide how to put fuel into the fuel rail and fill the spill tubes.

The Pieberg cylindrical pumps used by Duel are quite small flow and also relatively low pressure - I think they are rated at 2.5 psi.

In general terms pressure is the enemy pf this system. The spill tube design will only operate correctly when there is a consistent head of fuel. If you develop a pressure drop across the spill tube it will mess up the jetting but if the pressure drop were constant you maybe able to make allowance but if the pressure varies so will the fueling.

[lars1965]

What will be the most secure/safest way to go?, I am looking for the most driveable/safest solex setup, because I use the car a lot, also on long trips in europa. Does everybody remove the floats? + float valve?.
I`m looking for the most simple sollution, because if I have a breakdown in one of those trips, the chances for a skilled porsche/solex mecanic arround, it very small :-)

They pirburg pumps come in 2 version 1. 2.5-3.5 psi 2. 4-5.5 psi
How much pressure is correct for the solex?

thanks again

Lars