Replacing a mechanical fuel pump with electric.

My V-4 Saab had a mechanical fuel pump, I found the corpse in a bucket that came with the car but no rebuild kits are available.  Mechanical pumps are available but there are three different models for the same engine, each has a different in-out location and each has a different depth to the cam lobe.  My corpse is missing the push pin so I have no idea what the depth should be.

The car came with an electric fuel pump of unknown character.  Easy enough to wire up the electric pump, but will it over drive the small carb float valve?  If I put a gage on it, how much is too much or normal for a tiny one barrel?

(P.S. - I'm only here so you appreciate the easy questions.)

Dan

Every carb is a little different, but ~4psi is what I'd be looking for. You can always put a regulator in line. Are any of the mechanical pumps available? If so, you could just get that plus the matching pushrod and do it that way.

They make low pressure pumps just for that application (replacing a mechanical one on a carb system.)  Get one of those.  Yeah, 3-4 PSI.  There's even 2 kinds of regulators, ones that drop from like 5 PSI to 2 or 3 and ones that drop from like 50 PSI to 2 or 3, if you happen to have an EFI pump pushing to a carb.

For safety wire it so it shuts off with loss of oil pressure. 

A number of years ago I got a Carter electric rated at 3.5 psi for my Capri.  32/36 Weber could handle that fine.  If I were to do it over again I would probably look for a regulator just to make sure the pump wasn't varying pressure much.  

I un-forgot how much I don't miss carbs just writing this.

Also remember, a rolled over car with a carb and an electronic fuel pump will have the tendency to pump out a nice pool of very flammable liquid from the now wide open carb (floats going wrong direction).  Some sort of cutoff is a good idea. 

They used to be very easy to find in junk yard in the trunks of Ford(?) cars.  You know, those ones you always had to reset when someone bumps you from behind.

As Aircooled said you should add a safety like wire the ground side to a relay tripped off the oil pressure sensor.

Thanks guys, I didn't really want to reinvent the wheel.  I luckily found this guy who has everything I need.

Fuel pump for $89 and the fuel tank sender for $135, still cheaper than a fuel cell.

Thanks again, Dan

"Tired Iron Repair" in Sauquoit  Ny (near Utica)  specializes in SAABS.    Claude Hutchins is the owner.

One method to shut off the electric pump if you experience an accident that stalls the engine is to wire the fuel pump relay or the pumps power supply through an oil pressure activated switch. They come in various P.S.I. ratings as to when they open if the oil pressure drops below that number.  All you need is a port on the engine to screw it in to.

When I use one of these I also wire in a bypass circuit via a push button switch that I can push and hold to prime the carb with fuel if the car has sat for long enough that the fuel level in the carb may be low.