<VV> Oil Presure Inertia Switch (long)

[Ewell Mills]

    Although it is true that the Vega OP switch will allow the fuel pump to run while cranking the engine, if it is the same one sold by one of the vendors, it creates another problem.  It does not contain what is needed to cut off the fuel pump in case of an accident and the engine  stops (due to loss of oil pressure). This creates an extreme fire hazard.  True...if one has also installed an inertia type switch in series with the fuel pump (and assuming it tripped as designed) the fuel pump would not keep running.  But what if the collision was not of sufficient force to cause the inertia switch to trip.

My advice is to install an OP switch that contains a set of N\O contacts that will keep the engine running when the engine has oil pressure, but will kill the circuit to the fuel pump if oil pressure is lost.  OP switches are available that have this set of N/O contacts, plus a set of N/C contacts that one can use to operate the idiot light on the dash. (A normal OP switch contains only one set of contacts, a N/C set that is used to operate the idiot light).  Use of the type switch that I suggest, (along with an inertia switch) does not alleviate the cold (or dry carb) problem, but this can be overcome by wiring a momentary switch to the fuel pump to prime the carbs before cranking, which allows the car to crank quickly.  Works for me on two cars with zero failures since installed, which is a better track record than I was having with manual fuel pumps.  Somewhat more elaborate but covers all the bases.

This was covered in detail in the December 2003 Issue of the Communiqué in a Tech Topic article that I authored.  I still have copies that I can supply if anyone is interested.  Since this is a very debatable subject, and it is not my intention to offend some that disagree with my thinking or to start a fuel pump flame war, please contact me off line if you are interested, and I will forward you a copy of the article.

Cecil Mills
Cocoa, Fl.