Revolution Electronics Fuel Pump Shutoff

[Monzaguy]

Ordered the electronic fuel pump finally, and decided to go with the above fuel pump shutoff switch. (As a side note, Clarks is out of inertia switches and unknown when they will get some in). I looked at the PDF install instructions and it seems pretty straight forward except for the diode. Has anyone that used this found a need for the diode? It appears that the diode gets installed near the fuel pump and gets connected to the + and - wires of the pump. Wouldn't this short the fuel pump out being connected to both sides? Thanks, Mark

[bbodie52]

Since the internal electronic design of the fuel pump controller is not revealed by the company that makes it, I cannot explain why some brands, or designs, of electric fuel pumps cause a malfunction in the Revolution Electronics controller. But for whatever reason, Revolution Electronics has discovered the problem, and includes a solution if your specific pump is not functioning correctly, and is misbehaving as described in the instructions. The "fix" under these circumstances is to add the diode provided by Revolution Electronics to the circuit, which according to their engineers will correct the fault. Diodes are not a direct electrical short in both directions (like a wire). They are an electrical short in only one direction. In the schematic diagram, the diode conducts electricity in the direction of the arrow. On the physical diode, electricity is conducted in the direction toward the end of the diode that has a marker line on it (the CATHODE end in the illustration). If your fuel pump is installed without the diode, and misbehaves as described in the instructions, adding the diode should correct the fault. BE SURE TO WIRE IT WITH THE MARKER LINE (CATHODE) CONNECTED ACROSS THE FUEL PUMP WIRES, AS SHOWN.

If you initially install the fuel pump and the electronic controller without the diode, and it works properly, you can forget about the diode because your chosen electric fuel pump installation does not need it.

The installation instructions are displayed below, and are simple. It basically involves providing ignition switched power and ground to the controller, connecting the tachometer sensor wire to the coil negative terminal, and connecting the power leads to the electric fuel pump. It is no more complicated than the oil pressure switch alternative, and offers many advanced features over the oil pressure switch. It also avoids the plumbing problems associated with connecting the oil pressure switch to an engine oil pressure sampling point, like the oil filter mount using the adapt-a-bolt.


Revolution Electronics Electric Fuel Pump Controller
https://www.revolutionelectronics.com/P ... _Pump.html https://www.amazon.com/Revolution-Elect ... 023&sr=8-3

[bbodie52]

» Sat Oct 02, 2021 4:57 pm

Ordered the electronic fuel pump...(As a side note, Clarks is out of inertia switches and unknown when they will get some in)...

https://ssl.corvair.com//user-cgi/catal ... nd_page=66
Part number C9848: FUEL SAFETY INERTIA SWITCH

Weight: 1 lbs 0 oz
Catalog Page(s): 66
Price: $ 83.70


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Brand: Standard Motor Products
Part Number: FV-7
UPC: 091769141714
Weight: 0.25 lbs
Condition: New
On Sale: $46.83
Availability: 17 in Stock

[Monzaguy]

Thank you sir, did not know that about diodes.

[bbodie52]

I first ran into diodes when I was a kid — when my father gave me a "HeathKit" electronic learning project for Christmas to teach me something about transistors, diodes, resistors, etc. That early knowledge helped me to be selected in my late teens to become an electronics technician in the Air Force, and 24 years in that Air Force career field didn't hurt, either!

That inertia safety switch you want for your fuel pump installation is widely available and very common. I hope my last post above helps you to get the components you want to allow you to finish your installation.




My second HeathKit from the mid-1960s. It included a single circuit board that I had to learn to assemble, with a two transistor amplifier. The wired intercom allowed me to install a system between my bedroom and my sister's bedroom, so we could talk over the battery-operated intercom (4 D-Cell batteries, I believe).

So my father's interest in Corvairs was passed on to me as he used Corvairs to teach me to rebuild my first engine, and his HeathKit electronic project gifts that were given to me at Christmas time in the mid-1960s helped to shape my Air Force career path, my future as a computer technician and network administrator, and my continuous interest in Corvairs, as reflected here on the Corvair Forum!

[Monzaguy]

Everyone on this forum has helped greatly . I'm slowly getting the car ready for next spring. Just curious, was the diode necessary for your installation?

[bbodie52]

No, but I guess it depends on your fuel pump brand and model selection, and the pump's electrical characteristics that may or may not impact its interface with the electronic fuel pump controller circuit design. Apparently some pump designs cause a problem for the electronic pump controller, that sometimes requires the addition of the diode to make it function properly.

[gbullman]

… (As a side note, Clarks is out of inertia switches and unknown when they will get some in)…

FYI, I received my inertial switch from Clark’s on Saturday so I believe they have some in stock. It appears they did have an issue with a number of inertial kits missing the actual switch, at least that is what I was told when I called when my package was missing the switch.

I went with an inertial switch only and feel comfortable with that decision. Note I also installed a toggle cutoff switch so I could have the car on Acc but not have the pump run. I took my power for the pump off the heater / backup lights fuse but the pump is fused through an inline 7.5 Amp fuse that came with the pump.

[bbodie52]

» Mon Oct 04, 2021 6:09 am

...I went with an inertial switch only and feel comfortable with that decision. Note I also installed a toggle cutoff switch so I could have the car on Acc but not have the pump run. I took my power for the pump off the heater / backup lights fuse but the pump is fused through an inline 7.5 Amp fuse that came with the pump.

The electronic controller takes care of all of those functions. It eliminates the need for an oil pressure sensor switch that provides power to the electric fuel pump only when there is oil pressure or when the engine is being cranked, because it only provides power to the pump for a few seconds to prime the pump when the key is turned ON, or when the engine is running and the electronic controller senses ignition activity at the coil. It also contains an internal relay to handle the bulk of the fuel pump current draw, and it contains a 7.5 amp circuit breaker that takes the place of an inline fuse for the fuel pump. With the electronic controller there is no need for a manual toggle switch to turn the pump off when the key is ON. Control circuit power for the Revolution Electronics controller itself is tapped from the ignition switch circuit that provides power only with the key in the ON position. That wiring configuration does not provide power to the electronic controller with the key in the ACC position. Power is provided to the electronic fuel pump controller only when the ignition coil is energized, and power is passed on to the electric fuel pump only when the coil on/off switching activity from the distributor is sensed by the fuel pump controller (equivalent to a tachometer sensing function to detect a running engine).

So the Revolution Electronics controller eliminates the need for the manual toggle switch and the inline electric fuel pump fuse, and the oil pressure safety switch. The only external safety switch that is still desirable is the inertia cutoff switch, that cuts fuel pump power in the event of a vehicle impact that might leave the engine running even after an accident occurs. The inertia switch senses the high impact crash and cuts power to the electric fuel pump, even if the engine is still running after the crash.

Fuel Pump Controller
This universal electric fuel pump controller is designed for cars and trucks being upgraded from a mechanical fuel pump to an electric inline or in-tank fuel pump.

• Pump only runs if there is a tach signal from the ignition (Just connect to the negative side of the ignition if you don’t have a factory tach)
• Primes the pump for three seconds at initial key-on.
• Includes a 7.5 amp circuit breaker.
• Includes an internal relay.

[azdave]

Just curious, was the diode necessary for your installation?

Many small e-pump designs use a pulsing diaphragm to move fuel through the system. Those systems all have a solenoid with a plunger that turns on and off very rapidly push and pull the diaphragm. With each pulse there will be back-EMF generated from the coil field collapsing. My guess is that this pulse gets into the controller circuits accidentally and either makes it think the engine is still running or just simply overwhelms the digital circuits with brute force electrical noise. The diode serves to suppress this pulse that occurs when you remove power from an electromagnetic inductor. You'll also see diodes like that called snubbers, freewheeling or flyback diodes.

[Monzaguy]

Thanks for the explanation Dave. You still own all 8 of those Corvairs or is it a list thru the years of previous ones?

[azdave]

Thanks for the explanation Dave. You still own all 8 of those Corvairs or is it a list thru the years of previous ones?

It's actually nine here at home right now. Just didn't bother changing the sig line after the last purchase. Can't pass up a cheap Corvair it seems.

[Monzaguy]

Thanks for the explanation Dave. You still own all 8 of those Corvairs or is it a list thru the years of previous ones?

It's actually nine here at home right now. Just didn't bother changing the sig line after the last purchase. Can't pass up a cheap Corvair it seems.

Nice, I'm jealous