OPSS Switch question
 

Greetings - a couple questions as I upgrade to a electric fuel pump (working with the MM conversion kit)

1) the brass plug I need to remove to install the OPSS is giving me grief. Instead of fighting this any longer, I got a bright idea.....wondering if I can add the OPSS to the same outlet as the Oil Pressure sending unit. To avoid any extreme torque on that location, I would use a “AN” fitting, and remotely mound the sending unit and OPSS. Any reason this won’t work?

2) I am adding a fuel shutoff solenoid. Any reason I can’t power this off the coil “+” terminal ? Turn off the engine, solenoid closes. This is over and above the valve on top of the tank.

As always, I value, and appreciate the input of this group.

Cheers
Jimmy

Jimmy, I have made a similar change and it is perfectly acceptable. Mine is made up using AN fittings and stainless braid hose. In my case I'm feeding four units, the OPSS, two oil pressure gauges and a Cole Hersee low oil pressure alarm.
Tom

1) That's how mine is, oil pressure actuated sender/switches mounted on a bulkhead, connected to the engine with 300psi oil rated hose. Be sure to run a ground wire to the sender array, the oil pressure gauge won't work without it.

2) Yes, you can power the solenoid shutoff from coil + with this advisement: to do it right, as you add load to the ignition circuit (this valve and the new electric fuel pump) you should measure the voltage at all components on the circuit. You don't want voltages lower than 3% of the source which for the engine circuit is the alternator. Voltage measurements below 3% indicate the entire ignition wiring circuit needs bigger wire. We have a voltage drop calculator on the USCG/ABYC Standards forum category.

One more question...
 

Thanks for the feedback guys. Last piece to this mini refit, is to relocate the coil, on a bulkhead. Like the idea of cooler ‘smoother environment. In doing so, I will need to increase ( replace with longer )the length of the coil wire that runs between coil and distributer cap. Any pit falls?

Again, Tnx

Cheers
Jimmy

No pit falls with coil relocation, rock on. It would be interesting to get some IR temp readings of the coil before and after relocation to compare.

Future coil temp comparison
 

Thanks for the info.....
I will prep the A4 for a coil relocation, but not actually move it until after launch, around last week of April. I have a IR temp gun, so readings should be very accurate.

Cheers
Jimmy

Great! Please mark a target on the coil so you are reading the same spot.

I've done the remote mount of the pressure sender and the OPSS. I used an 18" length of hose meant for a grease gun (Home Depot stock). Don't forget to run a ground lead to the block.
I also tried the solenoid fuel shutoff, but wasn't comfortable with it and changed it out for a ball valve. Perhaps if I'd had the fuel pressure gauge at the carb inlet (which I now have), I would have kept the solenoid valve.

+1 on coil relocate working OK. I found a semi-custom wire available at my local NAPA. The high tension wire ended up being about 6" longer than A4 OEM to reach the bulkhead where I mounted the coil.

Look forward to your readings, Jimmy!

What’s ‘normal” fuel pressure/
 

Couple weeks later than planned, but finally splashed today. Will relocate coil after more seasonal temps set in.....single digits temps today- yuck

I noticed my fuel pressure gauge was reading a steady 2.5 lbs. ( just started running with a electric fuel pump)

Last year with the mechanical pump, I constantly showed 5-6 psi, on the same gauge.

What’s “normal ‘ fuel pressure? What would you consider “low’” fuel pressure?

Thanks for any pearls of wisdom you can share

Jimmy, about all the A-4 needs is 1 1/2 PSI, 2.5 is great and 5~6 is on the hi side and nothing to be concerned with.

Dave Neptune :cool:

Electric fuel pumps come in different flavors. Some are 4 PSI, some are 2, some are 8, etc.
The A4 really doesn't care, 1 PSI will run it fine and so will 6. 8 might be pushing things.

This made me wonder where in the Arctic you might be rocking that A4 until I realized...CENTIGRADE. Still cold, but...Canada.

Canada...the home of the elusive Atomic Four "Stevedore" edition! Have you got one? Limited HP version of the A4 to comply with a short-lived Canadian trade restriction.

http://www.moyermarineforum.com/foru...read.php?t=162

What is "AN"
 

"1) the brass plug I need to remove to install the OPSS is giving me grief. Instead of fighting this any longer, I got a bright idea.....wondering if I can add the OPSS to the same outlet as the Oil Pressure sending unit. To avoid any extreme torque on that location, I would use a “AN” fitting, and remotely mound the sending unit and OPSS. Any reason this won’t work?"

Thanks! My ignorance is boundless.

Coil on bulkhead
 

When I moved our coil to the bulkhead I attached it with a chunky piece of aluminum as a heatsink. Didn't have an IR temp gun at the times, so no comparison available...

Yeah, good question, I had to check it myself and I used to work for a screw company. AN is the set of standard sizes you find on little brass threaded flare fittings like we use in our fuel systems and find on the shelf at Home Depot. They were probably special order for Jimmy because of his metric surroundings. AN is an anachronous and somewhat unhelpful name for the standard - it stands for "Army Navy."

https://en.wikipedia.org/wiki/AN_thread

Jimmy, if you have the opportunity you might want to abandon the flare fittings for regular rubber hose and barb fittings, which are MUCH easier to move around and replace.

This would be an excellent time to install a fuel polishing filter just before the carburetor if you don't have one already.

TRUE GRIT

New configuration
 

Fuel path is as follows...
-Tank
-shut of valve immediately on top of tank
-steel (copper?) line down , around to side of engine compartment
-transition to rubber fuel hose
-Racor fuel/water separator
-electric fuel pump
-shut off solenoid ( opens when coil is powered)
-fuel pressure gauge
-polishing filter
....and finally, to the carb.

As you can see, I have a lot going on, hence my concern about a drop from 6 to 2.5 psi in fuel pressure.
All fittings are double clamped hose over barbed brass fittings, except the shut off valve / metal fuel line on the top of fuel tank. It has a compression fitting.

My using the “AN’ fitting/hose was to allow me to remotely mount the oil pressure unit.

Will Snap a picture next week and post.

Thanks for the feed back- this place is a awesome resource

Cheers-Jimmy

Picture is of my new fuel system set up
In the corner behind and above is where the coil will be relocated, after I get base line temp readings from its currant location, on the rear of A4

Cheers
Jimmy