SW OP switches FYI

[HingsingM37]

While planning my electronic fuel pump upgrade I discovered that the 5000 series Stewart Warner oil pressure switches actually come from Honeywell. I got it from a Honeywell dealer at nearly half the cost of Summit or NAPA

[NAM VET]

Tell me more about your electric fuel pump. I put in a marine 24v Facet, the small cube one, (not a knock-off Facet, a real one) rated at I recall something like 5-9 pounds, and also put in a plastic filter before the pump, both mounted just in front of the tank on the rear frame rail. I also installed new fuel lines. and a new fuel line shut off valve. I was worried about excessive fuel pressure to my carb, so also installed a high end pressure gage in the engine compartment, and found with the gage at max pressure, my dampened gage reads 3 pounds. It must be enough, as my truck has plenty of power climbing hills and such. What is your planned system?

NV

[Cal_Gary]

Hi Nam Vet,
Not to divert the thread but optimal fuel pressure is around 5 to 5.25 PSI (for what it is worth).
Gary

[NAM VET]

Yeah, I might put in a higher capacity pump one of these days. I can't see the pressure gage under load, but the truck seems to pull just fine now. But likely boarder line fuel pressure. Maybe the 8 foot of extra fuel line distance pulls the pressure down a bit.

NV

[HingsingM37]

Hello Nam Vet,

My plan is simple (aren't they all ) the OP switch is normally open and will close when minimum oil pressure is established. This will energize my fuel pump. The voltage will be supplied so that the fuel pump will only run if the ignition switch is on and there is sufficient oil pressure present. This will kill the pump if oil pressure drops low or if the engine ceases to run in event of an emergency. I am using a 24 VDC marine pump which will be mounted on the LH frame rail in front of the tank. I will fab a isolator bracket to give the pump a little anti-vibe mount. I should have my switch and pump Monday and hope to tackle this before Labor Day.

[just me]

So, are you putting an override pushbutton in to run the pump with engine off? To fill the bowl pre start after the truck has sat for a time or you've run it out of fuel.

[HingsingM37]

I try to start my truck weekly if not drive it. My fuel gage is accurate and have yet to run it out of fuel. I try to keep it full.

To answer your question, Yes, using an aviation primer solenoid assembly. This allows a single push to run the pump for only about two second cycles. I have seen folks just run a straight push switch and I never liked that idea. I have even seen shops do this and end up telling their customer "not to hit it too much, you got to get a feel...".

I am also putting a fuel filter before the pump, this I feel is most necessary as a few pieces of crud can really hurt an electric fuel pump.

[HingsingM37]

Then I thought if I set the switch to close at a lower pressure, I would not need a primer. I cannot locate the primer solenoid I had off the twin Comanche, probably lost in the move. I will tweek the set up as I go

[just me]

Holding the button closed until the pump stops by itself is all that is necessary. No need for timers or other voodoo. It isn't a primer system, you are just filling the carb bowl until the needle valve is closed and the bowl is full. The pump will stop at that point regardless if you are providing power to it.

[HingsingM37]

No timers involved. Just trying to put a part I had to use. I thought a had a Parker 20CC02PU4B lying about, These normally closed 2-way valves are direct acting and have only two moving parts, a viton plunger and stainless steel spring. No voodoo in my opinion.