yep! you can use that red wire i belive it is, its a hot line with the key. thats what i used to power my 2 pumps, i just tossed in a 10 or 20amp fuse? inline and called it a day.

 

I have my trigger tied into the radio power wire. That way if the radio doesn't work I know the fuel pump isn't. Only problem is you can't listen to the radio. With the key backwards. I'm going to change it but it works so I'm just gonna leave it.

 

Why do you even need the low oil pressure sensor on these trucks? If you don't have oil pressure the injectors won't fire, so why bother turning the pump off if the key power is on anyways? Don't you want the pump to turn on with the key to pressurize the system before you crank it?

 

My sentiments exactly....

 

Then, anytime the key is on and engine not running the pump will be running. I'm not saying that is a bad thing but all commercial products have the oil pressure switch. The port down by the oil filter has almost immediate pressure cranking. In reality the proper way to do it is to get a 1 shot solid state relay so the pump comes on, say 5 - 10 seconds or so to pressurizer the system then shuts down until cranking. They are not to expensive, Newark electronics has them. I'll probably go that route as I gather parts.

 

I can see needing that pressure switch in a truck with mechanical injection, like a Cummins, but not in a a 7.3 PSD

The one-shot solid state relay makes more sense to me...

 

Thanks guys ill be doing some shot solid state relay powered by bowl heater wire and skip oil switch. That's were I was getting confused

 

I've never put an oil switch in any of the systems I've done.
However, I think it is a good idea and I should.

The whole point is in the event of an accident and the motor shuts off, without the oil psi switch the fuel pump would keep running and possibly pump fuel outside the confines of the fuel tank, casuing a fire or polluting the surrounding terrain.

Oil psi switch, as soon as the motor dies, the fuel pump dies, too.

I'd like to know more about the solid state relay.

 

Jim, this is the one I'm looking at ...

AMPERITE|12D.2-20SST2|TIME DELAY RELAY, SPST-NO, 20SEC | Newark.com

Basically it's programmable from .2 to 20 seconds with an external resistor. When power is first applied it would ground the fuel pump relay for the timing period (shorting out oil pressure switch) then release, pressurizing the fuel system before cranking, such as waiting for WTS light.

I need to order one and bench test it to verify it works as described. Clicking on the Technical Data Sheet provides more information.

 

Thanks for the link.
Can you give a little more info, though? Trying to understand how it actually works myself.
So you wire this in to the fuel pump relay feed/hot/ignition source and as soon as it sees power, it starts a timer and runs the pump for say 5 seconds (whatever you set it for), then shuts the pump off.
How does it maintain power to the pump if it's a timer, after you start the truck?
Or does this work in conjunction with the oil psi switch?

Thanks,
Jim

 

The way I understand it is jumper around the oil psi switch through the ground. When you energize the timer it bypasses the oil psi switch and completes the ground. Once the timer stops of course the ground circuit is broken until the oil pressure comes up.

 

Those switches are really neat. I got to learn about them in my HVAC courses.

The problem with using the port on the Oil Cooler like you describe is that Tim is using that for his bypass system as well as other people.

While the bypass relay is cool. Whats stopping it from staying on the rest of the time?

The truck will energize it when the first pulse is sent, but as soon as its running, whats to stop it from getting power and bypassing the oil switch itself?

Just wanna make sure we think all the necessary items though.
This is a very viable solution.

 

It will more then likely run for the set time. Once you actually start it. Alot of key on things reset after cranking. So at worst it should only run for say the set 10 seconds then once it denergizes it will be passing the ground through the oil switch.

 

I've been running an oil pressure switch on mine for several years now.. IMO a time delay relay isn't necessary. My fuel pressure comes up maybe a second after I start cranking. Quick enough to not make a difference in start time.. I haven't seen a need to have the fuel pump power on with the key yet.

The only time I've needed the fuel pump to run without the engine running is when I installed the fuel system and wanted to bleed the air out. In that case, I just ran a jumper from the relay to the battery and let the fuel pump run until fuel pressure came up and I could adjust the fuel pressure where I wanted it. For that, I wouldn't have wanted to use the key anyways b/c I needed the pump running while I adjusted fuel pressure. So I would've had to run a jumper either way b/c I ran the pump for a few minutes while I checked for leaks, adjusted pressure, and bled the lines.

That's just my opinion though. Others may think differently I guess.

 

I just finished mine with a relay on the fender. When you rob another box to insert parts do you only need as many terminals as you have spots for or do you need to do something with that buss bar too?

Just wondering because I'd like to fill up my box for e-fuel and later stuff.