Fuel Pump Question/Ideas

[carolinamv]

I bought a museum quality restored '54 M37. I don't know who did the restoration though. The person put a eclectic fuel pump set up under the truck ,near the tank and did a very good job with spin on filter,mount,etc.

They put a switch on the dash for the fuel pump. My question for you guys, why wouldn't you just run the wire for the fuel pump to the battery switch on the dash, then when you turn the batteries on to start the truck the pump comes right on? Im open for answers ,comments, concerns.

Id like to run the wire for the flip switch for the fuel pump to the hot wire for the battery switch to make one less thing to do and taking off the non original switch on the dash for the pump since the restoration and originality is so well done.

Thanks Troopers.

[Cal_Gary]

Hi Jay,
Safety is an issue-electric pumps will continue pumping fuel if you're on the side, upside down, on fire, etc., and if you were rendered unconscious, who'd turn off the pump? Dramatic I know, but who knows?

I'd search the forum archives-someone adapted an oil pressure switch to trigger his electric fuel pump and posted pictures-Hingsing perhaps? Just a guess....
Gary

[ZGjethro]

I have the same dash mounted toggle for the fuel pump, and the separate ignition switch. I have meant to run the pump circuit through a pressure switch, but have not gotten to doing it yet. I also have a negative battery disconnect which I turn off when I leave the truck. A total of three switches instead of one like most vehicles have

[just me]

Every vehicle I have ever owned with an electric pump has had it come on with key on. (Except my airplane) you could always add in a tipover sensor if you were worried about it.

[M60TC]

You might consider adding the pressure oil safety switch in line with the original oil sending unit and then the electric fuel pump will not run with out engine oil pressure. Add a small (over-ride), push button switch to prime the fuel system for starting if needed. This priming push button can be installed under the dash out-of-sight, keeping your Truck looking original. If the Truck has been siting for a few days you may have to push this hiding primer button for about a two second count. Adding a main battery switch near the battery box would also be a good idea for safety when working on your M.

[ZGjethro]

I am unclear as to where the pressure switch would go? Probably anywhere in a pressurized circuit, but where is a good location? Any pictures?

[carolinamv]

You guys have some great points and ideas.

Who would turn off the separate fuel pump switch if it rolled over, etc? I figured it was a safety reason , but didn't make much since ,because you would still have to turn it off also.

I do have a battery shut off switch. That cant be seen.

Other that that and making sure it wasn't pumping fuel with the engine not running , do you guys see a problem running the fuel pump hot wire to the dash battery switch hot wire to get rid of the fuel pump dash switch?

[ZGjethro]

You want the oil pressure switch to cut the power to the fuel pump when the truck hopefully stalls during an accident. If the truck stays running, then there isn't as much of a threat, although I guess you could have a fuel line rupture and still have the truck running. The idea is that it shuts off independent of your actions

[carolinamv]

Roger that. I will look into a oil pressure censor.

But , then you could still run the hot electric fuel pump switch wire to the hot normal battery switch wire to make it easier to start and eliminate an extra step when starting the truck?

[jim lee]

Why do you need it at all? Mine has no extra fuel pump and it seems to work fine.

-jim lee

[ZGjethro]

Yes, you can wire it that way. I like the idea of the override like M60TC mentioned though. My electric pump switch is in series with the ignition switch. I don't want to risk flooding the truck or draining the battery if I inadvertently leave the ignition on but the motor is off. sometimes I turn on the power to work on various electrical components.

[M60TC]

Carolinamv and ZGjethro

By adding the oil pressure switch, override primer push button and having a good in-line fuel regulator you can now turn on your original M power switch with out a worry of fuel issues and your Truck safety has increased.

[eagle4g63]

While all good ideas for improving the "safety" of the truck. The simple question was asked about powering the pump without the use of a separate switch that looks out of place on a nice restore.

Yes you can just use the main switch. While I have not looked on the back of the m37 main switch, they may be the same as the ones used on the other M series trucks like the m35(deuce and a half) and have additional wire hook ups you can use for the fuel pump wires. Speaking of the m35, did you all know that there is a military installed electric in tank pump on those trucks....it is powered by the main switch and if you kill the engine.....it stays running!!

So while a way to kill the pump in an emergency is a great idea, it is not a mandatory thing....actually before they started implementing a fuel safety switch on many modern cars they would also run non stop till you turned off the key in an accident.

Not trying to start any arguments, just trying to get to the question and answer it clearly and easy....YES use the main switch...you know you won't accidentally leave it on when you turn the truck off.

[ZGjethro]

So where are people installing the pressure switch? Is there an unused port, or do we have to make some adaptors, which isn't a big deal

[M37N55]

This is a topic to consider when putting my M37 back together. When I got the truck a eletric fuel pump and shut off switch where mounted under the drivers seat... but my engine builder found and installed an original one on the engine... so I'm hoping to go original... I hope... would an original be enouph for a bored and stroked flatty (277cu)