I am one of the first to boo-hiss at modern stuff on old cars, but after a near disaster the other day (electric fuel pump stayed on after killing the ignition, I need a fuel pressure regulator apparently, enough fuel made it into the upswept fenderwell headers to cause me to soil my shorts upon firing the car again...), I decided maybe this is one area that I need to just swallow my luddite pride and remedy the situation. The engine block is an 89, .040 over 350, I left the factory knock sensor and oil pressure switch in place just to plug the holes...I'm thinking the oil pressure/fuel shutoff might be a good place to run the pump wire to so that the fuel pump shuts off if the engine stalls, etc. I could use a momentary switch for priming it if necessary...and yeah, I know I need to check why fuel went by the needle/seat in the Holley if it wasn't a matter of excess pressure. So, my question to those more knowledgeable than myself on modern doohickeys in 'puterized cars...does that oil pressure switch just above the oil filter on an 89 model 350 provide a ground when pressured up? Is this a reliable/viable option, or should I just wire up a circuit to do the same job? I drove it to work today...made working on a holiday almost bearable
No switch will provide a ground if it is on a dial system. If it is a idiot light it does ground to turn the light on If it is on a dial it is a variable resistor that changes resistance as it heats up. so, now you might be able to figure it out. Traderjack
Look at this incident as a message from your guardian angel. I prefer a seperate switch, wired in series, for the pump. I also have a ball valve in the gas line connected to a choke cable, located at rear of car.
93 isuzu trucks, rodeo's,amigo's etc. have a idiot light pressure sender that comes on at 4 psi, they are cheap cheap new, and almost free at a salvage yard, it is a ground sender (one wire) and is very small , just run it through a normally closed and let it open the relay when no pressure
I just finished wiring my roadster and was faced with the same decision. I used an Echlin OP 6118 Oil Pressure Safety Switch. Made specifically for this purpose. One terminal for power in, one for power out to the pump. Makes/breaks contact at 2 to 4 psi. The momentary contact switch for priming is a good idea too if you don't run it often. Bob
Their is a three prong oil pressure switch out there that will lite the lite and pump the pump when pressure is up.
Yep, something was wrong alright...I forgot to turn the temporary fuel pump switch off bad bad bad bad bad. But, it made me realize what could happen if...say...something went awry under the hood...I don't need a fuel pump spraying fuel onto something that could turn me and the Chieftain into a rolling inferno. I'm definitely going to look into the switches mentioned in the above posts and create some sort of safety circuit. Thanks y'all!
When I wired my coupe I added a rear crash switch from Ron Francis and a separate safety/kill/security switch in easy reach of the drivers seat. Also the ignition key MUST turn everything off.
I believe the 3 wire switch you are refering to is from a Chevy Vega. I use that in conjuntion with a push priming ****on wired hot on my carburated sprint car. NAPA stocks them.
I have a 3 prong switch from a Monza on mine, it has 3 terminals, marked I S P for Ignition, Starter, Pump. With no oil pressure, the starter wire connect to the pump, once it builds pressure the ignition wire connects to the pump. This way it runs the pump when you crank the engine...and it shuts it off when the engine dies.
It seems to handle current better than it handles heat, I need to replace it every few years when it starts dripping. it's warm above the oil filter, what with the header there I'm just running a holley blue pump, they don't draw a lot of current, since they don't move a lot of fuel. only about 700 hp worth.
Stewart Warner makes a nice pressure safety switch. Three terminals. Normally Open. Normally Closed. Hot from the ignition switch. A primer ****on wired to byp*** the safety switch when the car's been sitting for a while saves a lot of cranking. Wire this from the ignition switch. Here's the S-W switch mounted on the right side of the remote oil filter setup. This shows the primer ****on which is an early Ford looking starter ****on with two terminals. Definitely run a relay back by the pump. Without the relay you'll have about a 10% voltage drop at the pump with the long run of wire from ignition switch to safety switch to back of car. The low voltage will burn up the pump after a few weeks. Feed the relay with 10 gage wire and place it inside the car, but close to the pump.
Any of these switches should be wired to operate a relay, NOT the pump. The pump needs to be driven off of a relay designed to handle the current.
I put a 350 without mechanical fuel pump in an s10, used a 2 prong oil switch to operate a relay, nearly free at any junk yard.
I've never done this but.....I know outboard motors used to have a cut off switch if the motor overturned. Maybe make a friend in the outboard world, and get one. Be nice to kill fuel if you flipped your rod.
I use a switch that turns itself off if there is an impact. I think it was a Ford item. It is mounted on a board on the inside of the frame rail along with the pump and the relay like this:
I agree with the above posts. Years ago, the AlaKart burned up due to this kind of problem. I understand it caught fire and the electric pump continued to pump feeding the fire. I have always thought that if I were to run an electric fuel pump, I'd install a solder link for the pumps power wire in the engine bay. Any kind of fire would melt the solder and kill the fuel pump. I'd be sure to mount it on the top side where the heat would melt it quickly. Any thoughts?
The Jalopy Journal
