It came about that i ended up installing an electric fuel pump on a boat for my parents so my kids could go water skiing this summer. Well low and behold my retired dad found the weakness of an electric fuel pump connected to a 2bbl Rochester on the inboard GM....if you leave the key on it not only drains the battery, it also fills the oil with gas... read 1 quart high when I checked it, with the dead battery. I had simply connected the pump (10 amp fused) to the electric choke. Well this got me thinking of a better way to control the same pump I installed on my 59 4 years ago. Mine is connected to a relay which is hot whenever the key is on as well. I've heard of guys connecting the relay ground to an oil pressure switch, but that doesn't prime the carb and has to wait for oil pressure while cranking. I thought about building a simple circuit with a 5 second timer, then the oil pressure switch as ground. I wanted a simple solution and preferred a water proof one if I were to also use it on the old OT boat. This is what I found, and comes highly recommended. 2 wires for the dry relay contacts to power the pump, and 3 control wires. Black is ground, Red is keyed power (electric choke/ign coil etc) and Green is to a tach lead or the negative side of the coil from points/module etc. This gives a 3 second prime whenever the key is initially turned on, and then waits for a pulse on the tach wire. If the engines stalls, the pump turns off, and if the key is left on the pump won't run while the carb drips fuel into the intake, making your son have to use a mighty Vac to pull the oil out of the sump through the dipstick tube.... I put my module under the dash on the steering column mount. Was a convenient location as I have a tach and the fuel pump was powered off a switched fuse close by. Laying on my back under the dash reminded me why I only wrench for fun these days. I put a junk yard Ford crash switch inline with the pump circuit in the trunk so this makes the fuel pump as safe as reasonable for under $100 total for everything.
The advantage to the oil pressure switch is if you lose oil pressure the pump quits. I have had one on my 3W since I built it forty years ago. To prime the engine I wired a momentary push button switch across the pressure switch. I had a friend die when he was in an accident in his '32 Delivery. He was knocked unconscious and the electric fuel pump continued to feed the engine fire. A rollover switch is good to have but only protects you if the car is overturned. I feel that simplicity ,when it comes to safety, is of utmost importance.
Even if left on, the electric pump should not pump gas into the crankcase. Did you keep the stock mechanical pump? If so, it might have a leak in the diaphragm, which would allow the fuel under pressure from the electric pump to flow into the crankcase. If that is the case, bypassing or fixing the mechanical pump would be in order. Or else the pressure from the electric pump could be pushing past the needle and seat inlet valve in the carb, flooding the carb and the engine. This is worth looking into for safety. Boats with gasoline where it doesn't below can explode.
The Ford roll over switch worked by a sudden jolt also. I worked in a Lincoln-Mercury dealership when Ford went to electronic fuel injection. I can't tell how many Lincolns got towed in for no start, only to find golf bag in the trunk. Seems that they would bang into the left trunk flybrace and trip the roll over switch. We pushed the reset button and the car started immediately. Oh yes, Ford never paid for the tow or our button reset. That was the cost f
Had a Ford rollover switch trip after hitting a large pot hole. Was surprised it engaged that easily.
I also have the Revolution module and love it. You can turn the key on and off several times to fill the carb. Handy for a car that is not driven daily. It is better than the pressure switch as it also shuts the engine off when the tach no longer reads any rpms. No more cranking the engine over for minutes to get started.
Just wanted to give a good review for something that cost 65 bucks and provides a turn key solution. @Hemi Joel I didn't keep the mechanical pump, block off plate installed. I'm not convinced a carb with 3-5 psi applied continuously for several hours won't leak some fuel into the intake. I rebuilt it years ago, but the boat runs fantastic and starts instantly now. My parents are about the least mechanical people and I just want the boat to run as well as possible. I changed the fuel contaminated oil and went on the water for some fun.
Yes, aptly called tue fuel pump inertia switch. Simple mechanical switch which trips with enough jarring in any direction. When I was a mechanic we had the occasional no start which was towed in from hitting a pothole at speed. I've had the switch in trunk on my 59 all summer and have driven several thousand miles with out incident.
Or use one of these, which is found on propane powered vehicles like forklifts- This gives you power out for around 3 seconds if there is no ignition pulse on start -up.
Funny story about the Ford inertia switch. Used to be an SCCA corner worker and worked a lot of races at Nelson's Ledges when 5.0 Mustangs were new. And faster than Camaros that they raced against in showroom stock and Improved Touring. The Camaros would try to nudge the Mustangs somewhere on the track where we couldn't see them do it. And if done correctly, yup the Mustangs would mysteriously stop running.
With the pounding that boats take, going over waves or another boats wake, I don't think I'd want to use a Ford rollover switch in a boat.
Neat little module. Takes care of priming and engine being off in a crash, etc. I wish I had seen it last year when I was wiring up my 51 Ford. But because I have a manual transmission, I was able to go with an oil pressure switch on the fuel pump circuit and a clutch pedal switch on the starter circuit. By not pressing down the clutch pedal (I put my shifter in neutral just in case), the fuel pump runs but engine won't start and primes the engine. That module would be great for an automatic hot rod, though.
Yeah, people would miss the edge of a driveway and drive off the curb, and that shock would trip the switch too.
You mentioned that your dad left the key on........... Would the battery not run down anyway if the key is left on? Something has to be using power to tell the pump controller when to turn on/off. Nothing ever seems to be perfect, but it would seem that a simple "led light" that stays on when the switch is on would catch someones attention so they could turn it off. The only thing about adding something that controls the fuel pump is that its one more component that can fail.......and in a boat thats more problematic than a car. If the light were to fail, it would not affect the pump and an led uses very little power when lit.......and its really bright. I have several air compressors in different buildings on my property. Whenever I turn one of them on to do some work in that building, it turns on a red light on the outside of the building. If I go off and forget to turn the compressor off, I will see it from my house.......especially at night before I go to bed. Thats how I overcome my occasional forgetfulness. $10 on Amazon...and I think it blinks.
Hopefully you've also put a pressure regulator inline with the output of the electric fuel pump also, so it keeps the pressure down around 4 psi and wont overpower the needle in the float and flood the engine and crankcase. Too much pressure could have a bad result, even if the engine is running, so always good to have a regulator, and a gauge too.
Sorry, two different topics. Ford switch I put in my 59, along with the fuel pump module. I've had the Ford switch in my 59 for years and never had it trip. I tested it before putting it in, hit it with your hand while holding it in the other hand it it trips. Any direction of hitting trips it. The boat just has the module due to flooding. So I ordered 2 modules and installed the other in my 59.
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