QuestionQUESTION: Rebuilt the carb, new fuel filter, tank was cleaned, fuel pressure seems OK. Drove it a little farther than usual, so the engine had time to heat up. Engine died while idling. An hour later it started and ran fine. Sound like Vapor lock to you? If so, is an electric fuel pump the only answer? If so, and if installed, should we take the fuel line and bypass the existing fuel pump and go directly into the fuel filter container, or can we leave the fuel line going into the existing working fuel pump? Or is there a different problem, or better solution?
ANSWER: Yes, unfortunately the modern oxygenated gas is causing all of use old car drivers fits this summer, and it isn't going to get any better. The vapor pressure of the new gas is such that vapor lock is exceedingly likely any time you are driving in hot weather.
I'd add an electric pump close to the fuel tank, as low as you can mount it where it will be safe from road hazards. Run a short, direct fuel line from the tank to the electric pump, then run the outlet from the electric pump to the inlet of the mechanical pump. You will only need to run the electric pump for starting after a long layup, and during episodes of vapor lock. Be sure to wire the pump so that it goes off when you turn the key off!
Dick.
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QUESTION: OK, I am not a mech, so when you say to wire the pump so it goes off when you turn the key off, you mean, when you turn the key to the right to start the engine, and when it comes back to the nuetral position keeping the engine running, that is when the electric fuel pump goes off. You do not mean, turning the key off as in turning the engine off. In other words, it is only operating for just a couple of seconds or just as long as it takes to get the car started and that's it. Am I wording this correctly? I found a Facet POSI-FLO EFP-3, that I should be able to pick up at the local NAPA auto parts store. Is this brand OK, or would you recommend a better one for a 6 volt system? Thank you so much for helping me.
AnswerNo, and I'm sorry; I should have been much more specific - that's a hazard of this service: I never know how thorough I need to be in my response.
The last question first: If it is carried by a NAPA store, you can be pretty sure it is of a suitable quality - they are quite fussy about what they will offer. I have not heard of that specific brand, but I have bought other 6 volt fuel pumps from NAPA that have been very good (I have their pumps on all my collector cars) and have been satisfied with them. Just make very sure it is intended to operate on 6 volts, and that the output pressure is appropriate for a carbureted car - 5 PSI is typical, 3 PSI is the minimum, and 7 PSI is the maximum.
As to the wiring, the pump will come with two wires (or perhaps, if only 1 wire, the grounding to the pump will be provided by the mounting bracket), but in either case, the pump requires both a ground to the chassis or body of the car, and a supply of 6 volts.
You should purchase a small switch, either a toggle switch or a "pull on/push off" switch that you can mount under your dashboard in such a way that you can get at it while you are driving, but also such that it isn't too obvious. The switch should be a single pole, single throw switch (abbreviated SPST on the box), meaning that it will either connect or disconnect the two wires that you attach to it.
You will also need to purchase a roll of 14 gauge automotive hook-up wire, and a small quantity of crimp - on terminal ends, along with a crimping tool. All of this should also be available at the NAPA store, or you can pick up the switch, wire and terminal items at any RadioShack store.
Connect the wires as follows. To one terminal of the switch, run a wire to the fuel pump power lead (6 Volts). To the other terminal of the switch, you will have to connect a wire to a terminal that has 6 volts available only when the ignition switch is in the "on" position. The terminal on the ignition switch that is labeled "I" is the one to use, if you can get at it conveniently. If you cannot easily connect to that point, the other end of the existing wire on that point is also a good place to connect.
You will also have to connect a wire from the ground terminal or lead on the electric fuel pump to the chassis or body of the car - making sure that there is no paint or any other insulating coating on the place where you connect the ground wire.
With the wiring connected in this way, the pump will run if and only if both the ignition AND the toggle or push/pull switch you've added are in the "ON" position. The pump will also run while you are cranking the engine (because the Ignition is on when you are cranking).
I hope this is helpful - but if not, please feel free to ask for further advice.
Dick
