Elec. Fuel pump & Gas Tank

[hk45acp]

Hi

I've got a 63 riviera that needs a new gas tank and I'd like to install a electric fuel pump in it as well. Any options and sources are much apprecieated.

Thanks for helping a newbie out

[NTX5467]

Seems like I saw something in the current StreetRodder magazine about a company that had add-on in-tank fuel pump modules (pump and sending unit) for particular street rod applications? As for adding electronic fuel injection to those cars.

Some key items to consider . . . the older fuel tanks had anti-slosh baffles in them, generally, with the sending unit going in either on the front side or the top side of the tank. A sending unit that didn't mind catching a little air every now and then if the tank level was really low, for example.

With an electric in-tank fuel pump (which is part of the sending unit on fuel injected vehicles, either as a replaceable item or an integral item), that pump needs to "sit" in the fuel at all times. Not only to have a consistent fuel supply to keep the pump from sucking air, but for cooling of the pump itself--fuel being used as a "heat sink" of sorts. Hence, some internal plastic baffling (for an exposed pump, especially) in the tank would need to be added to a non-fuel injection tank.

The fuel pumps used for any kind of electronic fuel injection (even throttle body injection) on gasoline-fueled vehicles are much higher pressure AND volume rated than any carburetor can withstand. A fuel pressure regulator would be needed--period.

Adding an in-line electric fuel pump is a much easier and "friendly" thing to do, but it would require some expertise in engineering where to put it, getting it wired-in and plumbed-in with the existing fuel line. These "normal" pumps will usually hit the fuel pressure areas for carburetors, too, possibly with an internal pressure regulator.

In the realm of GMPerformanceParts, there is an in-line electric fuel pump that is used on the older 6.5L Diesel V-8s. It is often mistaken for an in-line fuel filter . . . except it has a wiring harness coming out of it. It is also (apparently) rated for gasoline as well as diesel, as it's in the PerformanceParts catalog. It might also be available in the aftermarket, too. Using something like that (which is production-based) would be an incognito way to go and something that you might not necessarily need to go to a hot rod shop to get. But it's "in-line" and not "in-tank".

And then you've got to consider how to replumb the fuel system around where the prior engine-mounted fuel pump used to be . . . plus an appropriate in-line fuel filter.

Just some thoughts,

NTX5467

[RivNut]

If you're adding an electric pump to your system, there's no reason that you can't also incorporate the orgininal mechanical pump as well. You might also consider adding a fuel pressure regulator to the line while you're at it. In line pumps are rated for different pressure; make sure you get one that's not going to give you too much fuel.

In the early 80's some Buick Skylarks and some Regals used electric pumps. One safe guard that Buick incorporated was to wire the fuel pump through a special oil pressure sending unit. The fuel pump would shut off if the engine lost oil pressure. Same scenario as having your key on, and the pump running without starting the engine. I use the same wiring on my 64 Riv's electric choke set up. That way the choke isn't pulling itself open until the engine is actually runnig. The threads aren't the same so you need to use an adapter between the sending unit and the block.

[hk45acp]

Thanks for the info

I just re-read my post and realize it seems a bit ambiguous. I didn't mean that I had wanted to install the fuel pump inside the tank just that I wanted to switch to an electric pump from a mechanical unit

[NTX5467]

When GM started using more electric-assist choke systems, they wired those through a special oil pressure sending unit. Not just on Buicks, but other carlines too. When I was researching a carb change/upgrade on my '77 Camaro (to a 4bbl with an electric choke, I investigated using one of the "multi-prong" oil pressure sending units, but could not make it work. I ended up wiring it direct to the alternator lead that would have gone to the idiot light (which my car did not have, having a voltmeter) as it would have spliced back into the main wire later on in the harness. Holley has a "ThermoDyne" thermocouple to modulate current through the electric choke coil depending upon engine temperature--the thermocouple is "the ground" for that circuit rather than through the carb itself or with a ground wire. I got one of those too, but didn't use it as I didn't really need to.

When the Chevy/GMC light duty trucks got throttle body fuel injection in 1987, they used a separate sending unit to run the electric fuel pump. On the Chevy V-8s, the normal oil pressure sender is on the top rear of the block, which is where the oil pressure sender is on those motors. The oil pressure switch that closed the circuit for the electric fuel pump was located on the side of the motor, near the oil filter (which screwed into an oil galley where a pipe plug normally was)--it looked just like an oil pressure sender for an idiot light. In the next few years, they went to a unified oil pressure sended/fuel pump switch (3-prong) situation.

So, there are some production-based situations which are similar to what you desire to do. On the factory electric fuel pump situations, there is also a timer that will let the fuel pump run for (about 45 seconds?) a short while and then turn off if the engine does not start (overriding the oil pressure switch at that time). Might also be a relay in that circuit too?

Just some thoughts,

NTX5467