Fuel System: Installing Electric Fuel Pump

[ColoradoHawk]

I’m tired of my ‘63 Hawk vapor locking on me, so I’ve made the decision to go to an electric fuel pump. My question to those of you that have done it (and I’m sorry if this is a dumb question) what’s the preferable way to run the wiring to it? Under the car along the frame rail? Inside the car under the carpet? Thanks

[Warren Webb]

I personally haven't done it yet but if & when I do I'll run it along the frame rail. My reason is wiring run under the carpet can (even remotely) be pinched by walking on it (getting in & out, ect) even though Studebaker ran the wires to the tail lamps that way. There isn't a protected area inside the car. At least running it along the frame rail one can secure it with plastic anchors with self tapping screws into the frame.
I would also make sure there is protection in the circuit such as a roll-over switch as used in Fords &/or an oil pressure switch that would cut off the fuel pump if oil pressure is lost.

[altair]

I am not conversant with all the issues that affect a vapor lock. At what location in the fuel delivery system does the vapor lock occur, at the carburetor or the fuel pump? It would occur to me that the fuel pump would have to be trying to pump vapor, is this the case, I don't know. On my 54 Champion there is an air vent through the grill directing air over the fuel pump, do other vehicles not have this feature? Is the fuel in the carburetor or the fuel pump boiling? A frozen heat riser can cause some erratic fuel issues. I cannot understand how the fuel could boil at the fuel pump as it is constantly fed with cool fuel. Intake manifolds can get extremely hot and boil the fuel in the carb particularly if the heat riser is frozen closed. Many later model cars introduced water cooled intake manifolds to avoid the vapor lock problem. I think vapor locking could be reduced substantially if the cooling system is assured efficient ie clean block and clean radiator and a 160 thermostat as well as a proper functioning heat riser.

[Dads Baby]

I zip tied my power line to the rear wiring harness which runs along the driver's side frame rail. I figured that it was safe enough for Studebaker, it was safe enough for me. I used black wire and black zip ties so it blends in...

[JoeHall]

I mount the electric pumps up front, on top of the gravel shield, in front of the radiator, where it stays cooler. So the wires are much shorter and easier to run.

[ColoradoHawk]

With my Hawk, it’s vapor locking at the fuel pump. I have a 1/2” phenolic carb spacer as well as heat protective sheathing covering the fuel line to the carb and I’m absolutely sure the heat riser is operating correctly. If I get her up to temp and then I shut down and let her heat soak for about 10-15 minutes the car will start and run for about 30-40 seconds and then die and won’t restart. Last time it happened, I sprayed water on the fuel pump for about 30-60 seconds and got her to start again, so I’m sure it’s the pump causing my issue.

[gordr]

Vapor lock occurs when fuel vaporizes in the suction side of the fuel pump, and the pump draws only fumes, if anything. The counterpart to vapor lock is percolation, where fuel boils in the carb, or in the pressure line between the carb and the fuel pump, and the excess pressure forces the float needle off its seat, and the intake manifold becomes flooded. If the latter happens while the engine is running, it will usually flood out and die, but revving it may clear the flooding. In the case of vapor lock, the engine runs lean and quits from lack of fuel. Given that modern fuels boil more readily than the good gasoline of the '50's and '60's, it seems to me that for a driver, one should do what the other manufacturers do, and install an electric fuel pump back near the tank, powered by a safety relay designed to stop fuel delivery if the engine stops running. Remove the mechanical fuel pump, and install a blockoff plate. Pushing pressurized fuel through a mechanical pump will work...until the pump diaphragm fails, and then the electric pump will do a fine job of filling the crankcase with gasoline.

[Studebaker1962]

I installed a fuel return line. I used a side port "return" fuel filter just before the carburetor. It is a NAPA filter with a about an .080" orifice grommet inside the side tape for hot vapor return to the tank. I ran 1/4" flex from the filter side tap to a 1/4" brake line that I flowed next to the 5/16" supply fuel line. Then went back to flex and connected to a 1/4 bard I had welded to the steel part of the filler neck. Just mark a spot on the filler neck at a location above the fuel tank but below where a gas fill nozzle would extend to when at the gas station . Take it out and have a piece of the tubing welded into a hole you drill. No more vapor lock, hot gases and fuel return to the tank and swirl around to cool off. I used no check valve in the return line. I am sure the .080" orifice was sized so small so there is no shortage of fuel to the carb, just acts as a pressure relief valve of sorts.

As my 1962 GT Hawk is not a daily driver, I want to install an electric fuel pump to "Prime" the mechanical so I don't crank so long. Picture to follow of my set-up.

Jim

[pinehurstbob]

Jim (studebaker 62) has an identical set up to what I have done to my Studes. Both are 259 Automatics and with the return line I have not vapor locked once in 4 summers driving. I kept installation simpler by using fuel injection rubber line zip tied to the steel line from the tank and used filler neck for access back into the tank. The power source is the "overdrive" wire that is built in to the wire harness. Power goes on and off with the key. It can be found under the hood near the steering column. If you are going to drive them,you will likely have to buy ethanol laced fuel somewhere, and this set up keeps you running.
Bob

[JoeHall]

Jim (studebaker 62) has an identical set up to what I have done to my Studes. Both are 259 Automatics and with the return line I have not vapor locked once in 4 summers driving. I kept installation simpler by using fuel injection rubber line zip tied to the steel line from the tank and used filler neck for access back into the tank. The power source is the "overdrive" wire that is built in to the wire harness. Power goes on and off with the key. It can be found under the hood near the steering column. If you are going to drive them,you will likely have to buy ethanol laced fuel somewhere, and this set up keeps you running.
Bob

I have used the same setup for many years, but have found after a few thousand miles, the relief valve in the filter gets weak, and begins to bleed off too much fuel. The result is fuel starvation. So I install a .060" restrictor in the return line, a few inches from the fuel filter. I have discovered a Kenin carb jet, from older Harleys, serves perfectly as a restrictor. But you could make one out of anything handy.

[Chicken Hawk]

Check your PM

[altair]

I asked the question as to what a vapor lock is and how to fix it on a question and answer site and the answers went something like this,
" A vapor lock is an unwanted condition where bubbles of air from the fuel line caused by boiling on the vaporizing of the fuel in the lines from excess heat".

"The boiling will interfere with the movement of the fuel"

" Sometimes this condition will cause the float chamber to over flow and will flood the carb and cause the engine to stall".

"Some owners have installed electric fuel pumps to push the fuel through the air bubbles".

"To prevent the problem wrap tin foil around the fuel lines to reflect the heat away".

"Engine compartment having high heat enough to vaporize the fuel in the lines and pumps".

"Vapor lock is not common to liquid cooled engines".

"The fuel pump can no longer move fuel through the system once the fuel transforms to vapor".

"As a consequence fuel is not able to get to the combustion chamber and the car may run rough or die".

"The car may not restart".

"Fans are not effective enough to cool the engine".

"The fuel is more prone to vaporize at higher altitudes than on level ground" .

"Ethanol increases the possibility of vapor lock in stop and go traffic as your engine works harder with constant acceleration and deceleration".

PREVENTION

"Install the fuel to the carb away from the manifold".
"Install an electric fuel pump near the tank".
"Use Bakelite spacers heat shields and fans".

"Energy created by the pump itself will heat up the product which starts to boil".


I have difficulty finding anything valid in any of the statements. I cannot understand how the fuel from the tank to the pump can boil causing the pump to cavitate.

I can understand how the fuel can boil at the carburetor and cause flooding and stalling and in some cases engine fires. When this condition occurs continued cranking will only supply more fuel to an already flooded condition. I fail to see how the fuel pump can be the part of the problem except to add more fuel to the already over fuelled condition. The fuel pump is constantly fed with liquid fuel and therefore will not cavitate. The base of the carburetor is subject to excessive heat if the heat riser is stuck closed or the engine is operating at an elevated temperature because of too high a thermostat or inefficient cooling , system. In my 40 years in the fire service I attended countless vehicle fires where the carburetor flooded over and ignited destroying the car. The car has stalled or in some cases is idling at a traffic light and the carburetor has flooded from over heating ie boiled over. In all of the cases the vehicles were older units most likely with compromised cooling systems.

Many years ago with carbureted cars where there was large traffic jams and countless stalling of overheated vehicles the media referred to the condition as VAPOR LOCKS. They did not know what the real conditions were so vapor lock sounded very professional and all the media picked up on it. Today we still refer to fuel issues as vapor lock where as in most cases vapor lock is not the issue it is more like boiling if the fuel in the carburetor and causing excess flooding. The only immediate quick fix is to let the engine cool back down to normal operating temperature. Many cars in these long traffic jams sat on the side of the road for 20 - 30 minutes and restarted ok. Some cars were towed only to find the car started just fine the next day.
The best practice to avoid boiling fuel at the carburetor is a clean cooling system, proper functioning heat riser, 160 thermostat and the correct design radiator cap usually 7 lbs. If the cap does release the pressure that will also keep the temperature down, if the cap is too high that will only increase the engine temperature and will directly effect the fuel temperature and cause boiling. With a 7 psi cap and there is excessive over flow would indicate a cooling system problem, by increasing the cap pressure may stop the over flowing but will only increase the engine temperature and cause other issues.

[gordr]

You absolutely can get fuel to boil in the suction line to an engine-mounted fuel pump, or even in the chamber of the fuel pump itself. And with today's alcohol-polluted fuels, it is more possible than ever before. Fuel pump suction itself reduces the boiling point.

[Skip Lackie]

What Gord said. The problem may be the use of the word "boil", which is really not accurate in these conditions. Vapor lock can occur both between (or at) the fuel pump and the carb, and between the tank and the pump. In the former case, excessive engine heat can cause bubbles of fuel vapor to form in the fuel line. These are compressible, so that the pump strokes expend their energy repeatedly compressing this vapor instead of moving liquid fuel through the line. In the latter case, the fuel pump action produces a partial vacuum in the line between the tank and the pump, again causing bubbles of vapor to form. The pump really can only push or pull liquid fuel -- vapor on either side of the pump will cause the pump to cease functioning.

Modern fuel is formulated to reduce emissions, and vaporizes much more easily than the fuel of 50 years ago. In addition, the fuel that has been refined for use in winter months is even more likely to vaporize when exposed to warm temperatures in spring.

[48skyliner]

If an electric fuel pump overheats, it is because there is not enough fuel flowing to keep it cool. If you have an electric pump and no return line to the fuel tank, you are asking for trouble. The modern fuel injected cars I have experience with are regulating the pressure to the injectors by means of a regulator in the return line to the fuel tank. In most cases the pump is immersed in the fuel tank, so overheat is not an issue. Most of these pumps will produce 50-60 pounds pressure if "deadheaded", meaning no flow, and operate at about 35 pounds in normal running.

The early Mazdas, late 70s and on, were carbureted, running an electric pump just forward of the fuel tank, and providing about 4 1/2 to 5 pounds pressure at the carburetor. Where the fuel entered the carb, there was a T-fitting, returning some of the fuel to the fuel tank through a separate line. The size of the orifice in the T-fitting controlled the amount of return flow, and thus controlled the carb inlet pressure. With a constant flow pushed from the fuel tank, any vapor that might form due to engine heat would be pushed back to the tank, and vapor lock was not a problem. Without a fuel tank return line, any vapor bubbles would have no place to go except into the carb. And without the return line, the electric pump is trying to supply the maximum flow even at idle or when the engine is not running, and the pump will overheat.

The Nissan Skyline motors which I have in two of my cars have an interesting feature - a resistor module in the power supplied to the fuel pump. When the engine is at idle or very low power, the resistor drops the voltage to the fuel pump to about 8 volts. When you apply throttle to accelerate or are running at high rpm, the engine computer bypasses the resistor and supplies the full 12-14 volts to the fuel pump.

About a year ago I began to have trouble starting my Ford truck, which has an Edelbrock 600 carb, whenever it sat for long periods. I replaced the mechanical fuel pump, but that did not help. We could not figure out where the fuel was going, but rather than spend a lot of time troubleshooting, I installed an electric pump forward of the fuel tank, pumping through the mechanical pump. I turn it on, let it run for 30 seconds or so, and then the engine will start. Once the engine is running smoothly, I turn off the electric pump, since I have no fuel tank return line.