Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


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blueyAU Offline OP
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hi there,
on hot days my 35 Chevrolet std experiences fuel evaporation and the carburettor becomes starved of fuel, the consequences is that the car grinds to a bumpy halt no matter where it is and is becoming a pain the the bum.This happened this Sunday and I had to get a tow truck lift home at great expense..........

The filling station now has a 6 volt fuel pump available

http://www.parts123.com/parts123/yb.dll?parta~partsort~1~cadefefx @ $69.50 USD.

and I wonder if anyone has converted to the 6 volt electric pump? It seems that I may have to go that rout to ensure a plentiful supply of fuel at all times?
Q:- would I totally disconnect the existing fuel pump and install the 6 volt electric pump in its place? or in tandem?
Q2:- if so, where would I install it, in the engine bay or near the fuel tank?
Any help would be helpful.

Peter
australia




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Peter
The experience I have had is with 12v pumps and found they work best at or below fuel level but doesnt seem to matter if they are near the tank or in the engine bay. I have no experience with 6v pumps and dont know about availability of them in Aus.

You could plumb it in as a feeder pump to the original or as a stand alone unit.
I would check the flow and pressure of the existing pump as it may not be functioning correctly especially if the diaphram is old and stiff, or the valves are leaking internally. If the pump checks out good I would then try to insulate the fuel pipe between the existing pump and carb especially where it goes near the front of the thermostat and over the front section of the manifold as this is where the most heat is.
Tony


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Several people including me have installed an auxiliary electric pump to overcome vapor lock. The pump is installed between the fuel tank and mechanical pump. When the engine begins to stall the switch on the electric pump is closed for a few seconds collapsing the vapor bubble and allowing the mechanical pump to feed the carburetor. Seems that the modern fuel is much more prone to vapor lock.

We had several vehicles on the recent South West Fall/Early Six Tour in Nevada experience vapor lock. The 7000 foot elevation coupled with long upgrades produced enough engine heat to vaporize the gasoline at the fuel pump.


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Seems that the modern fuel is much more prone to vapor lock.


The modern fuel being the junk Ethanol.

What Chipper describes above is exactly what I have done to one of my vehicles and it works great. I only switch on the electric fuel pump when the crap Ethanol tends to vapor lock while I am driving or when starting the vehicle hot and it is vapor locked. After the vapor bubble is cleared I switch off the electric fuel pump and the mechanical fuel pump takes over once again.

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blueyAU Offline OP
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Hi there Tony,
I replaced the diaphragm with a filling station (KIT) last year, and everything worked well in cooler months that have just passed.

It the now very hot days that cause the trouble, 35 deg yesterday and up around 40 deg c today. It is to hot to even go in the shed.
Last week we were still lighting a wood fire in the evenings!

I have insulated the fuel line from the pump to the carburettor with that special exhaust bandage made form fiberglass and impregnated with carbon, it works well, but not enough for the stinking hot days and vapor lock.

The new extra large truck fan blade and refurbished water pump do the job and the car does not boil, but only get a fuel lock up....
I dont know how to test the pump pressure and flow so that option out.

Has anyone re-routed the fuel line towards the back of the engine bay and over to the carburettor, where it is presumably cooler?

My concerns with a 6 volt electric fuel pump is that maybe it would try to pump too much fuel if setup in conjunction with the manual pump? there is no return line to the fuel tank for excess fuel, as on a modern day car.

Peter




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Originally Posted by Junkyard Dog
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Seems that the modern fuel is much more prone to vapor lock.


The modern fuel being the junk Ethanol.

What Chipper describes above is exactly what I have done to one of my vehicles and it works great. I only switch on the electric fuel pump when the crap Ethanol tends to vapor lock while I am driving or when starting the vehicle hot and it is vapor locked. After the vapor bubble is cleared I switch off the electric fuel pump and the mechanical fuel pump takes over once again.

laugh wink beer2

thats an interesting idea, so does the fuel flow through your electric pump even when it is TURNED OFF, and into the mechanical pump and onward to the carburettor?

Peter




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On my auxiliary electric fuel pump, the gas flows through the pump when it is off, and then on to the mechanical fuel pump and from there to the carburetor.

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Peter
Since you say the diaphram is only 12 months old and you have done the muffler bandage trick I would think both those suggestions are out of the equation.
The 12v electric pumps I have used allow fuel to syphon through if the pipe opening is in a suitable location so the mechanical pump will draw fuel through without a problem and most electric pumps for carburettor operate at about the same pressure as the mechanical.
You could wait until the engine flutters then turn the pump on or leave it going all the time.
Tony


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The insulation on the line from the fuel pump to the carburetor is not necessary as long as the fuel pump produces its normal pressure. It in fact may increase the problem if it hinders the air flow around the fuel pump. Vapor lock occurs when a bubble forms either in the line from the fuel tank or in the fuel pump. Insulating the fuel bump will only make the situation worse as the heat from the engine block will stay in the pump. Increasing the air flow around the pump may help.

Adding 10-15% diesel to the gasoline can help as it increases the boiling point of the gasoline. Keeping the gasoline liquid through the fuel pump is the key to trouble free hot weather operation.


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My experience with outside of tank electric pumps(12v) is that they can overheat and burnout on a hot day if used continuously and have an irritating rattle. I have not heard a quiet one but perhaps some high dollar units do not have those deficiencies. Otherwise, used only when
needed (vapor lock or failure of the mechanical pump diaphram) they get you home!
Chipper, I have tried the diesel fuel addition on three of my vehicles: a 4 and two sixes and did not notice a difference. But we have not had a hot summer so maybe not really tested. I wonder though if continual use might increase carbon buildup on spk plugs and valves?
Dan

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My experience with outside of tank electric pumps(12v) is that they can overheat and burnout on a hot day if used continuously and have an irritating rattle


My electric fuel pump is mounted on the outside of the frame rail on the passenger side and it stays nice and cool in that location. The pump is mounted on rubber insulators and when the pump is running it is whisper quiet. Even when standing outside of the vehicle I cannot hear the pump when it is running.

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Peter, Good quality New Zealand made 6 volt fuel pumps are available in Australia. Just look on ebay. The fact that your car comes to a halt as you are driving along makes me wonder if you have vapour lock or a blockage in the fuel tank or line. The only time I get vapour lock is after turning the engine off after a long trip on a hot day or climbing a long steep incline.


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Originally Posted by 345chevy
Peter, Good quality New Zealand made 6 volt fuel pumps are available in Australia. Just look on ebay. The fact that your car comes to a halt as you are driving along makes me wonder if you have vapour lock or a blockage in the fuel tank or line. The only time I get vapour lock is after turning the engine off after a long trip on a hot day or climbing a long steep incline.

Vapor lock may occur, under various circumstances.

As an example, back in the day, I owned a 1956 Chevy, with a "modified" 265 V8.

Until I added my electric fuel pump, it would "nose over/run out of fuel" on a hot day, while going down the drag strip. Fuel pressure gauge would drop, like a stone.

After electric pump was added, no more issues.



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I haven't seen it happen, but couldn't a failed diaphragm let gas get into the crankcase?
WL


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Yes, it can flow past your mechanical fuel pump diaphragm if it has a hole in it and into the crank case. Look to see if your oil is rising up on the dip stick! Or if you can smell gasoline on the dip stick. The oil may also appear to be thin, too. This is especially true if you are running a diaphragm that is some years old (before the introduction of unleaded gasoline).


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