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1948 Chrysler leaking fuel pump

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Replace this pump immediately!  If you have electric wipers (probably), you need only a single-action pump, not the dual fuel and vacuum pump.  Beware of NOS pumps on eBay and elsewhere which probably don't have ethanol-resistant diaphragm materials.  By all means replace the flexible fuel line as well, and that with ethanol-resistant material as well.  I enthusiastically recommend Then and Now's rebuilding service, which is about $95 + return shipping for a single-action pump such as yours.  You'll have it back in about 8 days--and that's for me on the West Coast all the way across country from their shop.  They do this every single day, so unless you value your time at $1/hour or want the experience of rebuilding it yourself with possible foulups, just send the darn thing to them. Attach a tag to the pump with your name and mobile phone number and make and year of car.  They'll call you back, ask for your credit card number, and have it in the mail pronto.

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The diaphragm is bad! That is how the fuel gets up where it can leak out. It needs one, period.

 

Old diaphragms may not be compatible with ethanol laced gas. You cannot expect any older fuel pump these days to just work. They are meant to rebuild when bad, so just rebuild it (or send it in). I like the kits from Then n Now.

 

I took apart a leaking pump on a 37 Buick a while back that had not run since the early 50s. The diaphragm was just a bunch of layers of cloth impregnated with something, probably shellac. You could see the remains of the impregnating substance under the part that was clamped by the flange. The rest had washed out and the gas was just running through the many layers of cloth. Ehtanol is the solvent for shellac. As others have noted, many types of older fuel system rubber also dissolve in ethanol, even if they are not rotten from age.

 

If the check valves are bakelite or something hard, don't screw with them if they seal. Check with a handheld vacuum pump. If they are made with some sort of elastomer, or if they leak, you will need to replace them. Make sure they seal.

 

Then, put a new diaphragm in, and a new stem seal if the one provided in the kit fits properly. The stem seal is somewhat non-critical as it is often not a positive seal, and mainly exists to help keep some of the gas out of the engine when the diaphragm fails. You can probably get away using the old stem seal if it isn't damaged and you need to.

 

Edited by Bloo (see edit history)
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7 hours ago, The 55er said:

If your fuel pump is leaking any gas anywhere at all, it has already failed. Stop fooling around with it and send it out NOW to a quality rebuilder. You should replace the old flexible fuel line NOW as well. Stop driving the car as you have a real fire hazard! After all this time your Chrysler deserves a new pump!

So I'm curious what might give you the impression that I'm driving the car, when the above photos clearly show the fuel pump off the car and in pieces. ????

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Sometimes replies to questions get “enthusiastic” responses.  We are all in it to help you out as I hope you have seen so far.  

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22 hours ago, Rusty_OToole said:

The long bolt is to hold the heat shield. It is a flat piece of sheet metal bent into a J shape that goes between the exhaust manifold and fuel pump. At the top, there is a tab that goes under the end manifold bolt. It is not a very complicated piece and you could make one at home, if you want to buy one I think Bernbaum or Vintage Power Wagons sells them.

 

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I'm puzzled about the purpose of the heat shield.  The fuel lines going into and coming out of the fuel pump are about 7-8 inches away from the exhaust manifold.  However as the fuel line goes past the exhaust manifold on route to the carb it is within about an inch to inch and a half away from the exhaust manifold. Why wouldn't there be a heat shield there too?

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I would guess the heat holding metal mass of the fuel pump along with its internal diaphragm of rubbery material might suffer more from exposure to engine heat over time.  Probably a way to ensure the pump does not die prematurely.  

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7 minutes ago, TerryB said:

I would guess the heat holding metal mass of the fuel pump along with its internal diaphragm of rubbery material might suffer more from exposure to engine heat over time.  Probably a way to ensure the pump does not die prematurely.  

oh ok.  I remember in drag racing pit crews would make efforts to keep the fuel cool because hot fuel robs the fuel of power so to say in layman terms.  So I had the impression that's what the heat shield was doing in this instance as well.

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Fuel expands when it heats up so in the same "charge" of fuel there is actually less fuel and thus energy when it is hot. Air also expands with heat so you get less oxygen in the mixture.

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The danger of vapor lock is in the fuel line coming to the pump, and the pump itself. After it leaves the pump it is under pressure and won't vapor lock. With today's more volatile fuel you could add insulation to the fuel line or reroute it farther from the engine but this is probably not necessary.

 

The heat shield reflects the heat of the exhaust manifold away from the pump, and helps direct cooling air around it.

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