430 fuel problems think vapor lock?

[Guest]

I am bring back a 1959 with a 430 engine all org. a family car that has been in storage 50 years. We have it running and driving great!! But now when the engine compt. gets hot after driving 20 minutes or so on the highway you come off to stop and go traffic the engine temp is fine but the fuel pump gets very hot and the filter goes dry, the car dies. When it cools off we crank up and go again. It has a new tank, pump, and rubber lines, and still the mechanical pump. Has anyone tried a pressure regulator with any success or have any other ideas! Thank you, Corey

[simplyconnected]

So the bottom line is, your engine is starved for gas. Correct OEM mechanical fuel pumps don't put out too much pressure.

If your filter is running dry you could have a pinched fuel line hose or the line is sucking air from a loose connection. You don't have vapor lock.

BTW, are you running with a vented gas cap? - Dave

[DKheld]

Apparently you have the original mechanical pump and an electric pump?

I had my original tank boiled out and coated. Replaced the fuel filter on the carb and installed a secondary clear filter just after the pump so I could see if there was fuel to that point. Still had fuel starvation issues so I guessed the line between the tank and fuel pump must have started rusting/clogging too.

Replaced the entire fuel line and fuel pump. More starvation issues so I bought a new tank thinking the coating on the original tank either was failing or had covered too much of the filter screen in the tank.

With a new line and new tank I still had fuel starvation issues. Switched to a vented gas cap from the original shown below - at least - it's original as far back as about 1980 - could be a replacement but had always worked fine.



The vented gas cap fixed the starvation issue but now there was a new problem. The vented gas cap lets air in the tank but not out. So at times there would be so much pressure built up in the tank that fuel was being pushed out into the carb and overflowing into the oil. (ever set a 1/4 filled milk jug out of the fridge and have the air expand in the heat?)

I used a vented cap like this (the tabs hit the license plate holder)

The inside of the cap looked like this
(pic is too big so here's the link)

https://sp.yimg.com/xj/th?id=OIP.M15fa5be94582031fd370551107608612o0&pid=15.1&P=0&w=300&h=300

I finally drilled a tiny hole (about 1/16 inch) in the filler neck of the new tank around the 2 o'clock position then reinstalled my original cap. No trouble since - BUT - with the tiny hole in the filler neck you risk raw fuel leaking out after a fill up. MIGHT happen if you filled the tank very full then took off fast and sloshed the fuel up into the neck and out the hole. Hasn't happened on mine and it's been about 1 1/2 - 2 years. I drilled at the 2 o'clock position to keep water from leaking into the tank when washing the car and fuel in up to a point if it ever sloshes that much up in the neck.

Eric

PS - My TBird is also a one family car purchased new by my Dad and Mom!!

[Guest]

Feedback

Thank you for the feedback, I do not have an electric pump at all just the mechanical. I do not have the vented cap at this point but I saw other notes on that and have tried running it with out the gas cap and still have the issue. It will idle all day long with the hood up but if you put it down you get about 20 minutes and the fuel filter goes dry.

[jopizz]

My first thought is that the fuel pump diaphragm is getting soft when it gets hot and is not strong enough to draw from the tank. How old is the pump. I know the 430 pumps are getting hard to find. Does your fuel have ethanol in it. I've found that the ethanol can wreak havoc with the diaphragms found in older pumps.

John

[pbf777]

I believe you are suffering from "vapor-lock". Heat seems to be the variable in diagnoses, w/vapor vs fuel present at the filter &/or pump area.
Fuels today are designed for (more) modern cars which have fuel injection vs carburetors, in-tank fuel pumps vs mechanical pumps mounted on engines and sealed fuel systems vs vented to atmosphere (tanks & carburetors), and don't behave well in the these antiquated applications.
In its function of fuel delivery, today's systems maintain the fuel under pressure, from the submerged pump in the tank, thru the fuel lines to the engine compartment and passed thru the injectors.
In your vehicle, the fuel must be drawn from the tank (which must be vented) and the length of the vehicle thru the lines under a vacuum (sort of) and unfortunately, in the case of a MEL engine, also lifted due to the high mounted fuel pump location (bad idea). Add heat and shazam! Vapor-lock!
Assuming, you conclude that the fuel system is proper and the problem persists; then we have found that if you add a small (not full race!) self regulated (2-4psi) fuel pump as close to the tank & as low as possible (reasonable) to push the fuel under pressure forward to the mechanical pump, this will suppress vapor-lock. Scott