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TR4/4A Fuel Filters and percolation/ vapor lock

RJS

Jedi Warrior
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Hi All,

Long time owner but, it's been a while since my last post. I just wanted to share some interesting thoughts on fuel filters. It all started with a vapor lock/fuel percolation issue I was researching. 99% of the time I drive the car in the cool morning hours with no issues. However, twice in the past year I had the car out, in traffic, mid afternoon on a HOT day and experienced running issues and traced it back to boiling fuel (either in the fuel line - "vapor lock", or in the float bowl - "percolation"). FYI, vapor lock leads to fuel starvation while percolation in the float bowl leads to overly rich running.

My car is 100% stock when it comes to fuel lines, fuel pump, radiators and engine driven fan. After tons of research, the ONE thing I became most suspicious of was the the (non-original) inline fuel filter b/t the thermostat housing and the float bowls. It is in direct proximity to hot air from the radiator and the exhaust manifold, and interrupts the pressure in the fuel line generated by the fuel pump. So, I replaced that with a stock 1/4" ID fuel hose running directly from the metal fuel line under the thermostat housing all the way to the front float bowl. Further testing is still required but, I am happy to share that the car idled at 600 RPM for over ten minutes in 83*F weather yesterday with NO running issues. Engine temp did hit 3/4ths on the gauge and measured 210*F on the top of the rad (which I am OK with).

To make a long story longer, I then also (after a lot more research) replaced the screen filter in the glass fuel pump bowl with a paper element NAPA 3034. This was implemented on the 1968 Jaguar E-Types and may be retro-fitted if you remove the wire gauze filter. You can read more about it here:
> E-Type Fuel Filter Elements <

This paper element cartridge filter is also known as the "New GF124" and is good down to 10 microns. Essentially, I was not satisfied the wire gauze would capture any/all crud from my oringal gas tank.

I'd be curious on any comments, thoughts, opinions on using this paper element. Also, have many of you been using solely the wire gauze filter (nothing more) successfully?

Bob
 
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