Racor Fuel Filter Pressure

[Ajfowlie]

Hello

I recently replaced the T handle on my Racor 500 with a pressure gauge. To my surprise I am getting positive pressure ( 5 psi) . I pulled all the hoses .nothing seems blocked. Changed the filters. I am still getting the pressure reading.

Anyone have any ideas? Should I be worried?

[DeepFrz]

YES, be worried! ;o)

Not enough information to make a call on this question. What size engine? What is the throttle setting when you get the reading? Is the pressure positive or negative?

[osirissail]

Simply looking at your fuel system will give you the answer. Where is your Racor Fuel filter in the system?
- - If it is between the fuel tank and the engine lift pump or any other pressure pump (electric), then the gauge is faulty.
- - If it is between the engine lift pump or any other pressure pump (electric) and the engine high pressure (injector pump) then the gauge if fine as you are "pumping" fuel through the filter.
- - If you are "pumping" fuel through the filter (positive pressure on the guage) then you might consider changing the plumbing to put the Racor fuel filter between the tank and any pumps. The concern is that "pressuring" fuel through the filter membrane is not a good idea as when the filter "clogs" the pump pressure could rupture the filter membrane and send dirty fuel into your high pressure (injector) pump.

[colemj]

Is your tank location higher than the engine or filter?

Mark

[Ajfowlie]

Thanks for your responses. To answer your questions:

The tank is above the filter and engine (i wondered if it was head pressure as the reading is the same when engine is not running)

The filter is between the tank and fuel feed pump with no electric pumps in between

It is a positive pressure at all engine speeds

I have got the same reading from three different gauges

[colemj]

I think it is head pressure. Try partially squeezing the inlet line to the filter while the engine is running and see if the gauge reading changes.

Mark

[twistedtree]

Each foot of head gives about .4 PSI, so 5 PSI is over 10 feet of head which seems unlikely. However, pressure gauges are not always the most accurate things in the world, especially at the beginning and end of their range, so I wouldn't worry to much that the numbers don't add up very well. Head does seem like the only plausible explanation.

[callistov42]

But if you don't have an electric fuel pump between the tank and the Racor, how do you refill the Racor after changing a filter?

[osirissail]

Aha! I just thought of something about when I installed my Racor vacuum/pressure gauge - - Did you remove the little piece of cellophane tape from the back of the gauge? That piece of tape covers over the "ambient" pressure sensing hole in the gauge.

[Target9000]

Originally Posted by osirissail

Aha! I just thought of something about when I installed my Racor vacuum/pressure gauge - - Did you remove the little piece of cellophane tape from the back of the gauge? That piece of tape covers over the "ambient" pressure sensing hole in the gauge.

Sometimes this can also come in the form of a rubber or plastic nipple that you must snip the tip off of. It can also be on the top of the gauge.

[Vasco]

Originally Posted by callistov42

But if you don't have an electric fuel pump between the tank and the Racor, how do you refill the Racor after changing a filter?

The easiest way is to fill the filter and bowl before attaching it and then it'll take very little pumping (the Racor housing has a little mechanical pump in it) to fill it up.

[crzhors]

Howdy, A neat trick to priming the Racor(presume 500series) is to put a good quality Squeeze Ball in line right before the Racor.Just hand pump the bowl full ,install the cover and away you go.The squeezeball freeflows beautifully when running.The Brand name balls use a rubber that is compatible with most all fuels.

[David M]

Since you say the gauge does not move at all I suspect the gauge is faulty. I agree with checking what osirissal says.

Does it still say 5 PSI when it is exposed to atmospheric pressure? It should read zero then.

[Seahunter]

I agree with the squeeze-ball application. If there's air in the gauge it'll give a false reading. The primary filter may also be plugged (should be 2M and the Raycor should be a 10M).