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see thru gas filter

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modandrocker Steve N
Greensboro, NC, USA   USA
Hello everyone. I've been having erratic behavior (car too) that seem to derive from not enough gas leading into the Carbs. I've had a clear/see thru Gas Filter for many years and change it regularly. Now that I'm looking into the fuel flow I see this filter has very little gas flowing through it. Appears to be 2 or 3 % of available consumption. I've changed fuel pump, new fuel lines not the steel OE and checked vent hose from gas tank. Of course a new filter too.
What I would very much appreciate is knowing if others w/clear filter have the filter completely filled with gas or almost. If my situation is normal then I'll start looking for other mysterious possibilities. But again, I've looked at a truck with the same filter and his filter is filled w/gas and doing fine. Thanks in advance Steve

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tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
It can be very difficult to exclude all air from a filter.

It may be possible to drive some out by repositioning it, even temporarily, while the engine runs, so that the outlet is right at the top.
You can take the filter off, fill it with fuel while blocking the bottom with a fingertip, and re-assemble, and there will still be air in the fuel line that appears in the filter!

If you think that the air is the cause of fuel starvation, replace the filter with a short length of tubing, or put in a longer length of hose, and drive it for a while. Unless you often see large bits in the filter, you'll do no harm to the carburettor(s), which automatically catch ebris that fallas to the bottome of the float chamber. Only injector cars must have fine filters inline. If you do see debris in the filter, then the source is a corroding fuel tank. Dirty fuel today doesn't happen.
If your ?fuel starvation? problem goes away, then your filter is the problem! If not, you can put it back.

JOhn

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barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
Over many years, nearly always with see-thru fuel filters, I've observed that the filters on my LBCs vary inexplicably as to degree of 'full'. Rarely have I seen one 'full' and more often than not well under 1/2 filled with fuel. AFAIK it makes no difference to the operation of the vehicle.

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modandrocker Steve N
Greensboro, NC, USA   USA
Thanks John for helping. I've never had a problem with air in the line. As a matter of fact, I didn't realize air could be trapped. But yes this sounds logical. Running completely out of gas could cause air in the line also. On a side note, I have recently installed a Gas Pressure Regulator that is set to 1 pound as well as 5 lbs.. This was done for experimenting, and a possible resolve to the cutting-out issue. Made no difference. I'll take it off and go back closer to OE and see what happens. Thanks for your advice.

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modandrocker Steve N
Greensboro, NC, USA   USA
Thanks Barry for responding. The see-thru filter, with it's almost empty condition, should probably be a See No Evil status. Wrap electrical tape around it for peace of mind. Could be bad gas. I use 100% gas and seems to be sold to customers during gardening and yard work in their weed eaters. The sales for this could be at minimum, this time of year,
meaning not enough cycling of product and leaving old moisture contaminating gas for me to use.

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Mikerr09 Mike R
Vienna, WV, USA   USA
My fuel supply issue was the steel (approx 8 inch) that runs from bottom of fuel tank, thru body, close to rear coil had restricted flow. Also, the spray liner in tank appeared to break down and may have been the cause.

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tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Is yours like this?
I had one, don't know why, but I was looking at it, one day, not touching it (honest, officer!) and I heard a light 'ping!' as the glass cracked.

My Facet lifter pump has a filter, and the Pi system has pre- and post-pump filters. So I threw the glass one away. Best place for it.
John


Attachments:
glass fuel filter.jpg    14.2 KB
glass fuel filter.jpg

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Tonyfixit Avatar
Tonyfixit Tony M
Duncan, BC, Canada   CAN
Funny, I put a clear filter on our ride on lawnmower yesterday and it only filled 25%, but the mower ran fine.

I just went to take a picture of it and it is now 80%. It makes me wonder were the air went??


Attachments:
20190313_093824.jpg    37.1 KB
20190313_093824.jpg

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tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
The way arpound you fit the filter affects it, Tony.
I assume that flow in yours is from left to right? The fule goes in fom the outer casing into the filter, which dips well into the pool of fuel.
Air will be drawn out of that, and fuel, but surface tension will stop it going through the filter paper..
John

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dicta dick Taylor
Downey, Callifornia, USA   USA
In reply to # 1601774 by modandrocker Hello everyone. I've been having erratic behavior (car too) that seem to derive from not enough gas leading into the Carbs. I've had a clear/see thru Gas Filter for many years and change it regularly. Now that I'm looking into the fuel flow I see this filter has very little gas flowing through it. Appears to be 2 or 3 % of available consumption. I've changed fuel pump, new fuel lines not the steel OE and checked vent hose from gas tank. Of course a new filter too.
What I would very much appreciate is knowing if others w/clear filter have the filter completely filled with gas or almost. If my situation is normal then I'll start looking for other mysterious possibilities. But again, I've looked at a truck with the same filter and his filter is filled w/gas and doing fine. Thanks in advance Steve

Here's another opinion: Fuel gaps in the see-thru (or maybe any style) filter can be tough to eliminate completely, or for any permanence. I also use the glass type but not with the filter enclosed. (There's one before the pump and a bronze screen right before the SU intake) To get it to where there is very little air present, it is necessary to burp out the air and reconnect the line. At one time, after installing an electric pump, air bubbles appeared in large quantities, thus the see-thru filter to try eliminating them.

Dick


Attachments:
Fuel Pressure Reg..JPG    49 KB
Fuel Pressure Reg..JPG

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LFMTR4 Avatar
LFMTR4 Lou Mijares
Scottsboro, AL, USA   USA
I run a see through plastic filter like the one in the mower picture before the stock mechanical pump. While running it might be 1/4 full, when sitting 3/4 to full. I also have a fuel pressure gauge before the front carb, it stays pretty solid at 3 psi regardless of the fuel level in the filter


Attachments:
A19A6112-65FE-410B-9293-B536E948D0EC.jpeg    57.7 KB
A19A6112-65FE-410B-9293-B536E948D0EC.jpeg

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barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
Now, can someone document a problem caused by a partially filled fuel filter (not as a result of blinded filter media)?

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ACMAUI Andy Herrera
Gig Harbor, WA, USA   USA
In reply to # 1601774 by modandrocker Hello everyone. I've been having erratic behavior (car too) that seem to derive from not enough gas leading into the Carbs. I've had a clear/see thru Gas Filter for many years and change it regularly. Now that I'm looking into the fuel flow I see this filter has very little gas flowing through it. Appears to be 2 or 3 % of available consumption. I've changed fuel pump, new fuel lines not the steel OE and checked vent hose from gas tank. Of course a new filter too.
What I would very much appreciate is knowing if others w/clear filter have the filter completely filled with gas or almost. If my situation is normal then I'll start looking for other mysterious possibilities. But again, I've looked at a truck with the same filter and his filter is filled w/gas and doing fine. Thanks in advance Steve

I recently put one inline with a new fuel pressure regulator and gauge. Mine shows 1.5 to 2.0 psi and the filter is full of fuel. New stock fuel pump, put on by the PO, and the regulator was full flow. I inquired of the forum and no one thought that was particularly low pressure. I run dual weber downdrafts, and on a down hill stop I think they are starving and the motor stalls. I didn't check the float level before installing, my bad. Anyway, my filter is full at 1.5 to 2.0 psi.

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ACMAUI Andy Herrera
Gig Harbor, WA, USA   USA
Also, I did let the filter fill before connecting to the regulator.

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tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
In reply to # 1601884 by dicta
Here's another opinion: Fuel gaps in the see-thru (or maybe any style) filter can be tough to eliminate completely, or for any permanence. I also use the glass type but not with the filter enclosed. (There's one before the pump and a bronze screen right before the SU intake) To get it to where there is very little air present, it is necessary to burp out the air and reconnect the line. At one time, after installing an electric pump, air bubbles appeared in large quantities, thus the see-thru filter to try eliminating them.

Dick

Thing is, (small) bubbles in the line are harmless to a carburetted car, as the float chamber 'filters' them out.
As they arrive, the level will drop by a tuny amount, the valve will open. more fule arrives and the air escapes.

They don't matter!
John

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