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PRE PUMP GAS FILTER

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Want to install a filter in the pre-pump gas line, but need to be certain about the design.

 

The most practical design is available from Moeller , and allows visual inspection, along with a replaceable filter.

 

Anyone have experiences with that type of construction ?

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I installed one on my 71 Cadillac ambulance.

Ambulance only - unobtainable fuel tank that was 'clean' but also had a lot of sandy type, surface rust in it. It completely plugged disposable filters continuously!!  Like 10-20 miles of running and eventually after just 30 minutes of idle run time. <yikes>

 

Yes the Moeller filter collected this sandy rust and yes it plugged up and it eventually stopped the engine.

I then removed and disassembled the filter and cleaned it out. The problem was that after 8-10 cleanings and dissemblings  the rubber O-rings were no longer sealing. 

 

I hoped that EVENTUALLY the sandy rust would all be sucked out but no luck. I ultimately switched to very cheap disposable see thru filters. (it was much quicker to swap in a cheap new filter than to disassemble the Moeller filter especially on the side of the road) 

I finally had to give up on the tank itself and adapted a passenger car fuel tank (not perfect, but it works) and I haven't changed a filter in a long while. 

 

So, yeah, they do filter well, but eventually the end seals need replacement and the advantages of having a cleanable filter faded. Especially in the light of 99 cent bulk purchased disposable filters. 

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The best way is a sock in the tank. I am sort of surprised the Cadillac didn't already have one. The crud will fall off of the filter when the car is shut off. Yes, some of it will get sucked back up there when the fuel pump starts running, but not all of it. A car will tolerate a lot more crud like this than it will with an inline filter on the suction side. Of course there are still limits to what you can get away with.

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Yeah Cad did use a sock in the tank. However the original was crudded up and torn. 

 

This previously trouble free car was parked for over a year while I sorted out the fuel problems. (and pulled out clumps of hair, and got a flat spot on my skull from banging it against the wall!)

Trouble shooting involved 2 fuel pumps, 1 carb and numerous fuel lines, etc, etc, etc . . . .

 

The sock was torn, and parts of it were sucked into the pipe plugging it(!). 

The filter in the pump became plugged, the filter in the carb became plugged. Of course the add on pre-pump filter would plug up also. Change or remove one it would run for a short time and then the other would quickly plug up. I kept hoping that I could eventually filter it all out. 

 

When changing tanks, I replaced the sending unit (gauge didn't work) with a reproduction one. The stainless steel sock on it was too fine of a mesh and fuel would not pass(!)  Remove it and the fuel flowed . . . 

 

It felt like a wack a mole game! Fix one problem and another would quickly pop up. 

All the exact same symptoms but each from a different source. 

 

A few times I came close to demonstrating just how flammable fuel is and setting fire to the entire car!! (I'm sure you all understand) but EVENTUALLY I worked through it all and now it is fine  😊

 

Edited by m-mman (see edit history)
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Wouldnt a large sediment bowl catch all the crud before it blocked anything ? Or even a couple in series?

jp 26 Rover 9

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