Fuel Filters

[fastfrontier17]

I am using a 1/4" fuel filter to a weber 32/36 on a stock 1600. I have no doubt this little filter below can handle the fuel flow, but I often see these little guys listed for lawn mowers, dirt bikes, etc stating they can handle up to 80 hp. I don't think a stock, 60 year old 1600 has any issue with that, but I wanted to see if anyone else out there has ever ran into any issues with these.

 

[sunalp]

Should be just fine. Just make sure you put the filter before the fuel pump.
You can add a second one before the carb if you want extra filtering.

 

[Scotty]

I have one on my 1725. No problems.

 

[Warren]

Many many VW miles on those filters. Stay away from those with the rubber gasket ones .
I couldn't change the MK2 around to put before the fuel pump so I fashioned a tiny screen in the hard line fitting.

 

[puff4]

I *never* put a filter before a pump.

The factory mechanical fuel pump already has a sediment bowl and screen, so there's nothing that can get through that screen that could foul up the pump - there simply aren't any orifices in the pump to get clogged. And remember, fuel pumps are made for developing pressure, not for developing suction.

Placing the filter after the pump allows the pump to force fuel through it quite easily. If you put the filter before the pump it's possible that the filter will slow the intake flow of fuel, meaning that the diaphragm won't fully retract (suction phase) and this will pull the pump arm away from the cam for a moment (or perhaps more, if the filter is really clogged and it takes longer for the diaphragm to return). The cam will come around and whack the arm, instead of the arm continually riding on the cam... and this can damage the cam and the arm. You want that diaphragm to quickly return and for the arm to remain in constant contact with the cam.

Now, if you're using an electric pump there's even more reason not to place the filter before the pump. There's a small capacitor in the Smiths pumps that will burn out if the pump can't pull fuel easily and once that's burned out the points on the pump will begin to arc, eventually leading to burned points and having to repeatedly whack the pump to get it going again (a familiar British car complaint).

SO...... that's a long-winded description of why NOT to put a filter before any fuel pump.

 

[Scotty]

I *never* put a filter before a pump.

The factory mechanical fuel pump already has a sediment bowl and screen, so there's nothing that can get through that screen that could foul up the pump - there simply aren't any orifices in the pump to get clogged. And remember, fuel pumps are made for developing pressure, not for developing suction.

Placing the filter after the pump allows the pump to force fuel through it quite easily. If you put the filter before the pump it's possible that the filter will slow the intake flow of fuel, meaning that the diaphragm won't fully retract (suction phase) and this will pull the pump arm away from the cam for a moment (or perhaps more, if the filter is really clogged and it takes longer for the diaphragm to return). The cam will come around and whack the arm, instead of the arm continually riding on the cam... and this can damage the cam and the arm. You want that diaphragm to quickly return and for the arm to remain in constant contact with the cam.

Now, if you're using an electric pump there's even more reason not to place the filter before the pump. There's a small capacitor in the Smiths pumps that will burn out if the pump can't pull fuel easily and once that's burned out the points on the pump will begin to arc, eventually leading to burned points and having to repeatedly whack the pump to get it going again (a familiar British car complaint).

SO...... that's a long-winded description of why NOT to put a filter before any fuel pump.

I didn’t even see that on a previous post, good catch! Mine is attached after the mechanical pump halfway between that and the Carb.

 

[sunalp]

I *never* put a filter before a pump

so....crap that comes out of your tank can foul up you fuel pump? Alpine tanks are notorious for shedding
the factory paint, especially on cars that aren 't driven regularly and with todays gas that's not kind
to rubber products. I've seen plenty of sediment get through the stock fuel pump mesh and wind up in
the carb. An extra filter doesn't hurt anything.
By the way, most electric pumps already have a filter before the gas goes through the pump.

 

[Bill Blue]

By the way, most electric pumps already have a filter before the gas goes through the pump.

And the ones that don't do not hesitate to tell you to use one. No warranty if the pump is not protected with a filter.

Bill

 

[Scotty]

[QUOTE="sunalp, post: 221991,
By the way, most electric pumps already have a filter before the gas goes through the pump.

And the ones that don't do not hesitate to tell you to use one. No warranty if the pump is not protected with a filter.

Bill[/QUOTE]

Ok, I'm confused.

So should my filter be BEFORE the Mech Pump or AFTER?

 

[Silver Creek Sunbeam]

I will have to look tomorrow to confirm it but I’m almost positive that my Carter P4070 voids the warranty without a pre-filter.
I have one before the pump and one after the pump at the pressure regulator.
I installed it a a little over two months ago, so I need to see the instructions to confirm.

I will say this…I did A LOT of research and it was hard find any conclusive because every other post contradicted the post before it.
My research was not limited to this forum by any means.

If I do remember correctly, I finally based my installation on the warranty.

 

[Bill Blue]

My fuel problems occurred when the lining stripped off the tanks. Plug the fuel pump? Nah, the line was so plugged nothing could get within shouting distance of pump. I seriously doubt that today's gasoline contains any particles large enough to harm the mechanical pump. No filter known to man can protect from the contents of saddle tanks with original lining.
Bill

 

[puff4]

Some of you may know of the late Dave DuBois, the widely acknowledged expert on rebuilding SU fuel pumps. He sadly passed from cancer in 2019, but he left behind a treasure trove of information, which has been preserved on the website below. I encourage folks to read his article entitled "SU_Fuel_Pumps_Facts_and_Myths".

https://www.dbraun99.com/Dave DuBois/

 

[Warren]

Ok then thanks for the link.
So basically it says that the SU pump can chew up and spit out it's epoxy sloughing off.
Do you think the new version with it's pointless features of the SU pump would tolerate a per filter or screen? I'm thinking it will not after reading the article thanks for posting.

 

[puff4]

According to Dave, the newer pumps are even more fragile when it comes to placing a filter before the pump. In the end, it simply isn’t necessary.

 

[getsmartguy]

Say, is the Carter P4070 the very best Electric fuel pump to put into an Alpine? I need to replace mine, and read this thread. I see the price is pretty low on the unit, so I'm wondering is there a higher model that either runs cooler, runs quester, or is simply better? I only want to do this once, LOL!

 

[Silver Creek Sunbeam]

Say, is the Carter P4070 the very best Electric fuel pump to put into an Alpine? I need to replace mine, and read this thread. I see the price is pretty low on the unit, so I'm wondering is there a higher model that either runs cooler, runs quester, or is simply better? I only want to do this once, LOL!

I put one on my Alpine last summer along with a pressure regulator and have been happy with the performance.
Audibly…it is loud, even with sound deadener between it and the car.
I don’t hear it when I’m rolling but it’s easy to hear at idle.

Is it the best? I can’t say but I can say I did a LOT of research on this site and on car sites in general before I made my choice.
Based on that research, I felt good about installing it.

 

[getsmartguy]

Say, is the Carter P4070 the very best Electric fuel pump to put into an Alpine? I need to replace mine, and read this thread. I see the price is pretty low on the unit, so I'm wondering is there a higher model that either runs cooler, runs quester, or is simply better? I only want to do this once, LOL!

PS- someone else said an EMPI AC1273193 is also good, just looking for some advice as I'm not very knowledgeable on this yet, and am getting the car over to the shop this Tuesday, thanks.

 

[getsmartguy]

I put one on my Alpine last summer along with a pressure regulator and have been happy with the performance.
Audibly…it is loud, even with sound deadener between it and the car.
I don’t hear it when I’m rolling but it’s easy to hear at idle.

Is it the best? I can’t say but I can say I did a LOT of research on this site and on car sites in general before I made my choice.
Based on that research, I felt good about installing it.

Thanks Todd, where did you install it?

 

[Silver Creek Sunbeam]

Thanks Todd, where did you install it?

On the forward side of the spare tire well under the car.
If you’re going to do it, one additional thing I did was put an inline cutoff just forward (like a few inches) of the cross pipe, so that I can cut the flow off if I need to work on the fuel system.

 

[alpine_64]

I put one on my Alpine last summer along with a pressure regulator and have been happy with the performance.
Audibly…it is loud, even with sound deadener between it and the car.
I don’t hear it when I’m rolling but it’s easy to hear at idle.

Is it the best? I can’t say but I can say I did a LOT of research on this site and on car sites in general before I made my choice.
Based on that research, I felt good about installing it.

Try mounting it on exhaust isolating bobins. The ones with a stud each side coming out of rubber that do not touch. Stops the vibration reverberating inside the battery box/ spare tire well or body