Fuel line return question

[jimk]

2 minutes ago, Son of Marty said:

Actually the 02 never was fitted with a gas filter other than the tank screen from the factory (tii obviously excepted)

I believe you mean upstream of the pump.  The filter on the Tii is downstream of the pump, yes?

 

Also +1 on what @mikea has said having done pumping systems design for 35 years.

[ray_]

The tii filter is between the electric pump and the KF pump, mounted on the radiator support, next to the battery tray.

 

Cheers,

[Son of Marty]

That's why the tii was excepted in my post, crap in the gas that would just go thru a carb will damage the k-fish pump. But yes the filter should go after the pump a diaphragm pump has a high ability to pass reasonably large junk through with out damaging it's self. 

Edited September 4, 2019 by Son of Marty

['76mintgrün'02]

The PO of my car had installed a tii filter before the pump and a plastic one after... don't get me started on the cigar-box air filter!  

 

 

[xr4tic]

If you know your tank is clean, then you can probably just run the in-tank filter, but......

 

My stock tank must be pretty nasty, because the filter I have attached to the fuel line coming through the firewall is constantly dirty.  If I didn't have a see-through filter there, I'd never have known that.

 

To the OP:  If your fuel bypass isn't 100% hooked up the way it should be from the factory, then either cap it/ditch it or hook it up as intended.  It looks like you have 2 ports unhooked in your pic.

 

[Stevenc22]

If you dont use the fuel return, you need to remove the rubber hoses from both sides (engine and tank side) and put rubber caps over the metal tube to stop it from rusting. If you only disconnect the front side, technically the tube is still connected to the tank and could have fuel in it.

[scatman75]

Thanks all the jeep filter looks like the most practical way for me to rehook the return line in thanks for the support

Sent from my SM-G960U using Tapatalk

[tech71]

On 9/3/2019 at 11:54 AM, '76mintgrün'02 said:

 

 

I am not implying that those people are wrong, just admitting that I am breaking their rule.

 

I should add that I make sure that filter stays clean. 

The Jeep filter would do the job all by itself, but I like the see through style and in my mind the first one is keeping the Jeep filter clean.

 

I also like using this filter with a larger element.

I also dislike seeing plastic filters installed out over the alternator, with hoses tugging sideways on those little plastic nipples, trying to make tight bends to the carb inlet.

 

We all have our preferences.  Mike's right from his side and I'm right from mine... we're both just one too many mornings and a thousand   miles   behind.

 

The tii filter arrangement is elegant, the way they hung it there by the battery/radiator.  That must be what MikeA has. 

 

Have you got a photo to share, Mike?  I have a sweet-tooth for eye candy.   

 

Ok I just have to ask: What is the purpose of that firewall mounted "electromagnetic" valve?   and why don't I have any?  And what is that on your dist. cap retaining clip?

Edited September 4, 2019 by tech71

['76mintgrün'02]

54 minutes ago, tech71 said:

Ok I just have to ask: What is the purpose of that firewall mounted "electromagnetic" valve?   and why don't I have any?  And what is that on your dist. cap retaining clip?

 

That electromagnetic valve was part of the emissions package and I repurposed it to be able to cut off the ported advance signal to the pod while driving, using the rear defroster switch to power it.  Pull the switch on and it cuts the signal off.  That gauge beside it shows what the pod is getting and there is another gauge in the console that uses a T fitting in the line to give the same reading.  

 

I had tried driving with and without the pod connected and could not tell the difference it was making, so I set up this way to get instant feedback.  If the vacuum is anywhere over 11 inches, it is adding/removing 12 degrees of advance.  The difference is subtle, but noticeable under certain driving conditions.  At even cruising speeds, such as highway driving, it lags a bit with it off and eases forward when turned back on.  Slight change in exhaust note too.  All that to say, it is just a learning tool.

 

The cap retaining clips have little bits of the beautiful wiper fluid hose.  Makes them easier on the finger tips and adds a little +BLING+

 

[AustrianVespaGuy]

I prefer to swap things around and use the external steel line as the supply line and the internal plastic line as the return.  In my view this has several benefits; it keeps fuel in the steel line and thus helps prevent it from rusting, and it also means that, should you develop a leak, it's more likely to be outside the car instead of inside (my preference).  I also like the diverter valves so that you're not hammering the poor carb needle seat with full fuel pressure all the time,but maybe that's overly conservative.

['76mintgrün'02]

Once while under the car I picked at a little booger on the steel return line, where it runs up beside the pedal box and it started leaking fuel.  I cut that section out and added a piece of hose there.  Leaking clutch or brake fluid can be hard on that thin little tube, especially when it gets trapped by that nasty sponge rubber pedal box cover.  (Hi Paul!)

My preference is using the plastic line, assuming it is under suction.  Putting an electric pump in the trunk and pushing fuel through the cabin is a bit sketchy.  In a return line situation the fuel is being pushed through the line, although the pressure is probably quite low.

 

I have read about DGV carbs that use both sides of the fuel inlet, with one supplying fuel and the other containing a nipple for a return line.  The return nipple has a restriction inside, to only allow a small amount of fuel to return, while still providing the beneficial pressure bleed-off after shut-down. 

 

My carb top is tapped on both sides of the inlet already, so it is somewhat tempting to try that setup; but with all of the "Jeep Filter" posts I have made, I feel somewhat obligated to keep one installed.