Cougar 21 saddle tank threading

**trickcraft** · 01-10-2022, 12:53 AM

I am converting from carb to efi. I have an 85 cougar with saddle tanks. I need to run return lines for the new setup and want to know the size fittings on the tank with associated threading if anyone knows as well as where the best place for the parts I need can be ordered.

Thanks in advance

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**FUJIMO** · 01-10-2022, 08:57 AM

...any good local tank manufacturer can weld in a couple of threaded bungs into the top of your tanks for you. 3/8'' pipe thread works. of course, tank cleanliness is imperative. you doing it yourself, you can source the bungs online. there are other ways also, such as hardware installed in the fill neck hose, etc...

**Chaz** · 01-11-2022, 09:38 AM

The easy way is to return to the second "inlet" side of a filter/water separator.
I use the 3/8 ths NPT housing, didn't see it listed though.

https://parts.promarineusa.com/produ...l/M50/1/1/7852

**Charli** · 01-13-2022, 01:36 PM

I have heard many people say DO NOT plumb it back into the water separator.

I have also heard many people say to plumb in into the water separator.

Mine is plumbed back into the tank with a 3/8.

**BUZZIN' DOZEN** · 01-14-2022, 09:20 AM

Originally Posted by Chaz

The easy way is to return to the second "inlet" side of a filter/water separator.
I use the 3/8 ths NPT housing, didn't see it listed though.

https://parts.promarineusa.com/produ...l/M50/1/1/7852

Originally Posted by Charli

I have heard many people say DO NOT plumb it back into the water separator.

I have also heard many people say to plumb in into the water separator.

Mine is plumbed back into the tank with a 3/8.

A buddy ran a HST/260 that the dealer rigged this way for YEARS with no problems.

**Onetime** · 01-14-2022, 10:15 AM

When Mercury Hi Performance first came out with the Bosch Jetronic based fuel injection instructions said to plumb the return line to the water separator that way then later changed.

The problem with it is there’s no way to get the air out of the fuel line. Used to have to run the pump with the return line off to get the air out then hook it up to the water seperator housing. If you ran out of gas it would never prime because the air was stuck in the loop between the water separator and the engine.

Best to run the return back to the tank. When a tank didn’t have an extra threaded bung for a return fitting would install an aluminum tube splice in the rubber fill hose that had provision for the return line. Best was having the flow angled down towards the tank.