Fuel supply/return and filter orientation

JohnJL · 02-15-2006, 01:05 AM

I've checked the workshop manual and my "disassembly pics," and search unfortunately no pleasure yet...

Can anyone pls confirm which is the supply and which is the return line labelled in this pic? 82SC. Everything is disconnected now so not possible to run the pump...

Also, does it matter what orientation the filter is installed? I know there is a correct flow direction, but can it be located horizontally or vertically with either the out at the bottom or top as long as the flow direction is correct?

thanks all

rfuerst911sc · 02-15-2006, 01:39 AM

"A" should be the supply and "B" should be the return, that's how I plumbed mine on my 83SC. I see your useing the relay board for your EFI conversion it's the same one I'm useing.Fuel filter can be mounted in any direction just pay attention to flow direction. I hope to have my car running this weekend.

JohnJL · 02-15-2006, 12:27 PM

Thanks a lot!

I guess we're both betting they're right. Good luck with your start-up. Are you using MS or MS2? Spark too?

rfuerst911sc · 02-15-2006, 01:39 PM

I'm useing MSII and for now keeping the CD ignition. Once the EFI is up and running/tuned and I'm happy with the way it runs I'm then going to convert to Ford EDIS distributorless ignition.

JohnJL · 02-15-2006, 04:34 PM

Same exact plan here too, though I am initially using MSD box and coil. Are you single or twin-plugged? I'm twin, but just firing one set of plugs until the EDIS is running.

Have the trigger wheel and sensor all mounted...Summit fuel rails, injectors, wiring, gauge, hose, aeroquip fittings, reg all arrived this week!

rfuerst911sc · 02-15-2006, 05:31 PM

single plug

real550A · real550A's Garage

Nice rear shocks! Did you go with nylon, or Hemp?

JohnJL · 02-15-2006, 08:38 PM

hehehe...hemp.....

MotoSook · 02-15-2006, 08:54 PM

Rick is right, A is supply, B is return. I suspect the factory place the fuel filter vertically to help fill the filter (reduce air pockets). As long as the flow direction of the filter is followed, it can be mounted to flow up or down, but I suspect the likelihood of air in the fuel is higher with a horizontal mount. Probably not a great concern, but flow into and out of the filter is central to the body of the filter...visualize a 1/3 full 2-litter soda bottle on it's side. See the air pocket?

JohnJL · 02-15-2006, 09:24 PM

Thanks Souk, you are referring to exactly what I was concerned about, which is why I was thinking if air pockets are a problem, wouldn't be "out" in the upward position the worst-case scenario?

MotoSook · 02-15-2006, 09:34 PM

In a vertical orientation, you will purge the system on intial running of the engine or priming of the fuel circuit. The check valve at the pump, your accumulator and regulator ( I would recommend an accumulator and your fuel regulator should be a back pressure type..most EFI regulators are back pressure type) will hold pressure in the filter and prevent fuel from emptying out of the filter...no matter if the outlet is up or down. It's a little more involved to purge the air out with the outlet pointed down, but it's possible. Go with what the factory did and you should be fine

On a horizontal orientation, the initial purging will not rid the filter of all the air, even if you have all the parts mentioned above. The void in the filter will just be that..a void unless you burp enough of the air out during normal running.