no return line & pressure issues on tripples

[strangethursday]

When I got my car I noticed near the alternator a hard line with a deteriorated rubber cap on it. It was leaking fuel slightly. I figured it was a return line for the stock setup (car came with tripple DCOEs). The DCOE setup doesn't have a way for me to hook the return back up. I just put a new cap on it & left it alone for the time being. My new problem comes when I park the car for extended periods of time. The system builds pressure until fuel starts coming out of the filters. Now I have to open the gas cap when I park which is working for now but, I don't always remember to do it. Last time I left the cap on over the weekend & when I opened it a big gush a gas spewed all over my arm. Is this caused by the lack of a return line or is it something else? I'm thinking of replacing the 3rd fuel line banjo with a 2 way one, routing it into a small catch/ expansion tank & then back into the return line. Any help with this?

[240jetjoc]

My tripple 40 DCOE's ran great without a return line and pressure regulated at 3.5psi. What fuel pressure are you running on your triples - general consensus for Webers seems to be 3.5 - 4.0 psi. I'm not an expert by any means, but it sounds as though you have a fuel tank venting issue.

[strangethursday]

I thought about the venting issue too. I'm gonna check all the on tank fittings & the surge tank. Any idea about the capped tube I was talking about? The 1 near the alt was leaking fuel but there's 1 on the drivers side rail that's capped too that I think is the return. I plan on doing a return anyway. The I've only been able to find a diagram for a 260 in the haynes manual. I have a 71 with a L28 swap. Are the factory service manuals still available?

[strangethursday]

Sorry. I'm not sure about the fuel pressure. It looks like a stock electric pump of some kind. Similar to the 1s in the haynes book

[240ZGL]

I'm doing a triple setup and plan on running the return line. I'm running a high volume low pressure pump and putting the regulator on the return line. That should keep the carbs full at high RPM and regulated at low rpm.

[strangethursday]

What kind of pressure you gonna run the return line regulator at?

[TBK1]

got a 77 with trip webers having some issues also, not the same but, here you go, came from main supply line to regulator off of reg taped to BYPAS to return line, vent line at charcol canister not capped or used, no leakage but do have over pressaure, just added a small small hole in gas cap, problem much better but still irradic idle, this is a 260 motor running both a electric pump and the mechanical pump!!!! almost like it loads up some times, usually when driving it hard, with windows down can smell raw fuel also, carbs set and flow balanced by me , maybe the probem

[Carl Beck]

Hi strange...

It would help if you told us exactly what model year Z you are dealing with. I will be thinking of a 240-Z in my answers - if you have something else - they may or may not apply.

The line by the alternator is the original Fuel Return Line to the tank.

The line on the Drivers side - is a fuel vapor recovery/air vent (when fuel vapors are not being sent from the vapor recovery tank in the rear to the engine - fresh air flows back to the tank (that is the purpose of the valve with three in/out's - that is supposed to be there on the fender-well).

A return line with the triples - allows fuel temp's to be averaged at lower temperatures - so with higher under hood temp's - a fuel system that circulates cooler fuel from the tank, past the carb.'s is a good idea. When you park the car with a hot engine - the fuel expands as it heats... so a return allows for that expansion pressure to be relieved.

If your set up doesn't have a provision for a return - then you simply need the same type of fuel fitting on the end carb, that you have on your center carb. - so a return line can be used. I don't see any need for a catch can prior to the return to the tank.

The Stock 240-Z fuel tank is NOT vented to the atmosphere - it is designed to trap all fuel vapors and either return them to liquid state or burn them in the engine. So with triples you need to be using a VENTED Gas Cap - or drill a small hole in your existing cap to allow the tank to vent and or breath in air to replace the gas your pumping out...

FWIW,

Carl B.

[Arne]

EDIT - Took too long typing - Carl answered it better than I did.

[strangethursday]

Thanks every1. I got it fig'd now. I uncapped the drivers side 1 & I'm gonna route it into the top of a vented catch bottle I have the valve cover hooked up to. As far as the other 1, I'll be getting another 2way banjo & hooking that up. Where is the stock expansion tank located? Up near the filler or do 71s not have em?

[Arne]

Inside the car, under the right rear quarter trim panel. Just above and in front of the filler.

[strangethursday]

Thanks every1