Technical Fuel Return

[David Britton]

I'm looking for advice and guidance.
I've just had a standard 650 engine and gearbox fitted to my 1970 L. I've had a couple of trips out and enjoyed the extra power enabling us to keep up with traffic and not been a moving road block !
Upon returning from one trip out I had a strong smell of petrol, got out and looked underneath. I was greeted by petrol absolutely pi***ng out from the car. I cannot believe how much was pouring out from a gravity fed system while idling!!!!
Sub optimal situation, hot exhaust and petrol!

I have a small piece of fuel pipe still attached to the return side of the carburettor but no clip to close it off. There was one there but obviously not up to the job. The question is -

What do people use to close this off ?
I could fit a return fuel line and 'T' it in just in front of the fuel pump, but am worried it might look crappy. I can't find any pictures of this been done.

Advice much appreciated,
David

 

[fiat500]

Most will say return via "T", but my experience of carefully directing it back to the tank via a new line and modified fuel sender has paid dividends in keeping fuel cool, avoiding flooding, and preventing leaks.
The downside is that it's quite a task to achieve safely and reliably.

 

[the hobbler]

Most will say return via "T", but my experience of carefully directing it back to the tank via a new line and modified fuel sender has paid dividends in keeping fuel cool, avoiding flooding, and preventing leaks.
The downside is that it's quite a task to achieve safely and reliably.

 

[the hobbler]

Hi David; I have fitted a return system to my 500, also with a'650'engine (although somewhat 'enhanced'!). I put a METAL (brass) "T" piece into my main fuel-line on the n/s side of the engine bay---in a position that I could afix/support it with a rubber covered "P" bracket. I then led a fuel-line from that "T" piece up, behind the big air-intake hose back to the carburettor. I led this fuel-line through an appropriately sized length of water-hose (to protect it from chafe). I secured the hose to the bulk-head, again with rubber covered "P" clips. Fitting the 'T'piece in place with the engine in is, I will admit, a bit of a faff and I will also admit to having the engine out when I modified my system. Always use "Ethanol-proof" fuel line and proper "fuel-line" clips rather than 'jubilee' clips to secure the fuel line.
The theory is that 'circulating' fuel will stay cooler than 'stationary' fuel---when I did my apprenticeship (on Mercedes) the early fuel-injected cars were on the market,and I will always remember that I was surprised as to how much cooler the 'returning' fuel-line felt vis-a-vie the 'supply' fuel-line. As to whether I have just been lucky, or that the 'return' system works I honestly can't say, but I have NEVER had a "hot engine" starting problem with my car.
Lastly, if you have a fuel-filter between the fuel-pump and the carburettor---TAKE IT OFF. (a) You don't need a 4th filter in the system and (b) it is a danger--a petrol-filled bowl just about on top of an electrical unit (the alternator)

 

[rusty500]

I've blocked mine off with a short piece of fuel line with a bolt screwed into the end and a strong, tight hose clamp to keep it in place. Never had a problem, even driving frequently in 80-95F weather. I do check on it periodically.

 

[Piet59]

Hi David. I removed the original brass pipes because they can get loose (one was so easy to remove that it would have come out later), then I cut threath M8 and fitted after adding Loctite 542, a new hose barb in the inlet and a bolt in the return to block it.

 

[JumpJet]

I had a T return setup for a time, but with so many splices, it lead to air in the system and problems starting after sitting for longer periods of time. I countered this by rigging a schrader valve to a spare fuel tank cap and carrying a mini bike pump to pressurize the system to help get it going. The catch was the valve-equipped cap didn’t vent, so I’d have to swap it out or she’d vapor lock.

Recently though, I went all out and plumbed a complete return-to-the-tank system, using braided lines throughout. Now, thanks to a very well sealed system and a nice constant flow, the car starts faster than ever and has had no issues in hot weather or long coasting hills (previous problem points thanks to fuel heat soak).