(Probably not in the right section - as it's not injection - but definitely fuel related...!)

I'm about to run the fuel lines in my Haynes Roadster. I am planning to run a send and return line (just in case I need the return in the future) but am only going to use the 'send' one for now. The fuel pump will be the standard mechanical pump on the Pinto engine.

Do I need to worry about the ups/downs in the pipework? Is there a risk of me airlocking or is there limit to how far the fuel can be lifted by the pump?

For now i'm thinking to run the hard pipework (send and return) near the top of my transmission tunnel which would mean it would be about 9" higher than the sump of the fuel tank but level with the 'return' feed back into the tank.

[Edited on 27/8/17 by jps]

As far as the pump is concerned only the height difference between the fuel level in the tank and the pump on the engine actually matters.

It can go up as far as you like and it can come back down again. The initial load on the pump may be higher but once it's run for a few seconds it all evens out and the pump won't notice.

My car is fuel injected and the feed and return pipes run along the top of the transmission tunnel

[Edited on 27/8/17 by JAG]

My Pinto had standard pump and a single feed because I used a minivan tank with no provision for a return pipe. I had a series of highly embarrassing breakdowns caused by hot weather vapour locking. I've fixed that by converting to a Facet electric pump but with hindsight I guess I would not have had the vapour locks if I'd retained the flow and return because there would always have been a flow of cool petrol with the original design