Injection installation RTN line - local or remote

[miked]

I am looking at doing fuel injection during winter. I will be running in a new fuel line. Whilst at it i was considering running a return line back from the front and pressure relieving/regulation there up at the front
As opposed to local pressure relief/regulation at the rear tank area. Seems a bit like cheating running straight back into the tank and pumping at a blind end.
What are the advantages of the full return line to the front?
Cooling of fuel due to it running there and back?
Would it give better pressure control?

Mike

[SimonH]

A lot of cars have a dead head fuel rail these days. Mainly as it reduces the amount of possible vapour leak paths for emissions testing. Not an issue in our old cars lol. It does give fresh fuel continually and allows it to be cooler but it will only really be noticed if you are somewhere really hot and the fuel will get used quite quickly anyway. Simpler plumbing is one advantage, not having to run two lines in etc. It will take a bit longer to prime especially if it’s been sitting a while and also there are more chance of pulsations in the fuel supply. If you have easy access I’d run a return system myself rather than returnless.

[c42]

I have fitted a return on my setup(Zetec), whilst there are more dead head fuel rails about these days I figured that in our older cars we do get quite a lot of heat build up so decided better safe than sorry.
Cheers
John

[HCA]

Yes it might help fuel pressure control, but for our cars any such help is theoretical.

Dead end fuel rails are todays technology, driven by cost saving of an extra fuel line - ok the cost of an extra fuel line on our one offs is not going to break tyhe bank, but when you are making cars in the tens of thousands, then a huge saving!

Go for a single fuel line - cheaper and less to worry about. I think more important are the connectors. Spend your money on good quality JIC fittings such as Speedflow...

[john.p.clegg]

I had a return fitted , worked well , tried doing without it...no end of problems ( vapourlock? ) re-connected the return and all was well.

John

[HCA]

By ‘reconnected’ and ‘tried to do without it’ - did you just disconnect the return line but leaving the pump and regulator in place?

[john.p.clegg]

Yes ( ish ) my HP pump , swirl pot and regulator were upfront , fed by a low pressure pump near the tank .
I seems it didn't like a small tank of fuel in the engine bay ( not being refreshed.. ).

John

[HCA]

Thereby was maybe your problem - not that it matters any more since you are reconnected.

Returnless fuel feed uses, or should use a different pump arrangement where the pump voltage is regulated to suit the requirements, whereas a return system has the pump working at full pelt all the time.

[john.p.clegg]

Not reconnected anymore, spent a week fettling the Dellortos and re-fitted them , ran as smooth as a swiss clock.

John

[HCA]

[miked]

Thanks very much guys.

[crypto]

I did one without return line quite a while ago. Never had a problem and did many 1000 miles since then. Would do it a gain for another car. Check this out:

viewtopic.php?f=31&t=39853

All the best,
Peter

[Terry Posma]

On some GM cars they have a filter/regulator at the tank end after the fuel pump. The regulator returns excess fuel back to the tank.

I have seen some where the whole arrangement is in the tank.

My appologies if the terminology is incorrect.

Cheers.

[miked]

Yes Terry, when we did my mates car we returned back to the tank in the boot/trunk with the pressure regulator. We did put a filter up front just before the injector rail.

[Terry Posma]

Thinking about this arrangement, it may be that modern ecu's and injectors can control the metering of fuel better than systems designed 30 years ago. I guess if you are going to use an up to date system then a non return system may well be feasible. Also looking at the wiring of the modern V6 I am currently jaming into a Porsche 944 the fuel pump is not controled by the ecu.

I am not sure it's use is a cost consideration as the bits used in the system are very high quality, probably for safety purposes.