Jump to content

mbarjbar

fuel return line needed?

Recommended Posts

It depends on the pressure of the pump, needs to be low. The return line does help with vapor lock.

Share this post


Link to post
Share on other sites

What would be the advantage of removing the return line? Not sure that I follow your line of thought on this. I installed an electric pump on my '71 35 years ago and left all plumbing in place. That same pump is still pushing gas to the carbs.

Dennis

Share this post


Link to post
Share on other sites
Electric pumps should NEVER be deadheaded.(No Jerry Garcia jokes,please)

I wouldn't go so far as to say that, I've done it (dead headded) several times with Carters, Holleys, Faucets and others, always with good results. Note that they were all internally regulated. But, if the return plumbing is all there and in good shape, I would use it.

Share this post


Link to post
Share on other sites
I wouldn't go so far as to say that, I've done it (dead headded) several times with Carters, Holleys, Faucets and others, always with good results. Note that they were all internally regulated. But, if the return plumbing is all there and in good shape, I would use it.
I'm deadheaded with outstanding results with my Mikuni's.

Deadheaded electrical pumps mean no fuel flowing thru it.No flow equals no cooling.No cooling equals shortened time to the pump being DEAD.Heat kills pumps,hence the reason most OEM's now use in-tank pumps.

"Outstanding" is a relative term.And since you never had a return line hooked up,the word "oustanding" is erronious.If you had a return lne,the fuel delivered to the Mikuni's would be cooler,thus they would run even better.

Share this post


Link to post
Share on other sites

Bill -

Thanks for the insight with my triple Mikuni's but I'll stick with the recommendation from Todd and Dave on the return setup for my fuel system (that would be the owner of Wolf Creek Racing and Rebello Racing) - thanks for sharing your thoughts though..................;)

Share this post


Link to post
Share on other sites

My old Stewart Warner thumper pump dead-heads into triple Mikunis and has since 1971 with zero problems and no vapor lock issues.

I understand the advantages of cooling the fuel, but that hasn't been an issue.... yet.

Share this post


Link to post
Share on other sites

those trips probably pull enough gas thru that pump to take care of any cooling needs (and what's not to like about that :-) It also depends if the needle & seat valves in the carburetors can handle the pressure...if they can resist being blown open and the fuel demand & supply requirements are balanced, there's nothing the matter if you nix the return line. My personal opinion is that it's better & beneficial to use one and it's safer too. If for some reason, gas has no place to go back to and must exit somewhere because of a fuel system problem (eg: a hot engine bay), then I'd rather it be allowed an escape route back to the fuel tank.

Share this post


Link to post
Share on other sites
Electric pumps should NEVER be deadheaded.(No Jerry Garcia jokes,please)

Huh? Do you want a list of modern cars that dead head the fuel system? Mazda RX8, Nissan 350Z, Audi S4,... Lots and lots of carb cars run a dead headed fuel system with an electric fuel pump.

Share this post


Link to post
Share on other sites
My personal opinion is that it's better & beneficial to use one and it's safer too. If for some reason, gas has no place to go back to and must exit somewhere because of a fuel system problem (eg: a hot engine bay), then I'd rather it be allowed an escape route back to the fuel tank.

Really? Adding a second fuel line running the length of the chassis with all its potential leak points and places for to fail in a wreck is safer?

Share this post


Link to post
Share on other sites

well I guess we all should bow to your knowledge, because you have all the answers. I don't drive an Audi or a Mazda. My 240 has carburetors and we're discussing an original design from Nissan in which they decided to include a "dangerous" fuel return line....I just looked at the one in my car and after almost 40 years all it's "potential leak points" are nice & dry. WTF?

Share this post


Link to post
Share on other sites
Bill -

Thanks for the insight with my triple Mikuni's but I'll stick with the recommendation from Todd and Dave on the return setup for my fuel system (that would be the owner of Wolf Creek Racing and Rebello Racing) - thanks for sharing your thoughts though..................;)

Even those guys can be wrong sometimes.

Share this post


Link to post
Share on other sites
There's really a lot of mis-information in this thread. Probably should be deleted.

Especially when your post about the "return line in a accident "suggests you know more than the factory.

Share this post


Link to post
Share on other sites
Even those guys can be wrong sometimes.
Especially when your post about the "return line in a accident "suggests you know more than the factory.
The word of three guys that 'do it for a living' coupled with the fact that the four vehicles I presently own with electric fuel pumps are 'deadheaded'. Not trying to take sides here but, as they say, I'm just sayin'......

Share this post


Link to post
Share on other sites

Based on my recent experience, seems like a carbed Z needs a return line just to help prevent vapor lock in the fuel rail. Fuel injected rails might be under enough pressure to prevent vapor lock, and thus not need one.

Share this post


Link to post
Share on other sites
Especially when your post about the "return line in a accident "suggests you know more than the factory.

I was disagreeing with the statement that having a return line was safer then not having a return line. My comment was not directed at Nissan's original design.

Share this post


Link to post
Share on other sites

From the above it is clear there are pros and cons to both sides.

It also seems to depend mostly on the ability of a pump to have an internal short cycle bypass path, if it sits in the tank, and the pressures and flow rates for the application.

My opinion (old school) for adding an electric pump to a carbed 240z is with Z train, the pump should have flow when on and not be dead-headed so as to minimize strain and to promote removal of internal heat. My opinion is weighted more for longevity of the pump rather than any other priority (safety risks, looks, convenience, etc.).

Share this post


Link to post
Share on other sites
My opinion (old school) for adding an electric pump to a carbed 240z is with Z train, the pump should have flow when on and not be dead-headed so as to minimize strain and to promote removal of internal heat.
My opinion would be with him also If that had been what he said rather than making a blaket statement and then trying to defend it by knocking anyone's opinion that differed. Now, I promise, I've got nothing else for this thread. Life is too short.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.