×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Speed of fuel flow in fuel lines? (As in empty fuel line...)

Speed of fuel flow in fuel lines? (As in empty fuel line...)

Speed of fuel flow in fuel lines? (As in empty fuel line...)

(OP)
Electric fuel pump. Gas tank in rear of vehicle...

Say you have a bad fuel pump check valve and overnight all the fuel drains back into the gas tank. And the fuel line is filled with air.

How fast does the fuel flow when the pump is turned back on?

Or how long would it take for the fuel to reach the engine?

(This would be assuming that there is a fuel pressure regulator and this regulator is sending excess fuel (air) back into the gas tank via the return line. If this is the way it works?)
 

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

It should not drain back unless an injector or the pressure regulator are leaking. For all but the smallest amount of fuel to get out, air has to get in.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

....or vapour forms during a hot soak and fuel is repelled into the tank via a poor non-return valve.

Bill

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

I assume that you know the pump's flow rating.  Estimating the fuel line volume shouldn't be difficult.

How quickly the pump regains its prime is another matter entirely.


Norm

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

If you've got 2.5mtr of 8mm OD fuel line and a 100 litre per hour pump, you'll need about 3 sec just to fill the supply line.

Bill

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

In my experience, electric fuel pumps self destruct fairly promptly if run dry. If I had an efi car that I suspected had lost its prime, I would turn the ignition on and off in fairly short bursts so the pump rollers did not get hot and gaul.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

Depends on how old the vehicle is Pat.
Anything thats less than about 10 years old, or that isn't a top HP machine will probably have a turbine. That doesn't mean to say that it WILL BE turbine, there's still quite a few OEMs using Gerotors and Bosch-type roller cells, just not as numerous as a few years back.

bill190 - what's the pump and/or vehicle in question?

Bill

RE: Speed of fuel flow in fuel lines? (As in empty fuel line...)

(OP)
No specific vehicle in question. I just see a lot of cold starting problems on the internet. They take a few minutes to start in the morning, but once they are started they start right up.

So I was wondering if fuel was draining back into the tank by morning (due to a faulty check valve), and the time it takes to start the vehicle in the morning is the time it takes for the fuel to get back in the lines?
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources