Air bubbles in my fuel line

Reply

Old 05-11-2014, 08:01 PM
  #1  
Tech Rookie
Thread Starter
 
Join Date: Apr 2014
Location: Birmingham,Al
Posts: 2
Default Air bubbles in my fuel line

Can anybody tell me why there's air bubbles in my fuel lines. my car is an associated rc8.2 with the reedy 121VS. The break in was by the book and I had some good runs then the bubbles.The engine sounds like it's gargling,if that makes sense.
meat63 is offline  
Reply With Quote
Old 05-11-2014, 11:49 PM
  #2  
Tech Elite
iTrader: (27)
 
dan_vector's Avatar
 
Join Date: Oct 2013
Posts: 4,028
Trader Rating: 27 (100%+)
Default

Change the fuel tube and check tank output connection for leaks. Also if you have an inline fuel filter fitted (you should have!) check it too for leaks. As a test you can remove the filter and see if the problem still exists if simply changing the fuel tube doesn't fix it.

Last edited by dan_vector; 05-12-2014 at 08:15 AM.
dan_vector is offline  
Reply With Quote
Old 05-12-2014, 05:40 AM
  #3  
Tech Lord
iTrader: (24)
 
wingracer's Avatar
 
Join Date: Nov 2007
Posts: 12,951
Trader Rating: 24 (100%+)
Default

And if none of that works, try a new tank.
wingracer is offline  
Reply With Quote
Old 05-12-2014, 08:15 AM
  #4  
Tech Elite
iTrader: (27)
 
dan_vector's Avatar
 
Join Date: Oct 2013
Posts: 4,028
Trader Rating: 27 (100%+)
Default

+1
dan_vector is offline  
Reply With Quote
Old 06-11-2014, 03:45 AM
  #5  
Tech Elite
iTrader: (11)
 
Bundy_Bear's Avatar
 
Join Date: Apr 2004
Location: Brisbane, Qld
Posts: 2,709
Trader Rating: 11 (100%+)
Default

Can air bubbles in the fuel lines be caused by the way a tank is mounted? Have had issues in the past with the KM H-K1 and now similarly the Xray NT1. Yet the same engine and pipe in a HotBodies R10 and no issue.

Curious and appreciate the feedback!

Thanks,
Andrew
Bundy_Bear is offline  
Reply With Quote
Old 06-11-2014, 02:39 PM
  #6  
Tech Master
iTrader: (16)
 
snuvet75's Avatar
 
Join Date: Apr 2011
Posts: 1,574
Trader Rating: 16 (94%+)
Default

Couldn't it be because the fuel line between tuned pipe and fuel tank is too short? I heard that if the line is too short, due to the temp, it generates bubbles. Correct me if I'm wrong.
snuvet75 is offline  
Reply With Quote
Old 06-13-2014, 05:42 PM
  #7  
Tech Elite
iTrader: (11)
 
Bundy_Bear's Avatar
 
Join Date: Apr 2004
Location: Brisbane, Qld
Posts: 2,709
Trader Rating: 11 (100%+)
Default

I have been running one and a half times the length of the pipe and header as recommended. Also, it is the same bit that was used with the same engine and pipe and manifold from the previous car that had no issues.
Bundy_Bear is offline  
Reply With Quote
Old 06-15-2014, 11:07 PM
  #8  
Tech Master
 
Geezatec's Avatar
 
Join Date: Oct 2007
Posts: 1,461
Default

Use o-ring on Tank mounts to cushion the tank from vibration. And use sealant on fuel hose b/n tank and carb(and fuel filter if used). Also could cause carb not adjusted correct(too rich). It will dissapate when adjusted correctly. Is there actually air inline of Air bubble like fish eggs?
Geezatec is offline  
Reply With Quote
Old 06-17-2014, 11:31 PM
  #9  
Tech Master
iTrader: (16)
 
snuvet75's Avatar
 
Join Date: Apr 2011
Posts: 1,574
Trader Rating: 16 (94%+)
Default

Originally Posted by Bundy_Bear View Post
I have been running one and a half times the length of the pipe and header as recommended. Also, it is the same bit that was used with the same engine and pipe and manifold from the previous car that had no issues.
I must admit that I had the same issue with my NT1. Get Serpent
snuvet75 is offline  
Reply With Quote
Old 06-18-2014, 12:42 AM
  #10  
Tech Elite
 
blis's Avatar
 
Join Date: May 2008
Location: Brisbane
Posts: 3,456
Default

Easy fix -> Don't buy translucent fuel line!!!

[The pressure line feeds into the tank at the top and the fuel to carby is drawn from the bottom of the tank. For bubbles to form in the fuel inlet tube it has to come from the tank feed, nipple and tubing... Or.... it's a hot carby!!? If the bottom mix is too lean and the carby heats up to beyond that of the boiling point of methanol 65c ( https://www.google.com.au/webhp?sour...nt+of+methanol ) then it could be a backwash of boiling fuel. Since methanol evaporating in the carb will cool it down, try a richer bottom and/or top.

Also something to consider is siphon, as there's not exhaust pressure either the tank may cool and shrink but hey, if it's happy and you're happy a few bubbles wont hurt it, unless there's an air leak and there'd be fuel residue there too.]
blis is offline  
Reply With Quote
Old 06-30-2014, 10:17 AM
  #11  
Tech Elite
iTrader: (16)
 
ToysRUsKid's Avatar
 
Join Date: Jul 2008
Location: Cinncinati, OH
Posts: 2,621
Trader Rating: 16 (100%+)
Default

I like the easy fix but you also have a great description of what's going wrong. I noticed that only the carb side of my fuel line produced bubbles this weekend. I say carb side because I use a fuel filter.

Originally Posted by blis View Post
Easy fix -> Don't buy translucent fuel line!!!

[The pressure line feeds into the tank at the top and the fuel to carby is drawn from the bottom of the tank. For bubbles to form in the fuel inlet tube it has to come from the tank feed, nipple and tubing... Or.... it's a hot carby!!? If the bottom mix is too lean and the carby heats up to beyond that of the boiling point of methanol 65c ( https://www.google.com.au/webhp?sour...nt+of+methanol ) then it could be a backwash of boiling fuel. Since methanol evaporating in the carb will cool it down, try a richer bottom and/or top.

Also something to consider is siphon, as there's not exhaust pressure either the tank may cool and shrink but hey, if it's happy and you're happy a few bubbles wont hurt it, unless there's an air leak and there'd be fuel residue there too.]
ToysRUsKid is offline  
Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Terms of Service