Fuel feed and and return lines how they affect the idle

[nkosi]

hey guys i have a problem with my idle and i was wondering it having too small of a fuel return line would affect the way the car idles ...its revving up and droping down the idle and i cant get it to steadily idle at 1000rpm ...im feeding the fuel rail with an intank walbro 255 hp and the second pump is also a 255 walbro external feeding through -6 an s/s hose but my return is the stock lines ...so can anyone tell me if this could be a problem and i might just have to run a larger new fuel return ... all inputs are welcome thanks

 

[92AWDHX40]

Never heard of an issue its fuel. Not air.

 

[nkosi]

Never heard of an issue its fuel. Not air.

so u think that the too smal return line can affect the idling of the car or can u elaberate on what u mean ...cause thats really the only thing i changed on the car was the double fuel pump and a built engine with 0.020 over bore

 

[92AWDHX40]

No idle issues is caused by other things now fuel flow through lines. Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge) try this for idle issues.

 

[steve]

As long as you can regulate the fuel pressure the return line is working. If it was too small your fuel pressure would be too high with the engine off or at idle. To prove this to yourself, try pinching it closed and watch the gauge.

 

[nkosi]

As long as you can regulate the fuel pressure the return line is working. If it was too small your fuel pressure would be too high with the engine off or at idle. To prove this to yourself, try pinching it closed and watch the gauge.

Thanks steve i will try what u mentioned ...i will also replace the ISC control valve as that is pretty old its self and work from there

 

[Absit]

Thanks steve i will try what u mentioned ...i will also replace the ISC control valve as that is pretty old its self and work from there

Don't just start replacing parts. TEST parts.

 

[99gst_racer]

So, your pumps are ran in series? One feeding the other?

You won't have any issues with running two pumps in series with -6 AN feed and a stock return line as long as your fuel pressure is in check. I've been running these fuel lines sizes for years without any issues. And it's surely not causing your idle issues.