Back up gas fuel pump

[015point9]

Posting on this site because many are familiar with hose sizes and what pressures do to floe.  I want to install a back up fuel pump in a small motor home.  Gas...not diesel.  On a small 5.4 trition.  I can work out most of the plumbing but I'm stuck on figuring out how much gas I can get through a certain size line.  I have a gas line much smaller in size that feeds a generator.  Much smaller than gas line to engine under the hood.  Would be great if I could use this small line.

 

What is it called...figuiring out how much fluid you can a certain size line at so much pressure?

If someone would give me a hint...I could google from there, but don't know what to look up.

 

Thanks

[Mopar1973Man]

The whole thing depends on pressure stability. Larger fuel lines will have better pressure stability compared to smaller lines that will have drastic pressure changes from idle to WOT operation. Personally, I would use a slightly larger line than stock sized fuel line then pressure stability will be optimal.

[Gamble]

Well, I'll start this party I suppose and throw my .02 in here......after Mopar1973man that is.

 

If I read your post correctly.  You are attempting to place a secondary fuel pump in the system in case your original pump goes down I assume.  This could be really complicated when getting into the head pressure vs distance vs line ID diameter, vs etc.etc.  

 

While I am not familiar with the type of fuel pump currently used on your motor home.  In my head I think the easiest thing to do would be to purchase an inline flow thru type pump like this one. https://www.amazon.com/Airtex-E8090-Universal-Solid-Electric/dp/B000DN7VLK/ref=sr_1_1?ie=UTF8&qid=1513374895&sr=8-1&keywords=airtex+E8090

This particular one may not be large enough for what you need but there are lots of different sizes.  I am sure you could find the GPM flow of the factory pump on the motor home and match it.

 

If you run an inline flow thru pump, it won't hinder your current pumps production and could easily be used via toggle should you need it.  

Edited December 15, 2017 by Gamble

[015point9]

Thanks for replies...after looking at flow charts I'm going to have to do more homework in order to get right size pump matched up.

1. Going to measure what psi I have at test port now. (Test port up by valve cover)

 

2. Inside diameter size on current (oem) fuel line and generator line that i want to use.  And distance of lines. 

 

So I'll be back...after I get above info.  Might be awhile because generator line is hard to get to, but should be able to tell size from spare generator fuel pump.