SB

iTrader: (1)

You can use the newer USCG rubber hose. You can find it in 1/2".

Budman II

iTrader: (1)

OK, then I'll go rubber up to the fuel/water filter, and then stainless and AN from there. That should save me a little bit.

Thanks for the help, guys. Have fun this weekend!

Rookie

iTrader: (4)

OK everyone, I need some educating. I understand how important it is to not run an engine lean due to an undersized fuel systems. But I have never changed my pickups,or up-sized hoses. I have gone from the Mercury sea/fuel pumps to electric Mallory 140GPH fuel pumps. Every winter I drain my tanks. I just unhook my fuel line from my fuel pressure regulator at my carb and turn on my fuel pump. I have timed it out and I can fill up a 5 gallon gas can in under 3 mins. That is almost 100 GPH actual gas the hose and my pickup can supply at free flow. I do understand free flow rates and that flow and pressure are inverse proportion and how to choose a fuel pump. But when it gets down to it by math, flow charts and actually filling gas cans, why can't a 3/8" hose support more than 500HP? I also understand that pickups and fuel lines are changed for electric pumps because it is important not to cavitate the pump and hurt it.

Rookie

iTrader: (4)

Wait till your stainless fuel line finds + battery terminal or a stray +12v wire that that got knocked loose in 3'-4's and is now glowing red hot in your bilge. I'm going to be changing out to rubber USCG rubber hose this year.

SB

iTrader: (1)

I had braided due that too me. Engine was running poorly. Noticed the fuel pressure was down a tad, so figured I'd adjust that first, until my elbow (same arm where my hand was grabbing theline and regulator) shot a inch or so long duration fat spark to the flame arrestor. Okay, it was a few sparks as I tried to move.

It hurt bad ! Thank god I didn't blow up.

Engine ground was bad, so I became a tad better ground.

Yikes !

SB

iTrader: (1)

A 3/8th's can move a bunch of fuel. Is sometimes enough for 500hp or more. But, it's getting close, so would never suggest it, especially when reaching 600hp or so.

That's all.

Budman II

iTrader: (1)

I'm confused. So are you saying to go with with rubber hose all the way up the the regulator or the carb? I was under the impression that rubber lines were not allowed between the pump and the carb by USCG regulations. All the factory Merc motors that I have seen had hard metal lines going up to the carb. Wouldn't these conduct just like the braided SS lines?

I also thought about using something like the push-lok hoses and fittings. Those are non-conducting, aren't they?

Rookie

iTrader: (4)

BSFC of 0.55 at 700HP = 385lb/hr fuel needed. 385lb / 7lbs/gal = 55 gallons/hr actual gas needed. I have extracted over 50 gallons out of my boat many times in less than an hour. I just don't understand what I'm missing.

I also am not recommending any hose size just trying to understand.

SB Not trying to argue or disagree. I know that some times conversational tone and inflection can not always be conveyed through written text. It's all good

Rookie

iTrader: (4)

The tubing is rigid and secured. I'm not saying you would run your fuel lines all half assed like I did. Not thinking of +12v sources. lol

Cole2534

iTrader: (1)

For one you're missing the pump's flow curve - as pressure increases flow decreases. When you're dumping your boat there's no pressure to buck vs ~7psi for carb or 30-40-??? for EFI.