Baja Rooster

iTrader: (1)

So, as many of you have followed my saga here...

http://www.offshoreonly.com/forums/b...ectations.html


The motor still tops out at 4800 regardless of prop, so I want to take fuel supply out of the equation. I'm bolting on the Holley 130gph bottom to the top of the stock fuel pump, but everything else is plumbed for 3/8" lines including the line from the tank and the fuel/water separator even has smaller flare fittings to boot.

So how do I go about upsizing everything? Where is the tank pickup on this beast? Is there an aftermarket fuel separator set up with larger fittings?

502/500hp QF850 carb

What are you guys running with what power?

gsxr1216

i didnt read all of your other post but mine makes 470hp (454) with a holley 850 on it runs about 69 on the gps with a dinged up 4 blade 24P prop and i didnt mess with any of my fuel line sizes but i do have the holley 130 pump on it and it does not drop pressure at WOT so i know i'm getting enough flow to keep the carb full at 5200rpm. Do you have a fuel presure guage on your boat and does it show a pressure loss at WOT?

Baja Rooster

iTrader: (1)

That's helpful to know. I did have a friend watch the guage as I opened it up. He's not a mechanic but I told him to just tell me if it dropped below six, and he said that it was all good. But, just doing the math the stock pump inadequate and cheap enough to swap out. Good to know that I shouldn't need to reinvent the whole system.

Is your boat the Islander or cuddy? Pretty impressive numbers.

gsxr1216

cuddy on mine.

By stock pump you mean you are still running the OEM pump on the boat currently? how long WOT while he watched for pressure to drop?

Do you have dyno sheets on your motor with LB/HR fuel consumption at various rpms, that will help with what it really uses fuel wise for GPH? Also have you done any WOT/ turn it off plug checks on it to see what they all look like?? I'm always a little nervous as to what the dyno says for A/F VS what you get in the water in the boat, in my case i did several WOT checks and all the plugs looked good, so that along with my steady fuel pressure i never bothered up sizing the fuel lines as it seems to get the job done.

Baja Rooster

iTrader: (1)

Yes, still the OEM pump pump currently. I did not have it dyno'd. Short story, bought it off another member here with low hours, fresh machining, etc. I've only got about 20 hours on the motor thus far working out the teething. It was only wot a few seconds as my buddy watched the gauge. I haven't done any plug checks yet, but I did think that they were rather white. The insulators weren't even a coffee brown yet. The last 1/4 of the throttle does nothing as well. Zip. Nada. Doesn't bog, misfire, or anything.

gsxr1216

OK a few things, again i didn't read all your other thread...

Does this engine really make 502hp?? not saying anything bad about who you bought it from ETC as i have no idea who it was nor do i care, but you really need to know what your dealing with here for true HP to determine how much of an issue you have or do not have?

Is this boat new to you? or have you run it with other power and know what it does?? if so what power and what did it run for speed and rpm compared to now???

As for your tests, a few seconds at WOT isnt going to tell you if you are fuel challenged or not, you need to run it 15-30 seconds IMO to see if the pump keeps up the fuel pressure.

if your not doing WOT plug checks after a decent run i would not make any assumptions as to whether its lean or rich from plug color alone.

Are you sure you dont have something easy like a pair of plug wires crossed, dont ask how i know this..........

good luck!