540 BBC running poorly
11-13-2018 | 05:29 PM
#91
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From: Murrayville Georgia
none of this is going to work, right now the electric is supplying the carb and the mech is robbing it of what little it supplies. if you want the elect to help fill the bowls or as a back up then it needs to pull of one of the outs of the filter. then to a tee on the outlet of the mech pump with a check valve in between to keep the mech from feeding back thru the elec when it is not running. the you need an out from the filter to the in of the mech pump with a check valve in between so if the mech fails the elect wont back feed to the filter. right now you have two line out of the filter. one to the elect and the other is going where?
11-13-2018 | 07:16 PM
#93
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From: NW Michigan
11-13-2018 | 07:58 PM
#94
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From: ALTO, MI
If it is piped as you say than that is a problem. Your starving for fuel at high throttle settings.
I still would have the fuel / water separator in front of both pumps.
That stock filter head has enough meat to be able to go up to the next fitting size. From 5/16 to 3/8 I believe.
I modified mine on the Scarab.
I still would have the fuel / water separator in front of both pumps.
That stock filter head has enough meat to be able to go up to the next fitting size. From 5/16 to 3/8 I believe.
I modified mine on the Scarab.
11-13-2018 | 07:59 PM
#95
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From: NW Michigan
F2 Shouldn't the electric pump be after the filter/seperator though. Regardless part of me understands what the particular boat manufactures did on the other hand I just personally don't think it's necessary. Something compatible to the Baker 9373 (7-9 pds) with no regulator needed and eliminate as many 90 deg fittings as possible. The very same pumps are used on 800 plus SC builds so would be more than sufficient. You can always recoup some monies and sell the recently purchased low hour Holley red electrics on the swap or eBay. Just another thought but sometimes simplicity can solve many issues. Also like MT mentioned I believe to up the size on the needle and seat or at least confirm what's in the carbs. Both front and rear.
I chased a similar problem many moons ago with a two stroke arctic cat 800 zrt that was worked over big time with porting and all the black magic good guy parts. Sled would fall on its face after it emptied the bowls. Couldn't get enough fuel to the carbs quick enough so upped the size of the needle and seat. Problem solved. Lesson I learned was no matter what size pump, fuel fittings, hose etc didn't matter if the fuel couldn't replenish the bowls quick enough. After 300 ft WoT it would fall on its face. What took hours of testing to figure out at the time was such a simple solution. Kinda wish I still had the sled as it would to this day make a Great Lake runner.
I chased a similar problem many moons ago with a two stroke arctic cat 800 zrt that was worked over big time with porting and all the black magic good guy parts. Sled would fall on its face after it emptied the bowls. Couldn't get enough fuel to the carbs quick enough so upped the size of the needle and seat. Problem solved. Lesson I learned was no matter what size pump, fuel fittings, hose etc didn't matter if the fuel couldn't replenish the bowls quick enough. After 300 ft WoT it would fall on its face. What took hours of testing to figure out at the time was such a simple solution. Kinda wish I still had the sled as it would to this day make a Great Lake runner.
11-13-2018 | 11:04 PM
#96
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From: Chicago
after that how about just ripping all that undersized junk out and converting to a real fuel system, that would help a lot , thanx
Line from tank to water separator, then to mechanical pump, and to carb. Done.
Last edited by ICDEDPPL; 11-13-2018 at 11:08 PM.
11-14-2018 | 06:31 AM
#97
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From: Midwest & T-Rock
11-14-2018 | 08:04 AM
#99
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From: Olmsted Falls,Ohio Marblehead,Oh
no, goes from tank to electric pump, then to jolly mechanical pumps then to carbs, I ran it that way this past season, but changing that this winter and going only mechanical as I feel they are more reliable, if I shut these electric off the starve for fuel I was hoping they were just to prime, on mistress I had -8 to Baker mechanicals only and was perfect. My air fuels are fine this way but I don’t want to deal with electric fail then can’t run it so I want all mechanical.
11-14-2018 | 08:06 AM
#100
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From: Olmsted Falls,Ohio Marblehead,Oh
