SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: damstarr on September 13, 2009, 05:08:14 PM
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Hey whats up guys. I just got back from the buenavista for 3 days.Just curious.I went through about 45 gallons of fuel.I wasnt on the lake non stop and i wasnt buried in the throttle the whole time.Does this sound about right? Its a pretty much stock 460 with a holley carb.i know the timing is off(backfire through the carb when u fire it up)could this cause any problems.I just rebuilt the carb and it runs really good,could i just be running way to rich?Thanks for help guys
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when i was on vacation i was monitoring this very thing, any way i was getting about 2 miles to the gallon at 3500 rpm. 2, 15 gallon tanks and the gps would very from 62-68 miles
and yes its bad if the timing is off :screwy:
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A ten day trip with about 15 people at Lake Shasta can burn 400-500 Gallons of gas without even trying (four pleasureboats, two Sea Doo's and 1 houseboat)...
You will find that your 460 probably burns 8-10 gallons an hour....again, without even trying.
When we were racing, we could burn 25 gallons of gas in about 45 mins....Time to do some math. ;D
The tune up could easily make a 30% difference...
GT
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lol i know that the timing being off is not could just didnt know how much that would effect fuel issues
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If you have back firing on the start up there is a chance of a blown power valve. That can also make a diffrence.
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A few years ago my family spent a week at Shasta, and my kids managed to burn at least 40 gallons per day. They thought it was great--just give the guy my credit card, and he'd give them another 40 gallon fill up. Years ago (mid 70s), I had a jet that would run into the mid 80s mph (pretty good for a basically stock BBC with logs) and I loved to take it to the lake on Sunday afternoon and race anyone that floated. I could run through 25 gallons in less than 2 hrs. However, seems to me that the 99 octane pump gas was less than $1.00 per gallon. Hah, the good old days.
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;D That's one of the joys of boat ownership..
The pop at start up doesn't mean the timing is off, you're just lean. If the timing were the
cause it wouldn't just be at start up. Is it dogging? Knocking??
I agree you may have a blown power valve too from the back fire. You may also be running the wrong power valves. If you're dumping fuel from them when it's not needed you'll see the gas pumps more often.
Your fuel consumption depends on your miles traveled and what you were doing. Plowing pulling a tube will suck you dry with only a few miles traveled. My boat fully loaded uses more gas than just two people in the boat too.
I use around 24 gallons when we run up the lake and back, that's about 26 miles one way. I usually cruise around 38 mph. 23' with a modified 460. Remember the old saying:
"you'll pay when you play"
:sly:
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well i ordered a rebuild kit from holley and put in the power valvle it came with.when u take off if u bury the throttle it wil die.I crack the throttle and hold it then when i get a responce i can get into fine.Like pulling a skier out is difficult but once it hesitate i can get them up.Sorry for all the questions this is my first boat and im not real strong on carbs.
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What carb is it? Did you clean the shit out of everything when you rebuilt it? float levels good? gimme some more details
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Hey damstarr,
I'm not busting balls here bud, but there is a whole lot more to rebuilding a carb then pulling it apart and putting it back together with new parts...
It sounds like you may have missed something like Stiffy says :D
I would pick up another kit and go through it again...only this time, get a can of Berrymans carb cleaner and spray it through every orifice and make sure everything is clear, put the accellerator pump together and bench test them before you put it back together, make sure the squirters are clear and so on..
I have seen something as simple as a bowl gasket put on backwards do something similar to what you are describing.....
IMHO it needs to come apart again, you should be able to hammer he gas to the wood and not skip a beat.
Lemme know if you need some help... :thumbup:
GT
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yah it was cleaned very well and put back together correct.We set the floats to a dry setting that holley recommended.When we pull the site glass plugs the full level is right below the plug where it should be.
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yah it was cleaned very well and put back together correct.We set the floats to a dry setting that holley recommended.When we pull the site glass plugs the full level is right below the plug where it should be.
If you give the throttle a stroke, do all the accellerator squirters pee like a racehorse, or do they just sort of spit?
GT