SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: nolongergreen on May 23, 2014, 05:31:32 PM
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I just installed a tunnel ram on my 460 with 2 holley 600 carbs and it won't run right. Both carbs are supposed to be rebuilt and ready to go but it seems like the front ones acting up. I pulled it apart and sprayed all passages with carb cleaner but no change. It runs like 1/2 the motors not firing. If you pull plugs 2 and 5 nothing changes, but they are firing. I put a spark plug in the wire and it sparked. So it would seem no fuel to those cylinders..?
It has 15 lbs vacuum at idle and 19 while revving.
Both floats are set right and its getting fuel to the bowls, but if you look down in the carb you dont see fuel.
Once you rev it, it gets better but still has a miss in it.
Any clue what could be wrong?
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Fuel pressure?
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I believe it about 6.5. I had a gauge on the 850 dp and havent changed the fuel pressure but I dont have a pressure gauge on it right now.
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Double check your firing order. Is it possible that you got a couple wires swapped?
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i will check but we never pulled the wires off the cap
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Also, where are you checking vacuum? Manifold vacuum should drop as the throttle is opened. This vacuum drop is what causes the power valves to start adding fuel.
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I'm not sure which port on the carb he hooked his Gauge up to, I was on the other side of boat, but let's assume the big port on the bottom plate of the carb... how much should it read ? When im Looking into the carb I'm not seeing fuel coming off the "hoop looking things". Are they supposed to have fuel misting off of them at idle?
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I have another Avenue to look at when I get back to the shop on tuesday. Being as I have no fuel going into cylinders 2 and 5 and I did hear a little of a rattle like a sheet metal (very faint) but I'm wondering if a couple of poly locks have failed and it's backed of so far out of adjustment that there not opening the intake valves? Maybe just an adjustment and hopefully no serious damage or anything bent.
Maybe this could be the cause?
It did get a vibration in it towards the end of the day on the last time it was out....
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I'm hoping that was from it being out of adjustment and stopped allowing the valves to open then?
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I have another Avenue to look at when I get back to the shop on tuesday. Being as I have no fuel going into cylinders 2 and 5 and I did hear a little of a rattle like a sheet metal (very faint) but I'm wondering if a couple of poly locks have failed and it's backed of so far out of adjustment that there not opening the intake valves? Maybe just an adjustment and hopefully no serious damage or anything bent.
Maybe this could be the cause?
It did get a vibration in it towards the end of the day on the last time it was out....
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You definitely need to pull the valve covers for an inspection. Because of the design of a tunnel ram it is physically impossible for a single or pair of cylinders to not be getting fuel unless there is a valve is not opening. That's why I was trying to direct you to something other than a fuel issue.
Good luck with your inspection.
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Thanks, It makes more sense than anything at this point.
What are some things i need to look for besides being loose?
Is there a high possibility of major damage or is it most likely just a re-adjustment issue?
I'm sure there's no way to tell but i'm just hoping for minimal damage.
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Get it opened up, if you don't find anything obvious, we can tackle it at that time.
Good luck
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Everything good on topside and after chasing everything out I had a few plugs that had backed out and was causing the loss of vacuum drawing fuel into a couple of cylinders.
But.......The story gets worse! That vibration I felt after sucking up gravel into the pump which caused me to rebuild the pump...... is still there and even with the coupler disconnected from the driveline.
So as the world turns, now the motor is coming back out to pull the oil pan and take a closer look at the crankshaft
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Still has 160 psi on all cylinders
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