I’m having a big issue, I got an 85 carrera 205 that will run fine on a hose, but as soon and it’s in the water it runs like total shit then not at all. This is with it on the trailer still just backed up far enough that the pump and exhaust are in. The motor was just rebuilt last month as a long block and hasn’t even been broke in, Heres the specs:
454 BBC roller motor w/mild cam
Weiand intake
Quick fuel 750 dp marine carb
DUI marine HEI distributor (timed 10-12 initial, 34-36 total)
Ac delco plugs gapped at 50
Indmar through transom exhaust
High torque mini starter
Rebuild Berkeley 12JG with ride plate and electronic jetovator

There doesn’t seem to be any wires touching the water or anything when I back it in the water on the trailer, it seems to me like the ignition shorts out when in the water somehow, but I’m completely perplexed on how that could be a thing, I thought maybe the starter is shorting internally causing it to somehow short through the block when the exhaust tips or grate are in the water? I can pull it out on the launch ramp, wait a minute or so, then it runs normally, but the second I back into the water ( even when still running) it idles like shit, has no power and eventually just dies then can’t be restarted til I pull it out of the water. If anyone has any ideas or has been through this before please let me know, here are some pics

So I’m imagining that when your boat is on the water hose your boat is on flat ground but when your on the launch ramp you boat is at an angle. It makes me wonder if your float in the carb is stuck or something and your starving the engine of fuel.
Just my thoughts and possibly something to look at.


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So after I first put it together the intake was poorly sealed and leaked water into the oil when I first started it on the trailer, but I realized very quickly, and pulled and resealed the intake and drained the milky oil and cranked what was left out with the oil filter off, then put new oil and filter, so there’s probably a tiny bit of that milky oil still in it, but otherwise it looks pretty damn clean. I probably should have mentioned that. As far as the float level is concerned, I have glass sight bowls in the quick fuel carb and they’re adjusted right to the middle and still look good on the launch ramp, fuel pressure is at 6.5psi at idle. I don’t think it’s flooding

Holley mechanical pump with regulator and gauge on rail

Seems to crank the same in and out of the water

Duel should dribble out if they are set correctly.


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i maybe completely wrong but the common denominator here seems to be your jet. when its loaded???


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It’s not a fuel issue, floats are adjusted correctly and fuel pressure is at 6.5 psi running. I don’t believe it’s a pump issue either since it cranks fine in the water and can’t be restarted once it dies leads me to believe it’s a electrical short but that’s why I’m scratching my head, doesn’t make sense that it would short when touching the water

Just double checked water lines, they’re routed correctly, also runs fine on the hose

I wonder if you took a second water hose and sprayed the pump and exhaust tips with the boat running if that would make the boat stall out.


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Rpm


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Ok idles fine then. Float check time. Crank it with the coil wire off for a few revolutions then check


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The only other thing I can think of is that the pump is putting more water pressure into the motor and you have a breach either in the intake manifold gasket or the head gasket.


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