Runs fine on hose, won’t run in the water. HELP!

« **Reply #25 on:** June 16, 2020, 08:45:39 PM »

Check the oil

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« **Reply #26 on:** June 16, 2020, 08:52:15 PM »

When starting it on a hose in your driveway, is the pump running or do you disconnect the driveline?

You can stick a floor jack underneath the trailer hitch and jack it up in your driveway to simulate a launch ramp.

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« **Reply #27 on:** June 16, 2020, 09:15:48 PM »

Float levels are set correctly, it’s a quick Fuel carb and has the glass sights for the bowls, they’re adjusted to the center of the glass as specified, fuel pressure is 6.5psi on the rail while running.

I have the pump connected while running it on the trailer, but only because of the style of bellhousing I have and the bolts to the flex plate are Allen heads makes it basically impossible to disconnect without unbolting and jacking up the motor first, definitely sucks. But I don’t run it long that a few minutes at a time to keep from getting the pump real hot.

I don’t have flaps on the exhaust, never have though since I got the boat in 2002

« **Reply #28 on:** June 16, 2020, 09:21:24 PM »

And what does the oil on the dip stick look like?

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« **Reply #29 on:** June 16, 2020, 09:21:55 PM »

Also it will start and run fine out of the water on the launch ramp on the angle, it’s only when it’s put in the water that the problem happens

The oil looks good still, if it were a bad enough breach that water was getting in the cylinders wouldn’t I be seeing steam? Had a water breach from a cracked manifold on another boat I had and was getting white steam pretty bad out of the exhaust, but the thing still ran great, it was a 460 though, might be different.

« **Reply #30 on:** June 16, 2020, 09:35:36 PM »

Perplexing it is...

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« **Reply #31 on:** June 16, 2020, 09:38:23 PM »

Have you checked the carb nuts

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« **Reply #32 on:** June 16, 2020, 09:51:57 PM »

I did think maybe there was a vacuum leak. I was using bolts for the carb before but replaced them with studs and nuts and did a vacuum leak check when I resealed the intake. I have caps on all the ports of the carb. It’s hard to believe it’s a load issue too because of how great it runs on the hose, and the fact it’s probably pushing close to 400hp

« **Reply #33 on:** June 16, 2020, 10:01:38 PM »

Hopefully someone pipes in. I can’t think of anything else

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« **Reply #34 on:** June 17, 2020, 05:49:21 AM »

I had the same issue after I feshened up my motor and pump was super bummed in the driveway fine in the water fell on its face, my timing was off after doing some research with no vaccum advance you have to run between 28 and 32 degrees on the timing, this worked on my set up with a stock 454.

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« **Reply #35 on:** June 17, 2020, 07:12:33 AM »

It did cross my mind that it could be a timing issue but it’s very odd that it would run fine out the water then not at all in the water because of timing being off, given that it doesn’t really have a huge load on it at idle.

I’ll walk you guys through exactly what happens:
I back the trailer in the water to just where back starts floating. I’ll leave to front still hooked up, I’ll start it up, it’ll idle normal for a few seconds, then like shit almost like it’s missing, if I try to give it gas, it’ll stutter and have a total lack of power, if I shut it off or if it dies, I won’t be able to get it started again until I pull it out (just to where it’s out) then after about a minute, it’ll start back up normally out of the water and run fine. If it’s hooked up on the hose at my house it also runs fine. It seems like through the exhaust tips or pump/intake grate being it the water causing a short to the 12v ignition wire, but the wiring is completely intact and that also just doesn’t make sense to me.

« **Reply #36 on:** June 17, 2020, 08:16:00 AM »

Where is your ground attached?

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« **Reply #37 on:** June 17, 2020, 08:22:06 AM »

Here’s a thought, disconnect that choke and try it in the water...

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« **Reply #38 on:** June 17, 2020, 09:11:22 AM »

Could it be the alternator grounding out the electrical? Is it a marine alt?

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« **Reply #39 on:** June 17, 2020, 09:51:13 AM »

Just want to say it is super cool how you are all putting your heads together to figure this out. Very cool.

Jet boat community for the win!!!

Good luck figuring it out

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« **Reply #40 on:** June 17, 2020, 10:14:52 AM »

I would do the Ford vs Chebby thing but I’ll wait till he fixes it.

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« **Reply #41 on:** June 17, 2020, 11:47:45 AM »

The ground cable from each battery has its own cable that attaches to the bell housing bolts, i suppose I can take off the alternator belt next time and see what happens, it’s not a marine alternator, but it’s virtually brand new. Oh and my choke is not wired lol it’s adjusted all the way open.

« **Reply #42 on:** June 17, 2020, 12:14:58 PM »

Quote from: throttlejunkie on June 17, 2020, 11:47:45 AM

The ground cable from each battery has its own cable that attaches to the bell housing bolts, i suppose I can take off the alternator belt next time and see what happens, it’s not a marine alternator, but it’s virtually brand new. Oh and my choke is not wired lol it’s adjusted all the way open.

Just un plug the alternator and then try it

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« **Reply #43 on:** June 17, 2020, 12:20:13 PM »

Well we are narrowing it down at least.

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« **Reply #44 on:** June 17, 2020, 01:18:56 PM »

Is your feed point to the engine, the same from the hose as the pump?

When you rebuilt the engine did you change any of the coolant feeds?

Just wondering if some how you are back feeding water though the exhaust into the cylinders to cause it to shut down.

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« **Reply #45 on:** June 17, 2020, 01:45:09 PM »

just for shits and giggles!! pull the distributor cap and look for a crack!! and that theres no water in there

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« **Reply #46 on:** June 19, 2020, 03:01:22 PM »

Alright everybody, semi successful day out as we were able to actually run it on the water, the pump being freshly rebuilt with only one trip out since we rebuilt the motor seems to put a big load on it (also had an induced put in, maybe that’s why?) after starting it up and turning up the idle to around 2200 rpm out of the water on the launch ramp id be able to back into the water and it would stay running around 1200 rpm. So we putted it around in the marina at idle and checked timing, it was at about 19 degrees at 1200 rpm. If we tried to give it gas it would sputter and have no power, only after advancing it to around 36 degrees at 1200 or so rpm did it seem to run pretty damn good off idle, this of course means the total timing is something crazy Like 50 something degrees. And also the only way to start it back up after it’s turned off was to disconnected the batt wire from distributor, have my dad crank it, then plug the battery wire in. Any ideas why it would need so much time to run even decent in the water? It wouldn’t even stay running in the water at 16 Btdc. I does have a gnarlier cam than I originally thought and it’s got some big ass valves in the heads.

« **Reply #47 on:** June 19, 2020, 03:29:50 PM »

Too much timing. You’ll do damage if you keep it there and run it. Are we sure the distributor is in correctly?

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« **Reply #48 on:** June 19, 2020, 04:04:36 PM »

Just got off the phone with my engine builder, old hot rod guy that owns a machine shop building dragsters, he told me the heads on my motor are like 62cc chambers and my compression is probably close to 12:1, I guess this motor is way more bitching than I originally thought. He told me those high compression motors love timing and around 50 degrees total isn’t going to hurt anything if it’s running good and not missing or pinging or anything. He said in a jet boat it’s not uncommon to have a lot of time, which sort of sounded weird to me. I know for sure the distributor is installed correctly and firing order ect. Is good

« **Reply #49 on:** June 19, 2020, 04:10:30 PM »

Well if you’re 12:1 I would highly advise using AV has or race gas. Pump gas will detonate your motor. Believe me I know

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