'88 SN speed problem?

I think a compression/vacuum test would indicate what health this engine has left to play with, then he can start buying parts.

We need to know what propeller pitch is on the boat now.

do a compression test this will indicate if you'll be able to get over 4k rpm wise, I would throw on the other prop and see if you get the same results rpm and mph with it compared to the one that is on it.

Ha, naturally. The 540 is a pretty sweet prop- but all the 2001's that Ive been in that have upgraded to that wheel are used to ski and barefoot and arent running loaded or at altitude. I have no idea how Travis uses his boat.

I'll have to see if I can find a shop tach to borrow. The prop on the boat now I think is a 4-blade OJ 13x13 (stainless steel?). All it says on the hub is "OJ 13" and on the side is stamped "OJ102". The spare prop that came with the boat is an OJ 13x13 4-blade that is goldish in color.

travbo24 wrote: UPDATE gps reads 39.5 mph at the top end. That's well above what my speedo's were reading. The tach still read just under 3400...could it be wrong? If the tach is accurate, maybe I am overpropped. Travis

Second post:

8122pbrainard wrote: What WOT RPM's are you turning up? What prop is on the boat?

Get the dia. and pitch and post what you find.

Yes Pete I have timing lights but I noticed he didnt in my reading and believe me that what finger does the trick if you have a dead one! lol

Hi guys,
I did borrow a timing light and tried to check it yesterday. There was still a mark at 10 degrees BTC and the timing seemed to be a bit behind (4 deg. BTC)...but it wasn't running well at all. I used the timing light to check all the cylinders and found that #4 had no spark. The plug wire was intermittent. I replaced it and then it seemed to run much smoother...but my higher rpm problem was still there. Thought I had it for a minute there.

I'm going to put the timing light on it again today with all 8 cylinders..make any adjustments needed. I've almost burned through most of what was in the tank so I'll give it some fresh fuel. I did run it yesterday off a separate gas can...no difference so I don't think I have a tank problem.

I'll try to get a fuel pressure gauge and check that today also...there is a pressure adjustment in the throttle body. If none of that works, I'm considering a return to the carb. Any thoughts on checking or rebuilding the carb before putting it back on? Is that a job for a pro?

Thanks for everything...I'm amazed at how helpful you guys are. Much appreciated.

Travis

Check that all cylinders have "fire". After engine is warmed up and still at an idle, wet your finger and touch each of the eight exhaust outlets where they come out of the head. I had a brand new autolite that didnt work one time and it took a liitle while to find it. That would put your performance numbers where they are and being the boat is new to you it can be hard detect in sound sometimes.

Travis,
I mentioned before thinking there were 3 CCfan members who had the ad on injection systems. 2 went back to carbs but I remember 1 did get his to run after many hours of playing around with it. Do a CCfan search (older than 6 months) and see what you come up with. Maybe you'll luck out and be able to talk to the owners.

You said you have a manual. What does it have to say? Holley tech line?

Finding a mechanic to take a look at the issue may be a problem. They may just walk away from the engine once they find out it's been modified.

Your fuel pump is shot I would say or the pressure regulator is bad, it shouldn't be dropping in RPM so that is fuel related and the only issue.

the metal filter is the fuel and water seperator get a new and replace the old one, the plastic filter doesn't hurt but replace it with a new one to play it safe. You need to put a wrench to the fittings for all fuel lines leading to the throttle. Also look back at the tank for cracked hoses for the vent line as well as the fill tube. The anti-siphon feature is part of the fitting looks like a regular fitting but it's not. if you can see daylight through it make sure you removed the rght part, remove everything at the tank might be two fittings someone might have all ready removed it as well so double check everything.

Can you post some pictures.

do you have fuel pressure gage to verify that the fuel pump has issues?

I'm assuming the Pro-jection system is a way to convert from carb to fuel injection. Does it have an injector for each cylinder? Does it have a pressurized fuel rail? If so, you could have a leak along the fuel rail and as the pressure leaks down, it slowly sprays a mist of fuel out. And if there's a leak, it might be sucking air when you put the coal to it. Just a guess. I really don't know anything about that fuel system.

Hey 79,
To clarify the revving...I can rev up the motor in neutral to over 5000 RPM, but within a few seconds it will bog down to 3K or so and bounce around between 2500-3500 rpm. That makes me think it is a fuel delivery problem...like it has enough fuel to go at first, then gets starved. All of that variance takes place without moving the throttle from wide open or close to it. Under load, I don't even get one good rev...it can't get there.

79nautique wrote: check the anti-shipon valve at the tank where the fuel line connects to it. Try running off of a gas can instead of the tank and see what it does, doing this eliminates the anti-shipon valve, vent and pick-up as causes. I'm a little puzzled you say in neutral it revs to 5k but won't hold, does it go up then stay's steady at a lower RPM with the throttle in the same position? meaning going wot, the RPM peaks then backs off on it's own to a lower RPM? what does the spray pattern from the throttle body look like? even cone shaped spray from all injectors?

Are you really recommending flying down the lake at 35 mph with the fuel line stuck in an open can of gasoline??? Now THAT'S not Coast Guard Approved. I understand what you are trying to accomplish but that has the making of a Three Stooges episode. It would be a better idea to visually inspect those parts and clean them if needed. It's not that hard. You can do it in the driveway. Just expose the fuel tank, remove the pickup line, make sure it's clean (including the screen at the bottom. Also check the larger vent hose and through hull fitting for obstructions. You can also pull the tank out completely and drain it to rule out water in the fuel tank. I'd also change the fuel filter. It should be some oil filter looking device.
I still think the exhaust leak is causing a good portion of your problems.

check the anti-shipon valve at the tank where the fuel line connects to it.

Try running off of a gas can instead of the tank and see what it does, doing this eliminates the anti-shipon valve, vent and pick-up as causes.

I'm a little puzzled you say in neutral it revs to 5k but won't hold, does it go up then stay's steady at a lower RPM with the throttle in the same position? meaning going wot, the RPM peaks then backs off on it's own to a lower RPM? what does the spray pattern from the throttle body look like? even cone shaped spray from all injectors?