1984 sn2001 cuts out at higher RPM? Help!

Guys,
Hello....new to the forum as I just picked up my first Ski Nautique. Its a 1984 sn2001 with a 351 with a 1000hrs on it. I test drove it quickly before I bought it but obviously not enough.

The engine runs great - starts with a quick turn of the key, idles great and has great power out of the hole. It will run up to 4400 RPM without a problem. AWESOME!

However if I go above 2200 RPM for more then 2minutes (trying to pull a tube for instance) it starts to cut out. It bogs down, no backfiring drops a few hundred RPM and then will catch again....if I pull it down to an idle then I can take back off again without problem. Then the issue will reoccur. It seems to be fuel related because the higher the RPM the shorter it last without an issue.

So I pulled Fuel/Water separator out and replaced cartridge with a new one. checked the vent tube from gas tank and it's clear. I also have the old mercruiser style fuel pump, the one with the filter on the bottom of it - when I pulled it open there was only a spring in there with 'junk/rust' at the bottom. not sure if someone pulled it or it disintegrated over time??? Anyway I replaced it with a new one.   Also the strainer going into the carb was clear of debris.

Also the boat has electronic conversion on it so there are no points, cap and rotor look to be in good shape.

Any thoughts or where to start. I'm guessing this is still fuel related (pump?/clog on intake tube in gas tank/ or Carb? (has the 4160 holly) OR spark related (maybe coil?)

Kid's can't wait to learn to ski ----- Please advise!

Thanks for your thoughts in advance......

so yesterday I did take the black hose off of that connector and made sure I could blow through the black hose. Is the checkvalve in the 90degree part attached to the tank? I was able to push a small wire through it? it felt like it was a little stuck at first? not sure I'm in the right area?

thanks for the help.

SN2001_1984 wrote: (trying to pull a tube for instance) i

You bought a boat designed for skiing and you are pulling tubes???
Welcome to CCfan, Dump the tubes.

SN2001_1984 wrote: 8122 - gotta keep those kids happy - the good thing is that they are excited to learn to ski and wakeboard so its not a total loss :)

Get the kids out on the water

SN20011984 - There are some real pros on here that can help. Take a picture of your engine and post it. I was having the same type symptoms in my 1991 and thought is was fuel. Turned out to be something else once guys on here saw what type of ignition system I had. The knowledge on here is amazing. Welcome to the club.

did you take the cap off and look at the contacts?

I'm planning on putting in the water again tonight.....

what things should I be testing while in the water? [its a good 2hours by the time drive to lake/unload/test/load, so i would like to try as much as possible?]

I plan to ::
1. test fuel vent [remove gas cap if needed to verify]
2. test coil voltage to distributor to be sure the isn't any voltage drop.

I don't have a fuel pressure gauge, but might be a good idea to pick up some flexible fuel line and barb connectors and put a gauge before carb...?

any other diagnostic tests I can perform while its in the water that you guys can think of?

When I disassembled the AS tube yesterday - I was able to blow the hose out the back of the boat. Then I took a small diameter steel flexible wire and pushed it down the 90degree connector on the tank and felt some resistance and was then able to push it down.

Is there a different procedure to make sure this is clean/free/lubed?

Am I correct that is it still happens when running tonight that I can just undo the gas cap quickly [i know be careful of water entering] to test the AS valve system to eliminate that as a variable?

oh yeah --- and I did pull the dip tube [fuel feed] assembly out - no screen on the bottom of it and I was able to blow through it as well.

I thought when i looked at it last night the 90degree piece is aluminum and welded to the tank????

TRbenj -- I may be confused....is the check valve assembly inside the 'vent tube pickup' on the drivers side of the tank. OR is it in the 'fuel pickup' in the center of the tank??

thanks for your help!

perfect, thanks for the clarification 91naughtyQ - I do need to disassemble that completely tonight and check to make sure its clear.

thank you!

Not really. If it is like most you can unscrew it from the 90 degree elbow and check it.   I just did this when I was troubleshooting my problem. Once you get to it, it should be springy and move freely. If it is jammed up you will know it.

So, Apparently there is not AS valve on my set up.

Removed fuel feed tube and 90 degree elbow and there is no valve in it at all???

Guess that variable is ruled out :)

Fuel feed tube assembly ::




Vent tube::


taking it out tongiht but not even sure what to do next.....?????
Any ideas?
Could it be fuel pump?
What are the votes fuel vs electronic?

Ok, out on water and back .....the wife drove while I observed. I have only 6.8v coming from coil at idle. When at 3000 rpm I have 9.5volts. Seems odd to me. Also I'm pretty sure secondaries on carb are not opening at all....looks like a carb rebuild as they only opened if I opened them mannually.

Thoughts? ???

Ok thanks backfoot100.

What about the coil readings....anyone with advise on those?

" I have only 6.8v coming from coil at idle. When at 3000 rpm I have 9.5volts. Seems odd to me"

at this point - it seems like a coil or fuel pump???