85 SN 2001 rough idle, no acceleration after warm.

Hi all! New to the forum, and new to Nautique boats.

I bought an '85 Ski Nautique 2001 with the 351 and I am experiencing some weird issues.

The boat starts and runs great when cold. Good acceleration to full throttle, even though I think my secondaries kick in late. But, after tooling around the lake for a while, going back to idle causes the engine to run rough, and sometimes die. Restarting is hard, but it will restart if you give it enough juice, and then accelerating is tough without pretty much throwing the throttle to about 1/2 open.

It did this the first time I took it out on the water a few weeks ago, and I thought maybe it was just because it was the first run of the season, and maybe had bad gas, or the pickup had done just that and grabbed some gunk from the bottom of the tank. I also considered the coil and replaced that.

Well, as luck would have it, my tank needed repaired. The fill tube weld had broken and when I filled the tank, it overflowed into the bilge. Not cute. So, I took it and had it repaired, no big deal. Before welding it, they flushed the tank and dried it. So, clean tank when they put it back in.   Take it out on the lake; same issue.

So, now I am thinking possible vapor lock. Remember, I am new to marine engines, but not a stranger to these old carbureted V-8's. Now I am reading that vapor lock is very rare on boats because of the cooling system, and I can get behind that, but it doesn't help me with my issue.

Any one have any idea what might be going on? I feel like it is probably something simple that I am missing, but I just can't put my finger on it.

I have checked:
Coil - it's new
plugs - not new, but in good shape
rotor and cap - good (It has an electronic ignition conversion, so no points)
plug wires - new
choke - seems to be ok, may be running a little bit rich, but no black smoke
primaries - spit a little bit until I leaned it out a smidge
all vacuum hoses appear to be good, I have not put a gauge on the carb yet, but I do have one.
fuel lines - look good, no visible damage

I am open to suggestions.

Thanks in advance!

Scott

Thanks for that Pete. I will look the next time I am on it. I know it was spitting before so I leaned it out a little already. Maybe it needs more.


And, I was told by previous owner it is a Cleveland. I'll research that too.

Thanks,

Scott

Yeah, that's all I meant, really.

I didn't question it before. But, it's good to know so I don't buy incorrect parts.

Aren't the spark plug requirements even different because of the heads?

Scott

Nice to have that manual! I had a different one, but it wasn't anywhere as thorough.

Thanks!

Scott

Thanks MourningWood,

I was considering the choke as well. I will check it for proper operation and adjust it.

I have replaced the coil already, I don't think it is that anymore.

Vacuum leaks are such a pain to track down. I know it's a possibility that is an issue. I will try to figure out if that is it. Any suggestions? Any tricks for finding them?

Thanks again,

Scott

ViperSammy wrote: Also, I know these older engines were made to run on leaded gas, and that is not available anymore. Is there a need to run a lead substitute or anything like that? Scott

NO. BTW, there isn't a "lead substitute". Snake oil with a very high mark up that marinas love to sell!

8122pbrainard wrote:    BTW, there isn't a "lead substitute". Snake oil with a very high mark up that marinas love to sell!

KENO wrote: Your 85 has no need at all for gas with lead like Pete said in spite of what the manual says.

Just being devils advocate here    What is the basis of your comments? Any documentation

Just pulling your legs. I know the answer and results but read this from the horses mouth back in the day,interesting to note they recommended using an additive probably something to do with lawyers and warranties.....
Being that Sam's boat is an 85 the discrepancy in the decals must be due to the confusion at the time.

Original question and concern-


Reply-

And I've got a 64 and a 54 that have run on no lead for years without issues. The 77 I believe ether had hardened seats originally or they were added at a rebuild before I purchased the Tique.

Now, has everyone forgotten about the original "marine" fuel called White gas?

Thanks for all of the input on gas and additives.

A little update on the issue that started this...

I may have mentioned this, but I am no longer convinced that this has to do with heat.

We rented a condo on the lake for the weekend which has given me the opportunity to drive the boat more and under different conditions. Yesterday morning we went down to the lake for a ride, and the boat didn't want to stay running and would die when I went into gear. This was what I was experiencing, but until now, only when it had been running for a while.
Well, I was able to limp it out into open water, and get it to open up. It runs well at higher RPMs even though my secondaries come in when they feel like it..
When we slowed down for a no wake, it did well, but when we put the tube in the water to have a little fun, it went back to the rough idle thing. We were able to pull the tube, you just have to really throw the throttle forward to get past the rough part.

This is pretty much my last hoorah this summer as I have to go back to work overseas and won't be home again until Dec. My plan is to pull the carb off before I leave and rebuild it when I get back,

So, we shall see.

Scott

That thread is awesome!

This past weekend it was just the adults on the boat, so we did a little tubing, then I taught my buddy how to ski. He loves boats and everything about them, even owns a beautiful Baja, but has never skied. Next time we go out though, he will learn to slalom.

Scott