Engine won't go past 3100 rpm

[Martin93312]

I just bought a 1991 Sea Ray Weekender 200 with the 260hp Mercruiser 350. The first time I took it out, it only goes to 3100 RPM and 35 mph. If I try to push the throttle further, the engine starts to die as if the gas has been cut off.

What do you think is wrong?

Thanks

Martin

 

[BonBini]

Do you have a Quadrajet?

 

[Martin93312]

I don't know if it has quadrajet. The engine is new, with only 40 hours on it. I will look when I go out to the river again on Friday.

 

[Lazy Daze]

Dump the fuel filter out into a clear, glass jar and observe it immediately and after an hour.

Fuel injected or carb'd?

 

[BonBini]

Lazy is correct. First things first. Check that fuel.

I would add: that you most likely have a Quadrajet. And perhaps there isn’t enough fuel being delivered to the float bowl to feed the secondary’s. It’s not uncommon for a SBC to stumble a little when the secondary’s are dumped open, typically they will recover instantly and run fine there after.

To test this theory; let her idle for a bit and allow the carb fill to capacity. Then lay into the throttle hard from about 1100 rpm and see how she does.
> Normal… will be some stumble then a good hard pull rite up to WOT rpm.
> Not Normal… a good hard pull for a short time followed by some power loss and loosing rpms, would mean the float bowl is running dry of gas and fuel delivery should be looked at.(there may be a small inlet fuel filter at carb itself where the fuel line comes in)

You say she wont go past 3100 @ 35mph. If that things ever makes 4800 it will defiantly bring tears to you eyes. What prop are you running?

 

[Daddubo]

Will it rev up with out a load on it? Could be fuel pump or a fuel line colapsing also check the filter on the Carb where line goes in.. If you smell gas real heavy it could be the Choke sticking.

 

[Redhook98]

Don't rule out a bad coil either. Thats one that sneaks up on ya and people never suspect it. I chased a potential fuel issue around with my new '83. Changed all filters, checked fuel pressure, rebuilt the carbs, checked the anti-siphon valve, etc etc. Wouldn't get past 2900-3000 before stumbling. It was a bad coil..... Sounded and felt just like a fuel system issue.

 

[Daddubo]

Don't rule out a bad coil either. Thats one that sneaks up on ya and people never suspect it. I chased a potential fuel issue around with my new '83. Changed all filters, checked fuel pressure, rebuilt the carbs, checked the anti-siphon valve, etc etc. Wouldn't get past 2900-3000 before stumbling. It was a bad coil..... Sounded and felt just like a fuel system issue.

Good idea look at the coil one of the tell tail signs is an oily flim on it or looks like oil was driped on it also pull the coil wire out and look for an hair line crack at the top.

 

[Martin93312]

Thanks for all the good ideas so far. I am going to launch it on Friday morning and try all these suggestions. I'll report back on the prop too.

Martin

 

[Martin93312]

Update

Well, I dumped the fuel filter contents in a jar, but didn't see anything in there initially or after it sat for awhile. I don't know how to evaluate the prop, because it is not marked or stamped with pitch, etc. I took it out again after adding 5 gals of fresh premium gas, but I only got maybe 100 rmps more.

So I took it to the mechanic. He compression checked the engine and found that two out of the eight cylinders had low compression (140 versus 180-190 for the other six). But he said it would only make a difference of one or two mph at top speed.

But he decided that the problem is the carbureator, and that the previous owner probably let it sit too long. So he's going to call me on Monday to tell me how much it is going to cost to replace it.

Thanks to everyone who posted responses to help me out with this. I only regret I couldn't resolve the performance issue without a bill from the boat mechanic.

Martin

 

[shore]

Mine did this same thing...we chased everything it was the inlet filter on the carb.Right were the fule line goes into the carb is a small filter.It is very fine and gets clogged easily.