No power with weight in the boat.

[dahoopd]

I have a 18' Sunbird with an 88spl. I took the boat out with 4 average adults in it and it wouldn't go over 3k. The speedometer isnt working so I couldn't tell you how fast that was at WOT. The fuel bulb was collapsed while out so I had assumed it was a venting issue and the motor was starving itself.

Anyway, I checked the fuel vent and everything and found nothing out of the ordinary. I took the boat out again 2 days later with just 2 adults and the boat ran great. I assumed that maybe it may have been the fuel line. Well needless to say, I took it out yet again today with 4 adults and it again wouldn't do over 3k rpms just as before, seems like 10mph. I made people get out of the boat an it ran fine, put them back in and it wouldn't run right. Im stumped. Any help is once again, greatly appreciated.

 

[1946Zephyr]

Re: No power with weight in the boat.

88hp is a bit small for an 18 footer. If there's 4 adults in the boat, that will give it a good work out. You might see on the transome for the ID plate and see what that boat is rated for. If it's a fiberglass boat, I'm willing to bet it's rated for twice that size.

If your primer bulb is flattening out, then there is a fuel restriction somewhere between the tankl and the primer bulb. You might try a different tank and see if that helps.

 

[dahoopd]

Re: No power with weight in the boat.

Hello,

The motor came with the boat. The boat is actually a 17'4 and has run the boat since 1989 when new. I was under the impression that the 88spl had 90hp.

88hp is a bit small for an 18 footer. If there's 4 adults in the boat, that will give it a good work out. You might see on the transome for the ID plate and see what that boat is rated for. If it's a fiberglass boat, I'm willing to bet it's rated for twice that size.

If your primer bulb is flattening out, then there is a fuel restriction somewhere between the tankl and the primer bulb. You might try a different tank and see if that helps.

 

[tx1961whaler]

Re: No power with weight in the boat.

Is this boat new to you? It has a max rating of 88hp.
http://www.nadaguides.com/Boats/1989/Sunbird-Boat-Co

 

[boobie]

Re: No power with weight in the boat.

As said above, what's the hp rating on the boat ??

 

[dahoopd]

Re: No power with weight in the boat.

The hp rating has no bearing on the issue at hand, we can all agree the motor has 88hp. The boat has carried multiple passengers up to 6 adults for 23 years. It now will only carry 2 and run perfect, add weight (2 more adults) and it wont get on plane or go over 3000 rpm. Throw the same 2 (extra adults) back over board and the boat will take off and run fine as it did 23 years ago when new.

 

[tx1961whaler]

Re: No power with weight in the boat.

Ok, you answered my question. The boat seems to be performing differently now than it did before. There are two things that come to mind: There is a problem with the motor or the boat hull is waterlogged. Check the spark and compression on the motor to begin.

 

[boobie]

Re: No power with weight in the boat.

Sorry to have offended you by asking the hp rating of the boat!!

 

[dahoopd]

Re: No power with weight in the boat.

Boobie,

Please don't apologize, you didn't offend. I was more concerned with maybe not getting my question across and just wanted to get the issue at hand straight. This is my first boat aside from many John Boats.

Sorry to have offended you by asking the hp rating of the boat!!

 

[Chris1956]

Re: No power with weight in the boat.

Are you using the same prop from the last 23 years, or is it a new one with more pitch?

 

[dahoopd]

Re: No power with weight in the boat.

Are you using the same prop from the last 23 years, or is it a new one with more pitch?

Its the same prop. Other than a few nicks on the edge it seems to be fine. My plan was to replace it with a better prop after I get it running and can enjoy it some.

 

[Chris1956]

Re: No power with weight in the boat.

OK, now it is time to take a compression test and do a spark test. Likely spark is OK, but compression in one cylinder may be low...

 

[dahoopd]

Re: No power with weight in the boat.

OK, now it is time to take a compression test and do a spark test. Likely spark is OK, but compression in one cylinder may be low...

Chris, I finally got the compression check done. Its 120 on all cylinders. Does that seem correct? Thanks again.

 

[Silvertip]

Re: No power with weight in the boat.

You have totally ignored the collapsed primer bulb. That is not normal and fuel flow to the engine is being restricted. that also means "lean fuel mixture" which also means "lean oil content" which can destroy what may be a perfectly good engine. fix the fuel flow issue. With two people in the boat the fuel restriction may not be an issue. The extra demand caused by the added weight now means the restriction has an impact on engine performance. If the boat perforned fine for 23 with the existing prop, changing props will not make it perform like it did for the last 23 years. Something changed. Troubleshoot -- diagnose -- then repair. Shotgunning a problem is costly, frustrating, and a real waste of time and energy.

 

[1946Zephyr]

Re: No power with weight in the boat.

Yes, you obviously didn't read my post, which was the very first below yours. Check your fuel system out and find out why your primer bulb is flattening out.

 

[boobie]

Re: No power with weight in the boat.

I just read your first post again and missed the primer bulb issue. As said above fix that first or you'll be looking at a blown mtr.

 

[Haffiman]

Re: No power with weight in the boat.

Always interesting to drop by threads that have been going on for some time.
What in general surprises me is that almost never the question of the plugs condition are brought up?
Normally the first to check and the part that immediately will tell what is going on and mostly (if) which cylinders are not working properly.
In a case like this, the procedure should be:
1: Plugs - condition, colors, differences??????
2: Engine temp (thermostat/cooling)
3: Compression test.
4: Ignition verifying (spark test/timing)
5: Fuel supply (carbs/pump)

Without a clear system in the process, do the testing and not simply assume, it often ends up in a wild goose chase jumping here and there.
We have got the compression reading, but what is the condition of the plugs -PIC????

 

[dahoopd]

Re: No power with weight in the boat.

The plugs were replaced before taking the boat out. That was the only reason I didnt bring them up. The plugs that were pulled prior to taking the boat out for the first time were fine, I just figured new plugs cant hurt and they are a cheap replacement.

I have no idea why the ball is collapsing, thus the reason for my post. I mentioned the ball only because the ball was collapsed when running fine with 2 people in it or running bad with 4 people. I checked the vent tube on the tank and it seems to be fine. Forgive me for not asking or stating the obvious. I have never been a boat guy until now. I am a car guy, I can make anything run but until I have an understanding of boat motors its all a learning process. And yes at times, dumb questions. I am going to replace the fuel line again to see if the line is bad even though its new.

 

[dahoopd]

Re: No power with weight in the boat.

Shotgunning a problem is costly, frustrating, and a real waste of time and energy.

Shotgunning is the only answer until I understand the motor a bit more. Its also a lot easier than filling forum with 100 questions. Im a newb but not to forums so I have done some searching and did not come across the motor with the same issues.

 

[Scott Danforth]

Re: No power with weight in the boat.

the engine uses more fuel when loaded. so with only two people, the amount of fuel able to flow matches the need. when you have more load, the amount of fuel able to flow does not match need.

fix the fuel issue, and you may resolve the speed issue