WOT problems

[BayFisher]

Just bought a 1993 16' Predator center console with a Evinrude 48 spl. I've rebuilt the carbs, replaced the water pump, spark plugs, fresh gas, battery and quite a few other things. After working on it with the muffs I've finally got to put it in the water today -you heard right on mothers day- my wife is incredibly understanding. Took it to the lake and it started right up like it has usually been doing and was idling fine. Start to accelerate and it just didnt have the power there...figured I needed to run it so I cruised it around and ended up in WOT at 3000 rpm. I ended up getting in 4000 for a little bit but with nothing behind it. We couldnt figure out what the problem was. It just didnt have the power to get on plain at all. This motor has less than 50 hours on it and we checked the compression and they were both right around 150 psi. If anyone has any ideas as to what could be doing this I'd really appreciate it.

 

[Big Keepers]

Re: WOT problems

Sounds like a fuel issue to me. Did you check and/or replace the fuel pumps? When was the last time you did anything to the fuel system?

You said you just bought it, when and how long have you had it? Is the prop correct? Have you ever run this boat on the water to know that it isn't running like it used to?

Start checking the fuel delivery and fuel lines etc. Maybe you have a small air leak somewhere?

 

[BayFisher]

Re: WOT problems

That sounds like a good idea, I did have a leak at the in line fuel filter which I replaced and also replaced the primer bulb. I dont know how it ran before, it was my grandfather's neighbors boat, he said they only used it a couple of times , they were an older couple. It was bought brand new in 1993 from a local boat shop and they were the only owners. Since you mentioned it it does sound like a fuel problem, looks like I'm gonna have to spend more money on it. Thanks for your help.

 

[Silvertip]

Re: WOT problems

Check for spark on both cylinders. On muffs the engine may sound and idle like nothing is wrong if its running on one cylinder. Next, with the cowl off, move the throttle to WOT. Verify that the butterflies in both carbs are perfectly horizontal in the carb bores. If not, a linke & sync and throttle cable adjustment are in order. You need a service manual for the link & sync procedure. It's far too detailed to go into here.

 

[BayFisher]

Re: WOT problems

I checked all the carb adjustments, the butterflies are horizontal. I've been trying to think of what could be wrong with the fuel system. Someone said I might need a new prop, the one thats on there is the original one. It does have a little 1/4" nick in it. I guess it might be a good idea to replace that. It is creating a good wake behind it but just doesnt have the power to push the boat.

 

[Big Keepers]

Re: WOT problems

Well then let's start from scratch. As was suggested above. Check the spark. You checked compression, check spark then I'd check fuel. As far as the prop goes, you need to find out what the WOT rpm spec is, for your boat I'm thinking somewhere between 5000 and 6000 RPM. Then knowing that info, you need to know what pitch prop is supposed to be on that motor. I don't think a prop with a small nick will be capable of causing you to lose potentially 2000 RPM at WOT. If you have strong spark and strong compression, you need to check fuel. You'll probably find the issue there.

 

[BayFisher]

Re: WOT problems

My rpm range is from 4500 to 5500. I could only get it up to 3000 at WOT. I've been checking all fuel lines and connections trying to find a problem. I'm not sure what else to check. My fuel pump is clean and the carbs are clean. All the fuel lines are spraying fuel. Not real sure what else I need to do. I've been racking my brain over this, any help would be great.

 

[seasprite79]

Re: WOT problems

Check your throttle cables. If they are loose, or going bad could be in the engine something is sticking throttle wise.

 

[BayFisher]

Re: WOT problems

I've been messing with the throttle assembly quite a bit and I dont think that they are bad. I'm gonna try tonight to get a temporary fuel tank to stick next to the motor and see what kind of difference that makes. I've read on here that those old tanks dont work as well after a while. Also I havent done a complete carb rebuild, I just cleaned and soaked. Maybe it would be a good idea to buy those kits. I guess I should just rule out the carbs before I do anything else.

 

[Big Keepers]

Re: WOT problems

Did you really soak the carburetors? If so that may be your problem. I've been taught that soaking those old carbs is the worst thing you can do to them. If you don't have a sporadic ignition problem or a bad prop, I'll bet its those carbs.

 

[BayFisher]

Re: WOT problems

Well I just soaked them in the carb cleaner that I cleaned them with. But it's funny you say that cause my father in law was just telling me that he had some of that carb soak and he was telling me that's probably the problem. He told me I needed to soak them for 24 to 48 hrs. Is that not a good idea or what?

 

[iwombat]

Re: WOT problems

The newer carbs have a protective coating that the soaking chemicals take off. However, so does the newer ethanol-laden gas. I soak all mine and it works out fine. If you have access to a sonic bath (I don't anymore ) That's about best system for carb cleaning ever.

 

[BayFisher]

Re: WOT problems

I'm not even sure what my father in law is talking about. He just told me he has about 2 gallons of some carb soak that cost about $70. He said to soak the carbs and it will remove all the build up inside and out. I was just unsure cause of Big Keepers response to soaking them.

 

[perkdp]

Re: WOT problems

Try soaking in toluol or toluene. This is some strong stuff you can get at your hardware store. Carb cleaner contains a bit of it.

But, if your carbs have cork gaskets, and you soak in toluol, all you'll have left of the cork is little floating balls. The toluol will melt the glue that holds the cork together.

After soaking, use compressed air at about 40 - 50 psi to blow the jets out and dry the carbs.

 

[iwombat]

Re: WOT problems

carb soak usually comes in gallon cans w/ a little basket to hold the small bits. You disassemble the carb to remove all the plastic parts. Remove all the jets (w/ the special jet tool), remove the plug over the idle jets, and soak for about 1-3 hours. Then blow out with compressed air or a can of carb cleaner.

Reassemble.

You never want to put the whole carb in the soak solution, for two reasons. It will absolutely destroy some parts. It won't clean out some of the harder to reach passages.

 

[BayFisher]

Re: WOT problems

Well after completely rebuilding the carbs and doing alot of much needed maintenance and replacing fluids and some parts and etc. I finally found the problem. I decided the replace the fuel line completely. I fished a new line through the hull and when I started to pull out the old one I noticed it was completely kinked about half way from the tank to the motor. It looked like it had been kinked a while cause it had started a tear in the line from it. After that I took it for a test drive and it runs beautiful. Better than I had expected it to. I really appreciate everyone's help. I dont know of a better place to come and get advise. Like I said I really appreciate it.
-Thanks