Johnson 88 SPl 1993 low RPM problem

[DJ]

Re: Johnson 88 SPl 1993 low RPM problem

Great, I will take care of that in the morning. I am aware I want to be in the 56-5800 range with today's fuel. I started a thread about the prop sizing and style for this boat, any response there as far as RPM range and propping would be appreciated. I will check back in tomorrow afternoon with an update.

Once it's running right, it may wake up.

13-1/4 X 17 is a good place to start. Remember, every inch in pitch (last number) is usually good for about 200 RPM, up or down.

So, theoretically, a 15" pitch would get you 200 more RPM.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

Well I pulled the nipple from the fuel sender to the fuel line and it was totally open already. There was no spring or valve in there. I should have known this, my boat has 2 19 gal saddle tanks and they are setup through a water filter and they auto level. I do not a anti-siphon valve would allow it to auto level. What I did notice though was the lower elbow going into the plastic fuel bowl was loose as I was able to push it in an 1/8" or so with my finger.. I am also able to pull it out pretty easy and pop it back in. I am sure this is fixed and not supposed to do this. So here is the question now.

Can I get some good marine glue to reattached the elbow to the float bowl or do I order a new float bowl with elbow? Thanks for your help with this.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

I failed to mention the fuel pick up is on top of the tank above the rest of the fuel system including the outboard. Thanks again.

 

[DJ]

Re: Johnson 88 SPl 1993 low RPM problem

Well I pulled the nipple from the fuel sender to the fuel line and it was totally open already. There was no spring or valve in there. I should have known this, my boat has 2 19 gal saddle tanks and they are setup through a water filter and they auto level. I do not a anti-siphon valve would allow it to auto level. What I did notice though was the lower elbow going into the plastic fuel bowl was loose as I was able to push it in an 1/8" or so with my finger.. I am also able to pull it out pretty easy and pop it back in. I am sure this is fixed and not supposed to do this. So here is the question now.

Can I get some good marine glue to reattached the elbow to the float bowl or do I order a new float bowl with elbow? Thanks for your help with this.

The best way is to replace the float bowl. You can get air in there.

However, I've fixed several by crushing the old plastic fitting with pliers to remove it. I then drilled and tapped the housing to accept a 3/8" brass fitting. Worked fine, in all cases.

 

[DJ]

Re: Johnson 88 SPl 1993 low RPM problem

I failed to mention the fuel pick up is on top of the tank above the rest of the fuel system including the outboard. Thanks again.

That should not be an issue.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

I will go ahead and drill it out, that sounds better then the original design. I will let everyone know if all is well and I can move on to the prop.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

Ok so I put in brass fittings to replace the failing plastic ones on the fuel bowl. Took the boat out today and here is what is happening now.

When I got out of the harbor and went to take off I noticed my tach was not working. So I gas it and took off. I noticed the tach working, The motor revved to 4500 fairly fast and the boat planned out and picked up some speed. I am proud of my work as I have the wind blowing in my face at 36mph. I was a happy camper. Then....

The motor bogged down to 4200k, then 4000k, then 3800 then up to 4900k and back to 4k where she stayed whiled I cruised around for a min. This all happened within 60 seconds time. So cruising at 4k for a few min it jumps around a bit more. So i tried the launch a few more times. A few times it had power for a fast plane the others it was a dog. When it was cruising at 4k at WOT I pushed in the prime and got nothing. Going through the no wake zone at 6mph the motor was not running well. It was going from 1500-1700 and back down to 1200rpm.

I am really starting to loose faith. I have put in a lot of money, it has been to 2 shops, and in and out of the water countless times. I need some help! Anything would be appreciated here. It almost felt like it was a spark issue this time. I have a spare room a near the beach in California if anyone wants to come out and fix it

 

[DJ]

Re: Johnson 88 SPl 1993 low RPM problem

1. Make sure your compression is STILL good on all four. I suspect it is but the basics need to be covered.

2. You stated that hitting the primer made no difference. Do mean NOT AT ALL or made no difference as the engine was slowing down?

3. Fuel filters? Type an age?

4. Fuel pump. Any recent service?

5. What do the spark plugs look like?

6. I am now suspecting spark as your tach. can be an indicator of electronic components going south.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

Compression was done at the shop last week they said it was good. I can check it again myself tomorrow. While at WOT the prime did nothing. While trolling speeds it helped the motor run smoother and hold RPM when I would hit it for a sec. I will pull the plugs tomorrow as well. What should I check as far as electronics go? It has new coils and wires. Other then that I have not touched the electronics. I did replace the fuel pump a month ago. The fuel filter is a large water separation filter that was changed approx 6 weeks ago. Does this sound like a rectifier or power pack problem? Thanks for all your time on this and the great advice about the brass fitting.

 

[DJ]

Re: Johnson 88 SPl 1993 low RPM problem

Compression was done at the shop last week they said it was good. I can check it again myself tomorrow. While at WOT the prime did nothing. While trolling speeds it helped the motor run smoother and hold RPM when I would hit it for a sec. I will pull the plugs tomorrow as well. What should I check as far as electronics go? It has new coils and wires. Other then that I have not touched the electronics. I did replace the fuel pump a month ago. The fuel filter is a large water separation filter that was changed approx 6 weeks ago. Does this sound like a rectifier or power pack problem? Thanks for all your time on this and the great advice about the brass fitting.

1. Compression can change in two minutes, much less a week.

2. Prime. That is a big clue. If everything were ship/shape, the prime SHOULD have the effect of bogging the engine due to overfuel.

You still have a fuel restriction issue.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

Well I pulled the water filter which was changed not not ago and this is what I got. I poured it into a glass jar. Obviously not good at all, I am assuming now I need to service my fuel tanks. What does it look like to you? Thanks for your time on this.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

Sorry here is the pic.

 

[tashasdaddy]

Re: Johnson 88 SPl 1993 low RPM problem

rusty water and premixed fuel.

 

[DJ]

Re: Johnson 88 SPl 1993 low RPM problem

Sorry here is the pic.

Looks pretty bad. No wonder that engine won't run right.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

I read it should not be more then a couple tablespoons of water in there. How about a few ounces! I am going to attempt to service the fuel tanks myself. They are located in the sides of the boat and are very easy access. Any tips on the most efficient way to do this would be great. Both tanks are pretty much full 19gal each. I have an inline 12v pump with a long intake hose and a long exit hose that is used for changing oil in inboards. Will that pump safely work? Thanks for everyone's time.

 

[ezeke]

Re: Johnson 88 SPl 1993 low RPM problem

The pickups are at the bottom of the tank and everything made from oil floats on water. You have the results of pulling all water from under the floating gasoline. If you cycle your fuel through your water separating filter and empty it frequently, you should be able to get most of that water out. I would use an automotive fuel pump to do that.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

Sounds good, I put a fuel line to the bottom of the tank and used a hand pump. I pumped out a half gallon or so moving the pickup line around the bottom. I did not get any water. I will cycle my tanks through my water filter and empty out the filter often. Thanks sounds like good advice. It is a large filter, as you can see in the photo of the jar with water and fuel. I will get her out in the water this weekend and see what happens. Thanks again to everyone who helped with this.

 

[CharlieB]

Re: Johnson 88 SPl 1993 low RPM problem

Hopefully the fuel pick up tube is near a rear corner of the tank.

In the water, shift weight around in the boat to make that corner of the tank the low spot. Much easier on a trailer to jack and block to tilt the trailer. The water should settle in that low spot, use your pump and siphon hose reach to that bottom corner of the tank and suck out the water from under the fuel.

You may have to drain and flush out those carbs again to purge any water in there also.

 

[SteuryLover]

Re: Johnson 88 SPl 1993 low RPM problem

The pickups are at the low end of the tanks, east to get to with a hose. I will drain the carbs as well. Thanks again.

 

[tashasdaddy]

Re: Johnson 88 SPl 1993 low RPM problem

you are better off leaving the boat still, if you access to the tanks is in the stern, raise your bow, allow water to settle to the back of the tank, then siphon off. stirring the hose, moving the boat only mixes the fuel and water. you want the water to separate and settle to the bottom so it can be pumped out.