putting along (throttle??

[chads30]

I have a 1993 evinrude 115hp recently bought.

The first couple times in the water had no real problems.

Now I added some freezers on board, extra battery, gas tanks, etc. and it seems to not want to budge.

A rare few times since I have put on the extra weight I have been able to get it to full speed, but all the other times (99%) it just doesn't want to move past 10mph or so.

The engine is not bogging, or anything, and its **** stream is good.

Could it be something to do with the wrong pitch on the prop or could it be loose throttle cable???
How would I check this?

 

[The-Machinist]

Re: putting along (throttle??

So, if I read this correctly: Your motor is revving, but your not being pushed? Sounds like it could be a slipping hub in your prop. Do you or a friend have a spare that you could try?

 

[tashasdaddy]

Re: putting along (throttle??

take a permanent marker, remove the prop, draw a straight line, like the picture. take the boat for a spin, make it do what it is doing. come home remove the prop, if the lines are still line up, it is not the prop, if misaligned, the hub in the prop has slipped, and need to have a new hub installed by a prop shop, or a new prop.

 

[chads30]

Re: putting along (throttle??

no, it will go like 10mph but not go 25 or 30mph like it normally did...since i have put the weight on the boat it has only gotten up to full speed like 2 times...other than that it goes 10mph

so it cant be too much weight because it would have never gotten to full speed with the weight even those 2 times, correct?

 

[Silvertip]

Re: putting along (throttle??

The throttle cable would not have loosened just because you added weight. the next question is, how much weight did you add and what type of "freezers" are you talking about. Many folks can't tell the difference between an engine that is running with one dead cylinder and one that is running on all cylinders so it may be you think the engine is running ok when in fact it is not. The fact that it did get on plane with the extra weight would indicate you have a fuel or ignition problem. Depending on the amount of added weight, you may need to make a prop change but lets get these other things clarified first.

 

[chads30]

Re: putting along (throttle??

I am thinking its a fuel restriction problem or hub problem.
When i get it to WOT it is normally around 4400rpm or so.
When i get it to WOT when it only budges at 10mph it is around 3600rpm and wont go higher.
Could it be the fuel filter?
How hard is this to change?
Thanks

 

[iwombat]

Re: putting along (throttle??

If WOT is only 4400 then it's either not running right normally, or you've got a prop or setup issue. WOT should be in the mid 5k range.

 

[chads30]

Re: putting along (throttle??

Ususally WOT is around 4400-4600rpm I believe.
It should be 5500rpms? Is this always true?

So a lower pitch prop to give it more pulling power?
or what

 

[iwombat]

Re: putting along (throttle??

You should be targeting 5500 or more for max RPMs. That you're only geting 4500 or so means _something_ isn't right.

If we add that up with the current problem, I'd be willing to bet you've got at least one cylinder that's not behaving correctly and has been that way for quite some time.

 

[chads30]

Re: putting along (throttle??

All four are at 120 compression.

I am going to put a new bulb and fuel filter in tomorrow and see how it goes. Next step will be to change pitch of prop i guess.

 

[The-Machinist]

Re: putting along (throttle??

I would check the strength of the spark at all 4 cyl. It should be able to jump at least 7/16to1/2"

 

[chads30]

Re: putting along (throttle??

spark, compression, and ignition all check out fine everywhere.

Tonight i did find a leak in a cooling system hose near the back of the motor so that is why i didnt see it earlier.
I put a new clamp on it and then took her out for another spin.

She started off slow and then when i made a turn she cranked it up to WOT 4600rpm and around 30mph or so.

1. Could that have been the problem? Could that leak have caused it to vapor lock all this time and cause it to be WOT at 3600rpm 10mph sometimes and 4500rpm 30mph at other times?

2. It is works again tomorrow and stays fast as 4600rpm I will take the prop off and check the pitch. If it is to high I will lower it some to gain some rpm's.
What should the pitch be for a 115hp on a 21ft fiberglass triple pontoon weighing around 2700lbs i'm guessing.