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1991 Evinrude 150 hp Intruder low compression??

tmking66

New member
I have been noticing that my hole shots have been getting slower especially with a larger load (2 people and livewell full of water and fish). I had not run the engine at WOT for a couple of years but decided to open it up a few days ago. Last time I did this the engine would turn over 6000 rpms and push my javalin over 70mph. But now, It will only get up to about 5400rpms and 55 mph. No changes in props or anything else. I have checked for spark on all cylinders and that is ok. Fuel filter is clean. I then checked the compression for all cylinders and found that all 6 had compression of 80 to 85 psi. Seems low but I am not sure what the proper compression is for this engine. If that is low comp. is there anything to be done to try to improve this without a rebuild perhaps some type of internal cleaning etc to try. Or, is the loss of power potentially coming from some other source. The engine runs fine. Starts easily, idles well, and runs smooth but power and torque are lower than they used to be.

Ideas???
 
Re: 1991 Evinrude 150 Intruder low compression??

It has a lot of hours. It does not have a meter so I don't know for sure. I have not run it too terribly much in the last couple of years but before that it war ran quite a bit each year. Any number I put up would be just a guess but the hours would be way up there. It has never been rebuilt and I have owned it since 1992. Not the original owner but it was just 1 year old when I got it.
 
Re: 1991 Evinrude 150 Intruder low compression??

I'd decarb it before anything else. Your compression is a bit low but even which is good. The decarb may be all you need. I use Seafoam which can be bought at NAPA stores.
 
Re: 1991 Evinrude 150 Intruder low compression??

Yes, the decarb would be my first step - could have lot's of "cooties" from not being "opened up" for an extended period.

2 strokes will continue to work their best if you regularly "run the snot" out of them.

Each time out you should get them into their wide open throttle (wot) range for at least a few minutes....
 
Re: 1991 Evinrude 150 Intruder low compression??

I used to open it up everytime I went out but when gas started getting stupid expensive I started trying to be more economical.

I will give the seafoam a try and see what happens. I'm thinking that spraying the cylinders full and letting soak overnight would probably work best but I have not done this before so any suggestions on the most effective de-carb method would be appreciated.

Also, I think that this winter I may do a rebuild. Anyone have any idea on what I would be looking at cost wise and which parts should be replaced vs just cleaned up. I will do the work myself so labor costs won't figure into to equation.

Thanks again!!
 
Re: 1991 Evinrude 150 Intruder low compression??

Thanks for the link!

Anyone with ballpark price for parts to rebuild this engine??
 
Re: 1991 Evinrude 150 Intruder low compression??

To (quickly) decarb I use a product called "PowerTune" (Merc product, about 5 bucks a spray can - OMC has a similar product but the name escapes me).

It can be sprayed directly into the cylinders to let sit and is applied right into the carb throats, so it's "immediate", unlike SeaFoam which is a longer term solution.

An "average" rebuild on a 6 cylinder will run about $2000 - $2500 (at a shop), and there are a few places that (for about 2500) will do a direct swap with you - you send them your block and they give you an (already) rebuilt one.

If you have the mechanical skills you can undertake it yourself and generally save about 1000 bucks (that includes the services of a machine shop to bore or hone the cylinders).

There are a number of "rebuild kits" on the market that contain pistons, rings, bearings, gaskets, seals etc which retail for between $800-1000 (average).

Most machine shops charge about 50 bucks a hole (so $300 for a 6 cylinder).

Of course, you always find a couple other things "that should be done", but in the end you end up with a "like new" engine for well under 2K (rebuilding yourself).

Compare that to the 13K plus for a new 150.

I look at it as: a new motor for 2K with 10K left over for gas :)
 
Re: 1991 Evinrude 150 Intruder low compression??

i can rebuild that motor for a good price for or let you trade that one in for one that is already rebuilt i have a few 93 xr4 150 merc for 2800 1989 evinrude xp 150 2600 1994 jhonson venom 225 4000 and a 1985 jhonson gt 150 2300 all comes with free installment and we can take to lake to run it you can trade your other one in if it does need to be rebuilt call juan 770 7159738 im in atlanta but i can come to you but it would be a little more to cover gas thanks
 
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