Can't get more than 3300 rpm

[Nikegb7]

I have a 1986 force 125hp on my 19' Bayliner Capri. I can't get it to more than 3300 RPM at WOT (or at any time for that matter). Hole shot is pretty terrible as far as power goes and can't get above 26 mph (22 while pulling my 13 year old on the tube). I have compression at or above 100 in all four cylinders, cleaned the carbs, and put in new plugs. Any suggesting what to check next? Fairly new to outboard repair. Until now I've only really worked on my snowmobile engine but it's EFI so no carbs. Any ideas would be appreciated. Thanks in advance for your help.

 

[Tassie 1]

At or near 100 lbs is fairly low,
145 - 165 is what the manual says
but your gauge may not be good either
do the normal things
check for spark fuel
compression

fuel diaphragm

 

[Jiggz]

Check the following:
1. Carb throttles should be at full horizontal at WOT. Do not confuse the choke butterfly at the front. The throttles are way back at the throat of the carb.
2. Make sure all cylinders are firing. Do a cylinder drop test (while idling, pull plug cable one at a time and listen for change in engine rpm). If there's no change when plug cable is pulled , it indicates that cylinder is not firing at all.
3. If you haven't done yet, install a clear fuel filter between the fuel pump outlet and the carbs inlet. This will tell you if you have fuel delivery problem. The filter should stay filled at least half way throughout.
4. Verify timing is static 28 degrees.

Post results of your diagnosis from the above.

 

[jerryjerry05]

First thing do a spark test.
Check the condition of the plug burn.

Compression: All 4 cyl. at 100# that shows the gauge or the way it was done is the problem.

Does the ball pump up firm?

 

[Nikegb7]

Thank you all for the insight. I'll try all the advice and report back once I get down to the water and back on the boat!

 

[kbh121956]

When doing your compression test, did you remove all the plugs? You need the engine to turn over freely. Try a different gauge also as some read different then others. I have three different gauges and they all read different. Also, you want to do the test at wide open throttle.

 

[Nikegb7]

I only took one plug out at a time while conducting the compression test, all four should be out? Never done that with the sled so I never even thought to try that. Plus I should set it at WOT while turning it over? My gauge is brand new but it's just a cheap Pittsburgh set from harbor freight. Also the bulb does stay firm throughout the trip from the first time I prime it.

 

[Nikegb7]

And some plugs are definitely drier and have more burn than others with slight wetness on the others

 

[jerryjerry05]

Yes all 4 need to be out and the plug wires grounded if you use the key to turn it over.
The wide open throttle is recommended but not needed when doing the test.

Firm ball: once it starts the ball should go soft as the pressure is relieved when the motor starts.

Spark test?
Use a spark tester that you can adjust the length of the spark.
It should be 7/16:

 

[Nikegb7]

if the ball doesnt soften during and after use, then it could be that its not getting enough air? also the spark plugs i'm using are surface gap (BUHW i believe), so i wont be able to adjust the spark length. can i run a standard J plug and if so, do you guys suggest it and what kind?

 

[Nikegb7]

heading to the water today to try out the things i can while its in and take it out and bring it home to do the things i cant while its in the water if needed.

 

[Jiggz]

So have you tried any diagnosis besides checking the condition of the spark plugs?

 

[Nikegb7]

i am going to the water where its docked today. i seen the spark plugs when i put new ones in a couple weeks ago before putting it in the lake and before reaching out to you guys. one last question before i go try all these tips, and please forgive me for being such a newb at this because this might be something that could have saved all of you a lot of time and advice but would the air flow from the gas tank prevent it from reaching its full potential? i ask because i know there was bad gas in the tank when i got it. i siphoned it out but wasnt sure i got everything so i am going to put a cleaning agent inside and re-siphon that to make sure i dont get any of the left over water or ethanol that may have been in there still. also i plan to run ethanol free gas in it for the remainder of the time i own it so in the meantime, i bypassed the the original tank and line and installed a new line / bulb / small (removable) tank on it to be sure i was only running the new gas through it. i failed to mention this before maybe because i never thought running clean non ethanol gas would be the problem, and i'm sure its not, but the delivery of the gas could be. my apologies if i wasted anyones time by not mentioning this earlier.

 

[Jiggz]

Yes, if the vent tube from the main tank is clogged, this will restrict fuel flow to the fuel pump and carbs. So make sure the vent tube is clear and also on the portable fuel tank make sure it is open. Non-Ethanol or not, this should not be an issue to reach wot rpm.

Another thing that could also limit WOT rpm is exhaust leaks inside the cowling. While in the lake try running the engine with the cowl cover off just to make sure it is not an exhaust leak that is preventing it from going beyond 3300 RPM.

 

[Nikegb7]

Wasn't sure if the portable tank would be the issue or not. Stay tuned..

 

[Nikegb7]

Carb throttles are completely open at WOT. Took a pic but too big of a file for the forum. Bought a fuel filter and will install tomorrow when I pull it out of the water and bring it home. Can't do the cylinder drop test in the water, I'll perform that tomorrow as well. Exhaust seems to be no more or less with or without the engine cover on. Took video but again, file was too big. I will re-perform the compression test as outlined above once it's out of the water as well. I don't know how to check the static timing but i'll will YouTube it. Ball stays firm after start up and while running

 

[Jiggz]

Already. Keep doing all the diagnostic testing. It's the only way to find out what really is wrong with the motor. The more symptoms the easier it is to find the culprit.

 

[Nikegb7]

So I got the boat out of the water, rechecked the compression everything seems good. Bought all new spark plugs and installed them. Went to attempt the cylinder drop test and got the crap shocked out of me while trying to use rubber handled long pliers. Went and got the actual rubber tipped and rubber handled spark plug pliers and still got the crap shocked out of me. So needless to say, no drop test performed.

 

[Nikegb7]

Any suggestion where to get a good set of spark plug wire pullers?

 

[jerryjerry05]

Try standing on a piece of wood.
I got mine at autozone.