1990 Evinrude 175 up power loss

[Loche9]

Looking for some advice with issues I'm having getting my motor running correctly. Bought it a few years back and it wouldn't start. Have slowly corrected a few issues by cleaning carbs, replacing stator, some coils and regulaotr/rectifier. Currently it will run great when I drive to my fishing spot (5/10 min) then starts rough and won't plan, stuck around 8 mph. Was on a fishing trip and this happened everyday for a week, seems after it sits overnight it's fine until start/stop again.

E175stlese

 

[racerone]

For further input you need to post the compression numbers.------And does spark jump a gap of 3/8" or more on all leads.------Running with VRO or is oil injection bypassed ?-----Perhaps test run with a separate portable tank.

 

[Loche9]

When I had it on the water I tested the spark after it started acting up and it seemed one of the coils was bad. Changed it out with a spare and it started running perfect again until I stopped/started. Then I checked the spaks again and they all looked good.

VRO is disconnected with oil port plugged in the pump. Cheked the fuel lines for anything lose and it seems good. Portable tank seems like a good test, will have to see if I can get my hands on one.
​​​​​​​
Just tested the compression. If I remember correctly this is fairly normal for my engine?

84
82
89
82
75
79

 

[racerone]

I would say----" test with another gauge " ----Those numbers do not reflect a healthy engine.

 

[Loche9]

Seems unlikely to me that it would loss power somewhat equally across all cylinders. Testing with another gauge would makes sense if this one is just reading low. Did some searches and it's hard to find good numbers for the 90 and older v6, but do see some people talking about it being normal to have lower compression.

 

[Faztbullet]

That would be OK compression for a 149 ci 175 but the 1990 was a 160ci 2.6L with bubble exhaust and compression was way higher around 105 +psi. It would only be that low if low compression gaskets or heads was installed

 

[Loche9]

Thanks for the information. I will cross my fingers and hopefully the gauge is the cause for the low numbers. Sorry if this is a stupid quesion, but assuming the compression is low, could that cause it to run fine at WOT and start having issues when I stop/start back up?

 

[Loche9]

Tested compression with another gauge. Readings were 4-5 higher in each cylinder. Decided to have a look at the cylinders and pistons since it was still low. Cylinder walls have some groves and pistons have scraping on the side I can see with the covers off. Don't much experience with old outboards, but assuming this is abnormal and the cause for the low compression readings. At this point I'm guessing the only fix is to bore the cylinders and replace the pistons?