re occouring problems

[mars1]

ok so as in my previous post I thought I had the problem fixed with the motor idling rough and sputtering up to about 1500 RPM and the sputtering would go away and the motor within one great after that.however the problem has resurfaced again up to 1500 RPMs and the tachometer stops working.. I'm going absolutely crazy here I've tried a different fuel tank checked the ignition timing carburetors etc. even pulled out the thermostats to check them. My wife made an observation we had the same problem on the last engine which was a 150 XP my thinking is could be something in the boats wiring harness causing this problem both engines have their own wiring harness. The XP is a 1992 and the motor I have on the boat currently is a 175 Looper 1994. It has to be something simple I'm just not seeing it as I'm getting so frustrated attack, or is brand-new and it worked a few times but the stalling and sputtering has been a problem with both engines. The compression on the Looper runs anywhere from 105 to 120 on the XP it's 90+ or minus a couple of pounds on all cylinders. I've bypassed the built-in gas tank which I noticed had a bunch of crap in it I did clean out looks pretty good however I've been running the boat with two brand-new 6 gallon drop tanks trying to rule out anything in the fuel system but like I said both engines experienced the same problem so I'm guessing it's got to be in the boats electrical system. The boat is a 1992 Sea swirl 19 foot classic cuddy.
Any help would be greatly appreciated thanks

 

[oldboat1]

So anything shared by both engines would be suspect: tach in the boat, remote box if the same, fuel and tank. If you had contaminated fuel with the replacement engine, carbs would typically need to be disassembled and cleaned (soaked, poked, the whole nine yards.) Check setting and connections on the tach. (Any reason to believe the current rectifier is blown? Reversed polarity, bat. disconnected with engine running, etc.?)

 

[racerone]

Just post some facts about the looper 175.-----What are the compression numbers for each cylinder ?-----Does spark jump a gap of 7/16" on each lead , yes or no ?------Run with a timing light on each lead and observe spark behavior as you go to full throttle.-----Checked carburetors for warped bowls ?-----Running with VRO in service ?-----Check vapour separator pump ?----.

 

[mars1]

compression is between 105 and 120 105 being on the bottom starboard.( believe this cylinder runs low from what iv read ) spark jumps like 1/2`` on each lead VRO is bypassed have to check the timing and carb bowles .. thanks

 

[ldurmon]

I had similar issues with my 85 150GT and when I puled the flywheel to check the timing advance I found that all of the magnets under the flywheel were loose and sliding around as the motor revved, It would run ok one day and not plane the next but after tinkering at the dock and revving a few times it ran better especially at high speed. The magnets being loose was causing erratic power spikes. After epoxying them back in place it runs like a dream. Good luck.

 

[mars1]

Thanks I will look into that and post when i find it out