Question on GT 175

[fordb69]

I have a 90 GT 175 on the back of a Cajun Ricky Green Fishing Machine.

About a month ago, was running accross the lake at WOT and a loss of power happened.....dropped 10 MPH easy. Now the motor wants to stall when trimmed all the way down for the hole shot and when the throttle is floored, will not get on plane. Sounds like it is running at 50% at WOT. What I know......new plug wires last year, new ignition coils last year, fuel filter changed this year along with the plugs.......I would love to hear some thoughts or suggestions!!

Thank you!!

[omcforever]

Compression check first. Then verify spark to each cylinder

[fordb69]

Okay, update......I have good compression on all six cylinders, spark is good (new wires last season and I have gotten into the habit of changing plugs at the beginning of each season), and over the weekend, I replaced the pick up and fuel lines as it has been something that has needed to be done.

Something kind of odd, pulled the old line off and there was virtually no fuel in the line. The primer bulb was hard.....could there have been a blockage somewhere? I cut sections of the line here and there, found some small irregular spots but nothing out of the ordinary I wouldn't think. I typically carry a few spare fuel filters and will replace that before hitting the water this weekend for a test.....

Thoughts?

[316jughead]

Is the clear or now yellow plastic sleeve on the carb roller? It's about 3/8" over a small black roller, they will crack and fall off.

[fordb69]

I will check it out! Thank you!!

[ChampioNman]

Don't know if you have the ratchet clamps or Oetiker clamps on the primer bulb, but if you can take the hose off of the bulb on the motor end you'll know for sure if you have good flow.

[fordb69]

Throttle/carb roller is completely gone...….that would make sense based upon how the engine has been running. I am getting a new one today and will get it installed! I will keep you posted!!

[fordb69]

Update.... replaced throttle cam roller, gas lines are free and clear.....still the same. No throttle response out if the hole. Time for a mechanic I think.....

[316jughead]

Is your motor smoking a lot at idle? With changing the fuel lines you might be getting air in the fuel lines, an incorrect size hose for the fitting and the wrong clamps will cause air to be sucked in but not leak fuel. You can download a real OMC service manual for your motor, look in the stickies at the top of the forum page. Then you can read up on the synk and link, timing and carbs, for your motor. that could also be your problem.

[fordb69]

316jughead, it is smoking at idle. When I started this thread, I was running accross the lake and then sudden loss of power at WOT

[fordb69]

I would equate it to trying to suck something up in a straw then something somewhere gets plugged, that's what it felt like anyways......thats why I initally changed the lines from the tank to the primer bulb and a new inline OMC fuel filter. The primer bulb is new this year and over the weekend, I had a buddy suggest that I replace the lines under the cowling as well, just to rule that out. I really don't have the budget to take it to a mechanic and would like to try and figure this out...….I'm a basser on a budget sadly...…….

[ChampioNman]

What size primer bulb did you install? 5/16" or 3/8" and was the primer bulb a Evinrude OEM part with the arrow flow facing the motor?

[fordb69]

The primer bulb that was installed was a 3/8" and it was indeed an OEM part with the arrow facing the motor. That I am aware of, all of the fuel lines under the cowling (they have NOT been messed with) are 5/16"......

[316jughead]

316jughead, it is smoking at idle. When I started this thread, I was running accross the lake and then sudden loss of power at WOT

I am fully aware of your stated problem in your first post. Didn't you change lines after that? If you don't want to get a manual, check for air in the lines and read up on your motor so you can work on it your self, it's OK with me.

[fordb69]

I will do that.....I have a manual on the way. Thank you for the info :-)

[316jughead]

I will do that.....I have a manual on the way. Thank you for the info :-)

[ChampioNman]

The primer bulb that was installed was a 3/8" and it was indeed an OEM part with the arrow facing the motor. That I am aware of, all of the fuel lines under the cowling (they have NOT been messed with) are 5/16"......

That would be correct, are you checking spark with the lower unit covered with water. Those T packs will fire with no back pressure but not when back pressure is applied. Also check the linkage arm from the throttle linkage to the timer base and verify the timer base is moving to the full throttle stop when full throttle is applied.

[fordb69]

Update.....checked the spark with the lower unit in the water. Gap on the NGK's that I am using was set at .040....OMC manual says .030. Reset the gap to the correct distance. One thing that I did notice, the plugs on the port side cylinders (as you are looking at the back of the engine) appear to be 'cleaner' than the plugs on the starboard side. What would this indicate?

[316jughead]

All the plugs on one side being wetter could mean a low output voltage on one charge coil in the stator. I am not a fan of NGK spark plugs, their cross over chart is sometimes not correct for our motors, Champion QL77JC4 gap at .030 would be the correct plug.

[ChampioNman]

Update.....checked the spark with the lower unit in the water. Gap on the NGK's that I am using was set at .040....OMC manual says .030. Reset the gap to the correct distance. One thing that I did notice, the plugs on the port side cylinders (as you are looking at the back of the engine) appear to be 'cleaner' than the plugs on the starboard side. What would this indicate?

OMC manual also says to use Champion spark plugs not NGKs. You should check the head temps with an IR temp gun to verify the operation of the thermostats.