Need help with power loss 1997 50TRV

[pro470]

The motor has been running great this spring, have put roughly 30 gals. of fuel through it . I was out the other day, completed a 20 mile crossing of the bay, when I came off plane the engine stalled. Started fine and idled fine, got back up on plain and ran for another five minute then gradually lost power over 30 seconds, I brought the boat off plain, the engine idled fine. Then I could start out again and go another 1/2 mile then I would loose power again.This happened a few times, then the engine ran fine for 40 minutes, when I got close to shore I let off on the throttle and tried to reapply throttle and had loss of power again.

The motor was running at 120f and 25psi water pressure. I tried switching fuel tank and line and also tried pumping the gas line during power loss with no affect. I have cleaned the fuel filter on the motor, drained carbs, the plugs look the same.

The power loss it very smooth and gradual no vibration at all.

Where should I start, any help would be greatly appreciated.

Thanks....

 

[Ray Neudecker]

Re: Need help with power loss 1997 50TRV

Start by checking compression and fire.

 

[pro470]

Re: Need help with power loss 1997 50TRV

compression is 118,120,118
It fires right up with the ear muffs.

 

[pro470]

Re: Need help with power loss 1997 50TRV

Two week ago I purchased 10 gallons of fuel from a station, the first five gallon I added to my tank I noticed the the fuel was yellow, before my last trip I added the another five gallons. My last trip I used 8 gallons instead of the usual 5 gallons. Anyway I changed the plugs and added 10 gallons of 91 to my 12 gal tank. Seafoam is not available in this area.

Hope this works..

 

[pro470]

Re: Need help with power loss 1997 50TRV

Had the same problem today, slow loss of rpms. I thought it might be a loose throttle cable, so I removed the motor cover and applied full throttle the motor ran ok for 2 minutes then instead of loosing rpm I gained rpm. The rpm loss seems to like to happen after the motor has been run then stopped. Could it be heat building up under the cowl after I stop. I usually stop and fish for a half hour or so. The motor has been running at 122F water temp is 65F. When I stop the motor will heat up to 140F or so. Could it be some part like a coil failing from heat.
Any ideas......

 

[pro470]

Re: Need help with power loss 1997 50TRV

Had another look at the motor, the bottom of the three plugs is covered in a thick salt crust, the plug has about 1 hour of run time on it. So is the head gasket gone, and would this cause the problem.

 

[pro470]

Re: Need help with power loss 1997 50TRV

Replaced head and water jacket gaskets. Same problem today.

Any ideas, Fuel-ignition..........

 

[pro470]

Re: Need help with power loss 1997 50TRV

Dealer says cdi is giving reading different then the book. $800.00 plus tax for a new one, they will not take the new one back if it's not the fix.

Need help with this one, that alot of cash to throw away on a part I do not need.

 

[Ray Neudecker]

Re: Need help with power loss 1997 50TRV

Easiest way to confirm CDI problem is to take a timing light with you and check fire when it acts up. There have been some issues with the 3 cyl CDI.