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Canbt get over 2000rpm

K

Ken Danley

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"1998 Rinker with 350 300hp ME

"1998 Rinker with 350 300hp MEF1-2 motors. I am not able to get over 2000 rpm out of one of the engines when in gear. In neutral in will go above 2000. Started all at once. Marine mechanic connected to computer and no faults. Timing is OK. Replaced plugs, plug wires, dist. cap. Have used stabilizer/injector cleaner in gas. For awhile the rpms would fluctuate but not now. Has backfired when attempt to go on plane."
 
Sounds like you may have your

Sounds like you may have your spark plug wires out of sequence. Double check the firing order and wire location.

Not good with EFI myself so I cant suggest any possible ecm/electronic issues related.
 
"When I put on the new wires a

"When I put on the new wires after the problem started, I was very careful, but will check them.
I forgot to much the mechanic put on a new coil and conducted a fuel pressure test load and no load on the motor and it checked out ok."
 
"For awhile the rpms would

"For awhile the rpms would fluctuate but not now. Has backfired when attempt to go on plane."

pluged exhaust? flappers came apart and lodged in exhaust y pipe? Being a 98 I would do both engines. This would also NOT set any codes.

Kurt
 
I checked the flappers in the

I checked the flappers in the exhaust and the are still there and appear to be in good shape.

I would appreciate any other suggestions for not being able to get over 2000 rpm while in gear.

It seems to run up fine in neutral.
 
a failing tach could cause you

a failing tach could cause your problem. Use a timing light on the good engine and the problem engine to see what the differences are at different speeds. If the spark trigger module under the cap is rusted it can be a culprit along w/the ThunderBolt amp. module. You could swap modules and tachs.
 
"Guy, thanks for the suggesti

"Guy, thanks for the suggestions. I don,t think I have the Thunderbolt ignition system. But I will try your suggestions."
 
"Yesterday, connected external

"Yesterday, connected external fuel tank to strbrd engine, engine back fire at low rpm, then reached 3000 rpm and then dropped to 2000 rpm while attempting to get on plane. Disconnected tach at tach (sender connector). Engine did not appear to get over 2000 rpm."
 
Ken...

How about worn cam l


Ken...

How about worn cam lobes or stretched timing chain? Sounds very similar with the low rpm and popping. Just because ignition timing is on doesn't meen that valve timing is on or the valves are opening all the way. Also do a compression check.

Just a thought
Wrench
 
"Wrench, Thanks for your respo

"Wrench, Thanks for your response. We have checked the compression of the engine, but your idead of cam lobes or stretched timing chain is a possibility. Without some tear down how do we check this?"
 
Had similar issue on my MERC 3

Had similar issue on my MERC 350 MAG/MPI - I change the fuel water seperator and fuel filter and everything went back to normal...
 
Disconnect the battery and rem

Disconnect the battery and remove the distributor cap. While keeping an eye on the rotor use a breaker bar and socket to rotate the engine crank a few inches back and forth. If the rotor doesn't turn in unison with the crank the timing chain is stretched.
 
"Ken...

Sorry for the delay


"Ken...

Sorry for the delay. I was at the cottage watching it rain all over the boat for the last 4 days. Couldn't even take the cover off of it.

Check the the chain as Guy suggested above.

To check the lobes for wear. It would be best if you could run the engine for a minute or two to make sure that the lifters are pumped full of oil. Don't run it too long, or it becomes too hot to work on. Or take note if your engine has solid lifters. I'm not sure what your's may have. Find the spec for the lift of the valves. Get a dial indicator. Remove the sparkplugs so the engine is easier to turn over. Remove the rocker covers. Use that breaker bar and socket on the front crank bolt. Turn the engine over by hand using the breaker bar and keep an eye on one of the front rocker arms. Put a finger on the rocker arm when you think that valve is close and make sure the rocker arm is not moving anymore as you turn the engine. Magnet the dial indicator on the engine somewhere so the pointer can rest on the pushrod end of the rocker arm. Set the dail to zero. Turn the engine over, using that breaker bar, and watch the dial needle go to maximun lift. Compare that number to the spec for the motor. Do each valve in turn the same way and see what you come up with. A lobe will wear itself right off untill there is only a circle left on that bump stick.

Wrench"
 
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