Evinrude E-NATION, for those dedicated to water, power, fishing and fun
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Skipper
Posts: 12
Registered: ‎09-01-2014

2000 Ram 225 rough mid-range rpm

Hi,
My 2000 225 starts fine (2nd try cold),runs fine slow and at 4300 rpm and above. It runs terrible at mid range rpm though (3000-4200). I have changed filters, separator, and plugs (indexed). I cleaned the EPS. Running good fuel and xd 50. No computer faults. Any ideas?
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Admiral
Posts: 8,574
Registered: ‎07-14-2011

Re: 2000 Ram 225 rough mid-range rpm

What  is your full throttle rpm with a normal load on board?

 

What is the plug gap and what are the compression numbers?

 

What is the fuel pressure at the rough rpm range?

 

 

 


"There is never just one thing wrong with a boat";
                    -- Travis McGee, main character in a book series by John D. McDonald 


 



***************

The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.


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Captain
Posts: 31
Registered: ‎08-27-2014

Re: 2000 Ram 225 rough mid-range rpm

I had one of these that originally came from a ski team that ran the cheapest quickie mart fuel and it did this. I found two injectors that were producing a stream instead of a nice pattern of fine droplets. I found them by pulling one at a time and clamping a clear hose to the injector and then starting the motor on the hose briefly. At the time replacements were back ordered so I fixed mine by soaking them in pure Chevron Techron fuel additive from the auto parts store for a week. The motor ran lots better immediately and perfect after I ran 100 gallons of BP ultimate premium plus the max dose of Techron through it. The horrible midrange running is lean misfire and if you keep running one like that detonation will rapidly destroy the pistons in the affected cylinders. YMMV but that motor is still pushing a pig heavy whaler around and those injectors have never been replaced.
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Skipper
Posts: 12
Registered: ‎09-01-2014

Re: 2000 Ram 225 rough mid-range rpm

5600 rpm 37 mph trimmed out 15x15 ss prop on a Judge 24 pilot.
Gap .28. Don't know fuel pressure. I am concerned about possible lean condition, but I seem to be getting enough fuel at other rpm ranges.
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Skipper
Posts: 12
Registered: ‎09-01-2014

Re: 2000 Ram 225 rough mid-range rpm

Oh and compression is even and high, between 127-130 on all cylinders IIRC.
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Captain
Posts: 31
Registered: ‎08-27-2014

Re: 2000 Ram 225 rough mid-range rpm

[ Edited ]
As OMC learned in the hardest way possible existing engine designs retrofitted to direct injection are prone to developing stratified combustion under part throttle heavy load duty cycles. These strata form even when a mathematically correct amount of fuel is being delivered. Some of these strata then are so lean they do not support stable combustion while others are so rich that piston top or ring land deposits are created. Interestingly these strata do not form or more correctly are so transient as to pass unnoticed on efficient hulls with power to weight ratios of 10 lbs per horsepower or less. The strata also do not form at idle or WOT so a bad injector will not be as noticeable at these throttle settings.
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Skipper
Posts: 12
Registered: ‎09-01-2014

Re: 2000 Ram 225 rough mid-range rpm

This is an efficient hull but the power to weight ratio is low. What if I dropped an inch of pitch on my prop?
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Captain
Posts: 31
Registered: ‎08-27-2014

Re: 2000 Ram 225 rough mid-range rpm

[ Edited ]
Efficient hull for these purposes means low drag. I don't know how your hull compares to something like a Fountain or Yellow fin center console. Prop pitch will just shift the rpm at which strata form you need to check your injectors or borrow a known good set to try.
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Admiral
Posts: 8,574
Registered: ‎07-14-2011

Re: 2000 Ram 225 rough mid-range rpm

CvBrewer,

 

I'm sure that you are aware that there are posters on this site that offer opinions and ideas that are  not necessarily factory approved or recommended plus they are NOT Evinrude employees.

 

 

 


"There is never just one thing wrong with a boat";
                    -- Travis McGee, main character in a book series by John D. McDonald 


 



***************

The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.


Highlighted
Captain
Posts: 31
Registered: ‎08-27-2014

Re: 2000 Ram 225 rough mid-range rpm

Which is good otherwise all anybody would ever get is the approved company line. By no means should anyone take just my word for what stratified combustion and homogeneous combustion meant in the death of OMC or for two strokes in general. There is lots of information readily available both in general publications like Boating magazine or in published scholarly research that dive in deep.