Losing WOT rpm, 1992 200hp Evinrude - Moderated Discussion Areas

  ContinuousWave
  Whaler
  Moderated Discussion Areas
  ContinuousWave: Whaler Performance
  Losing WOT rpm, 1992 200hp Evinrude

search | FAQ | profile | register | author help

Author Topic:   Losing WOT rpm, 1992 200hp Evinrude

JMARTIN posted 09-26-2005 02:16 PM ET (US)
Pertinent information: Motor only has about 300 hours on it. Plugs are new, head bolts just re-tourqed, asked mechanic to do a link and synk, I do not think he did it.
Running a Plain Jane 14 1/2 X 19 propellor.
Last year at WOT I could get 5400 rpm. It took some time and trimming to get there. This year only 4800 rpm. I installed a Navman fuel flow sensor this winter. If you slowly increase throttle, you can get to 4800 rpm. If you are running about 4000 rpm and slam it down, you bounce up to 5000 rpm and then it drops back to 4800 rpm.
Motor runs smooth, good hole shot and cruises at 3500 rpm burning 11.5 gallons per hour pushing a 1983 V-22 Revenge full of gear and fuel at about 25 mph. At WOT, the Navman shows 20 + gallons per hour.
I know I am sort of over propped and a 17 pitch would be better. Could the Navman sensor set up be restricting fuel? Maybe I should by pass the sensor and try it again? Any thoughts by the OMC experts? John

Peter posted 09-26-2005 02:34 PM ET (US)
Are the connections where you spliced in your Navman sender tight (no air leaks)? Is the Navman sender vertical and is it secured to remain in the vertical position?
JMARTIN posted 09-26-2005 02:46 PM ET (US)
The sensor is vertical and secured. I used the stainless clamps that Naman said to use, not the plastic ones that I heard are better. I have not checked to see if they are still tight. Good idea to check. I ran new fuel hose from the filter, which is new, to the sensor and then to the primer bulb. The rest of the hose and bulb is 13 years old. That is first on the winter list to change out. I bought the replacement fuel hose from an auto shop, assuming fuel hose is fuel hose. John
Peter posted 09-26-2005 03:24 PM ET (US)
I'm not so sure that "a fuel hose is a fuel hose." Automobile engines don't consume fuel at anything near the rates that an outboard motor does for any extended period of time. You need a reinforced fuel hose that won't collapse under the high fuel flow rates "pulled" by the motor from the tank.
It is quite possible that your low WOT RPM is being caused by the collapsing of the new fuel hose section causing a fuel restriction. Don't run your motor at WOT as you risk leaning it out and causing damage. You are much better off using an appropriate sized reinforced marine fuel hose that is designed to withstand high fuel flow rates and the problems that go along with that.
JMARTIN posted 09-26-2005 04:15 PM ET (US)
Good advice, I will get new marine hose, the correct connectors, and a new bulb and intall. The motor does have a fuel restriction alarm, but maybe it did not have time enough to sound. I did not stay at WOT for longer than about 15 seconds. The 20 + gallons per hour thru the sensor sounds correct. Maybe that same 20 is not making it to the motor. John
The Judge posted 09-27-2005 12:55 PM ET (US)
Check your plugs and make sure they are burning the same. If one cyl is lean....POOF!
JMARTIN posted 09-27-2005 02:02 PM ET (US)
The plugs have been changed since this low rpm issue and the mechanic did not say anything. They also sell new motors, so I would suspect they are always looking for a potential new motor customer. If one was lean, I would hope he would have said something. Maybe not, I am still looking for a good OMC wrench puller in the area. John

Hop to:

Contact Us | RETURN to ContinuousWave Top Page

Powered by: Ultimate Bulletin Board, Freeware Version 2000
Purchase our Licensed Version- which adds many more features!
© Infopop Corporation (formerly Madrona Park, Inc.), 1998 - 2000.

Author	Topic: Losing WOT rpm, 1992 200hp Evinrude
JMARTIN	posted 09-26-2005 02:16 PM ET (US) Pertinent information: Motor only has about 300 hours on it. Plugs are new, head bolts just re-tourqed, asked mechanic to do a link and synk, I do not think he did it. Running a Plain Jane 14 1/2 X 19 propellor. Last year at WOT I could get 5400 rpm. It took some time and trimming to get there. This year only 4800 rpm. I installed a Navman fuel flow sensor this winter. If you slowly increase throttle, you can get to 4800 rpm. If you are running about 4000 rpm and slam it down, you bounce up to 5000 rpm and then it drops back to 4800 rpm. Motor runs smooth, good hole shot and cruises at 3500 rpm burning 11.5 gallons per hour pushing a 1983 V-22 Revenge full of gear and fuel at about 25 mph. At WOT, the Navman shows 20 + gallons per hour. I know I am sort of over propped and a 17 pitch would be better. Could the Navman sensor set up be restricting fuel? Maybe I should by pass the sensor and try it again? Any thoughts by the OMC experts? John
Peter	posted 09-26-2005 02:34 PM ET (US) Are the connections where you spliced in your Navman sender tight (no air leaks)? Is the Navman sender vertical and is it secured to remain in the vertical position?
JMARTIN	posted 09-26-2005 02:46 PM ET (US) The sensor is vertical and secured. I used the stainless clamps that Naman said to use, not the plastic ones that I heard are better. I have not checked to see if they are still tight. Good idea to check. I ran new fuel hose from the filter, which is new, to the sensor and then to the primer bulb. The rest of the hose and bulb is 13 years old. That is first on the winter list to change out. I bought the replacement fuel hose from an auto shop, assuming fuel hose is fuel hose. John
Peter	posted 09-26-2005 03:24 PM ET (US) I'm not so sure that "a fuel hose is a fuel hose." Automobile engines don't consume fuel at anything near the rates that an outboard motor does for any extended period of time. You need a reinforced fuel hose that won't collapse under the high fuel flow rates "pulled" by the motor from the tank. It is quite possible that your low WOT RPM is being caused by the collapsing of the new fuel hose section causing a fuel restriction. Don't run your motor at WOT as you risk leaning it out and causing damage. You are much better off using an appropriate sized reinforced marine fuel hose that is designed to withstand high fuel flow rates and the problems that go along with that.
JMARTIN	posted 09-26-2005 04:15 PM ET (US) Good advice, I will get new marine hose, the correct connectors, and a new bulb and intall. The motor does have a fuel restriction alarm, but maybe it did not have time enough to sound. I did not stay at WOT for longer than about 15 seconds. The 20 + gallons per hour thru the sensor sounds correct. Maybe that same 20 is not making it to the motor. John
The Judge	posted 09-27-2005 12:55 PM ET (US) Check your plugs and make sure they are burning the same. If one cyl is lean....POOF!
JMARTIN	posted 09-27-2005 02:02 PM ET (US) The plugs have been changed since this low rpm issue and the mechanic did not say anything. They also sell new motors, so I would suspect they are always looking for a potential new motor customer. If one was lean, I would hope he would have said something. Maybe not, I am still looking for a good OMC wrench puller in the area. John