200 efi bogs taking off and then when fully trimed out at 38 mph only makes 4000 rpm. If I hold the trim up button on , even thougk its trimmed as far as it will go, The motor starts to rev more and more till I get it up to 5700. if i let go of the trim button, the revs start to drop quickly and work back down to 4000. NOTE: Motor is still trimmed to the limit and not dropping on its own. The trim motor running seems to energize the motor to make hp and start to rev??/?/// Help lester
Only think I could think of would be a loose cable somewhere on the cranking battery or the motor. Double check that they are all clean and tight on the batteries and under the cowl.
If you have integrity, nothing else matters. If you don't have integrity,
nothing else matters.
Fuel filter?
Mark O'Brien
2011 Ranger Z520
2020 Mercury 250 ProXS 4 Stroke
I have had a similar problem last weekend. My 200 efi ran great when idleing and at low rpms but when I took it to WOT, there was an intermittent cut out and los of power. I was told that It might be my fuel filter....not sure though...when I was on the way back to the weigh-in it seemed to run better when i was messing with the trim....not sure if the two are related or not. Hope you figure it out and if I figure mine out I will pass the information along.
Mark O'Brien
2011 Ranger Z520
2020 Mercury 250 ProXS 4 Stroke
could the motor be overcharging causing the computer to act up, and holding the trim robs enough voltage to drop it down in spec?
Corrosion in or on a ground wire to the engine. When you hit the trim motor, it increases the current through the ground wire driving it toward -0- volts and improving the voltage difference to the engine ignition and if equipped, computer.
I`d start checking grounds especially on the switch boxes.
This is the only reply that could be the problem in my opinion.Originally Posted by tommy69z
I've seen voltage spikes drop rpm's and shut engines down.
+3.... I'd recommend monitoring voltage AT THE BATTERY with a DVOM when the engine is acting up. If battery voltage is exceeding 14.6 VDC... it's likely a voltage regulator problem.
More information may be available if you can provide SPECIFIC engine info (year, or PREFERABLY Serial Number).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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That problem will drive you up the wall and when it shuts down at 67mph it feels like you just hit a sandbar! I'm 51% sure my problem was in the cannon plug though as it was pretty nasty. No shutdowns since.
where is the cannon plug located??
Mark O'Brien
2011 Ranger Z520
2020 Mercury 250 ProXS 4 Stroke
Not sure about the 01 but on my '94 it's on the starboard side of engine under the cowl. It's a round black plug. I doubt it's part of your problem from what you described but sure wouldn't hurt to check it out.
We found a faulty battery switch on the possitive cable. This helped with the trim switch power increase
but now the motor is surging at wide open. We are going to check the final filter in the pressure regulator.
We found a faulty battery switch on the possitive cable. This helped with the trim switch power increase
but now the motor is surging at wide open. We are going to check the final filter in the pressure regulator. The bottom plugs are washed clean.
Be sure to monitor fuel pressure at the point the engine is surging, as it can be a key indicator of the problem.
Also recommend that you monitor BATTERY VOLTAGE at the BATTERY (specific instructions beyond that would require engine serial number... or at least the year of manufacture).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
valeroman and i have been trying to figure out this problem with little success so far. A loose ground was found and repaired on one of the switch boxes but this didnt fix the problem. Battery voltage reading at the battery is 14.4V when WOT, however when hitting the trim up button (to increase speed and rpms) the voltage reading drops to about 11.7V which is understandable considering the trim pump is running. Looking for any other suggestions. Would it be possible to have a ground/wiring problem inside the throttle control lever in which the trim button is located? The motor is a 1996 and serial number is OG34926
It is possible that the problem is inside the control/ignition switch harness.
Perhaps the SIMPLEST (and most effective) means of testing this would be to plug in a SEPARATE KEYSWITCH HARNESS directly to the engine, and then go run it to see if the problem persists.
This is often VERY helpful in determing if the problem is INSIDE the engine cowling (or in the control/wiring/boat).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Yesterday I wiggled/tugged on the wires coming from the ignition and throttle control unit. I didn't have time to remove and inspect the wires inside. I had a tournament today and everything worked perfectly all day. I am pretty sure there is a bad wire somewhere inside the throttle control but will have to take it apart to confirm.
Watch specifically for wires that may have been PINCHED between the two halves of the control... have seen this cause a WIDE VARIETY of problems (depending on which wire or wires were pinched).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Was the issue ever fixed going through this at the moment?!
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