mercury 250 efi will rev right up in neutral/ wont in gear

cjrama

Cadet
Joined
May 3, 2009
Messages
18
in neutral i can rev engine all the way up.... in gear it wont rev over 2000 rpm, which makes about 7 mph. compression is 90lbs and even across all six cylinders...... any help would be appreciated
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Check for a strong spark at all plugs. Outboards will rev up pretty good under no load conditions.
 

cjrama

Cadet
Joined
May 3, 2009
Messages
18
spark is good.....across the board. could it be a bad cylinder? I have even pressure of 90 lbs compression, but could i be leaking it down, or maybe bad gasket? I dont really want to open up the head until i`m resonably sure it is a head problem.
 

cjrama

Cadet
Joined
May 3, 2009
Messages
18
could the computer gone into gaurdian or limp mode? i would think that it would be unable to rev in neutral if this were the case, but i`m not sure.... any insights would be appreciated
 

enginepower

Petty Officer 1st Class
Joined
Jul 5, 2014
Messages
260
Does your alarm work? You should get beeps when key is first turned on indicating self test ok. When you ran it out of oil, should have triggered the alarm. The computer may be in limp mode possibly due to faulty float/sensor in your reservoir tank and your alarm would be sounding but you don't know it.
 
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