Merc 1.7 not going over 2500 revs in fwd..

[Dieseluser]

Hi,
I know this was asked before but the OP didnt post what the eventual solution was.

This week at cowes merrily going along then the revs dropped to 2500 in fwd and wont budge above that. Fine in neutral and reverse. Changed fuel fileter but no difference. Merc agen suggeted hole in piston to reoved the oil filler cap to feel for buffering but nothing. Got towed home by seastart and they had a look.. There is some bkack smoke but not much and engine sounds fine.... soooooo does it sound like this well known turbo issue???

[doggypaddle]

sounds like it could well be the wastegate stuck open or maybe a faulty compensator/split intake pipe losing boost.
if the wastegate is stuck open it may snap shut if you give the linkage a tap.......then free it up by disconnecting the actuator link and wiggling it back and forth with some plus gas. the one on my perkins prima sticks regularly and this always works.

best way to test is to connect the actuator to a bike pump and pressure gauge and watch the presure it opens at.


fit a boost gauge....far cheaper than overboosting and holing a piston.

[Pikey Dave]

Does it have a neutral limit switch? I.e the etecs have a switch that limits the revs when the engine is in neutral to stop it overrevving. These can go faulty & the EMM thinks the engine is in neutral & won't rev. just a thought

[Dieseluser]

Thanks doggypaddle ill get the hammer out!

[Dieseluser]

Problem solved, the actuator arm had become disconnected from the waste gate, all fixed and please to say the wate ,moves freely :-)