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1987 140 Evinrude Lagging on Acceleration

Ive posted here before last season, and after great responses, I have gone and tested everything everyone had suggested. Three mechanics have looked at this motor and not one can figure out what is going on. The problem is getting worse.

Here is what its doing :

The motor while trying to plane will only get to 2500rpms, and stay there for a good 30-45 seconds before the power from the engine starts to kick in and launches the boat to a plane and top end. If I back off the throttle once on plane, it takes 30-45 seconds again to ragain the power once I go full throttle. I did a compression check over the weekend, and its EVEN 125 on all 4 cylinders.

I would take the heads off, but I have heard horror stories of pulling the heads off and then not being able to put them back on because of the salt water destroying the head, and they would just crumble..

Carbs were just rebuilt and re checked, no clog jets, no stuck float, nothing all good. Everything on the electrical system (stator, power packs, coils, voltage reg, timing base etc), was checked tested and if bad was replaced with new. Flywheel is positioned where it should be, so its not a spun fly wheel. The timing is all correct. The link and sync for the carbs are where they should be. Before anyone asks the carbs have the correct Jets, they have been varified by three mechanics..

Fuel pump was tested and is performing as it should. Fuel pick up from tank and fuel line just replaced.


The motor runs perfectly at low speed. Idles smoothly, runs 4.7-7mph flawlessly.

Any new suggestions?
 
Put timing marks on the flywheel for each cylinder. Then check to see if electronics are behaving as they should with your timing light.---------------Or try another fuel pump,Maybe a cheap used one off say a 66-100 HP Johnson.
 
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Timing marks for on the flywheel for each cyl has already been done and tested. All the electronics were replaced with brand new. Ive had all brand new electronics put on to see if that was the problem. Problem was still there, so all those new parts were replaced by the old ones.

I was thinking more towards a fuel pump. But if it was the fuel pump, would I even be able to get up on plane?
 
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