mercruiser 4.3 MPI starts but won't take fuel

[wpowell323]

i have a Mercruiser 4.3 MPI that will start and run but will not take any fuel. It idles fine, but when you give it gas it bogs and tries to die out, if you close the butterfly it goes back to idling fine. I have checked all the sensors and they seem to be fine, DDT is not showing any codes, fuel pressure at the rail is where it should be, compression is good. Any suggestions, I am at a loss. Any help would be appreciated. Serial Number is OW68572

 

[wellcraft-classic210]

Re: mercruiser 4.3 MPI starts but won't take fuel

When you say fuel pressure is fine does it stay at pressure when the problem is happening?

I ask as the symtom does sound similar to a low fuel flow scenario. ( as in fuel filter , fuel pump or partial obstruction )

 

[wpowell323]

Re: mercruiser 4.3 MPI starts but won't take fuel

fuel pressure is constant. at about 2200 rpm's it starts missing like it on a rev limiter. I have literally replaced every sensor. Compression is perfect, fuel sample looks great. I have even tried another computer and nothing makes a change.

 

[wellcraft-classic210]

Re: mercruiser 4.3 MPI starts but won't take fuel

Based on your tests to date if its fuel related it could be the injectors themselves.

It seems it could be electrical also -- Timing and inputs to the computer from sensors would be in the list of items to check.

( Not my area of expertise but thought it might help to mention this) -- I have heard of some sort of limp mode that gets activated to protect an engine on some models. You may want to look into that & see if something is getting triggered on your comuter.


If it was an auto I would probably try to find someone with good skills and an engine analizer to help pinpoint the issue. Not sure if those are availablle for boats.