mercruiser 5.0 inboard/outboard with B3

[bob.traynor]

I am having an issue where when I throttle up the engine seems to bog down and you can smell gas. Slowly over time I can get the engine up to power and coast but as soon as I come off and try to get started again same thing happens. It seems like to much fuel is been fed. I have checked for fuel leaks and there are none. The engine compartment is dry. The engine has 100 hours and had run fine until noticed a start to this at the end of last season. Any ideas?

 

[tpenfield]

:welcome:

If you can give a few more details of the engine ( carb, moo, etc.) and even a serial number, that would help with the answers.

my initial thought is the fuel pump.

 

[bob.traynor]

It is a mercruiser 5.0L, 2008, installed in a Rinker 230 Atlantic. I do not think it is carbureted. When I throttle it from idle it immediately bogs down. A distinct smell of gas can be detected and it takes several minutes to slowly regain power back to normal level. I will need to get more info from boat.

 

[alldodge]

Need a engine serial number?
Guessing its fuel injected but could be TBI or MPI

 

[bob.traynor]

It is a 2008 mercruiser 5.0L 260 MPI with B3 outdrive.

 

[achris]

Are you getting any 'beeps' from the alarm? How's the engine temperature? (on an injected engine too cold is as bad as too hot)

Chris.........

 

[alldodge]

Measure the fuel pressure at the rail shrader valve.
Turn key ON (no start) and when pressure comes up, then turn OFF and see if it holds.
Next start the motor and the pressure should be 43 psi at 1800 rpm

 

[bob.traynor]

After some considerable research on this here and in other forums I am leaning towards a loose or bad crankshaft position sensor. I replaced the cooling impeller last year and on this engine it is right in same hard to get vicinity as sensor. I need to go to boat and check if loose or damaged which will not be for several weeks. But reading some past problems that read very similar I think this is a very good lead. I will also at same time check fuel filter and screens and overpressure relief not stuck. I am very interested in your thoughts regarding this approach.Thank you.

 

[alldodge]

Do see the crank sensor as the issue, it deals with timing, not how much fuel.
The MAP sensor tells the ECM how much fuel is needed. Your smelling fuel, so pull some plugs and see what they look like

The S/N would help to verify what you have

 

[bob.traynor]

http://www.marineengine.com/boat-fo...icient-power-to-get-boat-on-plane-RPM-limited

This post tells the story.

 

[alldodge]

Link does not work because its a competitor of iboats

 

[dubs283]

my first thought on this knowing you have an mpi with most likely the delco flat cap is corrosion at distributor contacts, i would check there first along with fuel filter(s)

CPS would be much lower on my list of things to check

 

[achris]

CPS failure would lead to a 'no start' condition...