Engine stalls after restart mercruiser 5.0 mpi

CJ76

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Hi all! I'm new here. I took my 2014 Stingray out Mercruiser 5.0 mpi. Boat ran fine however after sitting out on the lake for an hr listening to the radio the engine restarted ran really rough for a minute and died. I was able to restart...again it ran rough and died. After a few more tries it eventually would not restart. Changed both batteries, spark plugs and IOC and still getting the same results. At my wits end here! Any suggestions would be appreciated
 

alldodge

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If this happened only when hot then I would think vapor lock, but since you mentioned replaced bats then this would not be the case.

What is your serial number?
 

alldodge

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When motor is cranking is the tachometer showing at least 300 rpm?

Get a rag, safety glasses and a small screw driver or fuel pressure gauge. Remove schrader valve cap (item 19). Turn key to ON and then press in on center pin on the schrader and have the rag over it.

https://www.mercruiserparts.com/bam/subassembly/31758/15323/90

Did gas squirt out?
Do this a couple times to make sure air has been expelled, then try to start again
 
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CJ76

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Had a fuel pressure gage on it and when I turned the key to on it went to 40 psi, started the engine and it wavered from 35-40psi. When the problem occurs the psi is 0. I'll have to check the tac next time I'm down there!
 

alldodge

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Had a fuel pressure gage on it and when I turned the key to on it went to 40 psi, started the engine and it wavered from 35-40psi. When the problem occurs the psi is 0. I'll have to check the tac next time I'm down there!

Since it starts there is no need to check rpm

OK then the fuel pump is turning OFF
Need to find out if the relay is cutting out, power is being lost, or the ground applied by the PCM to relay is the issue
 

CJ76

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Here's a link to a short video of it stalling out. This was after I took the boat out, ran it for 30 min , brought it back to the slip and chilled with the engine off for about 40min.
https://youtu.be/t_PbHn4WHQk
 

Scott Danforth

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your fuel pressure is also a bit low. you should be 43 psi
 

alldodge

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No clue why it shuts off, need testing and a scanner connected would give a better idea. Might be loosing fuel pressure, the IAC, spark, other
 
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