Hard to start 502 mpi
 

97 502 mpi only 50ish hours. Will start right up when cold or has sat, seems to run fine until you shut it off. Will need full throttke and lots of cranking to fire...Has new F.P.R. positive lead on vst pump gets hot! Fuel pressure is 35ish after key is on, drops when revved up to 25 psi. Now shut it off wait 2 or 3 min and no start ..plugs are dry... Will not start with starting fluid at all?? Vst screen is clean boat panes fine and pulls fine up so not acting like fuel pressure issue when running. Also has a fuel cooler i assumed previous owner added.. I would say fuel pump is bad but no start with starting fluid confused me any help is appreciated

Anybody?

What is fuel pressure when it won;t start. ie: the part I put in bold above?

Fuel pressure @ 36ish psi, the pump is new, the F.P.R. is new , i also threw a ignition module in it as well. No fuel leaking into plenum from vst line or from manual pump vent line.

just checked your history real quick - like Dejavu..you and me. LOL.
https://www.offshoreonly.com/forums/...pump-beep.html

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You have a see through spark tester to see how strong spark is at this point of no start ?
Use a scanner to check live data while no start ?

https://cimg2.ibsrv.net/gimg/www.off...de7b4fad66.jpg

I only verified spark by eye not a spark tester. I only have automotive scanner, no access to a compatible scanner all the shops want me to book an appt. as they are busy. I wish i had a techmate or merc scan tool. I have also cleaned the IAC and throttlebody

I have a 454 efi and have the same issue. Have you fixed it yet?

Hi yes I have resolved the issue, after ruling everything else out a leakdown revealed bad intake valves. When my fuel pump was weak it leaned out motor and tuliped some intake valves. And I guess it would push the air fuel mixture into plenum and in turn flood the engine giving no start condition

I would go after the IAC solenoid!
Same issue here I had and found the IAC was not working properly.
$30 @ Auto zone and runs like new.
Scanner will tell you a lot, find one and see what it is telling you.