Huh

have 502/500 in a 2000 nordic heat have 648 hrs on engine. have post fuel flooding changed all injectors twice changed fuel regulator have to go to half throttle to start also shut down batteries after turning off ignition still floods

AllDodge

iTrader: (1)

What's the engine serial number?

SB

iTrader: (1)

What's the evidenced of flooding ?
Is this an OE 500EFI ? If so, where did you source the injectors..Asking because near impossible to find OE ones. Search for Articfriend's and BUP's posts on these and how the aftermarket replacements have way too many issues out of the box.
Here's one thread: http://www.offshoreonly.com/forums/g...0-500-efi.html

Do the 500EFI's have that dumb fuel screen in the rail in the return section from the regulator ? If it does and this get's clogged, fuel psi will be spiked because it chokes off the return. Engines that have this, if you take off the regulator where it mounts to the rail, you'll see the small screen pushed in the rail.

Trash

My bet is its a 502 Mag EFI/MP and the VST inside upper diaphragm is crumbling which causes exactly the issue he's describing. Fuel will vent into the manifold through those yellow vent tubes causing flooding.

Huh

serial ol 601124. bought 6 original injectors new from marine dealer in florida the other two are oe with no issues. sent other 6 to marine dealer to clean and test 2 were junk. merc gave me gm # 1-7090919. not one gm dealer had injectors. smell gas from exhaust on startup also some black smoke. removed. purchased injectors from jegs 44 pd all ohmed at 13. still post floods.

Huh

did not look for screen in rail will check out engine runs excellent and idles boat runs mid 70s on gps

SB

iTrader: (1)

Okay, it's a 500 EFI 0L001496 THRU 0L306499

Looking at diagram (which I also put up below) and parts list at : Genuine Mercury & Mercruiser parts. Fuel Pump And Fuel Cooler
the fuel psi regulator does have a tiny screen filter under it on the fuel cool assembly. See #16.

A clogged screen filter will restrict fuel here (after regulator) and thus it overides the regulator and thus causes higher fuel psi than you should have. Especially during idle and low speed when most fuel is being returned and not being used by the engine.

Also, make sure you make sure the vacuum line (#20) is hooked to the regulator and the intake manifold vacuum fitting for it. Along with no cracks/leaks in the vac line. This ill also cause higher fuel psi especially at idle and low speeds.

Before you go thru all that, have you checked your fuel psi ? If so, is it in spec ?

FYI: the fuel psi regulator on the fuel rail does nothing. You'll see the return side of it is capped...ie: no fuel returns out of it. Again, The regulator on the cool fuel regulator is what sets/maintains the fuel systems psi.

FYI#2: High octane gas can cause soot on the transom too,,,if this is your main issue ?

SB

iTrader: (1)

Here is the pic of the regulator on the fuel rail so one can see how it does nothing but blocks/dead heads the return side of rail and itself. Again, it does not have any influence on actual fuel psi.

http://www.mercruiserparts.com/bam/s...31335/4889/110

Huh

thanks to everybody for your help and advice on my post flooding i give up will live with issue to end of season. going to start working on my article cat snowmobiles. alleghneny forest here i come. thanks. kenny