92nsx

Hi guys,

Well this is my first post here on this forum and could use your help. Im new to boats but not engines. Only my experience is car engine's ( 7MGTE's mainly)

Boat: Repowered with earlier edition 502 EFI, (about 500 hours) 1990 Baja 265 DVX

Problem is #8 fuel injector is stuck open and this isn't the first time.!! When I bought the boat this spring it had the same problem that the marina pd to fix/replace the injector.

Now maybe 15 hours later same thing, same injector same cylinder!! Started blowing white white/blue smoke out the right bank, brand new spark plug has gas sitting it it, and oil pan is plump full of oil and gas mix.

I know there is always the "chance" to get a bad injector but it just seems odd to me that its the same cylinder. I already ordered a new one from Mercruiser and will have this bad one sent out for flow testing and cleaning that can be used a spare if needed..

Fell free to post other things to check or test, and your thoughts/ideas.

Thank you in advance , Rob

P.S. I love pics so here are a few of the vessel so we know what were talking about.







Madlin voyage pic. Girl friend holding it at the dock.

articfriends

iTrader: (1)

Your injectors are batch fire, 4 fire at a time, there is nothing that could make the same one go bad over and over again so I doubt its the injectors. Your pics are too vague but I'm going to guess you have a early mefi 1 or 2 motor wiith a VST tank. The VST tank gets fuel pumped to it from a mechanical furel pump then the efi pump pulls from it. When they go bad and they do go bad the fuel that overflows is piped into a intake runner so your boat doesn't blow up and start on fire. My guess would be you have VST efi and the cyl that is running rich is the one it vents to. The easiset way to tell the mefi1/2 vst stuff at first glance is the plugs go into the end of the ecu instaed of the side, if this isn't your problem get your injectors flowed before buying anymore and if actually bad buy brand new ones, Smitty

articfriends

iTrader: (1)

Your pics didn't open the first time but they just did and I can clearly see you DO have VST, see if the vent line from the vst is going to your rich cylinder, Smitty

FIXX

iTrader: (2)

+1
also check and see which number intake runner goes to the fuel pressure regulator's vacume goes to (i should be at the back of the intake at one end of the fuel rail)

when they go bad it will also dump fuel through the vacume hose and fill the cylinder with fuel in a hurry ..

92nsx

Thank you guys for the posts!

Vst? Ok that is new to me, ill have to Google it more and see how it works and what not. I'll check out the lines and see where they all lead to along with the vac line for the regulator.

I'll also get more pics of the engine and maybe some one can point me in the way once I get back home. If it helps the any for what gen the engine is, the SN = F070030.

tunertech

the VST tank dumps into # 7 cylinder runner... that is the port side of the motor, last cylinder, this is the typical culprit related to a needle and seat failure in the VST tank, floods the hell out of the cylinder and will fill the pan with gas.

Secondary, vent from the VST is the green polyvinyl tubing between the fuel pump and VST tank.. they are tied together and dump into the plenum.. not so common of a problem.

FP Reg refernce will will not cause this issue... it plugs directly into the plenum.

92nsx

Did a little googling and found this
http://www.justanswer.com/boat/281yy...on-system.html

It is the same thing that is happening on my 502. Sounds like I need to rebuild the pump ? Is that possible? Didn't see a parts brake down for the pump it self. Or do I just order a new pump?

tunertech

replace the needle and seat

articfriends

iTrader: (1)

I see on the link posted by op that it says #8 cyl for VST dump, so not sure if thats a error or Tuner tech is thinking backwards but either way rebuild your VST or at least check its vent line when running.
"If you do have the same fuel system as the one in the picture above, you have a VST fuel system. These VST fuel systems were notorious for blowing diaphragms and would dump fuel into the plenum then flood out #8 cylinder".

tunertech

yup 8 not 7 my bad thanks