Jerry B

First time out this year in my 93 Fountain with twin 502 EFI Mags. First day was fine. After running the second day was about to put it on the trailer and was getting allot of vapor out of the right engine. First thought it was steam but then smelled raw gas real bad and engine was missing badly.
I had to put in a new engine on the other side last year so I just knew this would be bad. Any way when I got it home I hooked up the water and started it. Lots of vapor out the right exhaust pipe. Left one looked normal. I took all the plugs out of that side. Of course they were soaked with gas. I cranked the engine over with those plugs out and blew gas everywhere. I did not have a compression gage at home but had my wife crank the engine over with my finger in each spark plug hole. Not a good test I know but no way could I keep my finger in there so I think this is a good sign.
Anyway before I call the Fountain dealer at LOTO does anyone have any idea why this is happening?
Thanks for any help.

Jerry B

superwrench0166

not a marine tech but i would suspect since only one side and all one side that for some reason you have to much fuel pressure and forceing it past the injectors

HiPerf2000

iTrader: (2)

could be a bad regulator. get a guage and check fuel pressure.

hillbilly24

It could be alot of things in the fuel system, first thing to check is fuel pressure, if that is correct than you need to see if any of the injectors are stuck open. The fuel pressure test you can do yourreslf with some basic tools, the injector test requires a scan tool to test fire the injectors with the engine not running so you would be best off to let a dealer check into that one for you after you check the regualtor.

superwrench0166

does any one know what motors have batch fire and which have seperate sequental fire injectors

Jerry B

I have been looking at the manuel I have. The only wireing diagram I find shows cylinders, 2,3,5,8 together and 1,4,6,7, .
Top of page only says MPI. Does not specifi 502. If the 502 injectors are batch fired this way this wouldnt may since for my condition. If each side were triggered and there was a grounded wire, shorted injector or bad ecm then I think I'm on the right track. My manuel just does'nt go into enough detail.
Probably have to take it to the dealer anyway cause I cant leave it in my driveway very long. Neighborhood rules.
I'm a GM mechanic by trade so it's hard not to work on my own boat but a place to do it is tough. I may take an injector test light home and see if I can plug it in to one of the injector connectors. I have a feeling the light will stay on solid.

Jerry B

Ok , Think I have the problem. Diaphram has a small hole in the VST Dumping fuel into #8 cylinder. I'm hoping the other plugs were nasty because the ecm was trying to adjust for the cylinder that was flooded. I know the IAC was really allowing allot of air to come in. Anyway parts are on order.
After searching this further on this site it appears this is a fairly common problem.
Thanks for everyones input.

Jerry.