Mercruiser I/O 4.3....... Fuel issue?

[Vamike757]

Greetings I have a problem I am hoping some of you may be able to lend some insight and help me remedy the issue.

I have a 2000 trophy W/A that I repowered about 3 years ago with the same engine a mercruiser 4.3 liter. So far it has ran like a champ and I am very pleased. Naturally I rinse it out after each use and keep it well maintained. I left it set over the winter which I dont normally do (With Stabil in the fuel) however it started right up this spring and never missed a beat. I was worried because we have ethanol in our fuel here and some boaters had issues when they started using the ethanol gas a few years back. Anyway I did my normal routine maintenance this spring but couldnt get the fuel filter off because of its location and it being overtightened.

Two weekends ago I was coming back from a fishing trip in 2-4 foot seas and it was a really ruff ride back in. I am sure during that return trip the fuel in my tank got stirred up really good. When I got to the dock I was washing the upper part of the boat (still in the water) and it stalled out while I had it running. It never does that so at that moment I figured it was the fuel filter since it hadn't been changed and the very ruff return trip. The next day I got a strap rachet and changed the fuel filter. It proceeded to start right up after a couple cranks and run perfectly. I proceeded to top off my tank with fuel and add about 3 ounces of stabil as a preventative measure. I got it onto a cleaning rack and washed it down as I keep it in dry storage at a local boatel. I started it back up while on the washrack and washed out the engine for about 15-20 minutes and it ran perfect again. It sat for about a week and when I went to take it out on Sunday of lastweek it wouldnt start at all. I had the engine cover open and I noticed a grey fog coming from the flame arrestor when I would attempt to start the engine. I dont know what that was all about but I dont think it was smoke but more of a foggish haze. It was also present down in the carb when I took the arrestor off and looked down in the carb.

When I changed the fuel filter I started it a total of 3 time that day and let it run for about 30 minutes total. I topped it off with 25 gallons of gas adding 3 ounces of stabil to the 65 gallon tank.

I am wondering if by not adding fuel to the fuel filter when I changed it could it have messed up the fuel pump? or caused some kind of vapor lock?

Other than that I have no idea at this point. I have ran over 100+ gallons of gas thru it this year and never had it miss a beat so I don't think I have bad fuel. Noone else at the marina is having any issues with their fuel that I know of. My engine oil got changed this spring and looks brand new with no water present whatsoever.

Sorry for the lenghty post but I wanted to cover things the way it happened and what I did leading up to this issue. Hopefully a small detail or two might give someone an idea to what might be wrong.

So does anyone have any suggestions or ideas? Thanks in advance everyone!

 

[Vamike757]

Re: Mercruiser I/O 4.3....... Fuel issue?

Wondering if anyone thinks it would be possible to crap up my new filter by letting it run for only 30 minutes after changing it?

Edit***

I am also considering that perhaps it could be the ignition coil at this point but considering the engine is like knew I did not take that into consideration at first. I did pull off the ignition coil wire to see if it was corroded etc but being by myself the other day I couldn't really check for spark etc. It did have that "greasy" look to it but not all together clogged and dirty.

 

[moetr]

Re: Mercruiser I/O 4.3....... Fuel issue?

This could be anything from computer problem to ignition problem to sensor problem to fuel pump, etc. Carb is simple, spark or fuel. Check for spark just to eliminate that. That fog may be unburnt fuel vapor from injectors.

Is there a place to check fuel pressure? Maybe pump or pump control problem. Can you drain some fuel into glass jar and check for crud?

I would get a Mercruiser manual for your engine and start there in troubleshooting. You can get these free downloads somewhere on this sight. Search for Mercruiser manual or free Mercruiser manuals.

Oops. I see now that it is a carburetor. This is easier. Check for spark first. If good spray a squirt of gas or starter fluid into carburetor. If it starts you have a fuel problem. Carb, filter, pump, etc. Good luck. I bet on spark.

If it is spark check all connections first, clean and tight. Check main connection at back of motor also as that feeds everything. Check cap for carbon tracks. Turn on ignition and I believe you should see 12 volts at positive coil. This is where the manual will help. Hopefully if spark it is only coil, not module. I don't know how to check distributor pickup.

 

[Bondo]

Re: Mercruiser I/O 4.3....... Fuel issue?

It sat for about a week and when I went to take it out on Sunday of lastweek it wouldnt start at all. I had the engine cover open and I noticed a grey fog coming from the flame arrestor when I would attempt to start the engine.

Ayuh,.... Welcome Aboard,.... That gray fog is atomized gas,...

Sounds like ya might be huntin' an Electrical issue....
Is it a T-Bolt VI, or V,..??

 

[Vamike757]

Re: Mercruiser I/O 4.3....... Fuel issue?

Ayuh,.... Welcome Aboard,.... That gray fog is atomized gas,...

Sounds like ya might be huntin' an Electrical issue....
Is it a T-Bolt VI, or V,..??

I am not 100% sure. It is a 4.3 Alpha, Model No. 4-211225U S if that helps at all. I am going down tomorrow afternoon to try and check a few things and will find out the answer to that question.

thanks!

 

[Vamike757]

Re: Mercruiser I/O 4.3....... Fuel issue?

Thanks for the help everyone!

Looks like its an ethanol issue! Changed the filter again and turn the ignition and it fired right over and never missed a beat. I let it run for about 30 mins then shut it down for about 20 and tried to restart. Wouldnt start again so my fuel water seperator is getting clogged by water. I am going to try to remove the water at this point and if I cant get to it then have the fuel pumped and filtered. Poured the gas from the old filter into a glass jar and theres water in the bottom after it settles.


When I got the boat on the racK I noticed I have gear lube drippin from my prop area. I must have picked up some fishin line on my last trip and ruined the prop shaft seal. I knew something was up the last time I tried to go out because I had to add about 2-3 oz of gear lube and I never have to do that.

The ethanol is a real issue. The Government needs to learn that corn is for cows!~

 

[Vamike757]

Re: Mercruiser I/O 4.3....... Fuel issue?

No fishing line wrapped around the prop anywhere and it appears I no longer have any gear lube coming from that area. Weird how sometimes things just seem to fix themselves isnt it.

Dosed my fuel with some Ezorb and startron and I'm gonna see how that works with the small amount of water I have in my fuel over the next week or so. Will prolly change the filters another 2 or 3 times if required in hopes it remedies the problem before removing the fuel sender to try to suck out any visible contaminants. The engine runs to good on a new filter to have much water in my fuel.