Merc 4.3L stopped won't restart

[pragen]

I have a 1995 Mercruiser 4.3LX Alpha one I/O on an 18.5 ft boat.<br /><br />First time out this year boat started fine and ran good for 30 mins over a 2 hr period with several starts, runs, stops. On later start, boat started fine, idled fine, but when giving power it got rough. I throttled back back. I may have stopped and restarted. Tried again. Same problem with loud noise (backfire?). Stopped engine. It will not restart. It cranks fine. Battery is new and charged. The nice person who gave us a short tow back looked said it was getting a spark.<br /><br />So I am guessing fuel problem. Water in the gas could be an issue. Tank was not full over winter but did have stablizer added. I can't get fuel filter off - to tight. It was replaced by shop as part of winterization. Will try end cap wrench next. Current wrench is deforming filter. <br /><br />Fuel pump sounds like its running. I can hear it run a second or two after ending cranking. Don't hear the same noise with pump electric disconnected. <br /><br />I pulled one plug after cranking and it seemed dry. Would that indicate fuel clog vice water? How do I test for clog? Would I see fuel coming into carb with cover removed when cranked? Is that dangerous? <br /><br />Any other obvious possiblities? I can change plugs, etc, but I am not a mechanic.<br /><br />Anyway, busy time of year so seems like a week or two before I can get into a shop. Any help would be appreciated.<br /><br />Patrick

 

[boatguy19]

Re: Merc 4.3L stopped won't restart

check your coil,they can go bad in a blink of an eye

 

[Rickles]

Re: Merc 4.3L stopped won't restart

Get that filter off and pour it into a clean container to see what you have.This will tell you what you have in the tank.Take off the outlet side of the filter,remove the coil wire, and crank the eng.See how much fuel you get in 3-4 seconds.Should be alot(10-12oz.)If not you'll need to check fuel pressure.Without a pressure gauge you're stuck from here.Hope this helps.

 

[pragen]

Re: Merc 4.3L stopped won't restart

Thanks for the help. Some follow up...<br /><br />I am pretty sure now the carburator is getting gas, but not putting out gas. I disconnected the line into the carb and the electric fuel pump was pumping gas. I see no gas coming out of carb when cranked w/o spark, or throttle put full foward and back. <br /><br />The gas in the fuel filter seemed fine. Although there were a few small dark flakes in it - could some have got through the filter?<br /><br />I did confirm spark (just tried 1 plug).<br /><br />I am tempted to pull the carb off and clean it. Can I just soak it whole in some carb cleaner once off - without major disassemby, or should I just take it somewhere? I don't feel confident to fully dissasemble my self. (actually the re-assembly)<br /><br />Should I try gas or starter fluid in carb to see if it will run for a short time first? I have read good and bad things on starter fluid - bad being it could wipe away oil causeing major wear. One site recommended gas with oil mixture. How much gas would I use, do I have time to get flame arrestor back on, or it that all just a bad idea?<br /><br />Thanks for any more help.<br /><br />Patrick

 

[Chris1956]

Re: Merc 4.3L stopped won't restart

Patrick, Spray regular gas into carb throat while cranking motor. It should run for a few seconds. If not then the problem is likely spark (or lack there of), or timing. Since timing is caused by ignition module, maybe backfire was signal that it went bad. I had an Thunderbolt ignition module fail on me while I was comming back from fishing last November. Just went dead at 30 MPH.

 

[Bondo]

Re: Merc 4.3L stopped won't restart

Pat,<br />You No Doubt have a Fuel Issue..........<br />Dunking the Carb in Cleaner,<br />Or Spraying the Carb with Cleaner,<br />Is Not the kind of service you Need.......<br />If you're getting Good Fuel Flow to the carb,<br />and with the way you describe it,<br />a Carb Rebuild is in order........

 

[Blk-n-Blu]

Re: Merc 4.3L stopped won't restart

Pat, Sometimes there is a fuel filter in the carb where the fuel line is connected under the big nut make sure you change that before pulling anything. good luck