vinnimon Posted May 21, 2011 Report Share Posted May 21, 2011 I have a 3 ltr mercruiser inboard engine, I have rebuilt it from top to bottom. I had my boat out last week as she ran like a dream As usuall I run the engine the night before an outing as I tried tonight and it wont start. I have spark and replaced the plugs tonight. I have plenty of fuel pressure and delivery to the carb I replaced the carb fuel filter as well. Main filter at the pump is good. Now I tried pouring fuel down the carb, and I didnt even get a back fire or a burp out of it.This tells me that my carb is plugged, or im sucking up seperated fuel. Possibly a stuck float Any opinions would be appreciated Thanks in advance V Link to comment Share on other sites More sharing options...
skinny Posted May 21, 2011 Report Share Posted May 21, 2011 altho late when you discovered that it didn't fire after dumping fuel in the carb (therefore bypassing any proper things it does) did you by chance check for spark I was always taught if you have fuel(you dumping) and you have spark it has to run first I would pull a plug and check for spark. if plugs are wet burn them off (I use propane torch) turn over the motor several times with out the plugs to get extra fuel out of bore. if you have spark you can put the plugs back in (always check plugs when you buy them with ohm meter when we use to drag race more than once we found bad plugs out of the box) After the plugs are back in it you can try it or give it a drink(dump some in carb) and try it. it should buck or bark but go back to the got to have's no fuel no run no spark no run Link to comment Share on other sites More sharing options...
Canuck2fan Posted May 21, 2011 Report Share Posted May 21, 2011 (edited) Three things an engine needs to run. If it is turning over but not firing 1 spark which you say you have 2 fuel which you dumped down the carb If it is turning over but not firing 3 the last thing is compression.... Have you checked your timing belt or chain? Edited May 21, 2011 by Canuck2fan Link to comment Share on other sites More sharing options...
vinnimon Posted May 21, 2011 Author Report Share Posted May 21, 2011 Three things an engine needs to run. If it is turning over but not firing 1 spark which you say you have 2 fuel which you dumped down the carb If it is turning over but not firing 3 the last thing is compression.... Have you checked your timing belt or chain? Its gear on gear(cam to crank) no belt or chain., and theres lots of compression. Link to comment Share on other sites More sharing options...
Big Cliff Posted May 21, 2011 Report Share Posted May 21, 2011 Its gear on gear(cam to crank) no belt or chain., and theres lots of compression. Then it can only be spark or fuel. Canuck2fan is right on all three counts. I would check those plugs though, just in case. If you remove the plugs, squirt a small amount of fuel into the cylinder, replace the plugs and try to start it. If it still won't fire then there is a problem with the ignition. If it does fire then quit then there is a problem with the fuel supply. It is always possible that one of those gears has sheired a key throwing it out of time. Not likely but I have seen stranger things. Link to comment Share on other sites More sharing options...
OhioFisherman Posted May 21, 2011 Report Share Posted May 21, 2011 I almost always had a can of ether around to check for starting problems, ether will fire when gas won`t, weak spark. For safety reason? blow off the plugs with an air compressor rather than a torch? An engine needs 3 things to run, fuel, air, ignition, and the proper timing of the 3. With a carb the engine is getting fuel if you spray ether or pour a little gas into the carb, and it is also sucking air if it turns over, even with low compression, so spark and timing are suspect. Link to comment Share on other sites More sharing options...
irishfield Posted May 21, 2011 Report Share Posted May 21, 2011 Then it can only be spark or fuel. Not if this is the engine with the old stripped cam gear issues????? Has it happened again??? Link to comment Share on other sites More sharing options...
vinnimon Posted May 21, 2011 Author Report Share Posted May 21, 2011 Not if this is the engine with the old stripped cam gear issues????? Has it happened again??? No, the disributor is turning. Seems to me its a week spark Link to comment Share on other sites More sharing options...
Terry Posted May 21, 2011 Report Share Posted May 21, 2011 No, the disributor is turning. Seems to me its a week spark so what do you need a day spark or month spark:oops: sorry seemed funny at the time Link to comment Share on other sites More sharing options...
Big Cliff Posted May 21, 2011 Report Share Posted May 21, 2011 Not if this is the engine with the old stripped cam gear issues????? Has it happened again??? You are right Wayne, could be a lot of things! Link to comment Share on other sites More sharing options...
vinnimon Posted May 21, 2011 Author Report Share Posted May 21, 2011 You are right Wayne, could be a lot of things! Well I walked away from it for an hr or two, picked longer plugs(as advised on iboats). Regapped the plugs to 35 thou. I went with the mr43lts instead of the mr43t plugs. I went to crank it over and it started for a minute then died out. What I did notice at times while checking for spark, it was intermitant(high and low spark or no spark) Im assuming that the distributor is is cutting in and out. Moisture, point breaker,condensor, rotor or cap may be faulty. Best to replace it all. On top of that I need a new starter now Terry, it will be a week, before she sparks again. Maybe I hope. Link to comment Share on other sites More sharing options...
Terry Posted May 21, 2011 Report Share Posted May 21, 2011 well my boat is STILL in the shop I sure hope it's home and working by next weekend Link to comment Share on other sites More sharing options...
vinnimon Posted May 21, 2011 Author Report Share Posted May 21, 2011 well my boat is STILL in the shop I sure hope it's home and working by next weekend I guess we are in the same boat Terry Hopefully yours is all said and done, and ready to roar by next weekend. Mine wont be Link to comment Share on other sites More sharing options...
mrpike Posted May 22, 2011 Report Share Posted May 22, 2011 HI ! IT could also be the coil if the coil is old or as a bad ground . IT may not fire under a load. But fire fine with the plugs out . JUst my two cent. hope it works out for you. Link to comment Share on other sites More sharing options...
Tybo Posted May 22, 2011 Report Share Posted May 22, 2011 One of the most common problem after a cam change is the pintel roller on the bottom of the distridutor.If the pin and roller is warn you will decrease in spark. For the timing will always be a little out.Could also be a weak coil. Get yourself a spark tester, This is the only way to tell if you have the right spark. Link to comment Share on other sites More sharing options...
skinny Posted May 23, 2011 Report Share Posted May 23, 2011 just a thought here I have talked with vinny and he has told me the motor is the same as what was in a chev car . I have seen that many times the multi purpose for engines. now my question is if it did match a cheve motor from a car could he upgrade the ignition to a HEI type and eliminate the points and condensor and all that sorta old school stuff. He would also be getting away from some of the over priced parts because they are marine Link to comment Share on other sites More sharing options...
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