Mercruiser 4.3 LX

[larr630]

Re: Mercruiser 4.3 LX

By the way guys, the safety switch/oil pressure sending unit cuts spark to the motor. Thats why it won't fire. I really hope this will fix the problem and that I was able to help. Alot of responses on here have helped me. Hope it works, Larry

 

[RogersJetboat454]

Re: Mercruiser 4.3 LX

You need to replace the oil pressure safety sending unit. Its located on the passenger side of the motor right below the last spark plug. Runs about $65.00 These sending units go bad even if you have good oil pressure. It stops you from blowing the motor if you loose oil pressure. But mine went bad and it would run for a few seconds and die. I replaced this sending unit, and it runs fine. Let me know if that works. It is the oil pressure switch and the safety switch that both need replacing.

Let's do a proper diagnosis to this before we start throwing parts at it!
What fixes one boat, car, lawn mower, airplane, or gasoline powered blender, may not fix the next, even if the symptoms are similar.

 

[fat fanny]

Re: Mercruiser 4.3 LX

Good one Bond-o ! Tell your husband to read the adults only stickie at the top of this forum and then read the manual cover to cover. I think this poor thing is soo far out of adjustment and loaded up with fuel and carbon you have no choice but to re- build the carb but do the proper trouble shooting 1st don't throw money into something until u know what to throw it at. Do yourselves a favor

 

[TraceyHill]

Re: Mercruiser 4.3 LX

Everyone: Quick update on the boat problem from hell......you were ALL right (as I suspected). The carb was gummy and choked up with crap. This is what happens when Ethanol gets put in gas and you have to fill your boat tank with it - at least that's what I've gathered. Stablilizer is key. ANYWAY, put most of a can of carb cleaner in the carb and quick spray in each plug. Turned it over and LET it turn over (and over and over and over) for about 90 seconds. Gave it couple minutes and tried again, let it turn over and at exactly 60 seconds, it FIRED! Bunch of smelly smokey fumes for a couple minutes, then cleared up and ran light a charm! Taking it in to get the oil changed, etc. Crisis averted on the low oil issue and invaluable lessons learned, namely FUEL STABILIZER IS OUR FRIEND!

Thanks to all the fellas who posted - you're all awesome and I've learned a ton just by reading your replies.

Have a great summer out on the water this season, y'all! And don't forget to vote this fall.......it DOES make a difference!

Happy travels!

 

[get smart]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

OK.. The plugs you should have in are NGK BR6FS or AC Delco MR43T. Please, throw that seloc manual in the garbage, they are worst than useless. Download a proper manual here -> https://docs.google.com/open?id=0B1TAvwZ3TjhfYWRiMDZmNDctMzgzZi00MmIzLTkxNGItMGY1NGExYjJmOGJh, and here's one for the drive -> https://docs.google.com/viewer?a=v&...YWRiNy00ODUyLWFmNzgtMTBmMzhlNGY4Mzk3&hl=en_US

Now you need to determine why it isn't starting... I know that sounds obvious, but there are 3 possibilities (basically).
Spark (at the right time), fuel (in the right ratio with air) and compression.

Don't know who told you a compression test was no good... They got that seriously wrong... Go ahead and do a compression test. Then get an old spark plug and connect it to one of the plug leads, lay it on the metal of the block and crank the engine. You should see a nice fat blue spark....

HTH,

Chris.........

I have a 4.3LX Gen II, 1995 with the word Vortec molded in to the valve covers. I have the original Operation and Maintenance Manual. It shows AC plug MR44T or Champion plug RV8C. Why does everyone on the different forums for this engine keep saying use AC plug MR43T? Thanks.

 

[Bondo]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

I have a 4.3LX Gen II, 1995 with the word Vortec molded in to the valve covers. I have the original Operation and Maintenance Manual. It shows AC plug MR44T or Champion plug RV8C. Why does everyone on the different forums for this engine keep saying use AC plug MR43T? Thanks.

Ayuh,... You should be startin' yer Own thread with this question,....

But,....
The MR43T has been the go to Chevy marine plug since the invention of dirt...

Donno why yer book says the MR44T...

'n yer motor is Vortec, only in that the valve cover has the name,...
The actual Vortec heads came out in '96...

 

[get smart]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

Ayuh,... You should be startin' yer Own thread with this question,....

But,....
The MR43T has been the go to Chevy marine plug since the invention of dirt...

Donno why yer book says the MR44T...

'n yer motor is Vortec, only in that the valve cover has the name,...
The actual Vortec heads came out in '96...

Thanks Bond-o. I put my question where I put it because the in post with quote I replied to the person was talking about the spark plugs for the 4.3LX. As far as the heads go, I spoke with merCruiser and their tech said if my valve covers where attached with the bolts in the middle of the cover (which mine are), then I have Vortec heads. Happy boating!!

 

[Bondo]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

Thanks Bond-o. I put my question where I put it because the in post with quote I replied to the person was talking about the spark plugs for the 4.3LX. As far as the heads go, I spoke with merCruiser and their tech said if my valve covers where attached with the bolts in the middle of the cover (which mine are), then I have Vortec heads. Happy boating!!

Ayuh,.... Unfortunately, that's Untrue....

True Vortec heads are Id'ed by the number of intake mountin' bolts.... Vortecs are 4 bolts per side...

Yer heads have the D shaped combustion chambers, 'n use the standard length spark plugs....

Vortecs, from '96, 'n up, are heart shaped, 'n use the longer reach plugs...

 

[RogersJetboat454]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

I spoke with merCruiser and their tech said if my valve covers where attached with the bolts in the middle of the cover (which mine are), then I have Vortec heads. Happy boating!!

GM has been using center bolt valve covers on both the 4.3L and small blocks since '87. They also started calling these engines "Vortec" before the head re-design in '96. Unless you had newer heads installed on your engine, I am doubtful you have actual vortec heads.

Like Bond-o said, please start a new thread if you want to elaborate.

 

[get smart]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

GM has been using center bolt valve covers on both the 4.3L and small blocks since '87. They also started calling these engines "Vortec" before the head re-design in '96. Unless you had newer heads installed on your engine, I am doubtful you have actual vortec heads.

Like Bond-o said, please start a new thread if you want to elaborate.

................................

 

[get smart]

Re: Mercruiser 4.6 LX

Re: Mercruiser 4.6 LX

GM has been using center bolt valve covers on both the 4.3L and small blocks since '87. They also started calling these engines "Vortec" before the head re-design in '96. Unless you had newer heads installed on your engine, I am doubtful you have actual vortec heads.

Like Bond-o said, please start a new thread if you want to elaborate.

I didn't really want to elaborate on the heads. Like I told Bond-o, the statement I made about my spark plugs was a reply to someone who had already made a comment about spark plugs in this thread. The point of my reply was about spark plugs, not the heads. He is the one that started the conversation about the heads. If you follow the chain, I never directly asked anyone about what kind of head my engine has.