Wont start ...help!!!!

[jonny rotten]

Hopefully I can get some help as I have been killing myself for 2 weeks getting my boat together after 5 years and have plans tomorrow morning and now my boat wont start.

1990 Mercruiser 4.3
2 BBL Rochester carb

Yesterday it fired up cold but it took some effort to get there. Thern when it was warm it fired up instantly over and over.
Now to today it wont start cold.
The gas is 5 years old but smells ok and like I said it was running fine yesterday for a half hour in the driveway so I'm thinking the gas is ok. I had plenty of power and seemed normal

I sprayed starter fluid in the carb and it doesn't even sputter.
I cleaned the screen filter in the carb/gas line
The choke is closed at start up. Tried it closed, then opened a crack, then fully opened. And not a sputter with starting fluid. I was watching it yesterday and it opened slowly as it warmed up so I thinking its working correctly
I put a new ignition switch in so that's not it.
With the gas line off at carb I cranked it and the fuel pump is working fine
It crank over strong and has a good battery

The fact that it starts fine warm and doesn't start cold must mean something
Could that be a coil issue?
Electronic module? (That thing on the riser)


Any help would be great as I have about 4 hours to figure this out or I'm going to let down some people
THanks in advance

 

[alldodge]

The gas is 5 years old

That old and thought it would run.
Pull the filter and dump the contents into a clear jar, it will be yellow (if not brown) and may even have water in it. The motor once running will keep running with bad gas with motor being warmed up. Once it cools back down there just is not enough fumes to burn

Use a gas can and run it from it after replacing fuel filter

No serial number but may have TB4 ignition. Here is the troubleshooter

 

[tank1949]

Hopefully I can get some help as I have been killing myself for 2 weeks getting my boat together after 5 years and have plans tomorrow morning and now my boat wont start.

1990 Mercruiser 4.3
2 BBL Rochester carb

Yesterday it fired up cold but it took some effort to get there. Thern when it was warm it fired up instantly over and over.
Now to today it wont start cold.
The gas is 5 years old but smells ok and like I said it was running fine yesterday for a half hour in the driveway so I'm thinking the gas is ok. I had plenty of power and seemed normal

I sprayed starter fluid in the carb and it doesn't even sputter.
I cleaned the screen filter in the carb/gas line
The choke is closed at start up. Tried it closed, then opened a crack, then fully opened. And not a sputter with starting fluid. I was watching it yesterday and it opened slowly as it warmed up so I thinking its working correctly
I put a new ignition switch in so that's not it.
With the gas line off at carb I cranked it and the fuel pump is working fine
It crank over strong and has a good battery

The fact that it starts fine warm and doesn't start cold must mean something
Could that be a coil issue?
Electronic module? (That thing on the riser)


Any help would be great as I have about 4 hours to figure this out or I'm going to let down some people
THanks in advance

I suspect carb is full of crap. 5 years???? Pray lines and filters are just the only things packed with crud because you may need a carb or at least have it rebuilt. My gut feeling is that you will have to drain tank someway. You can purchase a cheap automotive 7-9 lb electric fuel pump for < 100 bucks. Recycle all 5 year old gas into something and discard. It may be getting some gas from filter but 5 years will reduce octane significantly. If boat sat for 5 years, check all grounds especially if salt water used. Does fuel pickup tubes have screens inside them?

 

[jonny rotten]

Thank you for the responses and helping me get on my way.
I embarrassed to say that when I was power washing the inside of the boat I blew off the little Kill switch rope up and under the side wall so I didn't see it laying around. I popped it in and it fired right up
Lessen learned. Check the kill switch