Engine not Starting

[Lorri]

I have a 1995 Maxum 2000sr. It will start on muffs, but when we back it in the water will not start. Replaced fuel pump, bellows, and fuel filter. Please help

[mmwjr]

What engine do you have? Did you check to see if there is spark and fuel when it doesn’t start? Is this a new issue and was anything done since it last ran on the water? Lastly when you say doesn’t start, does it turn over but not start or nothing at all?

[Lorri]

4.3XL. Has spark and getting fuel. This is an issue that happened last time we tried to take it out last year. Turns over, starts and runs on muffs. Emerge lower unit in water turns over but will not start

[mmwjr]

Originally Posted by Lorri

4.3XL. Has spark and getting fuel. This is an issue that happened last time we tried to take it out last year. Turns over, starts and runs on muffs. Emerge lower unit in water turns over but will not start

Did you check to see if the run/stop (kill) switch was in the run position?

[shrew]

Back pressure in the exhaust? I assume that this is a carbureted engine?

If carbureted...Did you try priming the engine? Between the trailer ride to the ramp and the ramp angle you might need to reprime the carb.

With Mercruiser engines...

1) Put the shifter in Throttle-Only mode using the button.
2) Give the throttle 3 full pumps from neutral to WOT.
3) in Throttle-Only, advance the throttle to the detenser.
4) Start and hold the starter. (If the engine doesn't start, slowly advance the throttle.
5) Once the engine fires, bring the shifter back to neutral.

[Lorri]

Yes we have done that

[Lorri]

We have done that. We are wondering if the exhaust flipper is bad

[mmwjr]

Does it now start back at your house? If so then no water ingestion occurred ruling out the flappers.

[Lorri]

It started on the muffs. Last season when we tried to take it out, it started on the trailer. I backed it off and when I put it in forward it stalled and would not restart. Ever since it will turn over but never start again. We did get it to start on the muffs. Took it to the river and it will not start.

[mmwjr]

Originally Posted by Lorri

It started on the muffs. Last season when we tried to take it out, it started on the trailer. I backed it off and when I put it in forward it stalled and would not restart. Ever since it will turn over but never start again. We did get it to start on the muffs. Took it to the river and it will not start.

Ok but after it didn’t start at the river have you tried to see if it will start on the muffs? Sorry I’m having trouble following what you said above.

[shrew]

Originally Posted by Lorri

It started on the muffs. Last season when we tried to take it out, it started on the trailer. I backed it off and when I put it in forward it stalled and would not restart. Ever since it will turn over but never start again. We did get it to start on the muffs. Took it to the river and it will not start.

Putting it in gear and having it stall is likely the result of the shift-interrupt. It stalls the engine for a split second as the shifter goes into gear. When they fail the behavior is an actual stall. The fact that you can't restart it, might also be caused by a bad shift interrupt.

It is unclear whether after the engine stalled when you put it in gear (then failed to restart) you brought the boat back home where it started on the muffs again, then back to the river where it failed to start again???

OR did it start at the house. Started on the trailer on the ramp. Backed of the trailer, put it in gear and stalled. Then failed to start....and it continues to fail to start?

If it is the latter, then I suspect a bad shift interrupt.

[Lorri]

I'm sorry I was confusing. It wouldn't start when we got it back on the trailer. We brought it home and put the muffs on and it fired right up. Took it back to the river and wouldn't start. We haven't tired the muffs again. Doing that this weekend

[mmwjr]

Originally Posted by Lorri

I'm sorry I was confusing. It wouldn't start when we got it back on the trailer. We brought it home and put the muffs on and it fired right up. Took it back to the river and wouldn't start. We haven't tired the muffs again. Doing that this weekend

Based on this information I doubt there is a water ingestion issue. If it starts at home again and you take it back to the river be prepared to check for spark and fuel at the carburetor if it doesn’t start. The only way to isolate the issue is to test while it won’t start. You can test for spark several ways; using a timing light to see if it flashes, a spark gap tester that connects inline on a spark plus wire to ground, and removing a spark plug wire and holding it close to a good ground to see if a spark is present. The last method is common way to do it but can be hard to see in bright sunlight. Using a timing light is pretty much foolproof.

[shrew]

That is a weird problem. The only variable that is different is that the outdrive is in the water and the is likely at an angle since it's sitting on a trailer on a ramp. I can't imagine either of those causing a spark issue.

I wonder if the angle is flooding the fuel bowl and carb.

[mmwjr]

Originally Posted by shrew

That is a weird problem. The only variable that is different is that the outdrive is in the water and the is likely at an angle since it's sitting on a trailer on a ramp. I can't imagine either of those causing a spark issue.

I wonder if the angle is flooding the fuel bowl and carb.

I understand your logic and if true they can try setting the throttle to full open and crank away to see if the flood clears and the engine starts.

[Lorri]

Just tried to start on the muffs. Will not start. Can smell fuel. Getting ready to test spark plugs

[mmwjr]

Originally Posted by Lorri

Just tried to start on the muffs. Will not start. Can smell fuel. Getting ready to test spark plugs

Did it turn over but not start? If yes not water ingestion, just checking.

[Lorri]

Yes it trys to turn over. Will not start.

[mmwjr]

Originally Posted by Lorri

Yes it trys to turn over. Will not start.

This is important, does it just try to turn over or turn over. I.e. makes several revolutions or not. Also were you able to test for spark?

[Lorri]

It turns over and tries to start. It is acting like it's not get fuel. We have change fuel pump and filter