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350 MAG MPI Flooding and Difficult To Start!

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F3LDY

New member
Hi,
Wonder If anyone can help.
I have a 2005 Mercruiser 350 MAG MPI with an Alpha Drive.
It gets serviced at least once a year and is very well maintained. It has less then 300 hours use.

At the beginning of the season after the UK winter and six month out of use, I always have trouble starting it for the first time. The engine always seems to flood.
It turns over but does not start. I end up taking out the spark plugs and drying them out, only then it will start with some effort.

Last year for the first time I noticed I had issues even when the engine was warm. I would stop the boat for half hour after a decent run and the only way it would start is if I would give it a little throttle in neutral when I felt that it was about to start. Otherwise it will just crank and crank until it floods. Note this is not the case always. Sometimes I will just turn key and go from cold. From warm about 75% of the time it will work as usual, however the other times the only way to start is it to blip the throttle as you feel it kick.
Post winter it is never just turn key.

I have changed the plugs. The leads are all good. Fuel filter is new, fuel filter gets changed and refilled with fuel before getting screwed back in.
I always hear the fuel pump kick in when I turn the key.
The problem seems to be getting more frequent!
Can anyone help please?
My Mechanic has plugged it in and it shows no faults. He cant explain it.
 
The serial number helps determine what engine we are looking at. Around 1999 Mercruiser does not list by year but by serial number.


If your spark plugs are wet with fuel I would say you have a lose of ignition. Pull the ignition coil and take a look at the bottom of it. Look for a leak.

Also Disconnect the shift interrupt next time this problem occurs just to rule it out. Don't forget to reconnect it.
 
Last edited:
I had the distributer cap changed today. It seems to have resolved the starting issue.
Time will tell.

Thanks for your help

Docksidemarineservices said:
The serial number helps determine what engine we are looking at. Around 1999 Mercruiser does not list by year but by serial number.


If your spark plugs are wet with fuel I would say you have a lose of ignition. Pull the ignition coil and take a look at the bottom of it. Look for a leak.

Also Disconnect the shift interrupt next time this problem occurs just to rule it out. Don't forget to reconnect it.
Click to expand...
 
F3LDY, I tried to reply a couple of days ago. I started to post and the page crashed on me. I have the same engine with a Bravo III same problem last summer. I changed plugs, wires, water fuel separator twice. I wouldn't start in the morning hours but by 3:00pm it kick over only if I was in neutral and giving throttle. mine was the distributer cap and really the components inside. Rotor head and contacts was full of debris. excessive moisture in the bilge during the morning hours with humidity is my conclusion. after the dist. cap change I added weather stripping to the bilge hatch. Bilge is 1000 x's drier than before. once found its an easy fix and I was told this is a very common problem. You should be brand new fast and get better gas mileage also.
 
Surprised my Mechanic has not picked up on it all this time. Seems like a simple solution. I will see how I get on in the coming weeks and post my result.
Thanks for your help

3-legged-dog said:
F3LDY, I tried to reply a couple of days ago. I started to post and the page crashed on me. I have the same engine with a Bravo III same problem last summer. I changed plugs, wires, water fuel separator twice. I wouldn't start in the morning hours but by 3:00pm it kick over only if I was in neutral and giving throttle. mine was the distributer cap and really the components inside. Rotor head and contacts was full of debris. excessive moisture in the bilge during the morning hours with humidity is my conclusion. after the dist. cap change I added weather stripping to the bilge hatch. Bilge is 1000 x's drier than before. once found its an easy fix and I was told this is a very common problem. You should be brand new fast and get better gas mileage also.
Click to expand...
 
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