Mercruiser 5.0L starting issue

[dvan1901]

My friends boat has a 1995, 5.0L Mercruiser (carb) with the Thunderbolt ignition system and an Alpha 1 drive. The issue he is having is, the boat will generally start fine first thing after priming the carb and turning it over, takes a few seconds, but starts and runs fine. The problem seems to be if he runs it for a while, say just cruising or skiing, whatever; then shuts it down and tries to restart it; you have to stay on it for like 10 seconds for it to ever turn over; really slow and tough to turn over. Last year we replaced the fuel pump as it was bad and he replaced all the spark plugs. Any thoughts on what would make it so hard to restart? Starter getting bad? Bad distributor cap? Thoughts?

 

[Bondo]

Re: Mercruiser 5.0L starting issue

Any thoughts on what would make it so hard to restart? Starter getting bad? Bad distributor cap?

Ayuh,... Or Bad wiring,...
Or Bad manifolds,...
Or Bad Carb,..
Or,...................

Probably the best bet would be to do some diagnostic Testing when it Happens....

 

[Don S]

Re: Mercruiser 5.0L starting issue

Choke inop and floods the engine when warm.

Engine needs a tuneup

Low compression

 

[dvan1901]

Re: Mercruiser 5.0L starting issue

Thanks Bond-o; I'm thinking that the first place to start may be to pull the distributor cap and seeing how bad it is worn. I read the sticky on testing the ignition system, but I'm not sure those symptoms are what he has, but we will also go through that to make sure he has good grounds and voltage. What is the best way to test the starter on these engines?

It just seems it isnt' getting enough "oomph" if you will to turn it over quickly...it cranks, cranks, cranks, coughs, cranks, starts. Know what I mean? Just seems like it is weak; but we are using fully charged batteries, and even using two batteries at times.

 

[dvan1901]

Re: Mercruiser 5.0L starting issue

Don, was posting as you were; will do a compression test as well. I believe the previous owner had moved the choke dial clockwise, which would make it rich according to the diagram; we moved it back to close to neutral, maybe need to move it some more or to true neutral.

 

[Don S]

Re: Mercruiser 5.0L starting issue

Maybe your starter is about shot.