94 Mercruiser idle problem

[dvan1901]

my buddy just bought a 94 Sea Ray with a V8 Mercruiser, carburated, with an Alpha 1 outdrive. The problem he is having is; when he first puts the boat in the water, it fires right up and runs good. The idle seems a little low, but is ok. Then, after he runs it for a while and then goes to put it in neutral, it stalls. Once it stalls, it is really hard to get started again; you have to stay on the starter for several moments for it to turn over. His idle RPM is about 700-750. Any thoughts? Also, what is the manual number for that particular engine (I don't have the SN handy). Thanks!

 

[DayCruiser]

Re: 94 Mercruiser idle problem

I had a similar problem with mine. Carb needed rebuilding. Also change fuel filter in fuel pump while you are at it

 

[Bondo]

Re: 94 Mercruiser idle problem

Ayuh,....

Idle is about Right,... Spec. is 650/ 750rpms at idle, in gear......

It Might be a Carb problem,....
Or,...
Possibly the Lower Shift Cable is dragging.....

 

[dvan1901]

Re: 94 Mercruiser idle problem

Bond-O, I compared his idel to mine just to see if it was close. Mine is a 5.0 MPI and they are about the same, his boat just sounds like it's low idle so maybe it isn't getting enough fuel? Maybe not enough air? I thought maybe it was a lower shift cable as well after reading similar problems here so we applied some oil to that to help. I forgot to mention, the only way we have been able to start it again after it has been running is to put it in full throttle neutral. Then it will turn over...

 

[Bondo]

Re: 94 Mercruiser idle problem

I thought maybe it was a lower shift cable as well after reading similar problems here so we applied some oil to that to help.

Ayuh,...... If, by chance, that Is the Problem,..... No amount of Oiling will Fix it...

I forgot to mention, the only way we have been able to start it again after it has been running is to put it in full throttle neutral.

That would lead me to believe it's Flooding....

When it Doesn't Start,.....
That's the time to Diagnose it...... Does it have Fire,..?? Fuel,..?? Too much Fuel,..??
Is the Shift Switch Centered,..??

 

[dvan1901]

Re: 94 Mercruiser idle problem

Agree about the shift cable...
I found the service manual and troubleshooting manual and what it sounds like is it is flooding. From the manual, the starting procedure for a flooded engine is "while in neutral, move to full throttle (be prepared to quickly throttle back to 1000-1500 RPM)" like I added before, this is the only way we could start it back up. It definately has fuel, I can verify that with the site tube up the side. I'm looking through the Tech book and one thing it says is if it is too rich, to adjust the choke clockwise to make it leaner. He had some outdrive work done and the mechanic said he should start with that same adjustment and see if that helps. Yesterday, while on the water, we adjusted it about 1/16", but may need to do more?

 

[DayCruiser]

Re: 94 Mercruiser idle problem

Oh ya, let me add the electric choke mechanism was bad too. Same problem you are having. So if its not the carb then check the choke

 

[Bondo]

Re: 94 Mercruiser idle problem

It definately has fuel, I can verify that with the site tube up the side.

Ayuh,......

The Fuel Pump is JUNK..... That Sight Tube is Supposed to be DRY......

 

[Don S]

Re: 94 Mercruiser idle problem

That "Sight Tube" is clear so you can see fuel in it IF the fuel pump goes bad. When the fuel pump diaphram is ruptured, raw fuel pumps into the carb instead of in the bilge thru that hose. Sure it causes flooding, but it also tells you it's time for a new MARINE fuel pump.

 

[dvan1901]

Re: 94 Mercruiser idle problem

AAAHH! Ok, thank you Bond-O and Don S; I thought the site tube was to verify, by site, that the carb was getting fuel. I just found in the manual what you said Don S. Which manual will help show how to replace the pump for us? Thanks again!

 

[Don S]

Re: 94 Mercruiser idle problem

Manual 17 is the one needed for a 93 to 97 V8, but it doesn't give any details on how to change a fuel pump except to say remove the lines and bolts, new gasket and reverse for installing.
You do want to make sure you get the push rod in the block on the arm of the pump correctly.

 

[dvan1901]

Re: 94 Mercruiser idle problem

When I click on manual 17 from this link: http://www.boatfix.com/merc/Servmanl/srvcovr.pdf
it says it cannot be displayed (broken link). Am I in the right area?

 

[Don S]

Re: 94 Mercruiser idle problem

It isn't a downloadable manual.