Mercruiser 4.3 / 190HP problems

C-17 Pilot

Seaman Apprentice
Joined
May 16, 2011
Messages
38
Gents and ladies,

First off, I am just now getting into boating so if my questions seem elementary, it's cause I'm not very educated on boats. I know it wasn't low on gas cause I could visually see fuel in the tank.

I "very recently" purchased a 2008 with the Mercruiser 4.3L 190HP V6. When I test drove it this past week with the original owner, it started right up, no issues. We ran it for about 10 minutes. The motor was very clean, had 60 hours on it. Again, I saw no issues. Fast forward to today, my first outing with my new vessel. Again...Started right up, but, as the day progressed, I found that it wasn't starting on the first (or second) attempt. I literally had to keep the starter engaged for 7-10 seconds, then, just maybe, it would turnover. Eventually, I gave up, and had to get towed back to shore.:facepalm:

!.) I fully charged the battery last night. I don't expect it to be the battery cause I could run the blower/radio/bilge pump with no issues.

Some initial questions:

1.) Can someone please explain if running an engine at approx 3000 RPM for 30-45 could overheat the engine. The temp gauge on the boat read within limits.

2.) Can someone explain vapor lock?

3.) How often do you recommend changing spark plugs? Could this be a potential problem. I haven't investigated corrosion in the area, but I did make sure that the wires from the plugs were tight.

If anyone has ever had these type of problems, I'd appreciate any advice for a completely novice boater. I am reading any and all forums at this time.

Thanks

**Forgot to add....once I was able to get it turned over (after 7-10 sec try), the motor wouldn't initilly respond to my power input. In fact, at times, I would move it from forward idle (in gear) to what I thought would be 3000 RPM...and the engine would just die.

I'm stumped.
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,322
Re: Mercruiser 4.3 / 190HP problems

have you checked the condition of the fuel in the water separator??
 

C-17 Pilot

Seaman Apprentice
Joined
May 16, 2011
Messages
38
Re: Mercruiser 4.3 / 190HP problems

What would I be looking for? I took the boat with an 1/8 tank, and I filled it up this morning (87 octane).
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,322
Re: Mercruiser 4.3 / 190HP problems

you would be looking for water in the filter - pour the contents into a glass jar and inspect

do you know where it is located??

87 octane "road" gasoline is NOT recommended for use in your marine engine

if possible always use a higher octane "premium" non-oxy gasoline
 

C-17 Pilot

Seaman Apprentice
Joined
May 16, 2011
Messages
38
Re: Mercruiser 4.3 / 190HP problems

1.) I do NOT know where it is located. I also do not have the service manual...I'm searching for it now.
2.) The original owner told me he used nothing but 87 octane.

Do you think I may not have enough "ump" because of the low Octane not allowing a spark? I could add an octane boost, or pump out the bad fuel? Suggestions?
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,322
Re: Mercruiser 4.3 / 190HP problems

actually lower octane fuels burn hotter than higher octane fuels, anyways, i doubt the lower octane is the problem, i mentioned it for future reference

the water separator is located on the lower STBD side of the engine, it is an oil filter style/spin on filter - i wouild check this first

have a look at this:

http://forums.iboats.com/showthread.php?t=295070
 
Top