Mercruiser 5.0 Difficult Start

[Sea Rider]

Hello all, having problems starting morning cold engine, so not to winterize it as our weather is not extreme cold in winter and to have this engine in excellent shape, it's started once a week for 10 minutes with muffs.

Data:
Engine is 100% operational
Gasoline used : 90 octane pure unleaded, non ethanol mixed
Carbed model

Would like to know:
This engine model uses a mechanical or electric choque ?
" " " " a mechanical or electric fuel pump ?
Is it a must to count with a water filter separator in case doesn't have one.
Usually takes 5 attempts to start and fires right up once warm.

Is there a starting cold procedure you guys would recommend ?

Happy Boating

 

[Don S]

Re: Mercruiser 5.0 Difficult Start

What is the Mercruiser serial number for your engine? Without that, it's impossible to answer some of your questions. Not all 5.0L engines are the same.

 

[Sea Rider]

Re: Mercruiser 5.0 Difficult Start

Thanks Don, will check serial number and place some engine pics...

 

[Sea Rider]

Re: Mercruiser 5.0 Difficult Start

Wow, 1/2 hour just to find this post , the engine is a Mercuriser 5.0 alpaha one drive with serial number : F792279

Just problems with first morning start, the boat lives out of the water at a marina next to sea boat parking lot. Starts fine when starting each 2-3 days, but longer will not. Is it a battery, fuel water separating filter or moisture issue ? No ethanol/gas mixed used, just non leaded high octane gas.

Happy Boating

 

[Sea Rider]

Re: Mercruiser 5.0 Difficult Start

The main problem is due to high moisture condensation on top electrical parts, once completely dried out, engine starts fine, The boat lives close to sea, at a marina parking lot and the boat has a thick cover on top. Question : If applying W-40 to all electrical parts, will this help to drive moisture out ? if not, what product would you recommend to spray or whatever on top electrical related parts. Thanks in advance.

Happy Boating

 

[Krapht]

Re: Mercruiser 5.0 Difficult Start

Move throttle to WOT two or three times when cold (sets choke, primes carb). Return to 1/4 throttle.

Turn key.

Adjust throttle to keep engine running until up to temp and choke opens.

My 2 cents.

 

[Sea Rider]

Re: Mercruiser 5.0 Difficult Start

Do I need to perform this procedure with contact on to set choque, prime carb ? then, turn key to start the engine ? Or, nope, is all done with contact "off" Thanks

Happy Boating

 

[bds85466]

Re: Mercruiser 5.0 Difficult Start

Do I need to perform this procedure with contact on to set choque, prime carb ? then, turn key to start the engine ? Or, nope, is all done with contact "off"

I think you're asking if you need to turn the key to the on position (versus off)? It doesn't matter really for setting the choke as it's all mechanical.

Using Krapht's recommendation on setting the choke should spray fresh gas into the throat of your carb and make for an easier start. 2-3 pumps might be a bit excessive. Start small. Once should be enough to get you going...You don't want to overdo it and flood yourself.

Aside: You can actually see the spray it in action if you remove the air silencer and have someone move the throttle to the WOT position. (if you don't see or hear it, you have another issue)

I see cables coming from your carb hence probably electric choke. If you open your air silencer, you should see the choke plate closed when you're starting cold. As you warm up, it should gradually open, letting more air into the mixture.

Not sure how your rig is, but if you have the key in the on position for a long enough time and you're not trying to start it, you may be warming your electric choke spring, opening the choke prematurely.

As Don said, finding your serial# can really help with more specific information.

 

[Utahboatnut]

Re: Mercruiser 5.0 Difficult Start

"contact" off (i'm assuming you mean the key) push the throttle only button in on the base of your controller, pump it 3-4 times and leave it at about 1/4 throttle. turn key if it doesnt hit right away try 1-2 more pumps and return to 1/4 throttle it should hit pretty quick. You could check the condensation issue but I would bet its a fuel issue on cold start. Mine is the same way if not run for a week or two I need to pump it 3-4 times on the first cold start and after that it hits as soon as I hit the key.

 

[Sea Rider]

Re: Mercruiser 5.0 Difficult Start

Thanks all for the help, the owner was moving throttle to wot 2-3 times, but left throttle at full wot, that's why took longer to start. One last issue, when moving throttle 3 times and returning to 1/4 position, if the engine doesn't start, should you perform again the cold starting procedure, no, just keep trying untill starts at 1/4 position. How many seconds do I need to turn key to start, pause, start at each attempt ?

Happy Boating