4.3l Mercruiser engine having problems, wants to die when running in low speed.

mperry8786

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I have a 1997 Dynasty 19 foot with a 4.3L Mercruiser engine. I just started to use the boat after it has been in dry storage for 6 years without use. It was winterized before stored. The boat was working great before. Here is my situation now. The boat starts off fine. It dies sometimes at the beginning when put in gear. After a while it runs fine at high speeds. When slowing down from moving to neutral the engine turns off. After a while of use, the engine at low speeds will pulse the RPMs. The boat will literally pulse back in forth as long as i keep it at low speeds. Typically at high speeds it runs fine but once the boat wouldnt accelerate and wanted to die. Typically after it dies it take 5 mins to restart. It feels like the boat isnt getting a constant flow of fuel. I have put fuel cleaner in the boat and new fuel. I am heading down to the lake this weekend and want to have some supplies to try and fix it. I have been reading on the forms and hear that it could be a few things including coil, fuel filter, spark plugs, carb, and vapor locking. Any ideas? Which things should i try to fix first. Thanks.
 

Don S

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

When was the last full tuneup, timing check, compression check, etc.
 

mperry8786

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

When was the last full tuneup, timing check, compression check, etc.


My guess is 6 years. The mechanic will take 2 and half weeks to take a look at it so I would like to see if i can fix some basic things first.
 

Don S

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

Along with the tuneup, change your water separating fuel filter. Don't just throw the old one away, empty the contents into a clear container and see if there is water in it.
 

mperry8786

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

Thanks, here is the parts page i found for the engine which is 430L100ks.
Is the filter that you are referencing part number 11004a 1?
Also when people reference to replacing the coil is that part number 811639 or 817378T?
"http://www.**********/parts/search/Merc/Mercruiser/1997/430L100KS/EST%20IGNITION%20COMPONENTS/parts.html"
"**********/parts/search/Merc/Mercruiser/1997/430L100KS/FUEL%20PUMP%20AND%20CARBURETOR/parts.html"

this site is blocking the beginning of the site which is boat.net
 

Don S

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

The coil is not a tuneup item, cap, rotor, and sparkplugs are. Along with a proper compression test, checking the timing, and adjusting the idle mixture and idle speed.

What is the Mercruiser serial number of your engine?

PS: model 430L100KS is a 3.0L 4 cylinder engine.
 

mperry8786

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

Looks like you are correct, i got that number off a Manuel but i am certain that it is a 4.3L so i am not sure the serial number. The boat is at a dry dock so i have no idea.
 

Don S

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

Then don't go buying any parts until you know for sure what you have.
 

mperry8786

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

the serial number is ok028941. model number 443Lc00ks. So what items do you recommend that i purchase?
 

mperry8786

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Re: 4.3l Mercruiser engine having problems, wants to die when running in low speed.

the serial number is ok028941. model number 443Lc00ks. So what items do you recommend that i purchase?

I ordered a rotor, cap, filter, and spark plugs. I did not order the coil yet. Hopefully this is what i should have done. Ill let you know if it helps. thanks for your help.
 
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