just put in new plugs and engine seems to almost drown when revving

[markn88]

So I put new plugs in and now when I'm reving engine quickly and bringing the throttle back it seems like the engine struggles to sustain the idle for a second then returns to normal. I took one plug out and it looks wet, is that normal and is it contributing to my rough return to idle



this is a picture of the new plug after about 2 minutes of running it

 

[alilley]

Re: just put in new plugs and engine seems to almost drown when revving

first question is what motor?? wha plugs did you put in it?

just by looking at the pic it looks to be runing a little on the ritch side but it sounds to me like your carb is still flowing to much fuel through it when you shut it down. only 2 mins of run time you really cant get a idea on how it is running as it is not warmed up jsut my thoughts

 

[Don S]

Re: just put in new plugs and engine seems to almost drown when revving

For one thing, it's the wrong plug. Look at the carbon marks on the plug. The threads of the plug are way past the threads in the head.

What kind of spark plugs are they? If champion, that alone would cause your problem.

 

[RogersJetboat454]

Re: just put in new plugs and engine seems to almost drown when revving

This only started to happen after you replaced the plugs?

Plugs that are wet and look like what you have are indicative of either a rich mixture, or misfire.
Did you get the correct plugs for your engine?
What engine is installed in your boat (year, displacement, model number)?

 

[Don S]

Re: just put in new plugs and engine seems to almost drown when revving

Assuming you are talking about the 88 3.0L in your profile, you should have the AC MR43T or NGK BR6FS (Short) plugs in your engine.

 

[RogersJetboat454]

Re: just put in new plugs and engine seems to almost drown when revving

Assuming you are talking about the 88 3.0L in your profile, you should have the AC MR43T or NGK BR6FS (Short) plugs in your engine.

Those plugs would also have the proper taper seal rather than a crush gasket too!

 

[Don S]

Re: just put in new plugs and engine seems to almost drown when revving

Those plugs would also have the proper taper seal rather than a crush gasket too!

But he got such a good deal on those plugs :facepalm:

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

alright i have 88 mercruiser 3.0... and i got these because the old ones were fromt the orginal motor and these are acdelco rapid fire plugs

 

[RogersJetboat454]

Re: just put in new plugs and engine seems to almost drown when revving

But he got such a good deal on those plugs :facepalm:

Reminds me of the time an older gentleman breezed into our shop and said "I need a spark plug for a lawn mower". We told him sorry sir, but we wouldn't have spark plugs for lawn mowers just regular automotive plugs. He replied "It's a lawn mower, you can put any spark plug in it". We tried to explain to him that he can't but he left in a huff. Later on I just so happened to be in the local hardware store, when I heard a familliar voice bellow "I need a spark plug for my lawn mower". Person at the parts counter said "OK sir, what kind of engine is on your lawn mower?". "I dunno, it's a lawn mower, any spark plug will do"! "Well no sir, there are specific plugs for specific applications, you can't just put any spark plug in there" "Grumble, ramble, grumble"......

And thats my long boring stupid story of the day...

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

Reminds me of the time an older gentleman breezed into our shop and said "I need a spark plug for a lawn mower". We told him sorry sir, but we wouldn't have spark plugs for lawn mowers just regular automotive plugs. He replied "It's a lawn mower, you can put any spark plug in it". We tried to explain to him that he can't but he left in a huff. Later on I just so happened to be in the local hardware store, when I heard a familliar voice bellow "I need a spark plug for my lawn mower". Person at the parts counter said "OK sir, what kind of engine is on your lawn mower?". "I dunno, it's a lawn mower, any spark plug will do"! "Well no sir, there are specific plugs for specific applications, you can't just put any spark plug in there" "Grumble, ramble, grumble"......

And thats my long boring stupid story of the day...

haha well i got these because they said they were the same size and "supposedly" have a faster fire which i figured would help when the engine is at WOT

 

[RogersJetboat454]

Re: just put in new plugs and engine seems to almost drown when revving

alright i have 88 mercruiser 3.0... and i got these because the old ones were fromt the orginal motor and these are acdelco rapid fire plugs

What's the part number on the new plugs you installed?

Don posted the correct part numbers for either AC Delco or NGK plugs that you should be using.

Word to the wise in the future, check what plugs work for your application in either the service manual, or with the person at the parts counter. When you actually replace the plugs, compare the plugs that you are pulling out with the plugs you are installing. They should be the same length, with either a taper where the threads end or a metal gasket. And the porcelain surrounding the electrode should be a similar shape. Make sure to gap your new plugs too!

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

What's the part number on the new plugs you installed?

Don posted the correct part numbers for either AC Delco or NGK plugs that you should be using.

Word to the wise in the future, check what plugs work for your application in either the service manual, or with the person at the parts counter. When you actually replace the plugs, compare the plugs that you are pulling out with the plugs you are installing. They should be the same length, with either a taper where the threads end or a metal gasket. And the porcelain surrounding the electrode should be a similar shape. Make sure to gap your new plugs too!

well they are ac delco rapidfire ac delco 037-4

 

[RogersJetboat454]

Re: just put in new plugs and engine seems to almost drown when revving

haha well i got these because they said they were the same size and "supposedly" have a faster fire which i figured would help when the engine is at WOT

Yep, they were wrong.

May be no harm no foul this time, but like I said in a previous post, you have to match what your getting to what your pulling out.

If your engine had a plug that went directly, or near directly into the combustion chamber instead of at an angle, you may have been looking at damaged pistons right now.

 

[Don S]

Re: just put in new plugs and engine seems to almost drown when revving

they said they were the same size and "supposedly" have a faster fire

Helluva salesman wasn't he

What they meant was "These will get them off our shelves faster, since they don't fit anything and we have had them in inventory for years."

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

This only started to happen after you replaced the plugs?

Plugs that are wet and look like what you have are indicative of either a rich mixture, or misfire.
Did you get the correct plugs for your engine?
What engine is installed in your boat (year, displacement, model number)?

how do i reduce richness

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

Helluva salesman wasn't he

What they meant was "These will get them off our shelves faster, since they don't fit anything and we have had them in inventory for years."

lol

 

[Don S]

Re: just put in new plugs and engine seems to almost drown when revving

how do i reduce richness

Put in the right spark plugs....................

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

out they go lol

 

[Don S]

Re: just put in new plugs and engine seems to almost drown when revving

What kind of plugs were they?

Your problem probably comes from the plug firing in the wrong location in the cylinder.

 

[markn88]

Re: just put in new plugs and engine seems to almost drown when revving

]well they are ac delco 037-4