looses spark now and then/ and runs rich when it runs...

76century

Recruit
Joined
Aug 13, 2004
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3
i have a 76 century with the 233hp mercruiser 351 cleavland motor. one minuit it will have spark the next it wont. i have replaced just about everything and the same thing.... also when it runs which is seldom... it runs really rich. it has the crappy 2 brl. rochester carb on it. how do i fix the problems with it.thanks
 

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: looses spark now and then/ and runs rich when it runs...

if you can hook a meter up to the ingition circut and run the boat the meter should show a power loss at the coil if the problem is in the wireing<br /><br />if you find that it is loseing power you have to start going through the ingition circut and looking for a bad connection of other bad part<br /><br />if your not loseing power you have to look at the coil and distributer<br /><br />it could be as simple as a bad key switch or lose wire<br /><br />i dont think you can say the motor has a carb issue until you get the ingition to work 100% of the time<br /><br />tommays
 
Joined
Aug 9, 2004
Messages
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Re: looses spark now and then/ and runs rich when it runs...

not sure what you have replaced in the ignition circut - startt with plugs, wires, do the condenser and points - make sure the point gaps and the plug gaps are set properly, also check the timing - when you tune up an engine, you need to reset the timing.
 
Joined
Aug 9, 2004
Messages
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Re: looses spark now and then/ and runs rich when it runs...

also - are you sure the spark goes away - it could be running so rich that the fuel is not burning away and the plugs are getting saturated
 

76century

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Re: looses spark now and then/ and runs rich when it runs...

i have replaced all of that. but i found out that the owner befor me had the wire from the points and the condenser on the neg. side of the coil... is this right. i swithced it back to the pos. side and had the same results. BUT when i switch them back it had spark all of a sudden???? i must be missing something. could this be a pos. ground system?? also it had been sitting for a year. when you put it at full throttle it would spray gas down it from the accl. pump which is ok. BUT thats all it should have done! but it dident it just kept dripping in which i know is wrong. befor i knew it i had about 1/4 inch if gas in the manifold. so i took the carb appart and cleaned all the varnish out and yet the same thing happend. what is going on here?? any ideas??? thanks
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
Re: looses spark now and then/ and runs rich when it runs...

the points wire does go to the neg. side of coil.if your oozing gas into the carb. throat by cranking engine over then your needle valve in the carb. is leaking by.common after sitting for a long time.
 

76century

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Aug 13, 2004
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Re: looses spark now and then/ and runs rich when it runs...

it has been sitting for a while maybe a year or so. now that you have pointed me to the right direction about the the the points. so i should get a tune up kit for the carb to fik my leaking problem? and how should i tune the carb. cuz i put it into the water and it dident want to run but when it wasent in the water it ran fine... a little rich but it ran. do you think it dumping gas down the manifold it the problem???
 

surfer23505

Cadet
Joined
Jul 18, 2004
Messages
29
Re: looses spark now and then/ and runs rich when it runs...

if it is indeed a carb problem it would be good to get it profesionally rebuilt. I had ebuilt mine many times before but always had slight problem and when i finally broke down and had it rbuilt it worked great.
 

ron7000

Banned
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Jul 10, 2004
Messages
498
Re: looses spark now and then/ and runs rich when it runs...

have a merc 233 here, but the windsor 351. Sure all the accessories are the same as yours.<br /><br />step 1: remove points, condensor<br /><br />step 2: throw overboard<br /><br />step 3: buy a pertronix ignitor II, along with their Flamethrower coil. You have a prestolite distributor, correct? With a clip down cap, you need pertronix 91581; with screw down cap it's 91582. Reference page 27 of http://www.pertronix.com/ignition_products/pdf_files/ignitor_ignitor2.pdf <br /><br /><br />Don't go any further with the points !<br /><br />On the pertronix, it's very very easy to install. Red wire goes to + side of coil. Black wire anywhere there is good ground.<br /><br /><br />With the carb, and I am familiar with Holleys since that's what I run now, but usually running very rich at idle with dripping gas is an indication of a blown power valve. In any case, you will need to pull the carb and have it completely cleaned out and rebuilt, especially if it sat for a length of time. Been there, done that.<br /><br />I don't know your situation and whether it's worth it for you but before you go dumping money into an old carb, for around $400 you can get a brand new holley 4-barrel marine carb and will make worlds of difference in performance and power. The only catch is you would also need the correct intake manifold for the carb to fit on, and modify the throttle cable attachment.<br />I got my new 351w with the holley 4 barrel in 1993. Went 9 years and 500 hours before I even had to think of working on the carb, which only needed a new power valve cause I wasn't getting top rpm.
 

HULKSTERUPS

Seaman Apprentice
Joined
Mar 4, 2004
Messages
44
Re: looses spark now and then/ and runs rich when it runs...

My boat looses spark too at times.I think after it rains something is getting wet.Could it be in the key.I dont know,maybe its the coil.
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
Re: looses spark now and then/ and runs rich when it runs...

all that fancy stuff is fine if u can afford it.my neighbors 69 120h.p sea ray purrs like a kitten after new points and condenser every spring.i did the carb. once about 3 years ago and its been fine.i use to drag race with point distributors back in the 70s.
 

tommays

Admiral
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Jul 4, 2004
Messages
6,768
Re: looses spark now and then/ and runs rich when it runs...

i think the point of this thread has been lost<br /><br />It’s about interment spark and you finding out why you are loseing it<br /><br />tommays
 

ron7000

Banned
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Jul 10, 2004
Messages
498
Re: looses spark now and then/ and runs rich when it runs...

Originally posted by xltier:<br />[Q] all that fancy stuff is fine if u can afford it.my neighbors 69 120h.p sea ray purrs like a kitten after new points and condenser every spring.i did the carb. once about 3 years ago and its been fine.i use to drag race with point distributors back in the 70s. [/Q]
it's not fancy stuff, it's very simple. And compared to a points setup, you get much more energy to the plugs and better performance, in addition to never having to go under the distributor cap again. Sorry, but a points setup does not belong on a marine engine. They don't last, and are the most common source of ignition problems.<br /><br />if you find something simple like a frayed wire, or a bad coil which is only $20, then obviously you don't need to spend $100-200 and convert to the pertronix. My point was don't be penny-wise pound-foolish. The $100-200 and work you put into converting to the electronic ignition will basically guarantee you a trouble-free ignition. It's zero maintenance. And it will fix your intermittent spark problem, unless of course you have a bad ignition wire elsewhere. So before you do anything, make sure all your wiring is 100%. And check your ignition switch. <br /><br />My '93 351w came with points. I converted to the pertronix in 1995 after replacing points twice. And it has purred since, and I have never gone back under the cap for anything, not even to change the rotor. It is money very well spent.
 

HULKSTERUPS

Seaman Apprentice
Joined
Mar 4, 2004
Messages
44
Re: looses spark now and then/ and runs rich when it runs...

I was losing spark too,I just happen to disconnect the tach wire from the coil and what do you know,I got spark,I put the wire back on as the motor was runnig and the motor cut out.Then I put the tach wire on as the motor was running again and she kept running.I must have a short in the tach wire.
 
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