problem on my 1990 mariner 75hp

[Timberghost]

i have a 1990 mariner 75hp 3cyl that has always ran great until i took it out friday.. at idle it seems to cough and back fire out the exhaust..i ran a compression check and all 3 cyl has 126 to 128lb,, anyone know what the problem could be and anyone here mind helping a fellow fisherman out with helping me get it fixed.,i cant fish until i get it straightened out. so your help would greatly be appreciated..thanks in advanced...

 

[smokinbasser]

My guess would be to check the fuel system for bad gas 1st then the ignition system 2nd

 

[Timberghost]

flushed fuel system replaced filter and put fresh gas and still have the idle coughing and back fire,,at wide open throttle it runs great no missing and i checked all 3 plugs has hot blue fire at all 3 plugs..seems after warmed up it doesnt back fire or cough, only at start up and when i hook the water hose to it and crank it here in the yard it acts like its loading up and smokes really bad like its flooding bad

 

[wrechin2]

That should be a CDM ignition engine. They run on 2 cylinder at a idle and at around 1800 pull the 3 one in. It may be a either.

It may be a lean sneeze (souds kinda like a cat sneezing) or if a true backfire will be in the igniton. There are a few possibilies. I see a few CDM's go bad and they run like dog do-do. Do you have access to a a timing light???

 

[Bubbakat]

Time for a good carb cleaning and rebuild. Sounds like some trash in one of the idle circuits.

 

[wrechin2]

You had posted the same time I did... I agree Bubbakat, but may also be a diaphram in the fuel pump with a pin hole flooding 1 cylinder. If you build the carbs also do the fuel pump so you can ensure the fuel system is good. JMO...

If you PM me your address I can email you the carburetor section out of the FACTORY service manual so you can do it correctly.

 

[Timberghost]

i dont have a timing light,,i have never had the carbs cleaned since i have owned it and i think that would be a good idea to have done..know anyone who can do that for me..

 

[Timberghost]

wrechin2 - 11/1/2009 10:44 PM

You had posted the same time I did... I agree Bubbakat, but may also be a diaphram in the fuel pump with a pin hole flooding 1 cylinder. If you build the carbs also do the fuel pump so you can ensure the fuel system is good. JMO...

If you PM me your address I can email you the carburetor section out of the FACTORY service manual so you can do it correctly.

pm sent thanks gary

 

[wrechin2]

Sent in email...Section 3a is for the fuel pump and 3B is for the carbs. Hope this helps...

 

[Timberghost]

i'll take a look at it tomorrow and see if its a job im capable of doing,,id hate to mess them up. lol

 

[wrechin2]

Pretty simple carbs.....

 

[Timberghost]

lol. i dont know,,looks harder to me to get them off than to take them apart and clean them..lol.,,,i might have to have a pro do it,,i could fix myself right out of a boat emoBigsmile

 

[wrechin2]

They are VERY simple carbs. Just follow the book and you will be fine. Just use common sense when working on them.