starting problems w/ 75 hp mercury 3 cylinder

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carlton casey

Recruit
Joined
Jun 18, 2006
Messages
2
I recently bought a 1992 17ft sprint bass boat w/ a 75 hp mercury 3 cylinder. The first time out the motor died after running about 10 minutes. The problem was the oil lines from the tank and injector were broken. Problem repaired, ran fine second day out, third day out ran fine all day then suddenly died running near wot. The engine turns over fine but was not able to get the motor started. Had to be towed in. Checked gas flow and seems to be getting gas past the inline filter. I let it sit several hours but still won't start. Any suggestions as to troubleshooting would be appreciated.
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: starting problems w/ 75 hp mercury 3 cylinder

you have to have 3 things,compression, proper spark, proper fuel/air mix. check compression and spark, if ok then you have a fuel problem. did it run hot? when was the last time the water pump was serviced? and the lower unit oil?
 
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bryancx94

Seaman Apprentice
Joined
May 22, 2006
Messages
43
Re: starting problems w/ 75 hp mercury 3 cylinder

Yes important to check all those things.. Had this happen to me actually.. Check your plugs, make sure they are not fouled. I had to lean out my mixture a tad to get it firing again.
 
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marinegrh

Petty Officer 2nd Class
Joined
Sep 1, 2003
Messages
196
Re: starting problems w/ 75 hp mercury 3 cylinder

oil lines from the injection tank will not cause your engine to quit running, its a self dependent system with only an alarm tied in to warn the operator of low, or no oil. I agree with the first post, you need fire fuel and compression to make a bang, no compression no bang, you get the picture right, check those first then repost
 
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carlton casey

Recruit
Joined
Jun 18, 2006
Messages
2
Re: starting problems w/ 75 hp mercury 3 cylinder

thanks for the input from everyone. I checked compression, fuel and both were ok. I dont seem to have any spark. I pulled the center plug to check spark and didn't have any. Motor mdl. # 1075412MD thanks
 
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marinegrh

Petty Officer 2nd Class
Joined
Sep 1, 2003
Messages
196
Re: starting problems w/ 75 hp mercury 3 cylinder

nows the time to get a service manual and start following the troubleshooting procedures for the ignition system, you may need to get a meter also in case you dont have one, the stator and trigger as merc calls em need to be carefully checked along with the coils, if you dont pay attention you may get a shock you'll remember. the outputs should be in the forums from other posts...but you should see around 120 to 180 volts on the stator, ans 2-5 i believe on the trigger, the coils should put out about 180 if im right but double check your manual..good luck and repost your results
 
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