150 merc problem

[djwant]

I recently bought a 1988 merc 150 black max that had low hours on it. I have replaced the stader and the impeller and had the motor runnihg real nice. Now recently, it has been acting up, one minute its going along good and then it will start to miss and the horn will blow and then beep. After shutting it down and restarting it, it may run great again.Endless circle. could i be looking at a switchbox now? and if I am, should I replace both of them?

 

[greasemonkeyozi]

Re: 150 merc problem

Lets see. Is your water coming out strong from your tail tell? What is your fuel/oil mixture? Are you getting good spark on all plugs? You may be having a swich box going out.<br /> Please, Feel free to Email me at www.greasemonkeyozi@yahoo.com if your interested in professional help for your motor.

 

[djwant]

Re: 150 merc problem

yes,the water is coming out strong. My fuel oil mixture seems good, maybe a little rich with oil. It smokes a bit off the hose. the spark is good on 5 of 6 plugs, the bottom right facing the back on the motor seems to be less than the rest. switch box on that side weak?

 

[ugalboogala]

Re: 150 merc problem

hello.<br />your problem sounds alot like the one i had.I bought two new switch boxes ...didnt help.My advice is to check all plug wires and check all connections at the coils .The best way is to use a meter and check for continuity .some times doin a visual isnt good enuff.I found a bad plug wire on mine ,$350.00 later!<br />good luck

 

[JohnnyS]

Re: 150 merc problem

I had this very same issue on my 87 150 BlackMax.<br />Mine was used in salt water.<br /><br />How is the water pressure on the gauge? <br /><br />I tried the modules like you did, and many other things (T-stats, wiring, oil sensor, temp sensor).<br /><br />Ultimately, a local mechanic flushed it some 'acid'. I wish I knew exactly what that is, but I know he removed the lower unit first, then poured the 'acid' in from above (wish I understood this better).<br /><br />A bunch of gunk came out and the motor has been running better than ever. And I always flush with fresh water after every use. Basically, it was a slight blockage in the water flow somewhere. Thats also when I noticed that the water pressure went up significantly (and varied with rpm) like its supposed to.<br /><br />Take a look into it. Good Luck<br />John

 

[djwant]

Re: 150 merc problem

Thanks for the messages guys, but heres the lastest,a friend stoped in and I asked him to check out my Merc. He stood behind the motor(plugs out and hanging), I hit the key 1 click and the horn sounded 1 solid blow, I hit the key and it was the same old weak spark on number 6. Moments later I tried it again and this time I turned the key 1 click and it gave out a round of about 5 beeps and fired strong on all 6.Its the same type of thing i'm running into on the water. Earlier I switched number 6 plug to coil wire with number 4 and still, 6 was weak, so I do not think its the wire.