Need to confirm what a new mechanic is telling me?

[Bull54]

I have recentlly relocated in Savannah, Ga adn had to find a mechanic and decided to try a local guy here that has his own repair businest. His prices are half of what he normal marine shops charge so......

I have a 1987 45HP Mercury. I was running good then gradually starting running slower and slower and I had excessive gas use, with fuel coming out of the top of the top carb. The WOT speed was approximately 6mph(Handheld GPS) and 2400 RPMS on tach. In the yard on the muff it would run fine with a small miss but nothing that was bad. Sometimes it was hard to start but always did eventually start. I chalked this up to the carbs needing to be rebuilt.

I finally was able to get the boat to the new mechanic to have the carbs rebuilt. He rebuilt the carbs and check the compression and the spark. He states that the compression and the spark are good but he states that cylinder #1 and #2 are dropping and he is thinking it is the switch box. He has not put it in the water only put it on the muffs.

I guess the question I have is this correct? Or could he be correct? Other than the excessive fuel adn the low RPM's at WOT I have had no issues and the motor has been runnign good. The stator was replaced about 9 months ago with a brand new one, so I am assuming that should be still good but I do know with electrical stuff you never know.

Anyone have any ideas on this? Being my mechanic is new to me. I am just not sure if I trust him yet or not. I don't want smoke blown up my butt for no reason but if what he said is true then I guess I can trust him.

Would appreciate any comments on this thanks.

 

[j_martin]

Re: Need to confirm what a new mechanic is telling me?

He is probably right. Put it in the lake. If it still balks, go back and have him change the switchbox. If carbs were puking, they needed overhaul anyway. Nothing lost so far.

 

[Bull54]

Re: Need to confirm what a new mechanic is telling me?

Thanks for the quick response!

I am wondering though what woudl be the chances of say bad wires or connections or maybe the coil packs? I realize there is a testing procedure for these but just wondering if based on what we know so far if I could rule those out and pretty much know it is the switch box?

 

[CharlieB]

Re: Need to confirm what a new mechanic is telling me?

There is NO RETURN on electrical parts.

Systematic testing makes for a simple process of elimination.

Verify each part tp eliminate it and move on to the next.

Buy a DVA meter or a DVA adaptor for a standarde volt/ohm meter.

Download and study the free Ignition Troubleshooting Guide found on the Support pages of CDIElectronics

Remove the sparkplugs and ground all the plug wires. Connect one wire at a time to an adjustable gap spark tester set to 7/16 inch gap.

Disconnect the throttle cable and while cranking, testing spark, move the throttle lever all the way open and closed. If spark fails during movement you may have a broken trigger wire.

Use the DVA test spelled out in the Troubleshooting Guide to verify trigger output, stator output on both low speed and high speed windings.

If motor still misfires under load verify spark loss using an inductive timing light, when spark fails the light will stop flashing.

If the timing light shows an intermittent spark loss AND both trigger and stator check out THEN order a switchbox.

 

[Bull54]

Re: Need to confirm what a new mechanic is telling me?

Thanks

 

[Bull54]

Re: Need to confirm what a new mechanic is telling me?

Well we did all the checks and everything seemed to be fine but from the switchbox to 2 of the coils there was hardly any readings of power going to the coils. Went and switched the switchbox out for a new one and now all 4 coils are receiving the same readings regarding power to them. It was only running on 2 cylinders. Now on the muffs it seems like it is running much better and will put in the water this afternoon after work to see how it runs.

Thanks for the replies and help on this.