How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Tan Your Own Question
Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10806
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
25721800
Type Your Boat Question Here...
Tan is online now
A new question is answered every 9 seconds

Have a 1995 Mercury 150 2-stroke. Would crank and run but would

Customer Question

Have a 1995 Mercury 150 2-stroke. Would crank and run but would not run at top end under load. We were told that the stator went bad. Replaced the stator. Now it won't crank. It seems like it's not firing.
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.
Hello. My name is***** the black/yellow wire from the switch box. Do you have spark now?
Customer: replied 1 year ago.
Hi Tan. The switch box... is that where we connected wires from the stator? There isn't a black/yellow wire.
Expert:  Tan replied 1 year ago.
Correct. This will be a black wire with a yellow stripe. Post the engine serial number please.
Customer: replied 1 year ago.
Found the black wire with yellow stripe. Disconnecting now.
Serial number OG229796
Expert:  Tan replied 1 year ago.
Ok
Customer: replied 1 year ago.
Disconnected it and it's still not starting.
Expert:  Tan replied 1 year ago.
Do you have spark?
Customer: replied 1 year ago.
We had spark to 2 of 4 we checked
Expert:  Tan replied 1 year ago.
Are these on the same side? So you have spark on only 2 cylinders? Do you have a peak reading volt meter?
Customer: replied 1 year ago.
I am not sure I checked the spark correctly. How would you suggest the best way. I have a 12 volt meter that's all.
Expert:  Tan replied 1 year ago.
The correct way to check for spark is with the use of a spark gap tester. The spark must jump a 7/16" gap on all cylinders. Now did you squeeze the primer bulb up firm and are you choking the engine when cranking? Just checking I'm sure you know how to start your engine but I have to ask.
Customer: replied 1 year ago.
The bottom right bit me pretty good when we turned the motor over. Bottom left just a bit.nothing with the others.
Expert:  Tan replied 1 year ago.
Ok we know the stator is good as it is new leaving the trigger and the switch boxes. Does your ohm meter have ohm scale to do ohm checks? We can do an ohm test of the trigger. If it checks good then the switch boxes are bad. There is no test for switch boxes.
Customer: replied 1 year ago.
My meter only just checks 12 volts. Will that work?
Expert:  Tan replied 1 year ago.
Sorry it will not. Are you sure you have all the wires connected correctly on the switch boxes when you replaced the stator? Here is a diagram to verify. You said it ran at low speed so something has changed besides the stator. Lets just be sure of the wiring just in case something got crossed.http://www.maxrules.com/oldmercs/Wiring/1966ona/79_88_V6.jpg
Customer: replied 1 year ago.
Don't think this is the correct diagram.I have four yellow wires. However the ble and red ones on the inner band outer switch box are the same as on the diagram. The purple wire on the inside switch box looks pretty worn, but otherwise everything looks the same
Expert:  Tan replied 1 year ago.
The ignition wiring is the same from 88 through your model year. The yellow wires are for the charging system. That is different but has nothing to do with the ignition wiring. So if it is wired the same on the switch boxes you are good. So now we are at a point we need to do some testing of the trigger. Now if any of the wiring is questionable it can cause an issue. Can you get a ohm meter?
Customer: replied 1 year ago.
Here's what it looks like on my end
Expert:  Tan replied 1 year ago.
Disconnect these 2 wires circled in red.See if the engine cranks. Be sure to have water connected to the engine. To shut engine off if it starts push the choke or disconnect the fuel.
Customer: replied 1 year ago.
Still doing the same thing. The engine is turning over but it doesn't sound like it wants to hit to crank.
Expert:  Tan replied 1 year ago.
Ok we have done all we can till we get a ohm meter. We really need a DVA adapter to do a voltage out put test from the trigger and the stator just to be sure. Here is the meter we need to find the problem with your engine. http://www.maxrules.com/fixtools530.html If you want to get this meter and post back we can find the problem.
Customer: replied 1 year ago.
Think we may have found one, heading to pick it up now...
Expert:  Tan replied 1 year ago.
Ok
Expert:  Tan replied 1 year ago.
Pick up a adjustable spark gap tester also.
Customer: replied 1 year ago.
Ok
Expert:  Tan replied 1 year ago.
I'll be here.
Customer: replied 1 year ago.
This is all they had. Will it work?
Customer: replied 1 year ago.
And they have a gap tester for spark plugs, but it's not adjustable
Expert:  Tan replied 1 year ago.
That is just a standard volt meter with ohms. We can do an ohm test but that will not be as accurate as the peak reading volt meter. The gap tester has to be adjustable as we have to check the strength of the spark.
Customer: replied 1 year ago.
Okay. There's nowhere else to try tonight, and I'm not sure what will be open tomorrow,but we'll keep looking
Expert:  Tan replied 1 year ago.
Ok it needs to be a peak reading volt meter. The other tester you can use is a DVA adapter. https://www.google.com/shopping/product/6839087715725588451?rls=aso&client=gmail&q=DVA+adapter&authuser=0&sa=X&ved=0CH4QuSRqFQoTCOvi8Ka998YCFdCbiAodBDACXw
Customer: replied 1 year ago.
Okay. If we have to order this stuff, we're only at the coast with our boat on weekends,so it'll be next Saturday before we have what we need to work on it again.
Expert:  Tan replied 1 year ago.
That's fine I work all the time. I'll be available. Just post back as you have been and I will get your reply.
Customer: replied 1 year ago.
Okay, thanks!
Expert:  Tan replied 1 year ago.
Your welcome.

Related Boat Questions