Mercury BlackMax 150HP: no power

[Tom##]

Can someone help before all the fish are gone!!! LOL

I have a 1985, 150HP Mercury BlackMax XR2 Ranger bass boat. The problem is that it will idle well enough but doesn't have enough power to get out of the hole. I changed the spark plugs and appeared to have solved the problem but it went back to the same problem. No power to get out of the hole.... I checked for water in the gas and leaking gas lines and all looks good. I also checked the compression and they average around 110. I also check that fuel was pumping into the carburetors.

I think the problem is either in the power pack or the coils. I tried to check the coils but it was hard to tell if it had a good enough spark or not. I was using a tool that I bought at the local auto part store. With this tool you can adjust the gap. One of the times I was checking the spark, I was holding onto the isolator part the coil and it zapped me.... OCHE!!! If I ohm the coil, what should I read? Is there any way I can check the power packs (inner and outer, P/N 18-5775)? Thanks for any help you can provide.

 

[AndyL]

Re: Mercury BlackMax 150HP: no power

Ahoy. Have you renewed the fuel pump diaphragms yet. Just thinking that if you had a weak fuel pump it will still probably supply enough fuel for idle running but won't keep up with the demand when piling on the power to get you out of the hole.
Only a thought!

 

[studlymandingo]

Re: Mercury BlackMax 150HP: no power

If you have indeed eliminated fuel problems (pumping the bulb while underway can simulate the engines fuel pump), then testing spark and ignition is the way to go. You could have stator issues which will either need to be tested with a DVA meter or by using an inductive timing light while underway on each of the spark plug wires.

While using the spark gap tester at idle, did you have a strong consistent spark at all cylinders?

Check the wiring over really well. I have had problems with wires from the switchboxes to the coils corroding off at the ends; I have since replaced all of this wiring which corrected similiar issues.​

 

[Tom##]

Re: Mercury BlackMax 150HP: no power

Ahoy. Have you renewed the fuel pump diaphragms yet. Just thinking that if you had a weak fuel pump it will still probably supply enough fuel for idle running but won't keep up with the demand when piling on the power to get you out of the hole.
Only a thought!

Mr. AndyL, Your help is greatly appreciated.... Thanks for advice... When i checked the fuel pump it appeared to be a little weak therefore i am going to rebuild the fuel pump this weekend and see what happens. again thanks for advise... i can already see a fish fry in the future!!

Tom##

 

[studlymandingo]

Re: Mercury BlackMax 150HP: no power

The fuel pump rebuild is a fairly simple procedure. I would go ahead and do it this week if you have half an hour somewhere, that way you can use the weekend for boating.​

 

[AndyL]

Re: Mercury BlackMax 150HP: no power

I would be delighted if the fix is as simple and cheap!!! Good luck with the fish!
Andy

 

[Tom##]

Re: Mercury BlackMax 150HP: no power

If you have indeed eliminated fuel problems (pumping the bulb while underway can simulate the engines fuel pump), then testing spark and ignition is the way to go. You could have stator issues which will either need to be tested with a DVA meter or by using an inductive timing light while underway on each of the spark plug wires.

While using the spark gap tester at idle, did you have a strong consistent spark at all cylinders?

Check the wiring over really well. I have had problems with wires from the switchboxes to the coils corroding off at the ends; I have since replaced all of this wiring which corrected similiar issues.​

studlymandingo, Well I have rebuild the fuel pump and appears that it is working fine. I also replaced the 1/4" holes as i found some them with cracks. However I was telling the mechanic my situation and he said that I could check the stator once I rebuild the fuel pump. He said to check the voltage at the switch boxes. The blue wires are the high signal going to the switch boxes and that the voltage should increase as I give it gas. I did this and the voltage went from 62@idle and to mid 50?s as I increased gas. Can you help?

Thank,
Tom##

 

[studlymandingo]

Re: Mercury BlackMax 150HP: no power

This is one that Dhadley could answer better than me. I would be looking at the rectifier for voltage issues though.​

 

[andy6374]

Re: Mercury BlackMax 150HP: no power

So rebuilding the fuel didn't help.

Try pushing in the key (for the fuel enricher) when attempting to get on plane. This will bypass the carbs, if this helps, then your carbs need a cleaning. If you have just a little crud in one or two of the orfices, then you'll have trouble getting up on plane. BTW: have you checked your fuel lines, make sure they are nice a soft without any kinks. Are you using a fuel/water separator/filter?

IF the fuel system checks out, move on to ignition system


You'll need a dva to check stator voltages, a regular multimeter will not cut it. However, take resistance measures for the stator and trigger.

If you don't have a factory manual, this will download will give you the specs.

http://cdielectronics.com/index.php?option=com_content&task=view&id=26&Itemid=34