1987 blackmax problem pls help

[james1980]

My boat starts fine and idles ok. the problem is its a 18 ft boat and i should be atleast running in the mid 40's. its running in the high 30's. last night foot to the floor running 39 it got a burst and popped up to 49. what is causing the lack of power? someone told me the switch box but i dont know how to check.
any help would be great. thanks

 

[sschefer]

Re: 1987 blackmax problem pls help

Go 1/2 turn richer on the idle screws and see what happens. If it cruises up smoother to 40 or better but smokes at idle then check the accelerator pump. Might have a dirt in it or a bad diaphram.

 

[wiretwister]

Re: 1987 blackmax problem pls help

Does the engine bog down under a load or misfire??

 

[james1980]

Re: 1987 blackmax problem pls help

sschefer i will find out how to do that and let u know. lol i am boat stupid when it comes to the motor.

wiretwister some times it does bog down when i try to get on plane some times. then ill back off and try again and it will get up.

It makes no sense because it sounds so good and starts right up. i just changed the spark plugs and wires.

thanks guys for the replys

 

[sschefer]

Re: 1987 blackmax problem pls help

Richining it up should help a little with the bog and if it does, then that's a pretty good indicator of a bad accelerator pump or circuit. The circuit being the injectors, tubing and filter that are fed by the pump. Just follow the lines and check them all. The fuel input to the pump comes from a T in the carb fuel line.

 

[james1980]

Re: 1987 blackmax problem pls help

Ok i am going to try and take the boat out tomorrow and i will let you guys know whats going on. thanks for the reply's and keepem coming.

 

[CharlieB]

Re: 1987 blackmax problem pls help

james,

Don't be too quick to blame the switchbox for any lack of power at WOT.

It takes three things to make that kind of power

Compression

Fuel flow

Intense Spark

Compression should be relatively even on all cyls, the higher the better, new these engine squeezed about 135 psi but they will continue to run acceptably well as low as 100

Fuel flow, the carbs and jets must be squeeky clean, any restriction in the fuel supply will cause one or more cyls to go lean, radically raising the combustion temp and start burning the pistons, causing massive damge. Carb linkage and timing adjustment MUST BE done perfectly for reliable performance.

Spark requires voltage, more speed and load increases the demand for voltage to make that spark. If the insulation in the stator windings begins to degrade then at operating temps the coils begin to short out, reducing voltage and the ability to create a hot enough spark to carry that load, resulting in a limited RPM. Testing stator output with a DVA meter is about the only good method of determining an ignition fault.

 

[Karl_Childers]

Re: 1987 blackmax problem pls help

Sounds like water in your fuel to me. Do you have a seperator? If you don't, get one. In the meantime, drain your carbs, and change your sparkplugs. Let us know what the outcome is.

Rob

 

[cannonford57]

Re: 1987 blackmax problem pls help

you didnt say if the engine was carbed or injected...if its carbed there is no low speed adjustment i dont think,if it picks up when you hit the enricher valve then you have a carb problem if not i.ve got to go with karl on fuel contamination

 

[james1980]

Re: 1987 blackmax problem pls help

hey guys i told you i was motor stupid right? well i didnt the spark plugs and all wires. started messing with the trim that doesnt work well with a leak and................ as long as i trim motor up on blast all works great. im getting out the hole fast and right on plane. running 52 with me and one other.

new problem i have a gas leak. i take the box off to get to the carbs and seal to the box is messed up. turn the key on and the middle left jet is spitting fuel witch is leaking out of the messed up gasket???? its always something huh?

 

[sschefer]

Re: 1987 blackmax problem pls help

While there are several things that can cause a carb to spit fuel the most common and least expensive to repair is a stuck float. Try tapping on the bowl of the carb with a wooden dowel to see if you can free it up. If that doesn't work then the carb should be disassembled and rebuilt.

Since you wisely admit to not knowing much about these engines you'll probably need a marine mechanic for the work. You should suggest that he perform a primary and secondary compression check on the engine. The primary check will give you information as to the condition of the crankcase seals and the reed blocks. The secondary will tell you about the condition of your cylinders, rings and pistons.

Armed with that info, you can make and informed decision as to the ammount of money you want to invest in further repairs.

 

[james1980]

Re: 1987 blackmax problem pls help

sschefer where can i get the info on a breakdown on the carb? like a diagram.

and thanks for the info. i am trying to do the least expensive way but with it being a FREE boat i cant complain. is there a way i can post a vid on here i took with my phone?

 

[james1980]

Re: 1987 blackmax problem pls help

sschefer i pulled the carb and cleaned it. it was a #@$@# putting it back on. well one bolt was. lol. Thanks for all the info. as far i can tell it works. im going to put it on the water tonight or tomorrow

 

[sschefer]

Re: 1987 blackmax problem pls help

Great, hope you got it. I go to http://www.crowleymarine.com for parts breakdowns and diagrams. I order from them occasionally but usually find the parts I need right here on iBoats.

FYI, I sent a note off to iBoats to see if they could come up with a similar parts id system for their website. Haven't heard back yet.

As for video you can put it on youtube or photobucket and then post a link here.

 

[james1980]

Re: 1987 blackmax problem pls help

I took the boat out last night for a tourny and she ran GREAT. the first 10 sec she didnt want to get on plane but as soon as she did i was running 50. hell and i took 3rd last night!!!!! lol thanks again for the info you guys rock.