Mercury sports jet problems

[Antfish]

Hi
I have an old second hand mercury sports jet 175 v6 on a 4m aluminium boat. I think its 99 model. When the guys built it they got a 2nd hand 175 v6 sports jet but combined it with a m210 pump. The boat was also very sluggish and never got up to revs. When i bought it, we changed the impellor to the correct sized one for the 175. I was told that the m210 pump and the pump for the 175 v6 are the same except for different impellors. I bought the boat as i got it for next to nothing.
We are still battling with it, we can barely get on the plane, doing max 32km/h but thats a battle to get there. Getting max 4800 rpm and have to drive full throttle. It kind of feels like the boat or impellor is heavily overloaded. Ive had a friend the said the intake grate can be too big letting in to much water?
I have also read it can be some type of ignition problem. But at 4800 rpm surely the boat should be on the plane?
When testing it out of the water it can rev up to 5600 easily. But in water stationary max is about 4000 .
Im a bit lost as to where to start looking? Unfortunatly based in Zambia, so to come across spares may take time.
Any advice/suggestions is welcome and is appreciated?
Thanx

cheers
Ant

 

[deubank1776]

Sport Jet 90 Will not plane and has no speed, HELP!

Ive been working on this boat for a few months and have her runnng great. My problem is i cant get the boat to plane out or gain any kind of speed. I thought it was the ride plate seal so i replaced that this morning and took the boat out for a test just to find out it still doing the same...

forums.iboats.com

Here this might help.

 

[Wrigman]

I recently became the second owner of a Alumaweld 17’ stryker with a sport jet 120. The motor crank, but not start at first. Got the motor to start, idle throttle up on hose, but once put into the water, it would stall and not start back up. The pump was in great shape, so knew it wasn’t binding. Put a small fortune in hard to find parts into it, only to find out there is a small fracture in the engine block. To find a new XJ2 block at a reasonable price was a lesson in frustration.
I learned that a re-power was the best plan. Even if I got the Sport jet running, when it broke down again parts would be a bear to find and expensive. Plus Mercury abandoned the platform long ago.
I live in Northern Idaho, I could only find one shop that would look at the boat about 60 miles from home. The owner told me he could put together a reliable package to together at a price point close to or less than rebuilding the whole Sport jet package. He sourced a Mercruiser 3.0 130hp motor new, an American turbine AP 390 pump with a machined impeller to match the motor, and a Kodiak adapter to join them together. The boat with three adults and some gear can get up on plane within 10 seconds And do 38mph at 4,500 rpm. It’s better on fuel than a two stroke and much more quiet. A lot of fab had to be done, but it has been done right so that there are no hull problems down the road. The big plus is it all has three year warrantys on the pump and motor. I know I can’t give the name of the shop, but I think I can say he is in Post Falls Idaho on the Spokane river. The guy is honest and does fantastic work.. oh and American Turbine is impressed with this conversion as am I.

 

[Diplomasta]

Hi
I have an old second hand mercury sports jet 175 v6 on a 4m aluminium boat. I think its 99 model. When the guys built it they got a 2nd hand 175 v6 sports jet but combined it with a m210 pump. The boat was also very sluggish and never got up to revs. When i bought it, we changed the impellor to the correct sized one for the 175. I was told that the m210 pump and the pump for the 175 v6 are the same except for different impellors. I bought the boat as i got it for next to nothing.
We are still battling with it, we can barely get on the plane, doing max 32km/h but thats a battle to get there. Getting max 4800 rpm and have to drive full throttle. It kind of feels like the boat or impellor is heavily overloaded. Ive had a friend the said the intake grate can be too big letting in to much water?
I have also read it can be some type of ignition problem. But at 4800 rpm surely the boat should be on the plane?
When testing it out of the water it can rev up to 5600 easily. But in water stationary max is about 4000 .
Im a bit lost as to where to start looking? Unfortunatly based in Zambia, so to come across spares may take time.
Any advice/suggestions is welcome and is appreciated?
Thanx

cheers
Ant

Check spark on each cylinder. You have one ignition box for each side of the motor. No spark at all, is bad stator (or both ignition boxes are bad, less likely). Only 3 spark on one side is bad ignition box. No spark on only odd or even cylinders is bad trigger. No spark on only one cylinder is bad coil. An intermittent dead spot in a particular throttle position is a bad trigger.
This may not apply to you, since yours runs, but for the reader make sure the key switch is opening the kill circuit. A Good keyswitch will deliver ground to the kill wire when shut off, and read open circuit when key is switched on. At NO time should 12v go to the ignition box! If it does, it WILL blow the ignition box (switchbox).
Check compression. 120 or higher is good. 100 is passable. 85 will work. But anything below 60 psi, won't light off from the spark.
Make sure all carb throttles are moving together at the same moment. If there is any question about the carbs, pull them and check that the float is opening far enough. And finally, rebuild the fuel pump, if you haven't in a while. It's just a couple diaphrams and springs. Make sure check valves are clear and able to close.
Somewhere along the way of doing all this, you should encounter what is ailing your motor.