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Sportjet 175 xr2 low RPM Issues

J

James Grant

New member
OK I have a Merc Sport Jet 175xr2. I can not seem to get above 4200 RPMs with her. Here is what I have done \ checked. Im kind of at a lost of where the issue would be. I lean towards timing but it was a mess to time the first round (see comments about stator).

Electrical:
New keyswitch and wire harness was installed last season - this was due to other issues. Merc certified installer did the install and from my double check all is right here.

New Stator - This was from a no start condition and resolved that issue. It was around this time the low RPM item showed up. They had issues getting the boat to time right. They set to factory timing marks checked with multiple guns but it was not timing correct. They ended up timing on the water and we got pretty good - was at least taching up to 4800. Its only run a couple times since.

New spark plugs - changed at the start of the season. Didnt expect it to work miracles but knew it would not hurt either.

Spark check - I used a spark light and all 6 cylinders are firing and seem to be firing strong.

Fuel:
Carbs rebuilt last season, cleaned this seasons with just a minor pull off sprayed through jets with cleaner etc. Simple clean basically. No change pro or con here.

Verified fuel flow - Fuel is spraying out very strong on the line to carbs. Fills entire hose and pulses as I would expect.

Engine:
Verified compression to be within specs and even over all cylinders​
 
Spark check - I used a spark light and all 6 cylinders are firing and seem to be firing strong.
Click to expand...
Spark at higher RPM may not be good enough. Read the spark plugs to figure out which coils may not be firing properly. Test the spark w/a gap tester set at 7/16"...spark should snap loudly w/a bluish color. Yellow or white spark is weak.
 
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That makes sense. Can you explain a bit more on the right way to do the spark test. Should the gap be set to 7/16 and then just try to turn the engine I assume? I don't have a gap tester in my tool set but I believe a friend of mine does.
 
Should the gap be set to 7/16 and then just try to turn the engine I assume?
Click to expand...
Correct. You want one that will test all the coils together so you can compare spark between them.
 
New Stator - This was from a no start condition and resolved that issue. It was around this time the low RPM item showed up. They had issues getting the boat to time right. They set to factory timing marks checked with multiple guns but it was not timing correct. They ended up timing on the water and we got pretty good - was at least taching up to 4800. Its only run a couple times since.


This is where I would look. Changing the stator does not effect timing unless you have the bolt holes wrong.
 
James Grant said:
OK I have a Merc Sport Jet 175xr2. I can not seem to get above 4200 RPMs with her. Here is what I have done \ checked. Im kind of at a lost of where the issue would be. I lean towards timing but it was a mess to time the first round (see comments about stator).

Electrical:
New keyswitch and wire harness was installed last season - this was due to other issues. Merc certified installer did the install and from my double check all is right here.

New Stator - This was from a no start condition and resolved that issue. It was around this time the low RPM item showed up. They had issues getting the boat to time right. They set to factory timing marks checked with multiple guns but it was not timing correct. They ended up timing on the water and we got pretty good - was at least taching up to 4800. Its only run a couple times since.

New spark plugs - changed at the start of the season. Didnt expect it to work miracles but knew it would not hurt either.

Spark check - I used a spark light and all 6 cylinders are firing and seem to be firing strong.

Fuel:
Carbs rebuilt last season, cleaned this seasons with just a minor pull off sprayed through jets with cleaner etc. Simple clean basically. No change pro or con here.

Verified fuel flow - Fuel is spraying out very strong on the line to carbs. Fills entire hose and pulses as I would expect.

Engine:
Verified compression to be within specs and even over all cylinders​
Click to expand...
Hey did you ever figure this out? Im having the same issues.
 
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