Engine looses rpm at full throttle after injector cleaner

[ErikC]

After running a tank of gas with injector cleaner additive, the engine looses rpm.
Description if issue:
At idle, I go to 3/4 throttle and rpm climbs to 3200. I then go to full throttle and rpm drops to 2000 rpm. If I throttle back slightly the RPm's climb back up or if I quickly cycle the throttle from full to half and back to full the rpm will climb back up to 3200 rpm and stay there at full throttle. Once on plane throttling is not an issue, only on start-up.

When I noticed the problem, I changed the spark plugs and that made a big difference on engine acceleration response but no change to issue above.

30 hours ago I changed the fuel filter so that should not be the problem, good fuel in tank. Is there another fuel filter that I should check? The engine has 100 hrs.

I ran the engine in the up position and rpm was ~3200 to 3400. Can someone comment on the health of my engine based on this test. :huh:

 

[Half Fast]

Tough to say anything about it without a better description. Engines don't have up positions. "Once on a plane throttling is not an issue" - what does that mean - what's your rpms when you're on a plane? More than 3200?

I assume prior to this your engine was in a normal rpm range at WOT - like close to 5000?

If your rpms are stuck between 2-3k permanently it sounds like the engine may be in guardian mode - maybe time to have someone put a reader on it and check for codes. If they are fine except for when you are giving it throttle to get on a plane - could be a variety of issues, none of which I can think of that would correlate to injector cleaner - but you need to be more specific about what specifically is happening and under what specific conditions.

 

[ErikC]

Half Fast
The rpm's at WOT is ~4300 at 40 mph.

"Once on a plane throttling is not an issue" - This means once on plane the engine does not bog down when I go to full throttle, it behaves normal. This could be because the engine torque is high, loading the engine. thats why I asked if there was another filter that could be restricting fuel at high torque requirements.


Someone here at this site told me the health of your engine can be measured by tilting your stern drive in the up position and looking at the rpm's at full throttle.