Yesterday I decided to blow out the cobwebs on my motor and opened it up, planned to let it go for a couple of minutes. After about 1/4 mile at full rpms it was like it the motor just lost rpms and would run only at about 5000 rpms. It didn't run rough, but if I tried to accelerate it was like I hit a rev limiter........nothing. So I came in, checked my fuel filter and opened the water drain (which no water drained out). So, this morning I took it out for another run. After warming it up, I opened it up for about a mile, and it felt normal. I fished for about an hour, then took off again at full throttle and after 200 yards the same thing that happened yesterday occurred. This motor is a 2009 model and since I've had it the high stage fuel pump has been replaced twice. The dealer/mechanic never found the cause of the fuel pump failure. I sure would appreciate any help anyone can give..............Thanks
Don, I took it to my dealer this morning.........the mechanic did the spark plug test as you described.....all normal. He did other tests and all turned out normal. He thought that the problem was an ignition coil and gave me a new one to start replacing one of my coils at a time and checking to see of one of them is the culprit. Since I live right on Toledo Bend, I did all that today and all of my coils performed the same......after about a mile at top speed and about 6000 rpms, it was like the rev limiter kicked in. I called and told my dealer the results and I think he seemed to think I have a faulty rev limiter. I'll know tomorrow after he researches rev limiter problems.
By the way, this is the same engine that would lose rpms when I used the trim or hydraulic jack plate and was a dog out of the hole.....also would only run 4500 rpms. That was solved when the high stage fuel pump was replaced.
If it does this again, take VERY CRITICAL NOTE of the RPM's it drops to.
This is important... as there's a substantial difference in potential "causes" based on the actual RPM's lost.
Example: 6000 beginning, dropped to 5000 is an indication that you may have lost one cylinder, whereas 6000 beginning, and slowly dropping down to 5600-5800 could be something totally different (in that case, give me a call).
Yesterday, I made 6 WOT runs, each after I replaced each coils with the new one. After each run, when I reached about 6000 rpms, the rpms dropped slowly as you described, then I went to idle, turned around, then made another run at WOT and the same thing happened, only sooner than the first time. This happened on all six runs. Also if I continued my run after the rpms dropped, the engine ran normally, only up to about 5000 rpms with no throttle response if I accellerated when at 5000 rpms. When I say it ran normally, there was no miss, and throttle response was normal at any speed up to 5000 rpms. On all the runs, my top speed was normal (about 72 mph) before the rpms began lowering. My hole shot was also normal.
I believe that had I not made a WOT run the first time (about 5 days ago) I would have never known I had a problem. I usually cruise at about 4000-4500 rpms. Rarely do I run at top speed.
Thank you very much for your responses to my problems..........greatly appreciated.