Engine will not spool up in RPM

[ctered]

I have a 91 2.0l block mounted on a 85 XR2 leg with a 96 EFI system on it. The motor idles great and will rev up in neutral. However when I had it out on the lake the motor will only rev up to about 2800-3000 rpm most of the time and then slowly slow down. Occasionally the motor will go over 3000 rpm and then it will go all the way up to around 5600 and push my boat to 58mph. I tried it about 4-5 times in a row with no luck and the next time it took off. Any ideas? It is confusing me as to why it works the odd time and the rest of the time it will not go over 3000rpm. I have tried adjusting the TPS without any success. I have gone from .225v to .295v with the only change being the max rpm being a little less at around 2400rpm. The plugs are new and all look good. Could the stator be the problem or is it a fuel issue. Why does it only do it under power? Any help would be appreciated.

Mark

[pyro]

Sounds like a high-speed stator issue.

Running the correct ECU or curve, right?

[ctered]

Will the high speed stator only cut out under load? If I rev it in neutral it will go over 3000 easy but when in gear in the water it will only go between 2400 - 3000. Sometimes it will go over 3000 and then it will run great. If I slow down and idle for a couple of seconds it will not go over 3000 again. T-Rex said it should run fine with the ECU off the 96 150 but maybe a litlle rich. If it is too rich Rapair can reprogram a different curve for me. I have ohmed out the stator and it is ok. I have ohmed out the trigger and it is ok. I do not have a DVA to test the stator further. I will call a mechanic tomorrow to see if he can help.

Thanks

Mark

[ctered]

Thanks Pyro. Does anyone have any other ideas?

Mark

[whipper]

I'm having a similar problem. Narrowed down I think to stator,scorn cylender wall, switch box, or like you say fuel pump. I thought it was water in gas at first. Then timming because I broke my trigger arm and had trouble resetting timming. Im an old pro at that now!:thumbsup: Timming advance box not working good not alowing full advance but took that off and no change yesterday.On Rapairs web site theres a trouble shooting guide for stators and switchbox related problems thats my next step. my motor runs fine up to 6000 were it just stops pulling rpm? Its a 225 promax with a 7500 limiter. Ive been testing with a 25 trophy that I should be able to pull 7 with at least. When I put on a 28 drag4 6000rpm was that props limit also? Stator is looking more and more like the culprit? Because I can still turn 6000 have been useing her every day with no change at all. I would check your switch box and stator first. I dont think it would be your fuel pump? but doesnt hurt to check pressure. If all this is good its time to pull the heads and see whats in there. I was told if a cylinder wall was scorn she would still run but lower rpm. That would be the last thing if all else fails.

[CharlieB53]

Mark,
Before you buy a stator you should test a couple things to be sure you buy what you need.
Tap into the fuel rail and check fuel pressure at WOT to rule out a failing high pressure fuel pump.
A DVA meter is a very reliable method of testing stator output, it is a MUST HAVE test tool.

Whipper,
A stator that will run 6K and no more? DVA test also, tap into the stator leads and test at speed.
Also research ignition modules, merc tech told me once of factory boxes on 96 200 EFI would ADD 6 degrees timing once over 6K. I haven't seen it, but those speeds do need more timing, be careful when testing with advanced timing.

[whipper]

Charlie I will check fuel pressure. Statoe out put once I figure out how. I have a brucato box with a 7500 limiter.

[whipper]

Mark,
Before you buy a stator you should test a couple things to be sure you buy what you need.
Tap into the fuel rail and check fuel pressure at WOT to rule out a failing high pressure fuel pump.
A DVA meter is a very reliable method of testing stator output, it is a MUST HAVE test tool.

Whipper,
A stator that will run 6K and no more? DVA test also, tap into the stator leads and test at speed.
Also research ignition modules, merc tech told me once of factory boxes on 96 200 EFI would ADD 6 degrees timing once over 6K. I haven't seen it, but those speeds do need more timing, be careful when testing with advanced timing.
I was at the ramp today trying to get 26 at 3000rpm like the manual says. At 3000rpm even with the advance arm fully open I only could read 25?? That was puzzling since a static test got me 26 no problem with lots of room for more?. At 3000rpm running at the lake in nutral on trailer that static turned out to be a 21. Ill need to check stator output and switch boxes. shes a a bit of a dog out of hole and 6000 is all she gets with a 25pitch that should get to 7000 no trouble. Is that strange timming differance reading an indication of something?? The manual does warn not to do static testing with my motor? Also I have removed the timming advance modual yesterday along with the oil injection. Everything runs the same as before so advance box was good. I had timming at 23 before now with out the advance box its 26 max timming but cant get there the way the book says at 3000 rpm? James

[CharlieB53]

Set timing while cranking, plugs out, on a spark tester.

This is only a base/general setting as the current factory ignitions vary timing, both idle and WOT once running, hence, reset timing on-the-water.

Solution, Unplug/disconnect/throw away the idle stabilizer.

[ctered]

I rebuilt the pulse pump with no real change in symptoms. I now have a DVA to test the stator. Hopefully today or tomorrow. The cost of the pump kit was cheap($20) and it hadn't been done in a long time so it was not a waste of money. I even pulled all 4 vent plugs out of my prop and that did not make any difference. I will let everyone know when I find the problem and I want to say thanks for all the replies.

Mark

[whipper]

Sounds like a high-speed stator issue.

Running the correct ECU or curve, right?
Stator! Turning 7000 now. Could have got more but not with the proMax. Thanks guys.

[ctered]

With my motor not running right I played alot of golf this summer and I finally got around to playing with the boat some more. Well after changing to resistor plugs(no change) and then changing stators ( no change) I decided to try and adjust the TPS a bit at a time. I got it down to .150v and it started to run better. Now about half the time it will work. I have since lowered the TPS again down to .135v and the motor will work about 80% of the time. The other 20% I have to rev it up in nuetral to clear the plugs and then it will go. It seems to load up when idling but is almost right now. I will do some more testing with lowering the TPS even more to avoid the loading up isuue. I wanted to say thanks to everyone for their help and suggestions.

Mark