Need help please, 2001 240hp efi idles but no power,many new parts,

[skipper6567]

Hi All, Thanks in advance for any help. I will try to keep this short and still give all info. Sea Doo utopia,2.5 sportjet,
oe405933. The engine starts and runs. It does not have any power as you move throttle. The rpm does not increase as it should after 1/3 open. It stays running throughout the entire throttle range. The throttle is working,plates open, trigger moves advances timing.?not sure if getting full advance. No major work done before problem started. The rpm max is 3k whether throttle is 1/2 of full. No real changes in performance from 1/2 to wot. Parts that have been checked and/or replaced :TPS new and within voltage specs. Stator new, several coils[cdm] .both head temp sensors, ignition pack. I have spark on all cyls,checked with digital rpm/time gun,all cdm reading +-10rpm while idle and up to 3000rpm. voltage is 15.5 while running. Have not changed rpm limit box.?? I did link/sync and now idles at 1100 instead of 1600 out of water. Burning lots of fuel!! oiler rod adjusted. Time light looks like 8 btdc at idle with all connections done. The plugs seem to be wet/oil when checked at least 20 times!! 28 psi fuel pressure,idle and running. Air temp sensor checked/changed,map tube clear and connected. I marked the flywheel and can watch all 6 fire with light. There seems to be a stumble, randomly at idle and time light you can see it miss for a split second. the flywheel outer magnets were loose and some cracked, all attached now with epoxy. The trigger and rpm limiter is one of the last parts that I haven't changed. The spark jumps 7/16 on all. Full throttle it sounds like bogging,but I can hear it and feel it surging like it wants to go. This problem just happended all of a sudden. I have run it off external tank,changed filter,checked lines,vst tank. Could trigger breakdown give these symptoms. Timming doesn't just go way off..? without screws moving or bad trigger. Ive checked the fuel injector circuits. If there is problem with injectors its all 6 at once? seems unlike. It is the engine not pump issues. What am I missing?? the ecm?? I tend to say no because im getting that light surge split seconds at wot. Im using lots fuel.Leaning towards injector pulse duration?? I will be standing by for one of you merc guys to tell me the stupid little item that Ive forgot..ps compression was 135 all 6 holes.Thanks Again. Skipper

 

[Dr Honda]

I'm seeing a few things here...


1) 15.5 v is too high. For giggles... disconnect the regulators from the system, and just run off battery voltage. See if that helps. I havn't seen this problem with the Merc engines... but on the Rotax engines, high voltage causes all kinds of random running issues.

2) 28 PSI is low. Spec is 32 to 36 psi. You may want to check the filter on the bottom of the pump.

3) If it's locking down at 3000 RPM... the neutral switch could be bad. (it won't give you full RPM in neutral and reverse)


Since you can't get past 3000 RPM... the Throttle Guardian could have gone bad. (I disconnected mine)

 

[Coastiejoe]

Low fuel pressure can create serious power losses.

It is a viscous circle kind of thing. The injectors are designed to operate within a allowance of a minimum and a maximum pressure.The brain is telling the injectors how long they should stay open based on input from many things, such as engine temperature, ambient temperature, demand of throttle (TPS) and things to this nature. If the fuel pressure is low, it will often run but poorly as the electronics THINK all is well.

So lets say you are at 3/4 throttle which is a pretty good demand and the injector is being told to open for .25 millisecond. If the fuel pressure is low the injector will open for the correct amount of time but less fuel than the correct amount will get to the cylinders. This is true from about 1/2 throttle up. At low throttle demand most fuel pumps even if they are only producing half of the correct pressure will normally do fine on the low end.

So not only does the fuel pressure have to be correct, all the things that feed it need to be.

For example, if the brain thinks the engine is cold it will hold injectors open longer and act as a choke. This will burn lots of fuel and create poor running and many times SMOKE the exhaust manifold as there is raw fuel being burnt within the manifold..

Clear as mud???

 

[skipper6567]

thanks guys for the help, UPDATE CONDITIONS,RANDOM LOSS OF SPARK ALL 6 CYL

I have proper fuel pressure now. I pulled all injectors and the screen filters were all clogged up. I cleaned em out and can see they are spraying nice. Fuel issue seems fine. NOW PROBLEM is RANDOM SPARK LOSS WHILE RUNNING. I am getting intermittent spark on all 6 coils,I have disconnected each one while running and no change, I swapped out a couple and no change. New stator, ohm test good. The trigger rectifiers and rpm limiter are only parts that I haven't changed. No change when I disconnect limiter box. The rectifiers ohm test good. The ohm test on the trigger 2 of the 3 were identical ohms,3rd was off a bit. WHAT WOULD CAUSE THIS RANDOM NO SPARK WHILE RUNNING ALL 6 CYLS?? I think if I can get this fixed my top end rpm issue is fixed. Im pretty sure that the clogged injectors were my problem. The ignition controller box is brand new mercury, I am going to put the old one back see if that changes things. Im leaning to trigger but timming is on when I get spark..

 

[Dr Honda]

OK.


Closing this, to continue on your new thread.