Problem with 241 stalling at about 3000 rpm

[Portugee]

Hi,
I have a 99 241 with a 5.0 Gi Volvo equipped with TBI.  I've developed a stall at 3k rpm that causes the engine to backfire and loose power until I back off on the throttle (it's happy to run at 12mph).  I've isolated the problem to the starboard injector shutting down when the engine hits 3k rpm.  I switched the starboard and port wires and found that the port injector would then shut down when the engine reached 3k rpm.  I'm concerned that I may have a faulty ECU, but the code reader shows that the ECU is fine even after the stall.   I would like to do some more checks before I take it in to the local shop and spend some big bucks for a new ECU.  Has anyone come across a similar problem or have any suggestions?
Thanks for your help,
Portugee

[231CALIFORNIA]

Just suggestions, I dont have schematics or diagnostic charts on that system but you have found that injector is ok, signal to injector is intermitant. your test demonstrates that.
You need to know if signal to injector is failing from wiring or connector issue between injector and ecu or if eco isnt sending signal . many fuel injection systems are driven by completing the "ground " 12v negative  and the 12v positive is "hot all the time"  key on.
If  if its the computer side you wont lose the + voltage during failure with that type of system.  If you did  lose + its likely a wire or connector if you lose - you need to verify circuit integrity to computer.
If all is well then you need to work back to sensor
normally things like crank or cam position sensor or coolant temp.
check the wiring and buisness ends of those sensors  before you
get into doubting ECU. diagnostics would dicatate a tool that monitors data streaMS AT THAT POINT , OTHERWISE ITS HIT AND MISS REPLACEMENT OF pARTS. look for the obvious first since wiring and connectiosn are the most common areas of fault.

[Portugee]

Thank you for your suggestions!  I'll check it out and let the folks here know what I figure out.  I'm hoping to find the problem before the YFT show up.
Thanks,
Portugee

[Portugee]

It turns out that the oil pressure sensor and connector were very corroded and were causing the engine to go into limp mode.  Both were replaced and the problem has been corrected.  The engine is now runnning great.
Portugee

[231CALIFORNIA]

 LIKE I SAID  SENSOR.

"If all is well then you need to work back to sensors
normally things like crank or cam position sensor or coolant temp.
check the wiring and buisness ends of those sensors  before you
get into doubting ECU"

Glad you found it.
Was it found by scan tool or some other method ? visual, etc?

[Portugee]

Hi
The scan tool didn't show that the sensor was having a problem, it was found using an old fashion ohm meter.  The sensor was on the port side at the back of the engine just under the manifold. 
Thanks for your help,
Portugee

BTW, do you fish off of LaJolla?

[231CALIFORNIA]

NO, VENTURA TO MONTEREY MOSTLY PSL AND MORRO, NORTH OF THE POINT, DONT LIKE FREEWAY TOWING, WOULD RATHER DRIVE BOAT, PROLINE IS GOOD FOR THAT, 138 GAL TANK, BUT FUEL COSTS MAKE TRAILERING LOOK BETTER,  WOULD DO IT THOUGH.


QUARRY ALBACORE,HALIBUT,LINGCOD,SALMON,WSB, ASSORTED ROCKFISH.
READ ALLCOAST,BD,GETBENT REGULARLY, HEARITS BEEN KINDA SLOW DOWN THERE LATELY

THIS IS THE TALK OF SO CAL.
http://www.ebaumsworld.com/video/watch/81057766

[Portugee]

Wow, that's great and I know lots of fisherman that feel the same way.
Thanks for sharing.
Portugee

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