TBI port injector cuts out at 2500 rpm volvo 5.0gi

[fdnyfirecracker]

I have a 2000 volvo-penta 5.0gi. Recently overheated to about 240. Fix impeller and therostat. Since then the engine drops the rpm to 1500 once it reaches 2500 rpm. I removed the flame arrestor and discovered that the port injector (TBI) was cutting out at the same time as the rpm drop. I switch the wire and the Right side was then the effected injector. So i have determined that the something is telling my one injector to cut out but i dont even know where to start. Any one with any thoughts please jump in. All my gauges read normal. The engine runs fine till it hits that 2500 mark.

Mike

 

[Don S]

Re: TBI port injector cuts out at 2500 rpm volvo 5.0gi

You are still in SLOW mode. Below is from the service manual. IF, and I mean IF the temp and oil pressure are ok, you may have a bad sensor or wiring in the system. Using a diagnostic computer and a mechanical oil pressure gauge and a temp gun can tell you which.

S.L.O.W.
The EFI system includes a protective feature called
Speed Limiting Operational Warning (S.L.O.W.). This
system prevents engine damage should oil pressure be
lost or engine coolant temperature become excessive.
The ECT sensor has a two-fold function; it supplies water
temperature data to the ECM in order to control spark
and fuel, and also triggers the S.L.O.W. system should
temperature reach or exceed 200?. A separate oil pressure
switch can also trigger the S.L.O. W. system should
oil pressure drop to or below 3-4 PSI.
Engine operation while in S.L.O.W. is distinctive. If the
system is activated at any speed above 2500 RPM, one
bank of injectors is immediately shut off and spark timing
is fixed at 8?. Boat speed will drop until RPM falls
below 2500. The engine will continue to operate on one
half the injectors at 8? unless RPM drops to 1200. At
1200 RPM, normal injector operation and spark timing
is restored (re-set point). The boat can now be operated
up to 2500 RPM in a normal manner, but if 2500 RPM is
exceeded and the cause of S.L.O.W. activation is still
present, one bank of injectors will again be shut off and
timing fixed at 8?.
S.L.O.W. will continue to perform in this manner until the
cause is eliminated. Should the cause be self-corrected
(i.e. weeds come off water screen, or oil re-covers
pickup), engine operation will return to normal when the
ECT senses water temperature at 180? or below, or oil
pressure exceeds 4 PSI.

 

[fdnyfirecracker]

Re: TBI port injector cuts out at 2500 rpm volvo 5.0gi

WOW that was some great info. Ok I dont have any diagnostic equipment. If i where to swap out all he sensors and check for bad wires or pins what systems would i look at and what sensors should i replace. Is it possible to have a bad sensor but not show a bad oil pressure or high temp. Does anything have to be reset or will the problem alwas self correct once the problem is resolved. And lastly Could IF temp and oil are both ok what else could cause this slow mode. IF i must get a diagnostic tool what do you suggest.

 

[Don S]

Re: TBI port injector cuts out at 2500 rpm volvo 5.0gi

As a DIYer, I would go with the Techmate (Mercruiser scan tool in the link below) it reads the sensors, gives the codes, covers Merc and Volvo even the new EGC from Volvo. It's slower than the computer program, but it's also a LOT cheaper. If you are planning on keeping a boat and want to do your own work, it's a " Must Have " along with the OEM service manual of what you are working on.

http://216.230.203.183/marine/mtspec.htm

You will also need a DVM and the ability to use it properly, none of the diagnostic computers let a mechanically challenged or electrical challenged person fix an EFI system...... Then we get into the proper fuel gages and adapters.

They aren't the ole Chevy 6 cylinder with a points distributor and a carburetor anymore.