2.5 EFI - runs but dies at speed???

[maverick1]

Just got the boat on the water since last fall. Fresh gas 1/2 tank on old gas.

Motor started fine, ran o.k. seemed a little "loaded up" first time on plan.

Top end o.k. - a little soft but basically the same as the other motor.

BUT about 10 times during the day at mid range when I went to POWER UP, or power down the motor just SHUT OFF!!! It would immediately restart - even before the boat lost speed IF I hit the starter!?!?!?!?

ONE OTHER THING the tach worked fine all day long BUT last fall and on the hose at the house BEFORE I PUT IT IN THE WATER - THAT TACH was acting up - crazy readings - 1,500 to 2,000 higher than the motor was really running --- like 2,500 -- when the motor was actually idling at about 800 rpm??


Are these issues related? Where do I start?

MAV

[maverick1]

C'mon!!! I can't own the only one that has ever done this!!!

[drasticplastic]

Issues are prob. related. Tach problem is prob. the rectifier part of the charging system. This is also tied into the ignition system through the 12 volt power circuit. They can back feed and give ya all kind's of problems.

[smallblockford]

test the voltage at the coils see what it is then rev it up see if it drops. then you will have to test the stater output. yes the voltage regulater send the pulse or signal to the tach and it isnt uncommen to see either a tack short out or a voltage regulater short out. see what your voltage is at the red wire and the blue wire to the switch box those are your high and low speed voltages. it wouldnt be uncommen though for something like a voltage regulator or a tach to screw thinghs up.

[smallblockford]

oh and the voltage i believe at low speed should be over 175 on the coils going from the green with or with whatever tracer being positive. rev it up i bet the voltage falls big time then we need to figure out if you have a good high speed voltage from the stator or a short or a bad switch box. i will have to find the manuel but what year and serial range i will get it for you and get you the specs from work

[Lakebum]

Don't overlook the little thinks.
I just replaced a set (BUZHW) on my 2.5 efi and it cured a problem that I thought was electrical like trigger or switch box. Motor was missing in the midrange but would not shut down. Really surprised plugs did it as there wasn't more than 30 hours or recreational use on them.
I had previously replaced Stator so i dreaded the diagnosing process that problem was.
Good luck fixing your problem.
-Ted

[euro scott]

i had the same thing on my 260, it would die running and you could turn the key off and back on before you even came to a stop and re-fire the motor, it ended being the ecu, it got fried due to a bad rectifier, i found it out by putting another ecu on it and it ran great {for awhile} and blew that one too