OX66 250 not firing injectors

[Kingfish999]

hello, my fathers boat has twin 99 OX66 250 and im always the one tasked to fix it yet never actually on it when the issues occur. one of our engines is not running because it doesn't seem to want to pulse the injectors, or is at least sending a very weak pulse. we recently started having this issue yet it also happened to our other engine and was unsure of its actual cause. i am one who is willing to diagnose before throwing parts at it, especially how expensive these parts are, i really could use some help on this. i have been fully using the advantage of having twin engines to swap parts back and forth to diagnose but i jsut cant seem to find this one out.

so about a year or 2 ago one our starboard engine had the same issue. we litterally swapped everything from all the snesors one by one and the wiring and the CDI, flywheel, pulser coil, stator, entire fuel system, nothing seemed to work. out of nowhere it finally started to work alright. things went on normal from there.

so recently within the last couple months we were having alittlebit of a headscratcher as we could not get the WOT rpm up above 4200 rpm on the port while the starboard engine was going up to 4800. we again swapped quite abit of things around and cleaned the o2 sensor, swapped props, adjust linkages. got it relatively close but decided it was msot likley because the starboard was rebuilt a few years ago while port was not so it may be some worn.

about a few days ago they told me the engine was not starting. started a quick diagnose because i had plans and ended up getting it running by starting fluid, they later told me they could not get it to make any power over 2k rpm and then could not restart it. today i confirmed the same issue of no fuel injector pulse but is getting spark. the injectors are getting power and i can force the pulse by grounding the return side. it will pop abit when i force a couple injectors to pulse abit but doesn't stay running. so again i spend a few hours swapping things around. pulse coil, CDI, flywheel. i did not swap the stator because i ran out of daylight. everything i swap seems to run fine on the working engine and im not sure what else is worth trying. i do have the winky blinky, it is flashing code 13 for pulse coil signal error. i have swapped it, the flywheel, and the CDI each one by one and there isnt anything else between them. i do have a peak voltage adapter for my multimeter and the voltages do look ok, both engnes have around 2.6v or so when cranking (i know 3v is spec) for all 6 wires

tonight while it was darker i did notice that when i force a few injectors open to get it to start up for a moment, my test light will show some flashes of the injector pulsing but it quickly dims out every pulse till nothing then the engine dies

could really use some help on this. any advice?

[rodbolt17]

my advice???
learn how the system works and QUIT splatter gunning.
at key on the injectors receive 12V via the main relay. the ECU controls the ground path. that path is only there for about 2.5ms per revolution at idle.myself I would test rail pressure and look at the injector filters.
if you lose a pulser signal you also lose spark and fuel on two cylinders. the six pulser coils control spark and fuel for six cylinders.

[Kingfish999]

no i can 100% verify its not pulsing the injectors. i can use a test light to very it pulsing on the working engine but not on the bad engine. i can verify it is getting spark. the injectors are getting 12v. i can use a paperclip on the connector going to the CDI and ground it out and i can hear the injector clicking. after doing that and allowing some fuel in the engine will run for a bit till it uses up that fuel. the fuel pressure is good and its getting spark. it is getting code 13on the winkyblink saying pulser coil signal error.

i understand that the CDI controls fuel pulse as well as spark. this is what i dont understand. i have swapped the CDI and its still doing it. the pulse coil connects directly to the CDI so there should be nothing like a bad harness to cause it. but there must be something thats causing this issue.

if you dont believe me ill try and make a ver videos demonstrating the issue. might be a awhile before i work on it again

[zenoahphobic]

I'd stop for awhile, as it seems you have covered all that is involved.
Instead go and check your 12 volt supply. If your engine is not running then you do not know if it is producing adequate voltage. Worth checking your alternator coils and rectifier system, faulty they could interfere with the supply to other circuits. Statically things may seem OK but what happens when the engine spins?
Sometimes it is necessary to check all connections thoroughly (both surfaces within the one connection), your CDI may simply not be getting enough voltage through a resistive connection when "asked" to do a lot more work.

[ausnoelm]

It's a bit hard to work out your trouble shooting and results, but it sure seems like you have a bad ground? you say you have 12V, and when you apply a ground, it works! but then, maybe I didn't read it right, moving from device to device with half tests confuses things.

[rodbolt17]

I am gonna try this one more time.
you already know the ECU fails to see at least one pulser coil signal.
code 13.
the ECU uses all six pulsers to trigger spark AND fuel.
#1 pulser gives the ECU the trigger signal to spark #1 and trigger injector #2.
#2 injector sparks #2 and triggers injector #3 and so on and so on.
loss of fuel pressure can trigger a code 13, so can a wire issue or loss of the pusler ground.
see how easy this is?
no splatter gunning just basic knowledge and a method.
myself I would carefully test pulser outputs, make sure the outputs make the ECU then test the voltage across the injector.
the injectors use 12v the ECU supplies the ground in the millisecond range. most digital meters wont see it.
use an analog meter..
by measuring the injector resistance and a bit o math using Ohm's law you can get an idea of what to expect the injector voltage drop will be.
the s and sx 3.1 motors are a tad different then a Vx.
the VX does NOT use CCS.

[Kingfish999]

so i have been really busy but decided to take another crack at it today.

using an LED test light, i watched the pulses of the pulser coil and they are consistent on all 6 wires. i did not get an analog meter to watch voltages but i may get one today. but as i said before i used a digital meter and a peak voltage adapter and it seemed to be giving relativity close to spec pulses

i ziptied all the injectors to the fuel rail and pulled the fuel rail off and see they they are defiantly not firing when cranking. when i put to WOT, they do the spurt alittle like an carb accelerator pump would do. so the CDI is connecting with them but not telling them to fire

i pulled the plugs and and grounded them and saw it is firing all the spark plugs consistently.

what i did notice is with the plugs out letting the engine crank abit faster, the injectors started firing again. when i put the plugs back in the injectors will not fire.

the starter is original but it seems to crank the engine relatively ok, maybe only abit slower than the other engine. not sure if a local shop can rebuild outboard starters and 600$ for a new one is expensive for just a guess to the problem. but if it is the pulser coil being worn out, ive already swapped it with 2 others to no avail along with the flywheel. where should i go from here?

[ausnoelm]

You are jumping from part to part again, test properly as advised by Rodbolt, no guesses or anything else, 100% good or bad only tests.

[Kingfish999]

well sorry, my service manual doesn't give me procedures to test this other than peak voltages of pulse coil. it does not give any description on 'how the system works'. but when i have injectors not firing with 4-6 spark plugs in but they are firing when only 0-3 are installed. the spark plugs are all firing correctly and consistently despite the injectors not firing, this leaves me to think its an cranking rpm issue more than a worn coil issue.

assuming i got a analog meter and the coil tested good, what would be the next step. because between swapping 3 other known good coils in i dont think its the pulser coil

and now i unfortunately i have 200 gals of gas with water in it i have to deal with and figure out why so much water is getting in the tank in the first place. so right now im alittle riled at everything

[ausnoelm]

Deal with your fuel tank (possibly related to your problem?) but, we can't help you if you won't help yourself by following tips and giving results, guessing and pulling things to bits might fix it eventually.

[Operaman]

Well, you swapped everything else and the above advice from Rodbolt is spot on. Go for it and swap the starter. Let us know.

[Kingfish999]

so the issue randomly went away, jsut as it did in our other engine. delt with the water in fuel. then a couple days later the engine blew a piston because the oil level sender failed and it ran without oil, no alarm, transfer pump works with manual switch, the float sensor itself failed. did a full rebuild, deleted the oil injection system, got the wiring to think the oil tanks are both full, doing premix for now on. the first bit of break-in, no problems, the other engine actually blew the high pressure fuel line so we limped home on the rebuilt engine.

today we went for second attempt of break-in and got the engine to plane out perfectly, keeping most of the stress on the other engine and trying keep under 3k rpm. made it about a mile and then the engine did not want to stay under 3k. over 3k and it ran fine but under 3k and it instantly bogged and tried to die. eventually it did die and could only get it started with high throttle and it would stay running at high rpm. soon as i lower the throttle it was like killswitch was pulled and died instantly unless i gave it throttle again before it stopped. limped it home on the other engine

did some more diagnosing and still coming with code 13. still not firing injectors. found an old analog voltage gauge i used to watch each pulser coil wire while cranking. each pulse on each wire is consistent and even. tested again at the connector for the ECM and still good signal and voltage. so the computer is seeing a good signal from the pulse coil.

where do i go from here?

[pstephens46]

How do you know the oil level sender failed? Lots to read here...

[99yam40]

If you are able to clear the code 13 and then it comes back, I would be looking at all of the things Rod said could being it back in

[Kingfish999]

How do you know the oil level sender failed? Lots to read here...

neither oil float had no continuity when it should. the engine mounted oil tank was empty but the manual fill switch worked so the transfer pump was not the issue. no alarm was sounded when it was out of oil but did sound with the sensor unplugged. 3rd engine failure due to oil injection system. decided its better to premix the fuel now on