260 EFI bogging

[Stoker boy]

I've been having a problem for the last month and a half that I have yet to figure out. My top crank bearing went and put a hole in the front half. Ever since I had it welded it has had this persistant bog. In neutral it will run perfect and the first holeshot is great but everything after that it bogs right down to the point of where it is going to die. At this point I have replaced all of the electronics other than the main engine harness and temp sensor. New sealing rings in the crank, new top bearing, new bleed lines, map sensor fitting cleaned and hose replaced, and swapped ECU with a known good one. I also checked and verified that my front half was still straight after being welded (which it was) but put a different one on to eliminate that. Fuel pressure is correct and staying a consistant 56lbs. Four button box confirms that temp sensor is reading properly. This motor ran perfect before the top bearing went. I have a hard time thinking it could be something electrical but obviously it's possible. There was a groove on the block and front half from one of the screw heads but that has been filled in with JB weld. Any help would be appreciated.

Have you flow tested your injectors and indexed your fly wheel?

[ShadowFlier]

Have you flow tested your injectors and indexed your fly wheel?

Yes injectors were flowed in March. I have not, it came with the motor when I bought it. Motor ran perfect before the top bearing went though. I didn't see any cracked or damaged magnets but I have another I could swap and try.

[Markus]

Someone Please help here..

I am trying, but it is very hard.__PRESENT

[G-Train]

I see you Markus...I know his frustration, as I have been trying to help him also. He has done an awful lot of work trying to figure this out...It will probably end up being something simple in the end (I hope).

[Stoker boy]

Yes injectors were flowed in March. I have not, it came with the motor when I bought it. Motor ran perfect before the top bearing went though. I didn't see any cracked or damaged magnets but I have another I could swap and try.

Indexing the fly wheel means you check the timing at each cylinder. You mark the fly wheel 0° and 25° then you check the timing of each hole that will let you know if your electronics is firing at the proper time.
.

[ShadowFlier]

Indexing the fly wheel means you check the timing at each cylinder. You mark the fly wheel 0° and 25° then you check the timing of each hole that will let you know if your electronics is firing at the proper time.
.

I see, I have only set timing with the first hole, not the other five. I will check that.

[Stoker boy]

Yes injectors were flowed in March. I have not, it came with the motor when I bought it. Motor ran perfect before the top bearing went though. I didn't see any cracked or damaged magnets but I have another I could swap and try.

Another thing you might check is your battery I’ve had motors do that and it was simply a low battery. It made the ECU do weird things. I’ve also blown up motors put them back together and for some strange reason I don’t know how but had some type of debris clog up an injector. Do you have Pyros installed on the boat?

[Markus]

I see you Markus...I know his frustration, as I have been trying to help him also. He has done an awful lot of work trying to figure this out...It will probably end up being something simple in the end (I hope).

Well, it seems to me that not using an ECU that is made for a drag engine and which will make a 260 run way too rich would be an obvious place to start if the problem is that your 260 runs way too rich.__PRESENT

[carsononefive]

I can tell you i have a 97 2.5 260hp that does close to the same problem.. i have been chasing it for a long time and can't figure it out.. it basically started like there was water in the gas.. Mine would run perfectly then bam! It wouldn't take any throttle at all. If you pushed slightly on the pedal it would bog through the intake..i could keep it on plane but giving it any throttle it would basically die.. let off and it would run fine.. i have checked everything my fuel pressure runs at 39 i think if im correct.
This motor is half a race motor stock heads with a reostat that i can adjust the fuel on the fly.. never seen anyone else have such a thing..
I don't get alot of time to play with this boat as its at my lake and with family etc no time to play with it..
I can tell you at 3k where mine likes to die the etg are 1020 so it's not puking rich or deadly lean.. i did fine taking it out for a family cruise keeping my fuel adjustment on the rich side of things and driving the boat at 4k it didn't bog down at all....
So things im figuring out is the motor seems to do this hiccup within the first 5mins of driving it now.. then goes away.. after it has its fit i beat on it back and fourth and its fine..
Seems to do it around 3k..
The things i can suggest is the TPI unit and the temp sender..
I have read you can jump the TPI so it runs rich.. might be something for you to try since mine did run better when set rich..
I want to try jumping the TPI unit as well to see if there is any change.. its hard to find much info on it tho. Still searching lol

[Soporific]

I vote to start with the indexing on the flywheel. ALL TIMING of the switch box trigger motors starts with the flywheel/trigger interaction. This includes all spark and fuel injection. Make sure the trigger signal is good for all six cylinders and then go from there.

[tomoad]

Is the choke on. Unhook the yellow red tracer

[tomoad]

Correction yellow with black tracer.

[FUJIMO]

Another thing you might check is your battery I’ve had motors do that and it was simply a low battery. It made the ECU do weird things.

...times two...

[ShadowFlier]

Sorry I haven't updated this is awhile. I lost a very close friend in a boating accident a couple weeks ago and haven't really touched my boat since. I went back to the spot it happened for the first time last Saturday and the damn thing ran perfect. I don't get it, I didn't touch anything from the last time I took it out and had problems but last Saturday it ran great. It was a quick ride and I'll try it again this weekend but I'm slowly easing back into it.