2.5 260 - Engine dies when giving gas....

[Big Johnson V8]

REPLACED: Fuel-pump, Stater, Switch-boxes, Voltage Regulator & ECU. Shined flashlight into gas tank and fuel is circulating. Boat is starting and idleing fine, sounds good and as soon as I put it into gear it wants to cut out and when I give it gas it dies, like I turned off the key....sometimes it will crank back up and do the same thing and sometimes it wont even start back up.
:confused:

[johnnyracer]

Questionable trigger wire . When ya move the trigger arm with the gas pedal it breaks the connection. Just a thought.

[hst714]

what year and what ecu???

[Dave Strong]

Questionable trigger wire . When ya move the trigger arm with the gas pedal it breaks the connection. Just a thought.

:iagree: Been there.

Dave:smiletest:

[johnnyracer]

:iagree: Been there.

Dave:smiletest:

Me too . Drove me insane. It was a brand new trigger.

[Jay Smith]

Stopped up air barb OR failed ECU...

my thoughts,
Jay

[P man]

If it's an analog box check the tpi

[Bruster]

Checking the trigger, stator and switchboxes is all spelled out here: www.cdielectronics.com (http://www.cdielectronics.com) Checking the trigger with a VOM is a snap and will tell you in a minute if you have a trigger wire problem (which I doubt). The trigger is made up of 3 switches. If a wire was failing this would only kill 1 switch and create a miss on 2 cylinders. I'm leaning toward the ECU.

[rock]

When Shawn called about this issue the first thing I told him was to get the ECU checked and we would go from there. Checked out fine. First thing I checked was the fuel pressure which is dead on 39 but I only checked it on trailer in gear up to about 2500 rpm. We found an issue with the voltage regulator. A hood pin bracket had been made and the previous regulator shorted out due to contact. It had rubbed thru the insulator on the wire. That regulator was replaced and a piece of plastic added but it looked as if the plastic had either rubbed thru or burnt thru so that is whay I changed the regulator again. Motor seemed to start better and sounded much better but still did the same thing once on the water. I then went to the stator and did the ohm tests. One set of wires showed 4100 with the acceptable range being 3900-4400. The other set showed 5000. Checked the reds to ground with the acceptable range being 70 + or - 5. First set showed 71 and the second set showed 106. Two of the 4 tests were out of parameter so we changed the stator. NO change. At that point we looked at the switch boxes. Changed to a set of known good boxes and still had the problem. Motor would run, die, and then not restart. Now the testing is being done by a friend of ours that is a professional mechanic which I am not. His tests showed spark and fuel but it would not lite. They checked for fuel flow on return line back into tanks and found there was flow. Put on a borrowed ECU and it fires. Returned the borrowed ECU and brought boat back to me. I put an A38 digital box on and it fires instantly. Put it in water and it will rev up nicely in neutral, sounds nice and crisp, but put it in gear and it pukes all over the place. Apply throttle and it dies but will start back up instantly. This sounds to me like the stator is not putting out sufficient voltage even though a new stator was installed. About the only things I haven't changed are the trigger and rectifier. I hate throwing parts at something but I am at a loss. All things we have changed were changed for legit reasons with none of them accomplishing anything. I guess the only thing left to do is change out the trigger even though I cannot imagine it being the culprit considering the symtoms. Don't see the rectifier having any effect. Certainly open to suggestions and thanks for the help and opinions. I do have a couple good 260s on the shelf and as a last resort will strip one to the block and bolt it all on Sawns boat so he can at least make the river run this weekend.
Rock

[zatchmo]

This may be a dumb question, but have you checked the reeds? I had a similar issue and it turned out to be a reed cage that had broken off and fallen down blocking air to another hole. Everything looked great through the horn, I had to actually pull it off to see the issue.

[Bruster]

Rock:
Here is the CDI troubleshooting for the ignition system: Should be something here that helps. Don't be afraid to call CDI tech support. They know this stuff, and are willing to help.
http://cdielectronics.com/downloads/troubleshooting%20guide/Mercury%206%20Cylinder.pdf


When Shawn called about this issue the first thing I told him was to get the ECU checked and we would go from there. Checked out fine. First thing I checked was the fuel pressure which is dead on 39 but I only checked it on trailer in gear up to about 2500 rpm. We found an issue with the voltage regulator. A hood pin bracket had been made and the previous regulator shorted out due to contact. It had rubbed thru the insulator on the wire. That regulator was replaced and a piece of plastic added but it looked as if the plastic had either rubbed thru or burnt thru so that is whay I changed the regulator again. Motor seemed to start better and sounded much better but still did the same thing once on the water. I then went to the stator and did the ohm tests. One set of wires showed 4100 with the acceptable range being 3900-4400. The other set showed 5000. Checked the reds to ground with the acceptable range being 70 + or - 5. First set showed 71 and the second set showed 106. Two of the 4 tests were out of parameter so we changed the stator. NO change. At that point we looked at the switch boxes. Changed to a set of known good boxes and still had the problem. Motor would run, die, and then not restart. Now the testing is being done by a friend of ours that is a professional mechanic which I am not. His tests showed spark and fuel but it would not lite. They checked for fuel flow on return line back into tanks and found there was flow. Put on a borrowed ECU and it fires. Returned the borrowed ECU and brought boat back to me. I put an A38 digital box on and it fires instantly. Put it in water and it will rev up nicely in neutral, sounds nice and crisp, but put it in gear and it pukes all over the place. Apply throttle and it dies but will start back up instantly. This sounds to me like the stator is not putting out sufficient voltage even though a new stator was installed. About the only things I haven't changed are the trigger and rectifier. I hate throwing parts at something but I am at a loss. All things we have changed were changed for legit reasons with none of them accomplishing anything. I guess the only thing left to do is change out the trigger even though I cannot imagine it being the culprit considering the symtoms. Don't see the rectifier having any effect. Certainly open to suggestions and thanks for the help and opinions. I do have a couple good 260s on the shelf and as a last resort will strip one to the block and bolt it all on Sawns boat so he can at least make the river run this weekend.
Rock

[rock]

Rock:
Here is the CDI troubleshooting for the ignition system: Should be something here that helps. Don't be afraid to call CDI tech support. They know this stuff, and are willing to help.
http://cdielectronics.com/downloads/troubleshooting%20guide/Mercury%206%20Cylinder.pdf

Thanks Bruce. I hope to have some time tomorrow.
Rock

[patchesII]

I had a rectifier recently give me a funny midrange miss. I'd borrow parts from a known good motor till you find the culprit and then buy just that part. Hate to see anybody out buying parts they don't need

[Dave Strong]

Has he tried DVA testing sometimes things show good with ohm meter but when they get a voltage load will fail. Just a thought.


Dave

[Bruster]

Agree, ohm readings only tell part of the story. The information from CDI gives the specs for both VOM and DVA readings. Having a DVA and VOM and learning how to use them is pretty rewarding when you can get to the problem in just a few minutes.

[Big Johnson V8]

Thanks guys for all of the info.

[Big Johnson V8]

We think it was a bad temp sensor, its running good now. I hope that was it, BIG thanks to Rock for countless hours and parts.