Mercury 175 efi driving me nuts help!

[calfisher71]

I have a 1996 mercury 175 EFI
Replaced the block a year ago.

I have a intermittent bogging issue.

Boat will run perfect. Then on a start it will fire up rough iddle and when I hammer the throttle it boggs.

I turn off re-fire up and runs like a dream?

Boat has been in the shop a dozen times trying to fix the issue.

Looking for tips.

Here is what has been done.

Fuel vent clear.
Anti Syphon valve replaced.
Fuel screen clear.
Tank has no debris.
New fuel line.
New fuel bulb.
New fuel filter.
Cleaned and replaced filter in VST.
Cleaned fuel rail.
Cleaned and tuned injectors.
Replaced cracked reed and cracked reed block.

new lower fuel pump gasket.

Boat will run about a tank and a half then it boggs.

Any advise would be great, Im tired of spending and taking to different shops with no results.


I think were missing something simple, but dont know what?

[Mike]

I had the EXACT same thing happen to my 1996 200EFI. Took it to the shop 3-4 times with them telling me it was fixed, but it would do it again on the water. (wont do it on in the test tank) I finally took it to Boatmasters in Livermore and thy said it sounded like the ECU. Instead of buying one to "test", they had a used one they installed on my boat to try. Problem Fixed!! I end up buying it with a 1 year warranty and it never skipped a beat since........... Well not until I ran it out of oil and blew it up

So to answer your question..... It sounds like your ECU. Not cheep

[chf8500]

I had a 98 EFI pretty much the same symptoms, changed out a bunch of components and each time thought the thing was fixed, run fine then bog down at WOT, this went on for about 6 months. wound up a piston had been siezing up and causing my problem, finally threw a rod through the block behind the uel pump. put a new XS on it and cured the bog. Not to say yours is the same thing but have a good mech. take a look at it or you may have to shell out some hard earned dollars.

[calfisher71]

Im gonna try the ECU.

The block is less than 2 years old with very low hours.

[fishwithron2]

Had similar problem on my 1998 200 EFI. Motor runs good then all of a sudden it quits. Starts rite up again and runs fine for awhile and it would quit. ECU was the problem and corrected and runs fine now.

[R73guide]

I would definitely spring for the ecu.

[RAC]

Any updates?

I've got a 96 200efi. Had a similiar problem where it would just die intermittently. sometimes at idle, sometimes at wot. At times it would start back up other times it would take about 4 hrs then it would start and run fine. Swapped the ECU and it fixed that problem but now I get the sporadic bogging down, i pinned it to the lower 2 cylinders that would not fire. Swapped out the trigger, now i get a high speed miss for just a moment 3 or 4 times a trip. I'm still looking.

Good Luck, keep me updated if you don't mind.

RAC

[calfisher71]

if it missed change the coil packs.

[calfisher71]

I have a 1996 mercury 175 EFI
Replaced the block a year ago.

I have a intermittent issue.

Boat will run perfect. Then on a start it will fire up rough iddle and when I hammer the throttle it boggs. Its idling on three cyl...

I turn off re-fire up and runs like a dream?

Boat has been in the shop a dozen times trying to fix the issue.

Looking for tips.

Here is what has been done.

Fuel vent clear.
Anti Syphon valve replaced.
Fuel screen clear.
Tank has no debris.
New fuel line.
New fuel bulb.
New fuel filter.
Cleaned and replaced filter in VST.
Cleaned fuel rail.
Cleaned and tuned injectors.
Replaced cracked reed and cracked reed block.
replaced stator
replaced 1 switchbox

new lower fuel pump gasket.

Boat will run about a tank and a half then it has the intermittant issue at idle then wot and it boggs.

Any advise would be great, Im tired of spending and taking to different shops with no results.


Now im having a missfire at idle original issue, a hesitation to get on plane and a missfire?

any help ??

I think were missing something simple, but dont know what?

[fishwithron2]

As stated in my earlier posting almost same problem. Sent it so Simons Motor sport and they rebuilt my ECU and no more problem since then. You can buy anew one for around $1000 or have it rebulit for $600. Simon have a one year warrenty.

[Mike]

Told ya!

[bigstick]

Take it to Boatmasters. They are the Merc guru's.

[Ceaser]

I had a similar issue that was a ghost, high speed miss that would turn to a bog as it missed more as it kept running. Comp, stator, coils, carb rebuild were all recommeded(and done) by shops as a fix. Problem was still there after paying for these... it was my top main seal under the fly wheel. It had become weak and was allowing air in and out around the crank. I found this because fuel started to puddling under the fly wheel. Shop told me they would have to split the block to replace I removed the flywheel, got a dental pick and pryed the seal out with no problems, bought a new one for $5 and installed it. Fixed all the symtoms. Vaccum leaks can cause a whole crap load of problems and be very hard to detect.

[calfisher71]

It may have been a combo of switch boxes and ECU, we changed them both and it ran good, need to run 2 more trips to make sure,crossing my fingers! I had already changed 1 ECU and still had the problem, #4 and #6 cylinders were missing.