150 EFI ongoing issue

[btclark0316]

So I have a 1999 mercury 150EFI. I have had to replace several things on it such as, repair leaking VST, switch boxes, trigger. The motor was missing at idle and wanted to die and cut out all through the mid range. It would run good on the top end if I could get there without it dying. As I was troubleshooting it I noticed that pulling any port side plugs at idle did not affect it. I started with switch box and then changed trigger after in hopes of fixing the issue. I have checked the stator and it is good. I have reset the time to the factory 20 degrees and adjusted idle speed. The boat is idling great out of water and hitting on all cylinders out of the water. It will also rev to the moon and back out of water without any cutting out. I put it in the water and, I can barely keep it idling and the cutting out is worse. It will scream at the top end when I get it there but it won’t run for long. Any ideas sorry for the long post, thanks in advance.

 

[allen russell]

i have the same problem right now! mine idles like crap found out it was a couple injectors leaking not spaying the right amount at idle leaking making it run rough at idle! i have had nothing but trouble out of this thing after it got about 20 years old i am right now changing it over to carbs bought everything off EBAY! those injectors ate 697 a piece of course you can take them to a dealer and have them tested like i did! but if you buy a used one will you get the same thing? i did the same thing you did put new switch boxes new trigger an stator on it and a 300 dollar pressure valve and even sent the ECM off and had it rebuilt 750 bucks! spent enough money to change it to carbs 3 times lol!

 

[Faztbullet]

Send injectors to Brucato ..cleaned,balanced and flowed less than $200

 

[Dave1027]

i did the same thing you did put new switch boxes new trigger an stator on it and a 300 dollar pressure valve and even sent the ECM off and had it rebuilt 750 bucks! spent enough money to change it to carbs 3 times lol!

How do they "rebuild" an ECM? I thought those were sealed in epoxy and they either work or they don't.

 

[Dukedog]

there were a few that said they could do it.. what i saw was some that could repair tha pump driver circuit (with success) and some that claimed ta be able change tha fuel map and raise tha limiter in some (not so successful).. i had a coupla of 'em done back in tha early 2000's without much luck... they came back (more than once) worse than when they were sent... think Merc has stepped in and nixed anyone opening up any of their ecu's nowdays.......... jmo.

there was one (11350 digital hi perf.) that had a "chip" that could be changed to increase/decrease fuel pressure, curve and max rpm......

 

[Drew0923]

Any update? i have an almost identical problem occuring