Mercury question!

[OK_BassBum]

Hi, I am asking this for a friend who is struggling with his mechanic.
1991 merc 175 xri, I don't have sn.
This is a run problem, motor runs fine, then will dog down and will only push boat
About 10 mph. The shop has replaced, stator, fuel system and tuned.
They state that if this doesn't fix it, the cpu will need replacement.
They said part no longer produced but a shop in Cali can either repair or replace. Thoughts!

I feel like this shop is quessing what's wrong, throw parts at it to see if they fix it.
Any way to test cpu? His old shop under new management won't work on anything 20 year's
Old or older. They have had his rig 6 weeks.

[EuropeanAM]

Entirely possible that they are correct. Keep in mind now, this is a 31 year old engine. It's not unusual for fuel system components and electrical items to need servicing or replacing after this much time.

The Cummins ECU used on these engines did have a tendency for loose drivers on the board. Since they're NLA, having that one repaired would be the right option (if fuel pump and/or injector drivers are malfunctioning at times).

[OK_BassBum]

Thanks Euro, His S/N: 0D78039.
Do you have a shop you use for ECU repair or replacement?

[EuropeanAM]

Missing a digit in that serial number.

I've had good service from one of our BBC Sponsors: https://www.simonperftech.com/products

[OK_BassBum]

Euro!
Thanks for your help.
Very much appreciated, he's calling simon monday.