Trouble in Sweden, merc 7.4 tbi running rich

[J.R rengen]

Hi fellow boaters, and greetings from sweden.
i have a problem with my mercruiser 7.4 tbi from 1996.

little background history,
3 years ago engine rebuild becuse of worn down valve seats in both cylinder heads.
engine remounted and working.

2 years ago engine started running rich on fuel,
changed parts so far, IAC, temp sensor, map-sensor. Checked both TBI injectors and replaces carb gaskets. Also checked the engine fault codes (put a pin between A and B, and used a multimeter to "pling" the codes) no fault codes found

1 year ago i noticed that i had tuned the ignition wrong, and not to the specs according to EFI. Now i have set the ignition correct, i think
This year it feels like the engine running even more richer then before, and according to the fuel consumtion meter from floscan that shows the enginge dont have a stabil fuel pressure.
When running idle with gear in, the fuel meter goes from 2 to 3,5 gph back and furth.

Here in Sweden, there are little help to find around the EFI engines. We mostly go with standard carb or diesel.

Dont know if i have missed or dont checked something yet, but is there anyone who might have an idea about my problem?

Best regards troubled mercruiser owner...

Ps. Sorry about the bad english Ds

 

[alldodge]

Happen to know the serial number of the motor?

Being a TBI it sounds like a L29 type, the serial number will confirm

 

[J.R rengen]

I am not around the boat right now, but 99.9% positive that the serial nr is like OKX9999 somthing if that help. Can get a true reading later this week.

 

[alldodge]

Plugs MR43T and gap 9mm (.035)
Timing 8 BTDC with distributor in base timing mode
Fuel pressure 255 kPa (37 psi)

To measure fuel pressure, you will need a adapter to connect to the throttle body, part number 91-806901



There is a small vacuum hose on the cool fuel module which is on the port side behind the motor mount. Follow this line up to the intake and Tee in a vacuum gauge to determine what it reads and if its steady