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2005 mercury 3.0 200hp loading up with fuel

B

BASSBUSTER648

New member
This motor is putting to much fuel in all six cylinders. The injectors have been cleaned, fuel pump kit, high pressure box completely cleaned, new engine wiring harness that goes to ecm,all coils checked. The ecm will not code anything. The mercury rep has looked at it and can't find anything. Parts changing is getting expensive. Could it be the ecm gone bad. How could you tell. To much money, just to see if it is. Need help bad.
 
All six cylinders are loading with fuel and dumping in the water and blackening the back of the boat. It' only turning 4800rpms, it should turn 5300 when it is right. The plugs are not fouling. But I'm getting about one mile to the gallon. The work is being done by professional mechanics, not shade tree. As I said Tim with Mercury messed with it for 3 hours and did everything to it. Yes a compression check and bleed down was done. I don't know the numbers. Answering the next post. The injectors were sent to Fla. and done. Back to specs. Whatever was done I don't think all six would flood at the same time. When you pull the p
 
Assuming they have tested and checked everything.......

A bad computer will do this. I would check the pulse width of the injectors from idle to WOT. You can do this with the Fluke 88 meter. The shop you are using will have one.

The only other test is to swap the computer with a known good computer. $$$$$
 
Thanks so much Dockside. It gives me something else to check. I guess I need to go ahead and order a computer or maybe someone with the same engine may come in to the shop and be willing to let me test and see if that is it. There is a place in Cal. that rebuilds them for $595.00. Have you had any dealing with them or heard of them.
 
I would not change the computer until all other avenues have been explored. I would definitely find one to try before you just purchase one or send yours out.

Dumb question, did you recently change the prop?
 
Could be one of a few sensors but mostly,

1. MAP sensor
2. Air Intake Temperature sensor

If one of these is faulty the ECU will go full rich to protect the motor
 
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