cutting out only at high speeds. need help

[daniel11077]

2000 merc 200hp. Cuts out at 4800 rpm and up but only sometimes. Runs perfectly other than that. It is like a really bad miss that tries to kill the motor but it picks itself up and goes again. I put new fuel line,filter,water separator,bulb,filled with new fuel,sea foam,and no difference. High pressure fuel pump is expensive but will replace if that is the problem. Repair shop told me their machine won't help and all they can do is start replacing parts. Need ideas and help. Thank-you

 

[Faztbullet]

Re: cutting out only at high speeds. need help

If its a instant shut off and return type miss its electrical, if is a surging miss its fuel.
Electrical
1) check connections at CDM modules
2) check grounding wires
3) check connection at ECU
4) check the voltage rectifiers/regulaters
5) ECU
Fuel
1) replace fuel pump diaphram
2) check fuel pressue on rail
3) injector/s
4) fuel pump(electric)
5) ECU
This is for a regular EFI not a Optimax