5.7 L merc will not time

[smorgan87]

Hi i have a 5.7 L mercruiser efi tbi type. started out running rich and missing. fixed the running rich with a new tps. now trying to time the ignition system and it wont take 8*btdc, i can advance it up to 15-20 and it will idle (though rough) put it water recently and it runs 4k rpm at full throttle with the torque of a four banger. i pop the seat up and advance it up some more and torque picks up and runs up to around 5500 rpm. im at the end of my rope with this boat and contemplating tearing the entire efi out and stickin carb and msd ignition in there. thanks in advance.

 

[Don S]

Re: 5.7 L merc will not time

Welcome aboard smorgan87.
If you are looking for exact answers to your question, you are going to have to post some exact information about your engine, like year, and Merc SN as year is only the year of your boat and not the engine.

Basically, with ANY type EFI engine, you have to put the ECM into base timing mode before you can set timing.

 

[SeanMcl]

Re: 5.7 L merc will not time

Hi i have a 5.7 L mercruiser efi tbi type. started out running rich and missing. fixed the running rich with a new tps. now trying to time the ignition system and it wont take 8*btdc, i can advance it up to 15-20 and it will idle (though rough) put it water recently and it runs 4k rpm at full throttle with the torque of a four banger. i pop the seat up and advance it up some more and torque picks up and runs up to around 5500 rpm. im at the end of my rope with this boat and contemplating tearing the entire efi out and stickin carb and msd ignition in there. thanks in advance.

It is not uncommon for the harmonic balancer wheel to slip on its rubber ring and throw the timing marks off. You can check by finding TDC for cylinder 1 (close is good enough, you don't have to be exact) and seeing if the timing mark reads 0*. You might -think- you are setting the timing at 8* but if the marks are off, who knows when that spark is really getting there. I'd start there.

BTW, how did the timing get off? Did you pull the distributor or something? Are you sure the plug wires are correct? Basic stuff, I know, but I thought I'd ask.

EDIT: just saw Don's reply, and if EFI has different requirements, disregard my post.

 

[TilliamWe]

Re: 5.7 L merc will not time

morgan, I'd post a photo or two that might help you, but I'll get yelled at. So just take Don's advice, you need to search on here for "base timing mode" and learn how to time your engine. It's very easy, once you figure out how to put the engine in base timing mode. And that's easy too. Good luck.