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MPI motor won't go over 2000rpm under load. We replace the…

Customer Question
MPI motor won't go...

MPI motor won't go over 2000rpm under load. We replace the low pressure fuel pump, IAC, TPS, and the MAP sensor with no change. When we disconnect the TPS we can go to full RPM under load.

Mechanic's Assistant: Sometimes boat issues seem like they'll be really complicated, but end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Marine Mechanic should be aware of?

It is a new motor, we replaced an old carb 305 with a new fuel injected Kodiak 350 motor that is the same as the mercruiser 350 mag

Submitted: 2 months ago.Category: Boat
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5/29/2018
Marine Mechanic: Jason, Marine Mechanic replied 2 months ago
Jason
Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 18,211
Experience: Degree in Marine Technology. Gas and diesel marine mechanic.
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Hello my name is ***** ***** am I speaking with? I read what you wrote. Have you hooked up a scan tool to the engine to check for codes yet?

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Customer reply replied 2 months ago
Hi Jason, i'm rick. Yes, before I replace the sensors the only thing that came up was the MAP and IAC but only when we disconnected them. Otherwise we had no codes. I don't have access to the DIACOM after replacing the sensors.
The motor has 50hours on it.
Marine Mechanic: Jason, Marine Mechanic replied 2 months ago

HI Rick. So you don't have a scan tool right now?

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Customer reply replied 2 months ago
no
Marine Mechanic: Jason, Marine Mechanic replied 2 months ago

Without Diacom or some other scan tool there isn't anything we can do to test things together. Was there some way I could help you?

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Customer reply replied 2 months ago
but I do have a fluke multimeter and the wiring diagram for the MEFI 4 ECM.
Customer reply replied 2 months ago
the thing is that we were not getting any codes. I will attempt to rent Diacom, but again, with it not giving any codes we only saw that the IAC was supposed to be between 0 and 40 value but ours was at 80value. That was the only thing that led us to replace those components
Customer reply replied 2 months ago
Do I still need Diacom even if it wasn't telling any codes?
Marine Mechanic: Jason, Marine Mechanic replied 2 months ago

I don't think this is something I can help you with unless you have diacom ready to go, and you can do a recording on the engine, and then send me that recording. If we can do that then I have diacom as well, and I can look at your recordings, but without it, there isn't really anything we can do here.

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Customer reply replied 2 months ago
ok, I will attempt to get diacom. do you know of a rental source?
Marine Mechanic: Jason, Marine Mechanic replied 2 months ago

No, I don't know of anybody that rents it.

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