Engine Bogging Down When Cold

D

dremison

Seaman
Joined
Jun 9, 2022
Messages
53
The past two times I’ve been on the water, my 5.0 MPI won’t get full power until it has been run for a while. Once it gets warm it will run perfectly all day, but that initial few minutes that it doesn’t get full power is nerve racking. Any ideas what I should look at first to try and fix this issue?
 
Scott06

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,382
dremison said:
The past two times I’ve been on the water, my 5.0 MPI won’t get full power until it has been run for a while. Once it gets warm it will run perfectly all day, but that initial few minutes that it doesn’t get full power is nerve racking. Any ideas what I should look at first to try and fix this issue?
Click to expand...
Would think probably temp sensor. Seems like it isnt thinking its cold and needs to richen mixture .

also would check two common mpi issues IAC valve and the crab style dist cap may be contributing .
 
D

dremison

Seaman
Joined
Jun 9, 2022
Messages
53
Replaced the sensor and also replaced the thermostat while I was at it. It has not been able to get up to operating temp all summer and now I know why - that thermostat was stuck open despot it being my 2nd time replacing it. Got it up to temp in the driveway and plan to do a water test asap. I’m curious if that thermostat keeping it cool contributed to the bogging issue? Thoughts?
I’m also curious what some symptoms of a bad IAC might look like, as well.
 
Last edited:
D

dremison

Seaman
Joined
Jun 9, 2022
Messages
53
Scott06 said:
Would think probably temp sensor. Seems like it isnt thinking its cold and needs to richen mixture .

also would check two common mpi issues IAC valve and the crab style dist cap may be contributing .
Click to expand...
Replaced the sensor and also replaced the thermostat while I was at it. It has not been able to get up to operating temp all summer and now I know why - that thermostat was stuck open despot it being my 2nd time replacing it. Got it up to temp in the driveway and plan to do a water test asap. I’m curious if that thermostat keeping it cool contributed to the bogging issue? Thoughts?
I’m also curious what some symptoms of a bad IAC might look like, as well.
 
Q

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,342
More than a good chance, it’s the distributor and rotor you need to replace. What you’ve described is standard symptoms. They do also over fuel a fair bit until they are up to temperature.
 
D

dremison

Seaman
Joined
Jun 9, 2022
Messages
53
QBhoy said:
More than a good chance, it’s the distributor and rotor you need to replace. What you’ve described is standard symptoms. They do also over fuel a fair bit until they are up to temperature.
Click to expand...
Thank you. I’m tracking on the distributor, but what is the rotor you’re referencing?
 
Q

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,342
dremison said:
Thank you. I’m tracking on the distributor, but what is the rotor you’re referencing?
Click to expand...
The rotor arm inside the distributor. Comes with the cap usually. I’m changing mine on the mpi this week. Be the 6th one in 7 years. Terrible for gathering moisture, cracking and just failing in general. 100’s of posts about them failing on here alone. It’s the flat (crap cap they’re nicknamed) type on your engine.
 
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