Issues after 502 Mag MPI swap in my 2000 Baja 272
05-18-2013, 03:54 PM
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Issues after 502 Mag MPI swap in my 2000 Baja 272
Hi,
I have a few issues that I was hoping the experts on this site could help me out with.
I have a 2000 Baja 272 which was delivered with the standard power, the 310 hp 7.4 MPI. Well, the boat only went 53-54 Mph, which felt way to slow. So I bought a 415 hp 502 MAG MPI, which I had completely rebuilt in South FL before I shipped it over to Sweden where I spend most my time. I had the engines swapped the other week, and didn't have any issues besides that we had to switch the shift and throttle cables, since they are located on the other side of the engine with the 502.
So first issue was that the alternator was wired incorrectly, so I couldn't turn the engine off. Easy fix, and then it ran great on the hose. So, I put it in the water (I keep it in the water, since I live by a fresh water lake), and it still ran great.
But, during the trip from the ramp to my slip it started to run rough, smoke, and overheat. The idle rose to 1600 rpm's, and the temp gague stuck to 190 degrees F. I barely made it to my slip, engine smoking bad, couldn't shift cause of the idle, and some wind too. It took maybe 5 minutes on idle to get there until I could turn the engine off.
So, I quickly realized the impeller housing broke. I had a spare sea water pump from the old 7.4, swapped it out, still didn't work. No water pressure. Gave up for the night and went back to it this morning. Turned out the impeller in the other sea water pump broke! I mean, what are the odds?
Anyway, when to get a new impeller, put it all back together in the boat. The cooling worked, finally! Oh well, the "out" hose cracked, so need to fix that tomorrow....
But, the idle is still waaay to high, and irregular. When cold it idles arount 1000 rpm, or occilating between 900 and 1100 rpm. After a while it pegs at 1600 rpm. I have no idea if the rough running is gone or not, since I am afraid to break the drive trying to get it out onto the lake to get it up to speed. I need to fix the idle first.
I have tried to remove the control cable, so I know that is not the problem. I checked the vacuum hoses around the throttle body, and for obvious signs of failing cables. Nothing that I can see. I also tested to disconnect the alternator, if that in some way could affect the idle. But no, still 1600 rpm.
So, 3 problems; alternator wiring, overheat, and idle problems. Are they related or what to expect when sorting out an engine swap? I feel the overheat and the idle problems occured to close in time to not be related.
I searched back and forth, and most threads point to IAC. Unfortunately I have yet to find a thread that actually tell me where it is located and how I remove it....
Anyone out there that can help me out with some ideas? Or point me to a DIY for treplacing the IAC?
Any help would be very appreciated!
Regards
Johan
I have a few issues that I was hoping the experts on this site could help me out with.
I have a 2000 Baja 272 which was delivered with the standard power, the 310 hp 7.4 MPI. Well, the boat only went 53-54 Mph, which felt way to slow. So I bought a 415 hp 502 MAG MPI, which I had completely rebuilt in South FL before I shipped it over to Sweden where I spend most my time. I had the engines swapped the other week, and didn't have any issues besides that we had to switch the shift and throttle cables, since they are located on the other side of the engine with the 502.
So first issue was that the alternator was wired incorrectly, so I couldn't turn the engine off. Easy fix, and then it ran great on the hose. So, I put it in the water (I keep it in the water, since I live by a fresh water lake), and it still ran great.
But, during the trip from the ramp to my slip it started to run rough, smoke, and overheat. The idle rose to 1600 rpm's, and the temp gague stuck to 190 degrees F. I barely made it to my slip, engine smoking bad, couldn't shift cause of the idle, and some wind too. It took maybe 5 minutes on idle to get there until I could turn the engine off.
So, I quickly realized the impeller housing broke. I had a spare sea water pump from the old 7.4, swapped it out, still didn't work. No water pressure. Gave up for the night and went back to it this morning. Turned out the impeller in the other sea water pump broke! I mean, what are the odds?
Anyway, when to get a new impeller, put it all back together in the boat. The cooling worked, finally! Oh well, the "out" hose cracked, so need to fix that tomorrow....
But, the idle is still waaay to high, and irregular. When cold it idles arount 1000 rpm, or occilating between 900 and 1100 rpm. After a while it pegs at 1600 rpm. I have no idea if the rough running is gone or not, since I am afraid to break the drive trying to get it out onto the lake to get it up to speed. I need to fix the idle first.
I have tried to remove the control cable, so I know that is not the problem. I checked the vacuum hoses around the throttle body, and for obvious signs of failing cables. Nothing that I can see. I also tested to disconnect the alternator, if that in some way could affect the idle. But no, still 1600 rpm.
So, 3 problems; alternator wiring, overheat, and idle problems. Are they related or what to expect when sorting out an engine swap? I feel the overheat and the idle problems occured to close in time to not be related.
I searched back and forth, and most threads point to IAC. Unfortunately I have yet to find a thread that actually tell me where it is located and how I remove it....
Anyone out there that can help me out with some ideas? Or point me to a DIY for treplacing the IAC?
Any help would be very appreciated!
Regards
Johan
05-18-2013, 06:33 PM
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Its pretty esy to change.. you need to start looking through mercruiserparts.com.. good tool w/pics!!
iAC is under the intake spacer.. 4 bolts.. easy and you will see it!!!
Oh.. its item # 34
https://www.mercruiserparts.com/Show...+INTAKE+PLENUM
iAC is under the intake spacer.. 4 bolts.. easy and you will see it!!!
Oh.. its item # 34
https://www.mercruiserparts.com/Show...+INTAKE+PLENUM
Last edited by nailit; 05-18-2013 at 06:38 PM.
05-19-2013, 03:23 PM
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Rhanks, appreciated! That will make it a lot easier.
One more thing I just remembered; I have an alarm sounding, which sounds like the low drive oil alarm. Checking the level I have well above half way up.
Could this somehow affect anything?
Johan
One more thing I just remembered; I have an alarm sounding, which sounds like the low drive oil alarm. Checking the level I have well above half way up.
Could this somehow affect anything?
Johan
05-19-2013, 07:38 PM
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The alarm is triggered by low drive lube, overheat or no oil pressure.
You should have someone with decent knowledge about the MEFI ecm to look things over.
With proper tools it is easy to check if the IAC is working, also the high idle could be a result of the ecm doing what it thinks is correct according to some other conditions that are not obvious to the eye.
You should have someone with decent knowledge about the MEFI ecm to look things over.
With proper tools it is easy to check if the IAC is working, also the high idle could be a result of the ecm doing what it thinks is correct according to some other conditions that are not obvious to the eye.
05-19-2013, 07:59 PM
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It's probably the IAC. Easy to replace. If that's not the issue, check the fuel regulator in the cool fuel system. It can affect idle and it is run off of vacuum.
05-21-2013, 05:29 AM
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It turned out to be a really filthy throttle body, that didn't close properly. I think the IAC is toast too, since it looks like crap and the boat wont idle cold. So I bought an IAC on Ebay that should arrive shortly. I still have the alarm, though, but I will start a new thread about that.
Regards,
Johan
Regards,
Johan
