5.0 mpi mercruiser

Stevo8

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Feb 11, 2019
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Hello all, I have a 2006 Tahoe deck boat with a 5.0 mpi mercruiser. My issue is I get a 2 beep alarm every few minutes or so and some times when I give it throttle the boat will shut completely off. It starts right back up and idles with no issues. Only when I give it throttle will it shut off. It does it all all different rpms. Whether it’s 1500 rpm or 4000. All of my fluids are full. Any thoughts?
 

scoflaw

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Jun 2, 2010
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962
Probably a 0W motor and that alarm could be many things. Most common being the water pressure sensor. Really need to get it read for faults.
 

Stevo8

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Feb 11, 2019
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0W344593. I had my mechanic replace the block in it 2 years ago because the guy I bought it from never Winterized it and it cracked. He said he replaced it with a 5.7 not sure if that will make a difference. I’ve taken it back to him twice since then because I’ve had this same issue. But apparently he can’t seem to fix it.
 

scoflaw

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That will make a difference, 5.7 has a different ECM. What fault codes are coming up ?
 

Stevo8

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Honestly I’m not even sure. I tried explaining it to him I told him exactly what’s goin on. First time he thought it was my injectors. That wasn’t the case. 2nd time I found water spraying out behind my starter so he replaced a cracked plastic piece that was allowing water out when I put a load under it. Then I noticed on the starboard side at the bottom of the bilge area there was some type of oil housing, not sure if it’s my gear lube or what, anyways there is 2 brass lines that come out of it and they were so loose that they were almost disconnected l. So I tightened them and it ran without fault for a full day or so. But now I’m getting that alarm again and the boat shuts down. Just trying to see if maybe I can replace some sensors to fix it.
 

alldodge

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Thanks, you have a 555 ECM and as mentioned by scoflaw, it can be several things. Killing the motor I would look for a bad connection on the 5V circuit and ignition. Best to get the codes read

replaced it with a 5.7

That can cause the motor to run lean if it was not reprogramed

Slide1.JPGSlide2.JPGSlide3.JPG ​​​​​​​
 

Stevo8

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Feb 11, 2019
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Thank you for the info. That makes sense because I could swear that there was a power restriction. I could feel it when I was running the boat. Sometimes it would take a really long time to get it to plane out. Other times it ran great. Also, I was only getting about 4200 rpm at full throttle. Not sure if that’s normal. I figured it should be around 4600. I’ll get the codes read and go from there.
 

Stevo8

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Feb 11, 2019
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Also, I need to replace my fuel pump relay. Any idea on a part number or can I just get on amazon and find one.
 

alldodge

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Also, I need to replace my fuel pump relay. Any idea on a part number or can I just get on amazon and find one.

The part number is 86-865202T and can find on line, but could also go in a local auto parts store or GM dealer and lay on the counter, they should be able to have one on hand
 

alldodge

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Thank you for the info. That makes sense because I could swear that there was a power restriction. I could feel it when I was running the boat. Sometimes it would take a really long time to get it to plane out. Other times it ran great. Also, I was only getting about 4200 rpm at full throttle. Not sure if that’s normal. I figured it should be around 4600. I’ll get the codes read and go from there.

You should have a 4600 to 5000 rpm WOT. If you have not had the prop or the drive changed then you should be over reving the motor. Only seeing 4200 and a new motor, things are not right. Start by checking fuel pressure at the rail, it should be 43 psi at 1800 rpm.

Since your mechanic does not have a scanner, its time to find a new mechanic

EDIT: fuel pressure should stay close to 43 psi for the entire rpm band
 

achris

More fish than mountain goat
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May 19, 2004
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...Since your mechanic does not have a scanner, its time to find a new mechanic...

This is the most important statement of this thread.

You can not work on injected engines without the right tools. No scanner, you're just guessing.

Chris.
 

Stevo8

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You are correct, I have another mechanic I’m gonna take it to. Problem is he is over 2 hours from where I live. That’s the closest one to me besides the one I used to use. That’s why I was trying to see if it was a simple ish fix. Maybe I’ll just buy a scanner.
 

achris

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Where could I find one? Just any auto parts store?

It's not OBD-II, it's marine specific. As AD said, Rinda is the only company authorized to distribute scanner software, and scanners (for Mercruiser).

You can get the top of the line, the Diacom software. Load it up on a laptop, plug it in via USB and you have realtime display and interaction with the ECU.
A stand-alone scanner (TechMate Pro) that also has some realtime feedback.
Then you can get the Codereader. Very basic, and no information about the output of each sensor...

Honestly, for the extra $200, I'd buy the Diacom over the scanner, and the codereader is by far the least useful (but still better than nothing)..

Chris.........

EDIT: Having just re-read the Rinda site (and found a new toy, eh tool, to buy :D) the Codereader is for MEFI1 to 4 only, not any of the ECM/PCM controllers. You have a choice of either the TechMate Pro or the Diacom software. I have the software. Expensive, yes, very, but after you use it twice, it's paid for itself... And you can scanner all you friend's engines too. :D (and charge them ;))
 
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scoflaw

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If it still has the 5.0 ecm it's never going to run to it's potential and could possibly damage the engine with a lean mixture.

There's a couple of companies that can reprogram it for you, Wipple being 1 of them. You can get the number off the ecm to see what you have there.
 
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thumpar

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Jun 21, 2007
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EDIT: Having just re-read the Rinda site (and found a new toy, eh tool, to buy :D) the Codereader is for MEFI1 to 4 only, not any of the ECM/PCM controllers. You have a choice of either the TechMate Pro or the Diacom software. I have the software. Expensive, yes, very, but after you use it twice, it's paid for itself... And you can scanner all you friend's engines too. :D (and charge them ;))

You can use a 12v LED and paperclip instead of the codereader, but that is for MEFI 1-4.
 
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