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ECM Fuse blown ???

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    Posted: May-03-2017 at 11:29am
So the 10amp fuse for my engine control computer ECM blew. I changed it and it blew again. So what has gone wrong that it is drawing so much current? I am guessing this may be the beginning of a long journey. I'm just praying someone else has an idea of where to start.
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Adam
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Post Options Post Options   Thanks (0) Thanks(0)   Quote quinner Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 11:43am
Perhaps you can start by telling us what motor you have. If it is a GT-40 a guy on PN recently just posted he was able to crack the code on it
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 12:18pm
It's a GM 350 PLL TBI. So there are two injectors visible under the air cleaner over the throttle bodies.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote quinner Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 12:25pm
This is fun, i get another guess, is it the Pro Ski??
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 12:56pm
It's a '97 Sport Nautique. The engine model number is PLLPRR12TBI. So it is not GT-40 (Ford I believe) and not the Apex GM. What is the best way to refer to it? I heard "Pro Sport TBI", maybe. It seems to always be confusing to tell people what it is, other than awesome.
I am guessing I am dealing with a bad ground that is forcing a high current pull to get the voltage needed to the system? I guess could be a relay with a bad contact as well that draws high current. My hope is that someone has a list of wires to chase that have external connections.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote quinner Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 1:13pm
Believe the Pro Sport is a 5.0 not a 5.7, Is your shroud missing?? Shroud should have lettering indicating which motor you have.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 2:22pm
This is fun can I play?

Looking at the serial number he gives, I think it;s a LH 280 hp 350 Chevy that has a 1.23 to 1 transmission turning a RH prop.

Found that in one PCM manual or another.

I don't think they're very consistent in their tags thru the years but there was one that had this all spelled out with the second L meaning it's a 280 HP 350 Chevy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote quinner Quote  Post ReplyReply Direct Link To This Post Posted: May-03-2017 at 3:11pm
To add to the mystery of the mystery motor

http://www.correctcraftfan.com/forum/forum_posts.asp?TID=16195
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-04-2017 at 10:42am
That is a good thread which highlights the chaos of this very well. What the hell is wrong with PCM that they just keep randomly grabbing motors out of a grab bag. Motors make HP. Have two options! mid power, recreational and high power, competition. I think the throttle can take care of any power adjustment needs beyond that. So I saw a picture of my motor in that thread.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-05-2017 at 4:52pm
I dug out my engine cover (don't keep it on the boat). It has a lot more info on it than I thought. I thought it just said "Super fast" written on it and flames or something. So I have a 5.7 EFI Pro Ski. What does the Pro Ski mean? It seems like they threw that term all over the place.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gun-driver Quote  Post ReplyReply Direct Link To This Post Posted: May-05-2017 at 10:15pm
Originally posted by BaccoBouncer BaccoBouncer wrote:

I thought it just said "Super fast" written on it and flames or something.


Ahh yea that's not it
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-18-2017 at 4:25pm
ANy thoughts on where to find the wiring diagram for the EFI system? The service manuals I have foudn have teh diagram for the general electronics but then have a not that EFI is in another diagram but with no reference where to find it. My motor is the '97 GM HO Pro Ski EFI    PLLPRR12TBI
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-19-2017 at 8:53am
I got the wiring diagram from DIM. My guess for a next component swap is the coil? It has a power circuit for the timing set that goes directly to that ECM through that fuse. Thoughts on that swap? ANythign else I should try and swap while I'm at it?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-19-2017 at 8:55am
The manual
ECM manual
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-19-2017 at 12:43pm
I've been going through the diagnosis manual and wiring schematics. I think my next guess is the knock sensor control module is creating a direct short. The two power draws off of that ECM fuse other than the ECM is the injectors and the knock controller. I unplugged the injectors and the fuse still blew. Where is the knock sensor on the motor? Maybe that connector got knocked off and is grounding? Where is the knock sensor control module? best guesses are welcome.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: May-19-2017 at 12:57pm
I think they are usually beneath the cylinder heads in the block
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-19-2017 at 1:02pm
ok thanks. I wonder if I knocked a connector off while changing oil or spark plugs.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-28-2017 at 7:18pm
Three things are powered off the ECM fuse, injectors, knock computer, and ECM. I disconnected each and it only still blows when the ECM is connected. i.e. I can disconnect all three and connect the ECM and it pops. So the question is... ECM is definitely bad or can there be an input to the ECM that can make it draw too much power? something grounds out etc?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: May-30-2017 at 12:38pm
PCM said they have no support for this. I think my only option is a conversion to another (modern) EFI system or Carbs and get the distributor so it doesn't look for a knock sensor (upgrade as well?). Ideas on where to source get support for an upgrade to some modern fuel and ignition systems.? This is a GM 350.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: May-30-2017 at 2:07pm
Skidim has a kit for the 351 ford motor, I think they are likely going to be your best option for plug and play, and suspect that they have, or could make you the kit for a 350 as well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: May-30-2017 at 2:17pm
Any idea who's ecm it is ? Doubtful PCM built it . I'd get what info you can on that and try to see who else uses it. Then search the net for ecm rebuilders and go from there, not many choices for you when the season has already begun. The thing that has helped the GT 40 owners is the Mustang tuners, you need to find a similar Chevy source.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: June-10-2017 at 10:39pm
Update: I sent to the ECM to OBD diagnostics in CA. They checked it out and said it is fine. So while they are sending it back I started to go through the wiring harness in as much detail as possible. I found a weird single wire plug from the harness that was just hanging loose. I say weird because it has an oval shape and an unusual thick o-ring seal. it just has a single pin in the middle. The wire coming out of it is a light blue. I started looking all around for a matching wire color coming out of the harness somewhere else to try and figure out what it was. there is a match going into the knock computer connector...which does pull power directly from the ECM fuse. But I can't find out what that plug goes too. There is nothing anywhere with the receiving end. If it is the knock sensor then there should be a sensor on the block somewhere with an open plug. Can anyone direct me to where the knock sensor should be? I think what I found before that I thought was the knock sensor was the oil pressure sensor right by the oil filter at the block. it is also a blue wire but a slightly thicker guge than this one.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: June-10-2017 at 10:59pm
I think it takes the place of the block drain plug on the drivers side of the engine and gets unscrewed when draining the engine.

Might be on the other side, but they usually go into a drain plug hole on Chevy 5.7 marine engines
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: June-14-2017 at 1:59pm
This is the plug I found loose that looks like it has a wire match to one going in the knock computer. Can anyone confirm what this very specific type of plug goes to? I also can't find anything on the block that could be a knock sensor to see if that is where it goes. Could someone provide a pic of their knock sensor and location if they have a GM motor from the '97 era? Thanks Adam
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DayTony Quote  Post ReplyReply Direct Link To This Post Posted: June-14-2017 at 9:25pm
That sure looks like a knick sensor plug to me.
It is possible a previous owner removed the knock sensor to drain and never replaced it, simply putting a standard drain plug in its place
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BaccoBouncer Quote  Post ReplyReply Direct Link To This Post Posted: June-10-2018 at 8:33pm
So I was doing ok for a while...
The previous engine control issue turned out to be a shorted fuel pump. When it was changed everything was ok. Third day out this summer and she stalls. There is no fuel coming out of the fuel injectors.   Played around with it today and if I bypass the fuel pump relay the fuel pumps run. But the injectors still don't fire. The fuel pump relay clicks back and forth like it's being toggled quickly. Is that the ECM? bad relay? Ideas?

I have a 5.7 EFI Pro Ski.
Thanks,
Adam
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