Calling all PCM GT40 Owners

I was hoping I could get some help from some of the GT40 ProBoss owners out there. I've got an 86 Ski Centurion TruTrac II (may be taboo around here, but I hope not) that is in great shape except for the engine. I found a good deal on a GT40 ProBoss out of an '01 Nautique that needed to be rebuilt. I have since rebuilt the engine and am working on the installation. I've got just about everything figured out except for a little bit of the wiring and a question on the fuel system.
The issues I'm having are on the front of the engine, there are a series of wires coming out of the harness that simply have eyelets on them to connect. One of them goes to the top of the water pump where there is a temp sensor. I believe this wire to be light tan. There are also three wires I believe to go to the alternator. What I can't figure out is there are two oil pressure sensors over by the filter and I don't know which wires are supposed to go to them. I know one of them gets a sheathed tan/black wire, but I don't know what is supposed to hook to the other one. If anybody could take a look, or possibly post a picture or two of the areas in question, I would greatly appreciate it.
The other question I have is on the fuel system. There is a hose coming off of the Fuel Control Cell that in the book shows to be a vent. I need to know if this is supposed to vent back to the tank, or vent to somewhere on the intake manifold.

If anybody can help, I would greatly appreciate it. I've been reading through this board and using the resources for about a month now and this seems like a good place to get help. Thanks in advance to anyone willing to help.

I don't think you're quite getting what I'm talking about. The centurion was originally a PCM marinization. The pinout on the plug where it hooks to the boat is actually exactly the same as the pinout for where the GT40 harness ties into the boat. The harness that is on the engine, to manage the pro-boss injection system is exactly the same as what would be on an '01 nautique. Other than an audible alarm, the wiring on the boat side to the ignition and gauges is basically identical. What I need to know is how the engine management harness was originally ran on the engine. I can't tell which wire was hooked to the two oil pressure sensors, and the sensor on top of the water pump.

Thanks for the link. I've printed that manual out before. It has helped a bunch so far. It show's the tan/black wires going to the temp sensor on the intake, and the other going to one of the two oil pressure sending units. Either I missed it or it doesn't show what hooks to the coolant temp sensor on the water pump and the secondary oil pressure sensor. Also, it shows that the hose coming off of the Fuel Control Cell is supposed to be a vent, but I want to confirm if this just needs to vent to the upper intake manifold, or if it needs to vent all the way back to the fuel tank. Thanks again to anyone willing to help.

Also, just for further clarification, I'm using the ENTIRE GT40 Proboss 351. Injection system and all. From fancy plastic engine cover to oil pan.

just because it is a PCM doesn't mean anything might have a lot of common stuff but the customer can and does request changes to meet their design specifications. So just because they have the same pin outs doesn't mean they have the same location or number of sensor's where the wires are going. It is also possible the the resistance of the sensors can be different too.

It really shouldn't be that hard to figure out if they do match up then the wores so lay out exactly where they should go I know that was the case when I replace the harness on my CC years ago, didn't need a wiring diagram to figure it other than back by the curcuit breaker.

79nautique wrote: just because it is a PCM doesn't mean anything might have a lot of common stuff but the customer can and does request changes to meet their design specifications. So just because they have the same pin outs doesn't mean they have the same location or number of sensor's where the wires are going. It is also possible the the resistance of the sensors can be different too. It really shouldn't be that hard to figure out if they do match up then the wores so lay out exactly where they should go I know that was the case when I replace the harness on my CC years ago, didn't need a wiring diagram to figure it other than back by the curcuit breaker.

Look, you might have rewired your nautique and you think that makes you some sort of wiring expert, but rewiring a carbed v8 in a boat from the late 70's is a little different than what I'm doing here.
You don't think I've thought there might be differences in pinout and resistance on the sending units? I realize they might not be the same sending units. Once again, that's partially why I want to know what wires go to which sending unit. The GT40 has dual sending units. One set for the computer, and one set for the instrumentation. The wiring diagrams do not specify which sending unit goes to which and they don't look the same. So I want to know which wires go to which sending units so I can verify that my gauges will in fact work, or if I'm going to have to change them. Thanks for the criticism though.    

Man, you ARE a badass. Look, I know enough about fuel injection to know that MOST systems have a return line. I was simply asking because the GT40 service manual makes reference otherwise. That's great you know a lot about fuel injection. I was simply trying to see if someone who owned one could provide me with a little help to save me some time. Diagnosing 4 sending units isn't a major deal, but I figured if I could rule out the two for the computer right off the bat, then I could move on to the next step. It's not that I didn't remember where they went, it's the harness was already off the motor when I got it. Sorry if you think I "wear my emotions on my sleeve", but you jumped in acting like a prick right off the bat simply because I don't own a nautique, so sorry if I seem short with you but you aren't helping. I'm pretty sure the title of this post is "calling all GT40 owners" not "calling all pompus pricks that think they know everything"

fredo, save your breath- it's not worth it. This is 79's way of breaking in new members. Stick around and I'll have your answer when I get back home.

Sorry, I left a letter out of pompous. Thanks for the spelling correction. Sorry to everyone else that my first post on this site has turned into a pissing match. 79, it might come off more as lighthearted ribbing if you used more smileys than the    You came off as a prick, and from what I gathered by M3 saying that you are working on your people skills, I figured that was his way of saying you were an ass. Guess I could be wrong.

M3, thanks again for the help.

79nautique wrote: but then you didn't choose to do that you chose to show your glut enstead.

"enstead" is spelled Instead.

Ease up fredo...if my count is right you have 5 of the most knowlegable members of this site interested in your thread. Give it a chance to be a joke among friends and you will benefit from this little place in the world. I've been here almost a year and have 0 regrets! (<<<-a few happier faces for you)

JoeinNY wrote: I am missing something or does not the first post make it clear that he is using a motor and harness out of an 01 Nautique. Its a good question and the right place to ask it.

Well I took it as he was using the centurion harness with the 01, why remove the harness on it,(01) when the plugs are the same to connect to the hull's harness? or is that just to easy? oooh sorry Joe see it was rebuild now that I look back

M3...you're a good man. EXACTLY what I was looking for. Thanks a bunch!

While I finish getting the rest of the wiring hooked up/sorted out, I'm waiting on a few parts to show up. Some new water hoses, an impeller, cap, rotor, plug wires, and new exhaust tubing. After that, it'll be ready for a test fire. I don't have any pictures yet, but I'll get some if you're interested in seeing the install. It's not much to look at right now except for a pretty motor sitting in a bare floor.

81nautique wrote: he's a passionate GT40 guy.

You bet! You take an already great base motor, then add the most dependable EFI system on the water, paint it all jet black and you've got a mill that means BUSINESS.

Thanks for the approval, of late here on this site I have been told just the opposite.So as not to offend you or others I need to share my slight Knowledge of these boats and motors and keep my opinion to myself.
I too will extend my hand to welcome your friendship, after all it is about the boats and the memories we make. Not the brand but the nut behind the wheel.......Gods Peace Brian

Greg, I've been keeping up with your threads (just not posting) and I must say your motor looks very impressive. I couldn't offer any advice about your punkin patch though because I've never restored a fiberglass boat. So I just sat back and watched. The only restore I've done was my old '59 Chriscraft. You've got lots of good help on this site as you already know. Almost everyone here has good advice to offer and is willing to do so. I do appreciate the props and will stay with you guys for as long as this site keeps going. I'm starting to feel the love again!