A lesson learned about TBI idling....

[Redhook98]

Well, for the past 3 months or so I have been dealing with a starnge situation on my boat. My Stbd engine would be working great for about 20-30 hours of use, then all of a sudden not be able to idle. I would start it,it would come up to a good idle, then an almarm would go off (continuous alarm), and the engine would die. I changed out the IAC, TPS and MAP and it fixed the problem. When it happened again, I put the old IAC back in and it worked great. (the old IAC was stuck and I was able to un-stuck it). It worked great again for awhile, but then it happened again...

Well, this went on for a period of time and all I had to do was swap a few parts around to fix it. I figured I could live with that until the end of the season until I could really dive into it. This past weekend I had had enough though. I swapped out the IAC, but it did not work this time. Swapped IAC from the other motor. No dice. Swapped computers, no dice.

After sitting for a few minutes, I put everything back together. I started it up again for the heck of it and it ran great! WTF?! I started wiggling wiring harnesses around and guess what I found?

It turned out that the small plug on the left side of the TBI (as your looking from the front) that has a loop-back on it was a bit flaky. It is a simple 2-prong type commector with a white loop-back wire on it. Not sure what it is for. I wiggled it and the boat started dying. Think I found my issue. Anyone know what this is? Has anyone read down this far in my rant yet? lol

Anyway, it seems to work great now. I figure in an emergengy I can cut it and splice the wires together if I have to. Anyone seen this? Or know what that plug is for?

Thanks!

 

[obsessive]

Well, for the past 3 months or so I have been dealing with a starnge situation on my boat. My Stbd engine would be working great for about 20-30 hours of use, then all of a sudden not be able to idle. I would start it,it would come up to a good idle, then an almarm would go off (continuous alarm), and the engine would die. I changed out the IAC, TPS and MAP and it fixed the problem. When it happened again, I put the old IAC back in and it worked great. (the old IAC was stuck and I was able to un-stuck it). It worked great again for awhile, but then it happened again...

Well, this went on for a period of time and all I had to do was swap a few parts around to fix it. I figured I could live with that until the end of the season until I could really dive into it. This past weekend I had had enough though. I swapped out the IAC, but it did not work this time. Swapped IAC from the other motor. No dice. Swapped computers, no dice.

After sitting for a few minutes, I put everything back together. I started it up again for the heck of it and it ran great! WTF?! I started wiggling wiring harnesses around and guess what I found?

It turned out that the small plug on the left side of the TBI (as your looking from the front) that has a loop-back on it was a bit flaky. It is a simple 2-prong type commector with a white loop-back wire on it. Not sure what it is for. I wiggled it and the boat started dying. Think I found my issue. Anyone know what this is? Has anyone read down this far in my rant yet? lol

Anyway, it seems to work great now. I figure in an emergengy I can cut it and splice the wires together if I have to. Anyone seen this? Or know what that plug is for?

Thanks!

Is it on the shift plate assembly? I remember reading in the manual that the shift interrupt switch is not used on the Bravo drives, and has a loopback connector installed. I'm unsure what would happen if the loopback was removed, but my guess is that an open circuit (i.e. removed jumper) kills the engine. In Alphas, it's used to keep torque from going through the lower unit when engaging gears (I think to save the shift-dogs) - Bravos (I think) have cone type clutches. Someone else needs to pipe in though...

 

[Redhook98]

Tats what I thought it was also. That makes the most sense to. Can anyone else confirm this? Thanks!

 

[SR Tech]

Confirmed:grin:

No interrupt needed for clutch, the loop back keeps the circuit live. Any connection problem will result in ignition cut out.

The one on the shift bracket is the shift indicator to avoid any confusion

 

[Redhook98]

So in a pinch, I can cut the connector all the way off and splice the wires together? The connector is just laying on the intake manifold.

Thanks for confirming!