2004 Supra Launch - Just stalls and won't start

[JerseyPEPE]

Having an issue with my 2004 Supra...

loads of issues last year which ended up with a bad chip that had to get reprogrammed... that didn't work so the marina put a new chip in it. During the diagnosis, the marina also recommended a new battery, cap, wires and router, plugs, starter and alternator. Oh and I had the prop reconditioned so it's perfect again!

We had a good few rides this year... no load... just motoring around and it ran great... REALLY great. It did stall once and restarted right away. I played it off to last years gas and some condensation. Next day I filled it up and parked it for 3 days. We went for a late afternoon cruise and it stalled again. Only, this time it didn't restart.

The fuel pump was not making any noise nor was any fuel being pumped into the carb. Next day we jumped the fuel pump and still nothing from the injector. We loosened the connector above the schrader test valve, jumped the fuel pump again and the pump is working. I'm hoping it's just a sensor that's stopping the injectors from firing...

Any suggestions on where to start.

It's been at the marina for 5 days and they're not sure when they can even look at it. I'm not ready to lose another summer on the boat.

[secondsupra2004]

Having an issue with my 2004 Supra...

loads of issues last year which ended up with a bad chip that had to get reprogrammed... that didn't work so the marina put a new chip in it. During the diagnosis, the marina also recommended a new battery, cap, wires and router, plugs, starter and alternator. Oh and I had the prop reconditioned so it's perfect again!

We had a good few rides this year... no load... just motoring around and it ran great... REALLY great. It did stall once and restarted right away. I played it off to last years gas and some condensation. Next day I filled it up and parked it for 3 days. We went for a late afternoon cruise and it stalled again. Only, this time it didn't restart.

The fuel pump was not making any noise nor was any fuel being pumped into the carb. Next day we jumped the fuel pump and still nothing from the injector. We loosened the connector above the schrader test valve, jumped the fuel pump again and the pump is working. I'm hoping it's just a sensor that's stopping the injectors from firing...

Any suggestions on where to start.

It's been at the marina for 5 days and they're not sure when they can even look at it. I'm not ready to lose another summer on the boat.

The first thing you need to do is to connect a scanner to the ECM and find out what codes may be stored. These boats use the MEFI electronic fuel injection and you need a scanner or a simple code reader to pull codes. Sounds like the marina has just been throwing parts at your boat hoping that fixes it. I have a 2004 Launch SS also and I bought a scanner to check for codes and to read live data when it is running. Cost me around $500.00 for the scanner, but you can go way over that quickly throwing parts at your boat and not fixing it. If the pump is not powering up when you turn the key on, then something in that circuit is the cause. Could be the fuel pump relay or I think I read there is a pressure switch which will not allow the engine to run if there is no oil pressure. The fuel pump has a relay mounted on the back of the engine near the ECM. Another reason I bought my scanner was because the closest Supra dealer to me is 3 hours away. I also found some of the manuals/schematics on-line and Skiers Choice/Supra has been pretty good about answering some questions pertaining to my boat.

[wontonrunner]

on the right side of the motor (when looking towards the back of the boat) there is a sensor that threads into the block. i always pull it to drain the block. It is rather large and takes a pretty good size wrench. That sensor needs to be plugged in and the connection between the sensor and the block has to be solid. you cannot use teflon tape. I dont know what that sensor is (i think possibly a knock sensor) but if its not plugged in that motor won't run. it is possible that it is loose or corroded or a wiring issue. i would try that.

[secondsupra2004]

on the right side of the motor (when looking towards the back of the boat) there is a sensor that threads into the block. i always pull it to drain the block. It is rather large and takes a pretty good size wrench. That sensor needs to be plugged in and the connection between the sensor and the block has to be solid. you cannot use teflon tape. I dont know what that sensor is (i think possibly a knock sensor) but if its not plugged in that motor won't run. it is possible that it is loose or corroded or a wiring issue. i would try that.

On my 2004, it is the Knock sensor and it is on the starboard side. Never heard that the motor won't run because it is unplugged, but if true, that is good information to have.

[wontonrunner]

On my 2004, it is the Knock sensor and it is on the starboard side. Never heard that the motor won't run because it is unplugged, but if true, that is good information to have.

I can't confirm that this is true. But I can confirm this was the case with my boat. Worth a try!

[JerseyPEPE]

Great tips... The boat is over an hour away so I'll start some of these tips over the weekend.
Where did you get the Code Reader?

[JerseyPEPE]

Sweet... I'll check that out too.

[secondsupra2004]

Great tips... The boat is over an hour away so I'll start some of these tips over the weekend.
Where did you get the Code Reader?

I bought the Techmate Pro from Rinda Technologies. $499.00 direct. They also sell a simple code reader for $60.00 I think.
https://www.rinda.com/rindashop/product-tag/indmar1

[JerseyPEPE]

Knock sensor is fine... I pulled the ECM and tested all the pins looking for a short. I found 2 shorts using a multi-meter doing a simple continuity test. I'm hoping the new marina can repair that. I spoke to the folks at Whipple Super Chargers ... they do ECM repair and reprogramming... the MEFI-4 is sealed and therefore can not be repaired.
Does anyone have experience replacing the entire wiring harness, ECM and getting full fresh start.
I just want to use the boat!

[secondsupra2004]

Knock sensor is fine... I pulled the ECM and tested all the pins looking for a short. I found 2 shorts using a multi-meter doing a simple continuity test. I'm hoping the new marina can repair that. I spoke to the folks at Whipple Super Chargers ... they do ECM repair and reprogramming... the MEFI-4 is sealed and therefore can not be repaired.
Does anyone have experience replacing the entire wiring harness, ECM and getting full fresh start.
I just want to use the boat!
Well, I’m sitting at the dock after getting towed 4 miles. Ran perfect for 4 days and just died in the middle of the lake. Fuel pump running, injectors seem to be spraying fine and engine turning over fine. No spark at the plugs. Pulled a plug, attached wire, grounded and cranked over but no spark. Hooked up my scanner and no codes showing. Checked all the fuses I could find and main relays. Had a brand new coil in the boat, installed it and still no fire. I’m out of ideas right now. I’m thinking spark control module in the distributor or the ECM. Either way,
Vacation is over. My 89’ Supra never quit on me in 24 years. Really disappointed. Any input would be appreciated.

[secondsupra2004]

Well, I’m sitting at the dock after getting towed 4 miles. Ran perfect for 4 days and just died in the middle of the lake. Fuel pump running, injectors seem to be spraying fine and engine turning over fine. No spark at the plugs. Pulled a plug, attached wire, grounded and cranked over but no spark. Hooked up my scanner and no codes showing. Checked all the fuses I could find and main relays. Had a brand new coil in the boat, installed it and still no fire. I’m out of ideas right now. I’m thinking spark control module in the distributor or the ECM. Either way,
Vacation is over. My 89’ Supra never quit on me in 24 years. Really disappointed. Any input would be appreciated.

Got back home, pulled out the manual and started checking the ignition system. Everything pointed to the ICM. Ordered a new one from Inboard Direct ($205.00) and installed it tonight. Boat fired right up. Found the same exact ICM thru Standard Ignition products for $47.00. I ordered one for a spare.
Part number is a LX-384.