I'm lucky my SSV did not catch fire!

[indo]

2002 SSV
Indmar Assault Multi Port Fuel Injection.
The last time on the water I smelled gas. I opened up the engine compartment and gas was flowing out of the throttle body down the block into the bilge.
Figured out that when the ignition key is turned from off to second position fuel starts continuously spraying from jets into the ports and never stops spraying until the key is turned back off. Anyone seen or heard of this issue before?

[KenG]

Indo,

The way the GM MEFI system (version 3 anyway) is supposed to work is that in start-mode, the fuel pumps are energized when the key is turned to the on position and/or the start position and the injectors will fire. However, if the ECM does not detect the engine speed exceeding about 300 rpm, it shuts down the fuel pumps and injectors. So in a normally operating system, if you turn you key to the on position only, you will hear the fuel pumps running for a couple of seconds and then shutting off.

It is unlikely, but I suppose possible, that the ECM is faulty or the sensors are telling the ECM to keep the fuel pumps & injectors energized. Keep in mind, it would take a lot of fuel to fill up the intake ports and intake plenum and then flow out of the throttle body all the while the intake valve(s) remain closed long enough to do so.

Did you remove the air filter, look into the throttle body and observe fuel flowing out with the key on?

It may be that you may have a leak in the fuel system. On the Indmar engines I am familiar with, there is a crossover fuel line the runs under the throttle body to connect the port and starboard fuel rails. Perhaps a retainer came loose and crossover fuel line is no longer securely inserted into the fuel rails or an o-ring failed. Less likely, you could have a hole worn through the fuel lines somewhere. The crossover line is steel and the clearances are close where is runs under the throttle body.

Good luck.

--KG--

[indo]

KenG "Did you remove the air filter, look into the throttle body and observe fuel flowing out with the key on?"
Yes, exactly. Air filter off. Switch key from off to second position. And the jets above the ports start spraying. After about 30 seconds the intake ports are half full and filling.
Shut the key off , jets stop spraying and the fuel slowly flows into the intake ports. I have not started the boat since the overflow and troubleshooting. At this point I have a lot of fuel in my intake, and will need to change my oil and possible fouled pugs once this issue is resolved.

My first thought/question was where is the leak? I searched. There’s not one.
This boat is immaculate. Before this I have never had any issues. The thing is I usually have it in the center position for only a half second between off and start. On the occasion I noticed the problem, it had been in the center position for some time. Hence fuel flowing into the bilge.

[KenG]

Indo,

Sorry, I misunderstood, I thought you had multi-port fuel injection, but you actually have throttle body fuel injection. Regardless, the ECM control is basically the same that is if the ignition switch is turned to the on position only and engine speed remains below about 300 rpm, the fuel pump(s) and injectors shutdown after a few seconds of operation.

Evidently, the ECM thinks the engine is running when it is not. The ECM monitors the distributor reference pulses to determine if the engine is operating or not.

Make any changes to the distributor or the ECM wiring?

--KG--

[indo]

KG,
No. Never had a need to touch any wiring or distributor.

[KenG]

Indo,

I hate to say this, but your best bet may be to call your dealer and explain the problem. With my limited experience, I don't know what else to tell you. Trying to diagnose an EFI problem is almost impossible unless you have the special tools and equipment.

Good Luck.

--KG--

[Brian Raymond]

Indo, I would deffinately make an appt. with your dealer. This is a high risk area, and should be looked at and repaired by a trained technician. Brian Raymond

KG and Brian,
I plan on taking it to the dealer next week. I will post what they find.
Thanks!

Just heard from my authorized Supra dealer Waterski Boats Dallas.
The ECM is bad. I’m four months out of the three year warranty. The tech said typically when out of warranty they send the existing ECM back to be re-flashed, but he could not communicate with it so that’s probably not an option. A new ECM card retails for $977.
They said they can get me one for $786. This boat has been babied, garaged and only has 150hrs on it.
Anyone had an ECM go bad on a practically new boat?

[indo]

Just heard from my authorized Supra dealer Waterski Boats Dallas.
The ECM is bad. I’m four months out of the three year warranty. The tech said typically when out of warranty they send the existing ECM back to be re-flashed, but he could not communicate with it so that’s probably not an option. A new ECM card retails for $977.
They said they can get me one for $786. This boat has been babied, garaged and only has 150hrs on it.
Anyone had an ECM go bad on a practically new boat?

[indo]

Dealer has sent back the bad ECM to Indmar to have them run DIAG on it.

[Safety Bob]

I just picked up a 502 MPI unit to install on an '88 454. Has anyone performed a conversion before? I know I will need the ECM reprogrammed? Where can I have the ECM reprogrammed?