Merc 30 4stroke EFI

[petekuhn]

"problem is it won't stay

"problem is it won't stay lit--starts, then stops after a few seconds.

Wierd thing is, if I disconnect the ECT sensor, it will idle until the Guardian system cuts in--that's the ECM program that prevents overheat and low oil damage by shutting down the engine. (I did this because that's how you check for sensor problems in car engines)

Compression, spark, fuel all good. Did resistance tests on sensors, oil pressure switch is fine, Engine Coolant Temperature sensor is fine, so is intake manifold temperature sensor, Manifold Absolute Pressure, and Throttle Position Sensor. Can't download codes, we don't have the digital diagnostic meter or cartridge.

--> can the codes be read through the buzzer?

Before, engine was cutting out after a few minutes at full throttle, but would restart immediately after shutting off keyswitch and restarting.

Checked Vapor separator, it was clean--we have Racor water separating fuel filters. Also checked primer bulb and hoses.

Next steps, I guess, are to substitute in our neighbor's ECM from their 40 hp EFI 4 stroke, since it's basically the same engine, and to check the mechanical fuel pump for cupped/warped valves.

Any suggestions on what else to do?

We don't have a road worthy trailer, and the local shop doesn't make house calls, so it's a pain to get it to a mechanic with a DDS

Thanks so much in advance for your help on this."

 

[beckerjs]

"that engine is to new for me,

"that engine is to new for me, anything with a computer and most of us old timers are out."

 

[petekuhn]

"I just called Mercury, the te

"I just called Mercury, the tech support said the engine is running lean. Disconnecting the engine coolant temp sensor causes the ECM to run the engine rich. Tech said to check the fuel pressure, suspect either the electric pump or the pressure regulator. Pinching the pressure regulator's sensing line will enable full pressure from the electric pump.

Tech also said there's no way to read the codes without the special diagnostic tool. Rinda says Mercury won't let them support the outboard ECM, they just make tools for the inboards."

 

[petekuhn]

"Problem was some fool enginee

"Problem was some fool engineering student thought that outboards run on diesel fuel, and got two jerry cans full. The California diesel fuel is very clean-smelling, and our jerry cans already stink of gasoline, so no one else noticed. We topped off the tank in the boat with the diesel fuel, and presto, we had a mixture of gasoline and diesel fuel that smelled like gasoline but the motor couldn't run on it except if the ECM was rigged to run the motor rich. After dumping 12 gallons of gas into the hazardous waste drum at the marina, everything is fine, and another engineering student has learned a valuable lesson."