500EFI Help!
 

500 efi issue. Anybody suggest a test to test an EFI coil output?

One motor started acting up where it would not want to rev past 2500rpm until the boat got on plane, then it was down 200 -300 rpm. A rich fuel smell at idle too. Then a few weeks later, it got worse. Both motors would barely start. Pulled plugs and found all 16 were fouled out. Replaced all 16 and took it out today, one motor started out lazy as before and at the end of the day I could barely get the boat on plane to get home. Again a rich fuel smell at idle. Any thoughts is greatly appreciated. 80 hrs on rebuilt engines. Compression is good and no codes showing on the ECM
I wonder if the coils are going bad. Anybody else have a similar experience with 500 EFIs?

I'd venture to say check the vacuum line to the fuel regulator for cracks.

could be bad coils,i would check the fuel pressure,might be regulators or as earlier mentioned vac hose going bad.also could be water in the fuel,dump the fuel from the filter/water seperator into a clear jar and let it sit.if it contains water the water will go to the bottom of the jar.

true,if both engines are doing something the same,,look for what could be common.may even be corrosion on the ground terminals.start checking.

Thanks everyone for your input. I'll check the ground, fuel pressure and vac hose too and post results.

Fuel pressure was 43psi at idle and dropped a bit to 40psi at 1500.
Checked vacuum lines - no leaks. Checked fuel – no water.
Threw the timing lite on and checked that the ignitions advance as rpms go up.
Also put on my Innovate Air/Fuel meter on one.
12.6 at idle
13.0 1500
12.8 2000
12.5 2500
Here are some pics of the new plugs I put in with less than 2 hrs on them. Only 1 looks halfway normal out of 8.

Anybody have any more suggestions?
[ATTACH=CONFIG]559329[/ATTACH][ATTACH=CONFIG]559330[/ATTACH][ATTACH=CONFIG]559331[/ATTACH]

you could try a new coolant temp sensor. I've seen those go bad, then the ECU sends a pile of fuel to compensate. Might shoot the IAC filter with some brake cleaner, make sure thats not plugged. Thats plenty rich at idle, unless thats an in-gear idle AF.

Good luck-

If you don't have a spare coolant sensor, swap them from motor to motor and see if the problem follows it.

Temperature gauge seems to operate on both motors. Was your gauge working when your ECU dumped fuel in the motor? Wondering if it would still effect the ECU if showing the correct temp on the gauge.

Those plugs are blacker than.......

Time to put a scanner on it and check coolant temp readings as mentioned above, and then tps and so on and so forth.

I check voltage strength to the plugs with a spark plug tester, but you kind of need to see difference of strong spark vs light spark to get an idea.ie: brightness of light blinking

http://www.obd2express.co.uk/upload/...-testerl-1.jpg

I have a Rinda Techmate Pro scan tool but I'm not too experienced with it yet. Do you know what temp parameters should be and how do I check the TPS with it?