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studstud1
01-09-2006, 06:36 PM
I have a 1999 Formula 312 fast tech with 2 454 mercruiser engines. One engine is giving me problems and I would like to know if someone has encountered this problem before. One engine under load goes into a cutting on and off sequence. I have changed rotor and cap module plugs and checked alot of other things. Nothing seems to be bad and the items that I changed did not help. Now again this only happens under load past 2000rpm. Can someone assist me on what to do next? Thanks.

Chris1956
01-11-2006, 05:01 PM
What about the fuel delivery system? Check/replace fuel filters or water seperator. Also check anti-siphon device if you have twin gas tanks.

scottc
03-10-2006, 08:05 PM
"Have someone monitor your power to the ignition while underway. Use a multimeter and someone that knows how to read it. Check wiring connection for loose / corrosion.

Hope this helps,

Scott"

Mark Romano
04-13-2006, 08:52 AM
I have a 2002 vortec 5.7 w/ 200 hrs and have only 100-120 psi in cyls. # 1-3-5. What could the problem be?? Help

chris bartok
04-30-2006, 02:03 PM
"Ofek, did you solve this problem. My 5.7L mercruiser, 1999, is doing the exact same thing. As I cruise at 2,800 to 3,000 rpm the engine just momentarily shuts down and I drop to 2000rpm and then it immediately goes back to speed. No rhyme or reason when, just sometimes. I did replace fuel filter, problem not solved. Let me know if you fixed yours."

jimn
04-30-2006, 02:42 PM
"Ofek- is your motor fuel injected or carbureted? If it's injected, you may have a bad impeller and overheating. Sounds like the motor is in RPM reduction. This is called "limp home mode" by the car guys but don't run it this way- you can kill your motor. If it's not injected, you may have a shorted wire to the ignition system or a loose ground. Don't neglect battery terminals and grounds. They can cause all kinds of odd issues that seem like they're someplace else.

After making sure your raw water intake is OK, I would start by checking the fuel pressure and quality, then go to the ignition."