Bought a boat with a 1999 Mercury EFI 200 Blue Water. Boat ran great but had an occasional alarm issue (over heating buzzer) but the boat was not overheating. The alarm only happened randomly and at higher rpm. Took the boat to the local Mercury dealer and they suggested replacing the high pressure fuel pump, the pressure regulator and rebuild the VST. I had them go ahead and do the water pump as i had no record of the last time it was done. They suggested to replace the wiring harness as well. When i picked the boat up everything had been completed but the wiring harness. The mechanic stated he had found the short that was causing the alarm and i was good to go. Well from that day on the boat has not ever run the same. The alarm was still there and the engine was now surging or "hunting" between 1500-3500 rpm. The motor idles great and run good at WOT but anything in between is not happening. So returned the boat only to spend a few hundred more dollars and was told the problems were corrected by replacing a fuel line. To the boat out again and the same problems exist. I returned it to the dealer a few more times before the manager told me they really don't specialize in motors this old. I have now sunk $4,800 in this motor that probably is not worth much more than that and still have same problems that did not exist when i originally brought it in. I solved the alarm problem as the alarm module finally crapped out. I replaced it and have not had any alarm issues since. I feel like the problem may be caused by water restriction in the exhaust, or something with the fuel system. below is the information and what i have checked so far.
Serial Number - 0g897236
These items done by the Mercury dealer at the original trip to the shop.
replaced both fuel pumps
rebuilt VST
replaced water pump
replaced fuel lines
These items done by me after my frustration with the dealer
Replaced plugs and wires
Replaced Thermostats
Replaced Alarm Module
Replaced engine oil tank cap and sensor.
Compression on all but 1 cylinder 100psi, the one cylinder is 95 psi
plugs all look about the same with no signs of fouling
Fuel pressure with key on is 35 psi
Fuel pressure running is 35 psi
Fuel pressure drops when turned off.
I have ordered a replacement check valve for VST to oil line connection.
Also the stream from the tell tale is not very strong. It has plenty of pressure on the gauge and does not overheat but just a small stream coming out.
Any help would be greatly appreciated
Sean
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, thats a damn shame ;;;;; questions ;; were any modules removed advance or idle stabilizer , how much does fuel psi drop , all link and sync done correctly , all sensors and switches set and verified , vst checked for over flooding , WHAT plugs are in mtr need number , what is fuel psi doing when engine surges , tuner in place and tight,water psi at idle and wot, answer these and report back
Originally Posted by JOE54
