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Hello.. i need some major help with a problem. basic problem before getting into details. high rpm coming into dock after extended period ( 1.5 hours) @ 4800 - 5200 rpm. engine ran perfect the month prior with shorter run times and variable rpm from one fish spot to another. I say the month prior because we have only had this boat( Weeres 20 ft pontoon, well maintained, looks almost new) for approx a month.
Major info.... this is a mercury branded yamaha engine that mercury only used for 05 and 06. the boat is an early production 07 and all original. I have talked to a couple of merc guys and they dont know. the one guy i talked to said i did more than he would have been able to do..greeeat.....
coming into beach or dock, I can not get it out of gear which i thought was a lower unit issue, but its because of the 2k high rpm. if i shut it off it will come out of gear.
when restarting it, it either goes to high rpm and then starts idling down maybe to 1500 rpms then starts running rough, low idle then die. restart it and its back to 2k rpm for a few minutes then starts running rough again or will stay at 2k rpm all day if you let it.
i can hear the air rushing into the IAC inlet. if i slowly restrict the air I can get it to idle at normal 700 rpm or so.
I pulled the IAC and its fully retracted. i extended the plunger and reinstalled. it stayed at idle for about 10 seconds or so then it slowly went back to 2k rpms. the ecm apparently is commanding it open, BUT why ?
I am a 40 yr experienced auto tech and am well versed in the efi theroy of operation of inputs and outputs. from what i found on researching this engine, there aren't many inputs to the ecm on this engine. cool temp, tps, map, shift switch and crank sensor. I have went over everything as best i can without a scanner. i have 3 auto scanners but that doesn't help me with this. all grds look good. i checked the cool sensor, before i had the book and the resistance does vary 1400 hot to 750 cold i believe it was.. i'm working from memory here.. i checked for 5v ref signal.. 4.9 i checked continuity on shift switch.. opens and closes with shifter operation. the rpm picks up about 500 Rs with disconnection of the tps
the only reasonable priced scanner i can find is 400.00 but it only scans, not sure if it will give live data.
Is there anyway to manually check codes by jumping wires like early auto computer control. i still have my gm key for jumping the aldl.
any info or suggestions would be GREATLY APPRECIATED. as a retired mechanic i really really really would hate to have to take this a shop.
THX, Gary
Major info.... this is a mercury branded yamaha engine that mercury only used for 05 and 06. the boat is an early production 07 and all original. I have talked to a couple of merc guys and they dont know. the one guy i talked to said i did more than he would have been able to do..greeeat.....
coming into beach or dock, I can not get it out of gear which i thought was a lower unit issue, but its because of the 2k high rpm. if i shut it off it will come out of gear.
when restarting it, it either goes to high rpm and then starts idling down maybe to 1500 rpms then starts running rough, low idle then die. restart it and its back to 2k rpm for a few minutes then starts running rough again or will stay at 2k rpm all day if you let it.
i can hear the air rushing into the IAC inlet. if i slowly restrict the air I can get it to idle at normal 700 rpm or so.
I pulled the IAC and its fully retracted. i extended the plunger and reinstalled. it stayed at idle for about 10 seconds or so then it slowly went back to 2k rpms. the ecm apparently is commanding it open, BUT why ?
I am a 40 yr experienced auto tech and am well versed in the efi theroy of operation of inputs and outputs. from what i found on researching this engine, there aren't many inputs to the ecm on this engine. cool temp, tps, map, shift switch and crank sensor. I have went over everything as best i can without a scanner. i have 3 auto scanners but that doesn't help me with this. all grds look good. i checked the cool sensor, before i had the book and the resistance does vary 1400 hot to 750 cold i believe it was.. i'm working from memory here.. i checked for 5v ref signal.. 4.9 i checked continuity on shift switch.. opens and closes with shifter operation. the rpm picks up about 500 Rs with disconnection of the tps
the only reasonable priced scanner i can find is 400.00 but it only scans, not sure if it will give live data.
Is there anyway to manually check codes by jumping wires like early auto computer control. i still have my gm key for jumping the aldl.
any info or suggestions would be GREATLY APPRECIATED. as a retired mechanic i really really really would hate to have to take this a shop.
THX, Gary
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