500 efi needs AIM and Thermotat Housing
10-16-2023, 05:45 AM
#11
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Something weird going on here. Put thermostat back in, boat would not even turn over. Turn Key and then move shifter slowly until engines turns over and it starts right up and run great like the starboard... not loud, but then about 60 seconds into, it runs harder and starts stuter unless manually controlling, then I hear the IAC kick on, and just runs rough and when more gas is applied it stutters until more gas then it jumps up to 2200 rpms and runs rough... I have had mechnic out with computer, they do not know.... replaced IAC last year tons of sensors... spark plugs, distributor cap, etc..
What about the spark module inside the distributer, those can cause all kinds of issues for starting/running as it can throw spark timing off. They get hot and fail over time
Had issues with mine going bad 3x, replaced the original distributors and ran perfect, then one started acting up and replaced it - ran perfect again. You need to buy a Merc module or distributor as automotive versions don’t work right ( a few perf companies offer them and work but it’s hard to know which are good)
Last edited by snowrunner; 10-16-2023 at 05:52 AM.
10-16-2023, 06:38 AM
#12
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iTrader: (1)
I agree on checking fuel psi and compression. Most diagnostics should start this way.
Also, yes, mag pick ups and modules can have issues in those dist’s.
Also, injectors can be issues on those motors too. Search Arcticfriends posts.
If salt damaged/ate thru the tstat housing, other components (intake/block/heads/exhaust) could be compromised too. Have we ruled out any of that ?
Also, yes, mag pick ups and modules can have issues in those dist’s.
Also, injectors can be issues on those motors too. Search Arcticfriends posts.
If salt damaged/ate thru the tstat housing, other components (intake/block/heads/exhaust) could be compromised too. Have we ruled out any of that ?
Last edited by SB; 10-16-2023 at 06:48 AM.
11-28-2023, 07:39 AM
#13
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Thank you guys,
Here is the update;
Found 1 problem was the shifter mechanism had apparently got tons of salt water on it and under the 4 arm shifter / gear was the neutral switch going bad.... Had to turn key and move gear shift back and forth until it engine ignition barely engaged and then the engine would turn over.. Fixed that, replaced all the plugs, rotor and cap.... engine start then fail as it has since summer of 2022.
Decided to swap the entire fuel pump, cooler and regulator from starboard to port. Sure Enough the Port started and ran great. But no Starboard did not start. Swapped out the fuel pumps and starboard does not start but port does... So got it narrowed down to the regulator or cooler. So it is the cooler but most likely the regulator part #15 - - which is 43 psi..... if it has gone bad, alot makes sense.... we smell gas, feels like it floods out.. and the pump sounds like it has too much pressure
Thoughts welcomed.... wish I could find someone in SO CAL to do all this.... I have a decent mechanic but not a big troubleshooter, called everyone and the shipyard charged me over $2000 and did not find it, wanted to replace the entire manifold and thermostat housing.... I love this boat and the layout but the lack of service for the racing engines coupled with salt water I might have to sell after I get it running....
Here is the update;
Found 1 problem was the shifter mechanism had apparently got tons of salt water on it and under the 4 arm shifter / gear was the neutral switch going bad.... Had to turn key and move gear shift back and forth until it engine ignition barely engaged and then the engine would turn over.. Fixed that, replaced all the plugs, rotor and cap.... engine start then fail as it has since summer of 2022.
Decided to swap the entire fuel pump, cooler and regulator from starboard to port. Sure Enough the Port started and ran great. But no Starboard did not start. Swapped out the fuel pumps and starboard does not start but port does... So got it narrowed down to the regulator or cooler. So it is the cooler but most likely the regulator part #15 - - which is 43 psi..... if it has gone bad, alot makes sense.... we smell gas, feels like it floods out.. and the pump sounds like it has too much pressure
Thoughts welcomed.... wish I could find someone in SO CAL to do all this.... I have a decent mechanic but not a big troubleshooter, called everyone and the shipyard charged me over $2000 and did not find it, wanted to replace the entire manifold and thermostat housing.... I love this boat and the layout but the lack of service for the racing engines coupled with salt water I might have to sell after I get it running....
12-01-2023, 06:51 AM
#14
Registered
Thank you guys,
Here is the update;
Found 1 problem was the shifter mechanism had apparently got tons of salt water on it and under the 4 arm shifter / gear was the neutral switch going bad.... Had to turn key and move gear shift back and forth until it engine ignition barely engaged and then the engine would turn over.. Fixed that, replaced all the plugs, rotor and cap.... engine start then fail as it has since summer of 2022.
Decided to swap the entire fuel pump, cooler and regulator from starboard to port. Sure Enough the Port started and ran great. But no Starboard did not start. Swapped out the fuel pumps and starboard does not start but port does... So got it narrowed down to the regulator or cooler. So it is the cooler but most likely the regulator part #15 - - which is 43 psi..... if it has gone bad, alot makes sense.... we smell gas, feels like it floods out.. and the pump sounds like it has too much pressure
Thoughts welcomed.... wish I could find someone in SO CAL to do all this.... I have a decent mechanic but not a big troubleshooter, called everyone and the shipyard charged me over $2000 and did not find it, wanted to replace the entire manifold and thermostat housing.... I love this boat and the layout but the lack of service for the racing engines coupled with salt water I might have to sell after I get it running....
Here is the update;
Found 1 problem was the shifter mechanism had apparently got tons of salt water on it and under the 4 arm shifter / gear was the neutral switch going bad.... Had to turn key and move gear shift back and forth until it engine ignition barely engaged and then the engine would turn over.. Fixed that, replaced all the plugs, rotor and cap.... engine start then fail as it has since summer of 2022.
Decided to swap the entire fuel pump, cooler and regulator from starboard to port. Sure Enough the Port started and ran great. But no Starboard did not start. Swapped out the fuel pumps and starboard does not start but port does... So got it narrowed down to the regulator or cooler. So it is the cooler but most likely the regulator part #15 - - which is 43 psi..... if it has gone bad, alot makes sense.... we smell gas, feels like it floods out.. and the pump sounds like it has too much pressure
Thoughts welcomed.... wish I could find someone in SO CAL to do all this.... I have a decent mechanic but not a big troubleshooter, called everyone and the shipyard charged me over $2000 and did not find it, wanted to replace the entire manifold and thermostat housing.... I love this boat and the layout but the lack of service for the racing engines coupled with salt water I might have to sell after I get it running....
good luck
