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500 EFI dies when shifting into gear.

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500 EFI dies when shifting into gear.

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Old 07-05-2019, 11:08 AM
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Default 500 EFI dies when shifting into gear.

Hey guys. Got a continual problem Got twin 500ís fuel injection motors in an Eliminator 36

motors are all brand new this winter. For the last several years when shifting into forward or reverse the motor dies. Drive has been checked for any binding up so I know thatís not it. Once you manage to finess it in gear and throttle it up at the same time it does run fairly good. Motor does not run smoothly at idle. It surges. We have checked for vacuum leaks, replaced iac, tps, swapped map sensor, swapped ECMís, even swapped the complete intake plenum from one engine to another. Timing is spot on! It also has brand new boush injectors too. But it did this before the injectors as well. You do not hear the hissing sound from the air intake like the IAC usually makes when it running. The other motor runs flawlessly. My thoughts now wonder if it could be a short in the wiring harness going to the IAC. My mercury scan tool shows no codes at all. I am really flustered at this one. It makes me look like a idiot when docking lol. Please any help will be appreciated. Thank you.
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Old 07-05-2019, 11:18 AM
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does it have the IAC muffler ?? cant remember on the 500
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Old 07-05-2019, 11:23 AM
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No sir. It does not. Thanks
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Old 07-05-2019, 11:29 AM
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what voltage is set on the TPS when you replaced it..sounds like you may need to open the butterflies just a tad with the set screw.

good info here, may lead to to the problem

https://www.offshoreonly.com/forums/...-merc-efi.html

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Old 07-05-2019, 02:24 PM
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Thank you. Iíll give that a try some good info there. I really appreciate the help.
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Old 07-05-2019, 02:41 PM
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You need to monitor IAC counts and make sure the parameters are within spec per a fully warmed up engine - per coolant temp sensor per correct idle rpms from the scan tool.. Also this style IAC is rare for being bad - it does happen but again it is rare - the wiring harness could be an issue for sensors / IAC issues. The connector is another possibility.

You need correct idle rpms as well. You need to check for a vacuum leaks as well. A propane bottle or Merc power tune is a great way to find vacuum leaks - I would check around the throttle body for leaks as well. Also you need to make sure your throttle cable is working properly and the throttle bladed is correctly adjusted. plus very free of movement. For the 500 EFI --- The TPS at the correct idle should read the correct parameters -- for volts thats .4 to .8 volts and the correct throttle angle for the correct idle rpm is 0 to 2 %. All this has to be within spec.

Correct IDLE rpms is 600 to 700 and I shoot for 640 to 660 rpm ranges again at fully correct warmed up temps. Per our discussion of 650 rpms

Their is NO iac muffler for any MEFI control marine engines. The 500 efi is a mefi ecm / controled engine.

Last edited by BUP; 07-05-2019 at 02:47 PM.
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Old 07-05-2019, 02:50 PM
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If none of these or points you in the right direction then I do have something that might help with the issue. I would have to draw it out on paper what is needed to be done.
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Old 07-05-2019, 05:49 PM
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Thanks Bup for all your information. Itís been a real challenge to find this gremlin. Iím leaving town Tuesday for a week with my son in the mountain so it will be the following week before I have time to tackle it. I may ask to text you or call you if none of this helps. It means a lot to have a stranger help me out. Thank you guys for your help. Iíll be in touch and let you know how this works out. 😄
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