mpi running rich at idle
 

Any help would be greatful

Not to sound like a smart ass but what in the world do you have. I am 99.99 % its a boat app but what engine and make & model and what year and what HP and what is the engine serial # and is this a stock OEM app if not what build is it. What testing have you done any ? have you scanned the engine with the proper diagnostic tools to check for fault codes and running parameters ?

have you done any fuel pressure testing if so what are the fuel pressure psi readings with key on no start and then at idle and then at 1000 rom, 2000 rpm and 3000 rpms ?

scan and fuel pressure tests is were I would start, Is your flame arrestor clean - spotless ? Possible MAP sensor problem but I have no idea what you have for an app here. A lot more info is needed - Not to dogging you but I hate guessing and impossible to even pin point a trouble spot here without all info.

Sorry new to this. I have a 99 baja h2x has a stock reman mercury 7.4 mpi and we have no dealers close with scan tool. Prob 3 hrs to closest one but the boat runs great just long no wake zones it loads up and when I go to take off its not right spits and sputters. After a while I can get it back on plane. And fuel preasure is im pretty sure it was 42 cant remember it has new pump in the cool fuel system k&n spark arrester is spotless just trying to get an idea of where to go next. New coil new plugs wires cap and button also. Where would you start if you was me? Thanks a million in advance!!

I would check plug wires, make sure there're on the right cylinders. Just a thought.

Is this a new to you boat ? Or engine ?

What have you performed for maintenance ? especially within last few years and then right up to this issue happening.

Does your check engine light stay on solid or does it blink ? Hah ! Just joking.

SB all catalyst marine engines have a OBD check engine lite at the dash so if he had a 2010 OEM engine under 500 hp - well heck yes his check engine lite is on and is glowing yellow or orange.

Had the boat about 2 yrs runs great has a brandnew 7.4 create motor and yes its the gen 6 factory rebuild with 5 yr warranty and its just loading up in no wake zones and runs rich on the muffs! Boat runs great just when we go through long no wake zones it does it! Im ready to intake carb and distrbuter it tired of fuel injection lol

I pulled the jasper motor out when I bought due to water in oil! It had a super charged motor in it guy pulled it put a jasper create motor in. Didnt winterize it so I had manifolds tested they were good put new starter every thing you could think of is new. The long block was $6,000 then $$$$$$ from there. Don't get me wrong it runs great fires up first turn of the key. It just runs rich the back of the boat has a kinda grease film after being out and plugs look to be running rich.

were and who remaned your Gen VI - who did the install and why did the original engine needed replacing ? did this reman engine ever run 100 % at all rpms ?

possible coolant temp sensor or that connection or that circuit or possible MAP sensor and or the same connection or circuit

On your reman did you replace the t-stat plus it needs to be 160 degree t-state if you have the stock ECM tune - what water temps are you running especially going thru long wake zones and on the water hose ? Possible T- stat problem or none installed

When I purchaced it had water in thd oil from non winterization . So I ordered a the new motor from a mercruiser dealer. And it has ran great just has always ran a little rich here and there! And I did a new 160 deg thermostat also. Not sure if it ever had a tune previous to my ownership very possible! I took it to the local dealer that put it on the computer and killed the timming advance and set the timming for me runs great in the river just slow movement at the lakes it loads up.im thinking it runs about 170 to 180 deg now on plane running it gets close to 200 thats trimmed up pretty good! And maybe no quit 200

On water hose 170deg im pretty sure

If I were you with the closest Merc service 3 hrs away, I would definitely buy a Rinda Scan Tool.

At this point its all guess work and a scan could pinpoint the problem.

If he was running a SC and using the EFI system, chances are he had pogamming done. Depending on the SC he may have had lage injectors put in to....it's possible.

So......you need to do some CSI work.

WAG don't wok well even on stock motors. Less so on those that have had non OE changes made.

Will SWAG be any more effective?

^^^ what SB said , if your running all the same stuff from the super charged engine, it should have a custom tune in the ECM and larger injectors, is it a mefi 2 or 3

If it's a Cougar Swag...then, YES !!!!

Wait, SWAG-Scientific Wild Azz Guess

Its mefi 2

IMO, you may have multiple things to address, sooner or later its going to foul the plugs so bad that they wont refire, I would find someone you can trust and send them the ecm and see whats in it, or put up with it for the summer and do it later, but with out scanning it you don't know if its sensor related or not, such as a map

Mefi 2 is what I have

Im going to call this dealer see if they will check the computer and size on injectors first. Where can I send my Ecm to get the stock toon put back in it if need be?

and keeps washing the cylinders down with fuel. You have the wrong ECM calibration for your app currently. AND THATS why I have learned up here to ask always is your app OEM STOCK. If not you have describe in detail what exactly you have.

contact Ben ( tunertech ) on this board, see if he can help

so what is your engine set up currently today ? I am lost here you are on second jasper engine or a completely new drop in engine that is a complete engine package with everything new or reman ?

who gave you a 5 year warranty - I would like to see the paper work on that one especially if this a SC engine. No way on that one. Merc is giving out 3 years on some black production engines and even on some remans.

do you have a super charged engine currently ?

what fuel system set up do you have TBI or MPI

Complete stock motor long block had to put in new oil pump and all my pan and covers fuel rail plentam all that stuff! I bought it with a jasper motor never started it pull the motor straight out of the boat and gave it away! It was 6 months old had water in oil! So new motor is stock motor and the owner before me had a super charged motor that blowed up I guess then he put in jasper and sold it I bought it cheap knowing I needed a new motor. So ive put everything new but I got a apt with a dealer 3 hrs away to see whats in the ecm cause I really think theres a tune in it that I dont need telling it to produce more fuel only sensors that I haven changed is IAC that will be changed tuesday Map sensor or throttle position sensor. Hope that might give you a idea what im using basically stock dependable set up is what im looking for I wish I could send just the ecm off to someone I could trust to check it and flash it back to stock or whatever I need it to be. And the mercruiser motor came from US MARINE great engines good wwarranty and mercruiser motor and oem parts

And I dont have no super charger and mpi is the set up

Ok please read this thread from the link below and click on the links in the thread. I hope you do not have this engine that is in the link. I have seen their engines in person from customers that bought them online. No offense but I will leave it at that and let you form your own opinion because mine wont be good. Just saying. They have so many complaints over the years that they changed their name at least 5 times and have many lawsuits.

With that said, miracles do happen and from the powers of the Lord above hopefully you got US Engines best engine they ever built humanly possible. You better go to church this Sunday and pray. All joking aside I hope it lasts for you and is very reliable but I had to show you what you might be up against.

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