2000 MERCRUISER TBI 5.7 injectors quit at idle

[rhays001]

Follow up.,
you were spot on correct on the alt. with a load tester reader on the battery, the voltage would put out 12. 13, then back to 11. I switched the alt out with a known good one and it went right to 14.3 v charging at anything over 1000 rpm and avg 13.2 at an idle. This immediately cleared the 4 bad codes that kept coming back. The voltage on the Gray wire on the map sensor is now at 5 volts. The map sensor readings raised from 11inHg to 14inHg. I checked again by spraying everything with carb cleaner along the intake, side of the throttle body etc and no leaks. I did pull the pcv valve, (it has an actual valve on it and plugged into the valve cover) and thumb blocked it off, the motor adjusted for a sec, and then continued to stay at 14inHg with the diacom scanner on it. I did try a different used MAP sensor, no change, same numbers. The only issue now is its still running rich, not as bad as it was, but still black exhaust and very noticeable.
Thank you again for your advice and help.

 

[rhays001]

Follow up.,
you were spot on correct on the alt. with a load tester reader on the battery, the voltage would put out 12. 13, then back to 11. I switched the alt out with a known good one and it went right to 14.3 v charging at anything over 1000 rpm and avg 13.2 at an idle. This immediately cleared the 4 bad codes that kept coming back. The voltage on the Gray wire on the map sensor is now at 5 volts. The map sensor readings raised from 11inHg to 14inHg. I checked again by spraying everything with carb cleaner along the intake, side of the throttle body etc and no leaks. I did pull the pcv valve, (it has an actual valve on it and plugged into the valve cover) and thumb blocked it off, the motor adjusted for a sec, and then continued to stay at 14inHg with the diacom scanner on it. I did try a different used MAP sensor, no change, same numbers. The only issue now is its still running rich, not as bad as it was, but still black exhaust and very noticeable.
Thank you again for your advice and help.

 

[rhays001]

Just a little more info. It is also still doing a lot of jumping between 600 and 800 rpm at idle, Like it’s trying to maintain the correct idle, the IAC continues To move in and out between 20 and 35 as the idle goes up and down. I put a used IAC on it and it still did the same.
thank you again for your help.

 

[alldodge]

Once the voltage comes up on the ALT it should stay up. Could be your bat has a bad cell

Your pic is hard to read because of the glare

Rich mix is controlled by the MAP and Temp. The injectors may need to be tested, might be leaking fuel. Many have bought injectors from ebay and regretted it.

What is the timing in base timing mode? Should be 10* BTDC

 

[rhays001]

n the manifold air temp, so we replaced that sensor also ( the one that g

voltage should be closer to 14V. Seeing 11.9V is close to a dead battery. Check output of the alt

s controlled by the MAP and Temp. The injectors may need to be tested, might be l

Once the voltage comes up on the ALT it should stay up. Could be your bat has a bad cell

Your pic is hard to read because of the glare

Rich mix is controlled by the MAP and Temp. The injectors may need to be tested, might be leaking fuel. Many have bought injectors from ebay and regretted it.

What is the timing in base timing mode? Should be 10* BTDC

 

[rhays001]

The boat has twin batteries with a perko switch, i load tested them both and one sent the needle down 1/2 way and would not hold a load the other was fine, Ill put a good overnight slow charge on the other and see if it'll hold or need replacing. I will check base timing and update. The injectors are ( i assume, the original) according to the hour meter, the boat has 200 hours, but according to the diacom, its 700. I will get the injectors checked out and update. Thank you again.

 

[alldodge]

With the Diacom showing 700 hours, someone has replaced the motor, the ECM or both. Could even be the hour meter was replaced or left unplugged for a long time. In any case someone has been messing with the motor.

Would be worth a compression test to see how it turns out. TB held WOT when doing it

 

[rhays001]

With the Diacom showing 700 hours, someone has replaced the motor, the ECM or both. Could even be the hour meter was replaced or left unplugged for a long time. In any case someone has been messing with the motor.

Would be worth a compression test to see how it turns out. TB held WOT when doing it

Thank you, i will do a compression test In the morning and will update you.

 

[rhays001]

todays update,
compression test on all cylinders. 175-180 on all. I had done a lot of reading on how a blown head gasket could cause loss of vacuum and cause the motor to run rich, but in this case not the issue. ( also - no popping trough the carb or exhaust or stumbling at revs that a bad head gasket would indicate, at least peace of mind on compression. All plugs that were replaced a few days ago are starting to show black again with real soot on them.
Put in base timing mode, it was set at 10, tried 4, 6, 8, 10, 12, not much difference, double checked firing order, all good, it did run best with least amount of soot between 9 and 10. set it back to 10.
pulled the injectors, they do not look original and looked like they had been recently replaced, They are red tip injectors and have the numbers R-546 on one side and 8298 on the other, I tried to look them up but cant find any cross over to see if they are indeed mercruiser and the correct ones. I read the 4.3, 5.0 and 5.7 all use the same injector, and the 7.4 uses a higher rated one. I did have an old 5.0 Volvo Penta tbi and intake laying on the shelf and pulled those injectors, they looked clean, so I dropped them into the mercruiser and they ran worse and also one dripped, definitely a wrong decision to try that.. Looking at the number on those from the Volvo 5.0, they have the numbers RIN 554 on them and are an aftermarket injector for a 7.4, which would explain why they ran way too rich, As I don't know what these in the mercruiser are, I am questioning sending them out to be checked and cleaned, or just get some new mercruiser ones ( definitely not in the budget).
Thank you again for your patience and guidance.
Bob

 

[alldodge]

I'm also unable to verify what the injectors are or should be. My guess is the PO changed them out for some on ebay so there is no telling where they came from, or what they were used on

Injectors that should be there are Merc 852956A1 or Mallory 9-33106

I would send them out for flow testing and tell them they need to meet the specs for the Merc part number

 

[rhays001]

Good morning, I called the PO and had a good fact finding discussion. He said old injectors were not flowing well and dripping, so he picked up a set of injectors from orielly's at $55 a piece. He did say that these injectors cross referenced to the mercruiser numbers so he thought he was doing the right thing. Sated the boat would run again, but never 100%..
I will order a set of mercruiser injectors and update again when they come in.
Thank you again for your help with this one.

 

[alldodge]

Did a search and Standard Motor Products and it came to TJ17 injector, also Sierra 18-7685

 

[rhays001]

Did a search and Standard Motor Products and it came to TJ17 injector, also Sierra 18-7685

interesting, so he did have the correct part? I always thought Std auto parts were decent quality.
Thank you again,
Bob

 

[rhays001]

Update...
New injectors came in yesterday. We installed them and immediately saw that the fuel pattern and pulse was much less than with the other injectors. After a few minutes of running the richness and excessive smoke all went away, and engine idled happily around 700 rpm. Took the boat out and it ran well. In review, the boat needed a set of injectors, alternator, ambient temp sensor, IAC valve, a missing wire jumper plug, and general tune up of plugs, wires, cap and rotor. Having the Diacom computer was a big help. Hopefully this will help others with some of the same issues of these TBI systems running rich.
I truly appreciate your help in walking me through these steps and getting this boat running well again.
Thank you.
Bob