8.1S Cylinders Loading with Fuel

[wakerider09]

All,

I have been having an on-going issue with my '05 8.1s port engine. We've narrowed it down to what we believe is one (or more) of the cylinders getting too much fuel and ultimately shutting down; so the engine is only running or 7 or 6 cylinders ( I can feel the vibration). When I pull the plugs they are really wet, which I suspect is causing them not to spark properly (or not at all).

The mechanic tells me that it's likely not an injector issue... and that his lap top should tell him if an injector is stuck open or closed, so he's not keen on removing the injectors at this time.

Compression was showing good as well.

Thoughts?

 

[Ididntdoit]

Cool Fuel III problem - have you checked your fuel pressure?

 

[wakerider09]

Cool Fuel III problem - have you checked your fuel pressure?

Yes i've checked fuel pressure... I also put an entirely new Gen III cool fuel module in.

 

[SeadawgVB]

All,

I have been having an on-going issue with my '05 8.1s port engine. We've narrowed it down to what we believe is one (or more) of the cylinders getting too much fuel and ultimately shutting down; so the engine is only running or 7 or 6 cylinders ( I can feel the vibration). When I pull the plugs they are really wet, which I suspect is causing them not to spark properly (or not at all).

The mechanic tells me that it's likely not an injector issue... and that his lap top should tell him if an injector is stuck open or closed, so he's not keen on removing the injectors at this time.

Compression was showing good as well.

Thoughts?

Coil? Since there is one coil per wire/plug, try swapping the coils from the good engine to the suspect engine. Should be pretty straightforward. When's the last time you changed plugs and wires? I heard a rumor the the 8.1 motors were hard on plugs, but had no issues with the NGK TR55IX iridium plugs. Buy the Volvo Penta 8.1 plug wires (part number 3861295), MUCH cheaper than the mercruiser wires and a perfect match AND also marine grade (so the haters don't get on you about using automotive parts, blah blaah, bla)

 

[wakerider09]

Coil? Since there is one coil per wire/plug, try swapping the coils from the good engine to the suspect engine. Should be pretty straightforward. When's the last time you changed plugs and wires? I heard a rumor the the 8.1 motors were hard on plugs, but had no issues with the NGK TR55IX iridium plugs. Buy the Volvo Penta 8.1 plug wires (part number 3861295), MUCH cheaper than the mercruiser wires and a perfect match AND also marine grade (so the haters don't get on you about using automotive parts, blah blaah, bla)

I've changed the plugs twice already this season. I swapped the wires from the good engine to the bad engine as well. I think I may try the coil packs although i did have a mechanic test them a couple months ago and say he had strong spark on all cylinders.

 

[ttmott]

I assume the mechanic then looked at all of the parameters at the ECM level which also includes the current rise and fall on the injector coils as you said. Just so everyone understands as an injector solenoid pulls and drops the armature (opens and closes the injector) there is a voltage/current signature as the armature passes through the coil that is seen and monitored at the ECM. Did he do a pressure retention test of the injector system? That is to lock up and pressurize the rails and injectors to around 60 PSIG and monitor for pressure drop. An injector pintle can leak fuel yet still indicate good on coil current. BTW it is not a big job to pull the injectors and have them tested, cleaned, and calibrated. The last thing on injectors is there are cases where due to wear or defect that an injector will flow fuel substantially in excess of it's rating yet still indicate good on testing. The only way to determine this is to pull and have it/them tested.