2007 Gxi-G 5.0 Rough Idle Issue

[FFR]

My Larson 223 Overheated due to a faulty Raw Water impeller. The engine was running fine until then and I turned it off when I realized the over heating, but I’m guessing it realized an “after boil” because I could hear a steam release sound afterwards for about a minute?

I change the impeller out and am now having issues with the motor running rough, as if it’s rich from too much fuel. I have to start it in the full throttle position then back it off, but it won’t idle without throttle. Lots of fuel smell in the exhaust. Reminds me of when an old carburetor choke would get stuck.

i installed new plugs before trying to initially start it because they were old, and found that and several plugs were wet.

My question is what could cause it to run so rich. Does this motor (2007 Gxi-G 5.0)....have an “Idle Air Control” module, if so where is it located?

Also, do I need a specific code reader (as opposed to one that fits autos for marine engines to check any DTC’s.

Thank you for any responses.

 

[alldodge]

I’m guessing it realized an “after boil” because I could hear a steam release sound afterwards for about a minute?

I think you blew the head gasket

For a code reader go to www.rinda.com

 

[QBhoy]

If the head isn’t blown, other thing that would cause this is a temp sensor thinking it’s cold and running it rich. There is an IAC next to the throttle body.

 

[FFR]

If the head isn’t blown, other thing that would cause this is a temp sensor thinking it’s cold and running it rich. There is an IAC next to the throttle body.

I performed a compression test and all 8 cylinders pressurized and held at 170 or above.

But dang if I cannot find the IAC unless it’s one of the two devices molded into the throttle body, each with its own electrical plug. I’m not very familiar with EFI systems.

I’ll check the temp sensor next.

FFR

 

[QBhoy]

I performed a compression test and all 8 cylinders pressurized and held at 170 or above.

But dang if I cannot find the IAC unless it’s one of the two devices molded into the throttle body, each with its own electrical plug. I’m not very familiar with EFI systems.

I’ll check the temp sensor next.

FFR

It’s on And usually behind the throttle body. If you look into throttle body there is a wee foam filter for it too. Not sure that’s the problem though. Could be.

 

[alldodge]

I performed a compression test and all 8 cylinders pressurized and held at 170 or above.

Either a bad gauge of there is liquid in all cylinders, should be 150 on a new motor

 

[FFR]

Either a bad gauge of there is liquid in all cylinders, should be 150 on a new motor

Thank you, but the engine is 13 years old.

All eight cylinders had fuel in them and it seems to me that a “bad gauge” wouldn’t show a consistent reading eight straight times?

 

[Horigan]

If it’s a bad gauge, it will read bad every time.

 

[FFR]

Ok, I’ve now entered bizarro land.

I wanted to eliminate that I have good spark at the plug wire(fresh plugs installed already)...so I got a spark tester and tested every wire and have good spark at each. But before I did I pulled the fuel pump fuse AND the fuel pump relay at the fuse box and unplugged the wire connectors to both the high & low Pressure fuel pumps to make sure I cut off the fuel to the injectors,...and at every crank to test the spark for a plug wire the engine fired right up immediately and my son had to kill it at the key switch. I have no idea how that’s possible?

So after testing every plug wire for spark I reinstall the fuse and relay and reinstalled the fuel pumps plug wires,...now it won’t hardly start at all without full throttle position...and won’t remain running without throttle and runs very rough..

I disconnected the fuses and pumps again and it fires right up and isles near perfectly????

So something is wrong with the fuel delivery system wether in it’s wiring, or an injector is stuck open or something? I have no idea and I don’t have a diagnostic code reader to find out?

 

[alldodge]

won’t hardly start at all without full throttle position

injector is stuck open or something?

Agree, sounds like your flooding
This would also be why the compression numbers are so high because of fuel in the cylinders. Depending on how bad its doing it the oil level will come up because cylinders are getting washed with gas

 

[FFR]

Got My boat a diagnostic reading and had it water tested.

The mechanic tested the fuel pressure and said it was good. He then got it started And got it up to WOT and it ran very strong until he throttled it back down and it continued to bog down again.

He feels it’s a bad injector but the shop didn’t have a set to change out. So instead of waiting on sending them out to be checked and cleaned I checked and cleaned them myself. They all work and were not very dirty imo. Earlier I had checked the fuel in the filter/water separator,...no trash or water in the fuel.

So I reinstalled the injectors,..installed the water hose to the outdrive and the motor fired right up....started idling PERFECTLY,..throttled up and purred like a tiger for several minutes.

My family heard it running and all came outside, to see it running, smiling, hi-fiving, singing songs and praises to me cause we’re gonna have the boat for the 4th....YAAAAAAY DAD!!!!!

Then just as I’m listening and watching a perfectly running engine and starting to believe I’ve actually succeeded I look down and notice that I had forgotten to plug back in the low pressure pump after reinstalling the fuel filter. As soon as I plugged it in the motor started to bog down and smoking again and died. And I can’t get it to run good again with either of the pumps unplugged or plugged.

Everyone went back in to eat ice cream and I’m out of ideas other than possibly the fuel pressure regulator is malfunctioning?

BOO DAD!

 

[ripjmk]

Everything leads me to believe you still have a filter on the fuel pressure regulator that is patially blocked (volvo removed it in a SB and replaced it with a C clip). If it was partially blocked, WOT would be ok as it doesn't have to pass muss gas back to the fuel cell. It could run ok with the low pressure disconnected as less pressure is developed! Pull the regulator see if it has a discharge filter and if it does look at it with a magnifying glass to see if it is clear. Compress the valveto check it is free to move clean the filter replace and try again!

 

[alldodge]

With the LP not working the HP pump is doing all the work and my guess, pressure was lower. Soon as its back on the pressure goes back up and floods. Its your injectors

 

[FFR]

Changed out the Fuel Pressure Regulator,...no positive results.

took out the Idle Air Control and saw nothing of concern, but accidently ruined it when I plugged it in, turned it on to see if it was actually working or not and when the key was turned off it automatically unscrewed the plunger all the off and shot across the engine bay...plunger & spring included. Found the plunger but cannot find the spring,...and I would have never gotten it back to its calibrated position anyhow. So...that’s next on the parts list.

 

[alldodge]

Sorry to hear that happened but also don't know why it was even thought of. Your getting to much fuel, not air

 

[FFR]

After five months and over $4,000 in hunting for ghosts & making unneeded part replacements I’m thankful to report that non of the suggestions given above were anywhere close to what was causing my boat to run rich and die.

It was the emergency over flow system built into the fuel pumps housing, dumping cups of fuel into the throttle body. That is the fuel system’s built-in fail safe that floods and kills the motor, letting you know something is wrong with your fuel pump.

All that was needed to diagnose this issue was to remove the breather cover on top of the throttle body, turn the starter key to the on position and look into the throttle body and see fuel being streamed and dumped into the intake.

A simple fuel pump change was all I needed...originally.

Lesson learned.

 

[Tail_Gunner]

After five months and over $4,000 in hunting for ghosts & making unneeded part replacements I’m thankful to report that non of the suggestions given above were anywhere close to what was causing my boat to run rich and die.

It was the emergency over flow system built into the fuel pumps housing, dumping cups of fuel into the throttle body. That is the fuel system’s built-in fail safe that floods and kills the motor, letting you know something is wrong with your fuel pump.

All that was needed to diagnose this issue was to remove the breather cover on top of the throttle body, turn the starter key to the on position and look into the throttle body and see fuel being streamed and dumped into the intake.

A simple fuel pump change was all I needed...originally.

Lesson learned.

Since this is an informational board and for the sake of clarity...You say the system dumped fuel into the throttle body is that correct? And your have a 2007 model yr gxi...?
And who may i ask informed you of this built in system?

 

[ggc]

I think what he is describing is the float and needle valve at the top of the Volvo fuel pump cell reservoir between the low pressure pump and before the high pressure pump. It functions like a check valve and prevents the fuel being pumped into the reservoir by the low pressure pump from backing up into the hose returning excess fuel to the reservoir from the pressure regulator on the fuel rail. There are youtube videos on this (Man Cave Mechanic) if you are interested.

 

[Tail_Gunner]

I think what he is describing is the float and needle valve at the top of the Volvo fuel pump cell reservoir between the low pressure pump and before the high pressure pump. It functions like a check valve and prevents the fuel being pumped into the reservoir by the low pressure pump from backing up into the hose returning excess fuel to the reservoir from the pressure regulator on the fuel rail. There are youtube videos on this (Man Cave Mechanic) if you are interested.

Let us not forget the fuel pressure regulator...just a thought.

 

[QBhoy]

After five months and over $4,000 in hunting for ghosts & making unneeded part replacements I’m thankful to report that non of the suggestions given above were anywhere close to what was causing my boat to run rich and die.

It was the emergency over flow system built into the fuel pumps housing, dumping cups of fuel into the throttle body. That is the fuel system’s built-in fail safe that floods and kills the motor, letting you know something is wrong with your fuel pump.

All that was needed to diagnose this issue was to remove the breather cover on top of the throttle body, turn the starter key to the on position and look into the throttle body and see fuel being streamed and dumped into the intake.

A simple fuel pump change was all I needed...originally.

Lesson learned.

Hi. I’m a bit confused how a gxi engine with multi point injection and not tbi injection would manage to dump fuel into the throttle body. Are you sure this is what’s happened ?