5.0GL-A Engine wont idle

[khombat]

Hi guys,

I have no problem starting my 5.0L GL (2001) however to keep it running I have to continually move the throttle.

I did a little research and a lot of people mention the IAC in their own issues on different engines, however I find a lot of schematics for my engine and I cant find the location or existance of an IAC, or the valves to attempt to clean.

Earlier I had to clean my carb as I couldn't get the engine started at all. I just disassembled the fuel bowl and cleaned the jets, inlet and bowl itself and replaced the float spring (Holley 2300). That did the trick. I have also replaced the fuel pump.

I thought it might be bad gas since I have a whole tank of fairly old gas (11 months), so I disconnected the fuel line from the tank into a fresh can of gas just to test. The same issue occurred; will start no problem just stalls when I try to idle, instantly.

Anyone have recommendations as to what this might be?

Thanks in advance for the help (as always).

Cheers,
Brendan

 

[Maclin]

Re: 5.0GL-A Engine wont idle

There is no IAC valve on a carbed engine, it is a fuel injection unit thingy (Idle Air Control).

Has this engine always acted this way? How long have you had the boat? Can it just be throttle adjustment?

 

[khombat]

Re: 5.0GL-A Engine wont idle

Well that explains my failure in finding it

I guess it could be, but I didn't think it was the cause since I didn't touch the adjustment screw.

Would a vacuum leak cause an instant stall when attempting to idle?

 

[khombat]

Re: 5.0GL-A Engine wont idle

Sorry I didnt answer your question. Engine has always run really well, but has been sitting for a while. It wouldnt start this year at all (unless i dumped fuel directly in the carb bowl, but it would stall when that fuel burnt), so I cleaned the carb and it now starts and runs on its own, just stalls when i go under 1000 rpm (attempt to idle).

 

[Maclin]

Re: 5.0GL-A Engine wont idle

Since it was ok before whatever happened then I think the carb needs a complete rebuild, something internal has been affected by the layup duration.

Vacuum leaks will cause a lean condition all the time. When idling usually the rpm's climb then go down and then it wants to die.

Flooding will act more like what you describe, but one other symptom is hard to re-start after it was running for a while, have to hold throttle wide opne to clear the flooding. Spark plugs will be very sooty, or if they have been misfiring they will be wet with fuel.

I would take the carb off and have a full tear down and soaking/spraying and rebuild done for it.