New boat- high idle 5.7 efi

[chartersj]

Just purchased a boat with a 5.7 efi. After it warms up the idle goes up around 1100 rpm and I believe it should be around 650. The throttle cable is not holding it there, I can see the lever all the way back to the non adjustable stopper. Even removed the cable to be sure.
Any insight to what to look at next?
I should add it smells like it’s running a little rich and had some soot on the transom after a 20 minute run. And doesn’t start up instantly when cold. Will start and die a couple times before it will stay running but that could be from last years gas still in it.
It has roughly 100 hours on the block due to bad winterize

 

[dubs283]

Vacuum leak? Pcv valve/hose assy not properly seated?

 

[alldodge]

what's the serial number?

 

[chartersj]

Vacuum leak? Pcv valve/hose assy not properly seated?

Not sure how to check for a vacuum leak. I’ll look for pvc valve

 

[chartersj]

what's the serial number?

L629574 is on the tag on the back starboard corner of the block.

 

[alldodge]

Fuel pressure should be 30 psi at 1800 RPM
EST distributor timing set at 8* BTDC using base timing mode

 

[dubs283]

Vacuum leak?

 

[chartersj]

Vacuum leak?

I will spray some brake cleaner around the throttle body today.
Also is two beeps at key on position normal? I don’t get any beeps while engine is running.

 

[chartersj]

Fuel pressure should be 30 psi at 1800 RPM
EST distributor timing set at 8* BTDC using base timing mode

Will verify timing.
How does one check fuel pressure?

 

[alldodge]

Will verify timing.
How does one check fuel pressure?

Your TB will have a plug on one side which can be removed and gauge attached (Item 1 or 3), other side is fuel line
https://www.mercruiserparts.com/bam/subassembly/31844/2704/110

Or can get 91-806901 and remove fuel line and attach it

 

[chartersj]

Vacuum leak? Pcv valve/hose assy not properly seated?

I believe it may have something to do with the pcv valve or lack there of,, on the starboard side of the engine,, there is an open 90 degree plastic fitting from the valve cover going to the top of the flame arrestor. On the port side, another open 90 plastic fitting from the valve cover goes to the front Center of the throttle body under the butterfly valves. If you pop that hose out of the valve cover and plug it with your thumb(that runs to the front of the throttle body) the engine calms back down to 650-700 rpm. So is there suppose to be a pcv valve on the port side valve cover that goes to the front of the throttle body?

 

[alldodge]

Port should be PCV

 

[chartersj]

Port should be PCV

Ok that’s probably my issue then.
Going to try to get one from GM this week if I can cross reference the part number

 

[alldodge]

Ok that’s probably my issue then.
Going to try to get one from GM this week if I can cross reference the part number

Anyone of the GM should do the trick, nothing special

 

[chartersj]

Anyone of the GM should do the trick, nothing special

Out of curiosity,, could you just block off the port to the throttle body and run the hose up to the other side of the spark arrestor?

 

[alldodge]

You could but motor was designed with the valve. Changing things is usually not a good idea. Also a properly operating motor will have some blowby, just very little. The pcv helps evacuate these gasses

 

[chartersj]

You could but motor was designed with the valve. Changing things is usually not a good idea. Also a properly operating motor will have some blowby, just very little. The pcv helps evacuate these gasses

Yeah i'll get one. They are cheap, was just thinking to get me by until I can get my hands on one

 

[chartersj]

Installed a new pcv valve and it’s idling perfectly