92' 5.7 Idle Problems - With VIDEO

[Natesms]

I have an issue where the motor doesn't want to idle when hot. If I mess with the choke (you will see in the video) it helps, so I'm guessing a lean condition of some type. I can fix the problem by cranking the idle up however when cold the motor idles at 1600 - 1800 rpm. Sometimes it will also come up high even while hot.

In the video you can see it idling poorly.

I sprayed carb cleaner all around the base looking for a vacuum leak and couldn't find anything.

Also, what is the hose that comes off the front of the carb and goes somewhere below the motor? I didn't have time to trace it tonight.

 

[achris]

Re: 92' 5.7 Idle Problems - With VIDEO

Question 1. Choke makes the idle smoother. That's usually a blocked /clogged idle circuit in the carb. Looks like it might be time to pull the carb, strip it and give it all a good clean and blow out. When you put it back together, do it 'by the book'... Take your time, work CLEAN and you shouldn't have too much trouble.

Question 2. That hose at the front of the carb is from the fuel pump. It's connected to the fuel pump between the main diaphram and a secondary diaphram. When the main diaphram fails the fuel is pushed up into the carb air horn and will stall (by flooding) the engine. This is also the reason for a proper marine fuel pump. Auto pump only have the one diaphram. When it fails the crankcase gets filled with fuel, and you have what we call, a bomb, in the back of your boat.... Not a good look when it goes off...

Chris.....

 

[Natesms]

Re: 92' 5.7 Idle Problems - With VIDEO

I could use some help finding the right carb kit if anyone can point me at the right one. Motor is a 92.

Motor Serial Number: 0D616972

I was worried that might be the answer, to rebuild. I've had mixed success over the years with rebuilds. I paid a pro to do my last boat but have done many truck carbs. I will see if I can hunt down "the book".

 

[achris]

Re: 92' 5.7 Idle Problems - With VIDEO

The part number for the carb kit is -823426A1.

Ya don't have to hunt too far for 'the book'... -> https://docs.google.com/open?id=0B1TAvwZ3TjhfdVNLbWdZMTRQTkE

 

[Natesms]

Re: 92' 5.7 Idle Problems - With VIDEO

Thanks so much! Overnight shipping here we come...nothing like pulling something apart right before vacation!

 

[Natesms]

Re: 92' 5.7 Idle Problems - With VIDEO

Ok, iboats pulls up different versions. Not sure the difference but the pictures are different. Suggestion? Also is one of the Mallory ones better in your opinion?

Carburetor Kit for Mercruiser 1397-8952 823426A1, GLM 76123 - Sierra 18-7077 - iboats

Carburetor Kit for Volvo Penta 855889-2, Mercruiser 1397-4329 1397-5635 1397-3306 1397-6638 823426A1, OMC Sterndrive Cobra 384743 979659, Chris Craft, Crusader, GLM 76160 - Sierra 18-7072 - iboats

 

[achris]

Re: 92' 5.7 Idle Problems - With VIDEO

The dearer one includes a few more parts.. And for a couple of dollars, that's the one I'd get (avoid Mallory)...

Chris.........

 

[Natesms]

Re: 92' 5.7 Idle Problems - With VIDEO

achris - Thanks for the info here. I rebuilt the carb yesterday and took the boat out. It's never ran better! I followed the manual and it was an easy project.

I think my issue might have been all the crud on the primary rods. They were almost twice the diameter with white stuff caked onto them.

 

[achris]

Re: 92' 5.7 Idle Problems - With VIDEO

Thanks, nice to have the follow-up...

Till the next time..... Have fun on the water.