Hard starting after engine warms up. Carburetor ID

[Skidude17]

I have an MCM Alpha 5.7L SN 0F598365. After the engine warms up, it has a hard time restarting. It will, but I often have to give it a lot of throttle. I assume this is a carburetor problem. I’ve rebuilt a 2 barrel Rochester in the past, and I’m not too scared of a carb rebuild, but I was wondering if there are some screens I could easily clean before tackling a rebuild. I don’t know what model carb I have, though. I need help with both identifying the make/model carb, and common/easy cleaning procedures before a rebuild. As an aside, the timing and idle RPMs are within specs.

 

[achris]

By serial number that's a non-vortec engine. That's Weber 9600 series. To know exactly which you'll need to find the red tag on it. That will have the number, and that will identify it completely. Merc used 3 different Webers on those engines. That one is a non-electric choke (uses a 'heat stove').

Striping and cleaning is easier than a 2bbl...

Chris.....

 

[achris]

Just be aware, these carbs are known for 'dribbling'. After shut down, the fuel keeps dripping out of the venturi, flooding the engine and requiring you to open the throttle a little to get it to light up again.

 

[Skidude17]

By serial number that's a non-vortec engine. That's Weber 9600 series. To know exactly which you'll need to find the red tag on it. That will have the number, and that will identify it completely. Merc used 3 different Webers on those engines. That one is a non-electric choke (uses a 'heat stove').

Striping and cleaning is easier than a 2bbl...
Chris.....

I can’t find a red tag. The number 8867 is stamped on top of the port aft side of the carb. Does that tell us anything?

 

[achris]

...Does that tell us anything?

Nope.

Once you pull it apart make note of the jet sizes and spring colours. We might be able to ID it from those, given they're still original.

Chris....

 

[AShipShow]

Is all else "normal" once it DOES start?

 

[Skidude17]

It appears to.

 

[Sterling Marine]

Possible vapor lock. Try running non ethanol gas, go to pure-gas.org to find a station near you that has it. I've had more than a few customers solve hard starting problems with that.

 

[QBhoy]

Likely the choke sticking

 

[Skidude17]

Possible vapor lock. Try running non ethanol gas, go to pure-gas.org to find a station near you that has it. I've had more than a few customers solve hard starting problems with that.

All I use is ethanol free in anything I have that has a carburetor.

 

[Skidude17]

That one is a non-electric choke (uses a 'heat stove').

Striping and cleaning is easier than a 2bbl...

Chris.....

achris What do you think about the heat stove choke? That could be something causing my problem too. I had one on my first boat, a ‘69 Glasply with a 225 oddfire V6. That choke gave me hell. I quickly upgraded to an electric choke.

 

[Bondo]

It will, but I often have to give it a lot of throttle. I assume this is a carburetor problem.

Ayuh,...... This sounds like the typical weber dribble,....

They start hard after sitting, because the float bowels are empty, 'n the fuel pump has to refill 'em,.....

Then they start hard on a restart, because the dribble has flooded the intake,......

Alotta throttle helps in both cases,.....

 

[Rick Stephens]

What Bondo said ↑

I have the later built Edelbrock version of the Weber. I never experienced the Weber Dribble, but did have issue with the fuel draining back through the pump and emptying the fuel lines when parked for a day. I put a check valve inline between pump and carb and solved that.

I would have to ask Bondo and achris if the Weber dribble responds to a rebuild. The Weber/Edelbrock is the easiest carburetor ever made to tear down and rebuild. Needs a minimum of a rebuild kit that can be had at your local auto parts store.

 

[Skidude17]

What Bondo said ↑


I would have to ask Bondo and achris if the Weber dribble responds to a rebuild. The Weber/Edelbrock is the easiest carburetor ever made to tear down and rebuild. Needs a minimum of a rebuild kit that can be had at your local auto parts store.

I've got a marine rebuild kit on order from Mike's Carburetor. I burned up the starter yesterday at the dock because of the hard start after warm up. I hope that at least helps my issue. Now I'm looking for somebody in my area that rebuilds starters. I don't want to have to fork over the $230 for a new one.

 

[Rick Stephens]

I think I paid $79 for my starter a couple years ago. Rock Auto maybe? As long as marine rated, no problemo getting one from an auto source.

 

[achris]

...I would have to ask Bondo and achris if the Weber dribble responds to a rebuild. ...

Rebuilding the Weber does not fix the dribble. I once had a Weber on the bench with the top off. I filled both sides with fuel. No dribble. I then blew air down one primary throttle barrel (with the throttle full open). I saw the fuel level in that side float chamber start dropping, and fuel being sprayed out of the bottom of the carb. I stopped blowing the air and refilled the float chamber to the same level as the other side. The venturi in that barrel continued to drip, and 2 hours later, that float chamber was empty.

The only conclusion I could reach on the reason was that the passages in the carb between the chambers and their venturis are so small as to allow fuel to be drawn up and to continue to make its way through the carb by 'capillary action'... When I suggested this to carburetor 'specialists', I get told that can not happen. When I tell them I saw it with my own eyes! they go very quiet!

Webers dribble, causing hard starting, and nothing can be done to fix them, short of putting a different carb on. End of story.

I did eventually fix my engine's dribble problem... See my signature.

Chris........

 

[Rick Stephens]

I did eventually fix my engine's dribble problem... See my signature.

Chris........

Thanks for the insights. For whatever reason, I haven't had issue with the Edelbrock version of that carb.

 

[Skidude17]

I think I paid $79 for my starter a couple years ago. Rock Auto maybe? As long as marine rated, no problemo getting one from an auto source.

How do you tell if they're marine rated? Is there a specific vehicle you look under, or do you just go to anything with a 5.7L engine?

 

[Skidude17]

Rebuilding the Weber does not fix the dribble. I once had a Weber on the bench with the top off. I filled both sides with fuel. No dribble. I then blew air down one primary throttle barrel (with the throttle full open). I saw the fuel level in that side float chamber start dropping, and fuel being sprayed out of the bottom of the carb. I stopped blowing the air and refilled the float chamber to the same level as the other side. The venturi in that barrel continued to drip, and 2 hours later, that float chamber was empty.

The only conclusion I could reach on the reason was that the passages in the carb between the chambers and their venturis are so small as to allow fuel to be drawn up and to continue to make its way through the carb by 'capillary action'... When I suggested this to carburetor 'specialists', I get told that can not happen. When I tell them I saw it with my own eyes! they go very quiet!

Webers dribble, causing hard starting, and nothing can be done to fix them, short of putting a different carb on. End of story.

I did eventually fix my engine's dribble problem... See my signature.

Chris........

Pardon the ignorance, but I'm looking at you're signature and don't get it. Is it because you changed to a 4.3L with a different carb?

 

[Bondo]

pardon the ignorance, but i'm looking at you're signature and don't get it. Is it because you changed to a 4.3l with a different carb?

4.3mpi