too rich

[FishHog]

been running too rich and lots of black smoke on a cold start. Rebuilt the carb last year, no change. Mostly ran fine, but still smokey.
Decided to buy a new carb and put it on today. Even worse on initial start (had to shut down and tighten the fuel line as it had a little drip.). then it flooded the engine out and took a long time to get it to start. Finally did and it just continued to smoke worse than the original carb.

This has to be a carb issue, but could use some suggestions as to next steps.

thanks,

FishHog

 

[Bondo]

Re: too rich

been running too rich and lots of black smoke on a cold start. Rebuilt the carb last year, no change. Mostly ran fine, but still smokey.
Decided to buy a new carb and put it on today. Even worse on initial start (had to shut down and tighten the fuel line as it had a little drip.). then it flooded the engine out and took a long time to get it to start. Finally did and it just continued to smoke worse than the original carb.

This has to be a carb issue, but could use some suggestions as to next steps.

thanks,

FishHog

Ayuh,.... Whatcha workin' on,..??

 

[achris]

Re: too rich

Make, model, year, serial number.... My crystal ball is in for it's 50,000 guess service.

 

[solar7647]

Re: too rich

Need some engine info.... Did you tune the carb? They aren't plug and play, you have to set you idler screw and needles, also need to adjust your throttle cables so that your not dumping fuel in, also is it an electric choke? Is the coke wired correctly? Is the choke functioning properly? Lots of info needed to narrow your issue down.

 

[FishHog]

Re: too rich

sorry, I know better, just not thinking.
1998 4.3L Mercruiser
0L078019

 

[Bondo]

Re: too rich

sorry, I know better, just not thinking.
1998 4.3L Mercruiser
0L078019

Ayuh,.... Some folks put a little boat info in their signature, at the bottom of yer posts,...

Is it a 2bbl. carb, or 4bbl. carb,..??

 

[solar7647]

Re: too rich

Did you replace it with the stock carb or go with an aftermarket replacement like Holy or Edlebrock? Have you checked/adjusted your trottle cable? What RPM does it run at idle once it starts?

 

[achris]

Re: too rich

sorry, I know better, just not thinking.
1998 4.3L Mercruiser
0L078019

That's a 1998 4.3L with single piece manifolds (batwings) and a 2bbl carb...

 

[FishHog]

Re: too rich

batwings were replaced a few years ago.
It was an aftermarket carb, supposedly all set up and ready to go.
When I rebuilt mine last year, I checked and adjusted everything. It ran good, but smoked a lot on cold start up. Thought the replacement might solve that problem, but it is even worse. I didn't do any adjusting on it, as the smoke was so bad on initial and second starting that I'm not convinced I'm not just going to go back to my stock one.

Is there anything other than carb settings that would make the boat run so rich? Its not the choke, adjusted that lots of times and even with it manually kept fully open, its still very smokey on start.

Thick black smoke, carboned up plugs. Not burning any oil, and it floods, so I'm convinced its too much fuel.

thanks for the help

 

[solar7647]

Re: too rich

i would be inclined to suggest a fuel pump issue, is it a mech or elec fuel pump? You should be running between 5 1/4 n 6 1/2 psi on your fuel line from pump to carb at adle, I would start by checking the currant psi your pump is putting out. I can only see the issue being one of three places, fuel delivery, carb and throttle linkage but since different carbs don't improve it i would double check cable linkage is correct and moving properly even disconnect it from the carb to isolate it as an issue and check fuel pump psi ouput.

 

[achris]

Re: too rich

..., is it a mech or elec fuel pump? ....

1998... That would be electric. There hasn't been a mechanical pump on V6 since 1991...

This is a TKS carb?

 

[solar7647]

Re: too rich

Really since 91? Learn something new every day. I thought it was later.

 

[FishHog]

Re: too rich

i would be inclined to suggest a fuel pump issue, is it a mech or elec fuel pump? You should be running between 5 1/4 n 6 1/2 psi on your fuel line from pump to carb at adle, I would start by checking the currant psi your pump is putting out. I can only see the issue being one of three places, fuel delivery, carb and throttle linkage but since different carbs don't improve it i would double check cable linkage is correct and moving properly even disconnect it from the carb to isolate it as an issue and check fuel pump psi ouput.

never thought of a fuel pump issue. maybe a dumb question, but how are you testing the psi. Just deadheading a fitting with a pressure gauge T'ed in, or somehow doing it inline while running.

 

[solar7647]

Re: too rich

I have a inline tester that I hook up in place of the original line, I'm not 100% sure if you would have to do it like that or if your system has a built in test port that you could just hook a gauge to, someone with more knowledge of ur system would have to guide you there. I would think it wouldn't take all that much to remove the pump an bench test it if its a real pain to get the engine to start and run so you can work on it.

 

[achris]

Re: too rich

Being electric you don't need the engine running to test the pump. Just put power to the purple/yellow lead that runs to the pump (you'll find the other end of that wire on an oil pressure switch, port side, low on the engine block, or on one of the small terminals on the starter-motor, or the electric choke, just pull it off that and power it) and it will run. Put a gauge in the line, either in-line or straight onto the end of the line, doesn't matter...

BTW, just turning the key to ON will not power the pump... The engine needs to be cranking, or running for the pump to run normally.

Chris......

 

[solar7647]

Re: too rich

I would just add to make sure the gauge you use has the proper resolution so you get a proper reading. You only need 0-20psi, smaller if you can

 

[FishHog]

Re: too rich

thanks guys, I'll see if I can find a pressure gauge tomorrow.

 

[FishHog]

Re: too rich

Well that wasn't it. New fuel pump did the exact same thing. I'm running out of things it could be. It flooded again right away with the new pump. Finally got it started and lots of black smoke again.

Starting to get frustrating. Any other ideas?

thanks,

FishHog

 

[solar7647]

Re: too rich

Did you check pressure of the old one before you bought new? How much voltage are you getting to your pump? Maybe get it started and get us a video to see were smoke is coming from and how dark it is....that might help figure it out

 

[FishHog]

Re: too rich

no didn't check, got a slightly used test pump from the dealer so didn't cost me much.
smoke is coming out of the exhaust (around the prop, lots and very dark black)
could a weak coil cause flooding/rich running? I have spark, but kind of think it seems a little weak.