Change carb to fix cold start issue???

[jrclocks]

I have a 1995 Merc 4.3 LX Ser # 0F297752 with the Weber 4 bbl , # 9600s.

I've searched this topic and it appears that this carb has a chronic cold start issue. Mine runs great and starts fine once its warmed up. The choke is adjusted and operating properly and the accelerator pump gives a strong stream. But it take many throttle strokes to WOT to get it going at the ramp.

Some have replaced it with the Edelbrock 1409 with the 1485 kit. However, no one states that this fixed the cold start problem. From the outside, the 1409 looks a lot like the Weber. I don't want to replace the carb to still have the cold start issue.

Does anyone know if the 1409 cures the cold start issue?

Thanks,
JR

 

[Bondo]

Re: Change carb to fix cold start issue???

I have a 1995 Merc 4.3 LX Ser # 0F297752 with the Weber 4 bbl , # 9600s.

I've searched this topic and it appears that this carb has a chronic cold start issue. Mine runs great and starts fine once its warmed up. The choke is adjusted and operating properly and the accelerator pump gives a strong stream. But it take many throttle strokes to WOT to get it going at the ramp.

Some have replaced it with the Edelbrock 1409 with the 1485 kit. However, no one states that this fixed the cold start problem. From the outside, the 1409 looks a lot like the Weber. I don't want to replace the carb to still have the cold start issue.

Does anyone know if the 1409 cures the cold start issue?

Thanks,
JR

Ayuh,.... It's the Same carb, all the parts are interchangeable 'tween the 2,....

Yer sufferin' from the float bowls leakin' off,....
The fuel pump has to reprime the carb after long non-use periods,...
Many, includin' myself have installed by-pass wirin' to the fuel pump for that purpose,...

 

[Volphin]

Re: Change carb to fix cold start issue???

Work with the carb you have... the only real difference between the two is yours has 3 step metering rods. Sometimes that is beneficial for mid throttle...

 

[bonzoscott]

Re: Change carb to fix cold start issue???

Don't know about all boats but the carbed ones I have dealt with, you have to squirt a good amount of fuel on start up and keep 'em running at about 1100-1200 RPM for 1 minute and then she'll start warming up and idle. And considering a good tune up when necessary.

 

[Wave thumper]

Re: Change carb to fix cold start issue???

This is what I did to my boat to fix the cold start issue

1/ My boat has a q-jet, but I retro-fitted an electric choke from a carter thermoquad to my carb and adjusted the setting at home to ensure it is good to go when I am at the ramp.

2/ Fitted an electric fuel pump which I turn on for 30 seconds prior to attempting a start. This fills the carb reservoir which was probably empty as the fuel would have evaporated because the boat is not used regularly. (note my boat also has a mechanical fuel pump in line)

3/ After running the electric fuel pump, I pump the accelerator a few times prior to attempting a start

Now my boat starts first time, every time.

 

[jrclocks]

Re: Change carb to fix cold start issue???

UPDATE... This may help others with a cold starting 4.3LX/Weber 4 bbl with the divorced choke.

I didn't think my carb's bowl was dry because when I checked for accelerator pump fuel, I got a healthy stream down the primaries. Yet the engine was hard starting when cold. No other performance issues.

So, I had my brother up to look at the engine. He worked with carbs a lot back when they were used on cars. He didn't like the "feel" of how firmly the choke was closing. I hate it when he says something like that. So to make his point, he had me watch the choke butterfly while he cranked the engine.

While the choke was closed before a cold start, The bi-metal coil on the intake manifold wasn't pushing it closed firmly. While he cold cranked the engine, the choke would flutter open from the vacuum of the engine about 1/4". This was not the vacuum choke pull-off, but just the suction of the engine past the slightly open primaries for fast idle. He adjusted the linkage from the bi-metal coil to keep it closed a bit firmer and I no longer have a cold start problem. We checked the vacuum choke pull off against the spec in the manual and let it warm up to ensure the choke was opening fully. It all looks good and it ran great.

The previous owner used it this way since he bought it and the original owner told him it was always "cold natured". I wonder if it came this way new? Glad I didn't buy a carb!

Sometimes it's the simplest thing. Hope this story helps another with this frustrating issue.

JR

 

[NHGuy]

Re: Change carb to fix cold start issue???

Good for you, I'm glad you didn't dig in your pocket for a carb when all that was needed was a knowing hand.