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 Any Carburetor Experts? Weber 4BBL Questions
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Author Previous Topic: Mysterious Coolant Disappearance Topic Next Topic: For Mercruiser only , stripped shift cable threads  

seachunk2

RO# 20886

Posted - Jul 07 2019 :  17:25:09  Show Profile  Reply with Quote
Running a 1995 4.3LX Mercruiser with with a Weber 4BBL carb.
Engine is in great shape, starts right up & idles smoothly. Compression is around 140 in all cylinders. Plugs, cap rotor and wires are new.

Boat isn't getting up on plane well. At wide-open I am only getting 3900 rpm. As it planes off I'll get about 4300 rpm. I should be getting 4800.

Suspecting that at wide open, not enough fuel is being supplied. Electric fuel pump seems OK but I haven't tested anything. It's not noisy so it seems normal in that sense.
I'm thinking of doing a good cleaning of the carb & checking linkage adjustments. I'll also double check that the firing order is correct but I doubt thhat's going to be the problem. While I am at it I'll also connect a vacuum gauge and see it that's in the normal range and steady.
Assuming firing order is all OK, anything particular about 4BBL's I should know about. Things like how to tell when the secondary's kick in, etc? All advice appreciated. Thx.

Homeport:

seachunk2

RO# 20886

Posted - Jul 07 2019 :  19:57:28  Show Profile  Reply with Quote
Also, the 65 gallon fuel tank was half full so I topped off in October just before I winterized. Sta-bil stabilizer was added. So fuel in tank is at least 8+ months old. Can this aged fuel be the cause of the problem?


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JVM225

RO# 28365

Posted - Jul 10 2019 :  19:31:30  Show Profile  Reply with Quote
Is this something that just started happening?
Is it possible that your motor isnít the problem?
Is the bottom clean? Have you checked the prop?


2002 Sea Ray 410 Sundancer
95 Eastern 22'
05 Maxum 18' Bowrider
C6 Corvette Convertible
68 GTO


Homeport: Farmingdale NY Go to Top of Page

seachunk2

RO# 20886

Posted - Jul 12 2019 :  05:51:00  Show Profile  Reply with Quote
Just rebuilt top end of motor. Turns out timing was off a few degrees & carb idle mixture was way off. Reset timing and adjusted carb and it's running great. On plane quickly and tops off at 4800 rpm.


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  Previous Topic: Mysterious Coolant Disappearance Topic Next Topic: For Mercruiser only , stripped shift cable threads  
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