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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Elpresidente on August 03, 2013, 11:19:50 am

Title: 350 hesitation & RPM drop
Post by: Elpresidente on August 03, 2013, 11:19:50 am

I've got a 350/700R that ran fine yesterday, but today it has a slight hesitation when accelerating from idle, and my engine speed drops almost to the point of stalling when I let off the gas and brake (ex., it does this when I have to brake hard for a red light or when braking to make a turn). Letting off the gas and not braking is fine, but gives me the hesitation when I do accelerate again. It cruises fine, and performs as it should when I step on it. Fuel filters clean, and couldnt find any vac leaks.

Title: Re: 350 hesitation & RPM drop
Post by: zieg85 on August 03, 2013, 02:13:31 pm

Take off the vacuum line to the power brake booster and plug it.  Note no power brakes will be like stepping on a brick but it will stop, just take a lot of pressure.  Sounds to me it is the start of a bad brake booster

Title: Re: 350 hesitation & RPM drop
Post by: Irish_Alley on August 03, 2013, 10:53:57 pm

Quote from: zieg85 on August 03, 2013, 02:13:31 pm

Take off the vacuum line to the power brake booster and plug it.  Note no power brakes will be like stepping on a brick but it will stop, just take a lot of pressure.  Sounds to me it is the start of a bad brake booster

x2

Title: Re: 350 hesitation & RPM drop
Post by: Elpresidente on August 04, 2013, 09:01:34 am

I never would have guessed that. Tightened the carb bolts, that helped a bit. I'll give the booster a look, thanks.

Title: Re: 350 hesitation & RPM drop
Post by: Irish_Alley on August 04, 2013, 10:21:05 pm

Can you hear it hiss when you press the brakes