Hesitation
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Freshman User
Joined: Jun 2007
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From: Rossville, IN
Hesitation
1978 F250 4x4 automatic with Holley 4 BBL carb. 400 engine (I think) I've only had the truck about 3 weeks, so I'm learning about it. A little history as I understand it. Truck has sat for about 2.5 years with little to no running about. Guages all worked until I filled the tanks with fresh gas, then rear tank (which is AUX on my truck) guage quit. Anyway, I'll solve that issue later. However, ALL the diagrams that I have seen on vacuum, fuel delivery, etc have been for a 2 BBL setup. Is/was the holley carb a standard setup for this truck back in the day? The hesitation occurs from a stop, such as a stop light/sign etc. Warm or cold engine. Additionally, the idle kickdown doesn't appear to be working correctly. It seems to have three settings, startup (high), mediup rpm and idle. Rarely, will it stay in the idle position. It wants idle high enough that I gotta be pushing on the brakes pretty good to keep from lurching forward when put into drive. I am going to put some more fresh gas in today and spray the carb down with cleaner. Any more suggestions?
Post Fiend
Joined: Jul 2006
Posts: 6,948
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With the engine off, and the air cleaner off, look down the throat of the carb, and open the throttle blades. Check to see for a healthy spray of fuel from the squirter. This comes from the accelerator pump. It is designed to give provide a shot of fuel during acceleration when additional fuel is is demand while air speed is already low, and vacuum drops. The hesitation is very common, and could be from a bad accelerator pump or clogged squirter.
If the idle kickdown you are talking about is the "high idle" then you have some linkage that could be in a bind, or is just dirty. A good cleaning should resolve this.
If the idle kickdown you are talking about is the "high idle" then you have some linkage that could be in a bind, or is just dirty. A good cleaning should resolve this.
Freshman User
Joined: May 2007
Posts: 47
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From: Sugar Grove Pa
Holley's are very simple to rebuild, It sounds like an 4150 or 4160, just got done rebuilding mine after sitting for nearly 10 yrs. when you push the throttle linkage you'll see on the front left of the carb will be a bolt with a spring, that bolt pushes the accellerator pump. push the linkage and verify the little lever on the accelerator pump is pushed. If it is, repeat this process looking down the throat, you should see fuel coming out the squirters on the primary side. If there's no fuel, either the accelerator diaphram is not working or the passages are blocked. Easy rebuild.
and no this was not a stock option.
Edited:
**damn too slow**
and no this was not a stock option.
Edited:
**damn too slow**
Last edited by aerobb; Jun 29, 2007 at 07:02 PM.
Thread Starter
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Freshman User
Joined: Jun 2007
Posts: 26
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From: Rossville, IN
I put some Lucas oil system cleaner into the system and sprayed the heck out of the linkage, primarys and around the base of the carburator. Wow, that helped out. Engine has better response from idle and holds good power through shifts. I checked the primary jets for squirting as requested and I am getting good amount of fuel. Thanks for the tip..........Now on to the next thing
