78 400 sputters underload
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Tuned
Joined: Jul 2006
Posts: 427
Likes: 5
From: Kennett Square Pa
78 400 sputters underload
So picked up another truck anyway damn thing runs fine at idle I can floor it in park no problems revs right up no hesitation no vacumn leaks etc
But so as u put it in drive ya gotta almost feather it. If you floor it falls on it's face. Sputtering and almost stalling out like when your about to run out of gas.
What could it be?
The whole running fine and being floored in neutral and not sputtering or acting funny. Throws me off
But so as u put it in drive ya gotta almost feather it. If you floor it falls on it's face. Sputtering and almost stalling out like when your about to run out of gas.
What could it be?
The whole running fine and being floored in neutral and not sputtering or acting funny. Throws me off
Senior User
Joined: Jun 2014
Posts: 211
Likes: 0
From: Middle Tennessee
The first thought I would have is how old is the gas. Gas spoils pretty quick. Draining it is the best, I would not put good gas in bad. I've had more than one gas engine not run well with old gas..
There are guys way smarter than me that'll chime in.
There are guys way smarter than me that'll chime in.
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Tuned
Joined: Jul 2006
Posts: 427
Likes: 5
From: Kennett Square Pa
Thought the same thing but it was on empty when I bought it the PO drove it often I put a few gallons of 93 in it and replaced a leaky accelarator pump diagram but nope still acting up
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Same as every other time this gets asked: accelerator pump integrity and stroke, idle transfer slots, vacuum leak, vacuum advance. New vehicle means full tune up anyway. It's anybody's guess as to what the plugs look like. Sounds like you haven't dived too deep.
This whole "no vacuum leaks" and "this can't be wrong" doesn't fly. If it's acting like a vacuum leak, you are wrong when you say there is no vacuum leak. We can assist with checking this properly if needed.
Why 93 octane in a stock '78 motor? The lighter wallet makes you go faster?
This whole "no vacuum leaks" and "this can't be wrong" doesn't fly. If it's acting like a vacuum leak, you are wrong when you say there is no vacuum leak. We can assist with checking this properly if needed.
Why 93 octane in a stock '78 motor? The lighter wallet makes you go faster?
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Tuned
Joined: Jul 2006
Posts: 427
Likes: 5
From: Kennett Square Pa
I replaced the pump since it was leaking and thought that was the problem the pluses wires and rotor are brand new haven't located a vac leak not can I hear one gonna have to check the timing.
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don_79f250
335 Series- 5.8/351M, 6.6/400, 351 Cleveland
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Sep 21, 2004 02:45 PM
