help, 390 falls on its face
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Senior User
Joined: Jan 2006
Posts: 217
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From: Dillon, Colorado
help, 390 falls on its face
I have a 1972 camper special with a 390 and it runs great until I drive out on the highway and it falls on its face. It will intermitently stumble like it's running out of gas, with a couple back fires and then start to run good again. It will do this to the point where it almost stalls. The fuel pump and fuel filter have been replaced and I just rebuilt the carbeurator. Any help would be much appreciated.
Posting Guru
Joined: Mar 2003
Posts: 1,622
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From: nevada
If a coil has bad secondary windings, it wont send any juice. had this hard to find prob on my 'Cuda long ago. If you have an old coil on it, replace it anyways, they are cheap.
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Senior User
Joined: Dec 2004
Posts: 236
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From: Southwest Montana
If this truck has the cab mounted tank, then check the bottom of the fuel tank for a small piece of paper or a fuel addative bottle seal or something. The suction pipe has a straight cut bottom to it, and goes almost all the way to bottom of the tank. When the paper slides by on the bottom and you are at highway speed, it will suck the paper up and cut off the fuel. Engine dies and the paper floats away. This is also a very mean trick to play on someone. This exact senerio happend to my sons 72. He drove it from MT to Indiana and back with it dying every 25 miles. After he changed all the stuff you guys are talking about he finally found a seal disc out of a heet bottle in the tank. That fixed it.
something to try
Ken
something to try
Ken
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Elder User
Joined: Jul 2002
Posts: 510
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From: Charlotte
I run the inline filter from the pump to the carb. Doubt it is that unless you got a blockage in the line. Check your plugs for color, check your coil like said before. Did it run this way before you rebuilt the carb? What carb by the way?
Post Fiend
Joined: Mar 2004
Posts: 6,056
Likes: 8
From: Union, Washington
Originally Posted by chump
yes it ran this way before I rebuilt the carb. I'm going to pick up a new coil today. Oh and by the way, is it true it is bad to have an in-line filter mounted sideways?
Freshman User
Joined: Feb 2004
Posts: 43
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Chump, Which carb are you running? I went through similar problems with a carb (Holley4412) I picked up from the wrecking yard and rebuilt. I am jetting it as I write this. The stock ones are just too rich. My stumble would kill the truck if I got at all vigorous with the throttle. Turned out to be bent accelorator pump linkage. Good Luck! Jamie
Postmaster
Joined: Jul 2005
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Remove and replace the point and condenser in the distributor, reset timng after with the vacuum hose removed off the distributor and plug vacuum hose. Check the choke on housing and make sure it not staying closed, the choke should fully open when the engine is warmed up. Check all vacuum hoses for crack or leaks. Check the 4 mounting nut on carburator and tighten down, do not overtighten. Check the all the fuel lines from the fuel tank along the frame rail, to the fuel pump, and up to the carburator, check the fuel lines for cracks or leaks. Check the electrical connections on the coil.
Pull the coil wire off the coil and check the color of spark, if spark is orange in color, replace the coil.
Pull the coil wire off the coil and check the color of spark, if spark is orange in color, replace the coil.