Can anyone solve this problem?
filed in 1966 Mustang
Question: My 327 Chevy engine was running well, but I noticed that the fuel pump had a small leak, so I installed a new fuel pump. After installing the fuel pump and cranking her up, the motor was shuddering like crazy, but then smoothed out, however the shuddering resumed as soon as I put it in a foward gear. I reinstalled the old pump but the engine is still shuddering. The wierd thing about this problem is that the engine will idle fine and will move in reverse gear with no problem, but as soon as I put it in a foward gear, it shudders and stumbles wildly. If I put it back in neutral it idles fine, and I can rev the engine way up without any problem.
So far I have installed a carb kit (Edelbrock 600) and installed new spark plugs but still have the exact same stumbling and stalling problem when foward gear is engaged. This thing has me mystified and I really would appreciate any ideas anyone might have as to the possible source of this problem. (Tranny is a 350TH).
Thanks in advance for any advice.
Answer: The cheapest/simplest thing that comes to mind and just a wild guess, as learned from past work on hot rods: Check the transmission-to-engine bolts. I’ve seen them work loose and cause the symptoms you mention. It does not sound like it has anything to do with the fuel pump, but just a coincidence it happened right after you changed it. First, check fuel pressure at the carb. Then do a quick flow check. Open the float bowls and take a look around. There may have been some debris in the new pump, and now it’s stuck in the small carb passages, or your in line filter is clogged up with it. Are the fuel pump hoses pinched. Could of pinched when removng the old pump or when installing the new pump. Putting the old pump back on would cause the same systems. Since both pumps do the same thing.
How about the fuel filter at the carb? I always put an inline fuel filter before the pump to catch debris from the gas tank. At the carb there is usually a little tiny fuel filter that when it clogs, allows idle but the engine runs out of gas above idle.
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