Engine Surge

[Ski]

To follow up on a previous problem I have a 96 XLT 351, I just had to replace the fuel pump for a no start problem and works great. However there is still a surging problem at low speeds, as well as an odd whistle that increases and decreases with the RPMs. Seems to be only when the motor is cold or it is humid out. Noticed today that it idles rough now as well. Any thoughts? Also does anyone know where I can get a vacuum schematic for my truck?

 

[Seabronc]

That whistle you are hearing is most likely a vacuum leak and could be causing the other problem. You may also have a sticking or defective TPS. Try using a small hose holding one end to your ear and moving the other one around your engine to find the source of the whistle. I have had quite a bit of success finding the source of noises that way. Another method of finding a vacuum leak is to use a hand held propane bottle with the valve slightly open and move it around the engine. When it is near the leak it will **** some in and the RPMs will increase. This is obviously a little more dangerous and you should keep a fire extinguisher ready, just in case.

There should be a schematic either on the under side of the hood or on the top of the radiator support. Each function is color coded and the vacuum lines have the same color.

Good luck,

 

[Ski]

To follow up on a previous problem I have a 96 XLT 351, I just had to replace the fuel pump for a no start problem and works great.  However there is still a surging problem at low speeds, as well as an odd whistle that increases and decreases with the RPMs.  Seems to be only when the motor is cold or it is humid out.  Noticed today that it idles rough now as well.  Any thoughts?  Also does anyone know where I can get a vacuum schematic for my truck?

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I will try that today, however, I cant find in my haynes manual anything about the TPS. I know where it is just by experiance however, how do I check it for operation? Thanks