jtc3200

This is actually a continuation of previous thread which I had difficulty starting my 94 LS400 sometimes. It sometimes takes several separate cranks, few seconds each time to fire up the engine.

I have found a way to ensure the engine fires up everytime on first try when I crank:

I would insert and turn the key to on, then I would step on the gas/throttle lightly one, two or three times until I hear a light, low CLANK/THUMP sound that originates from under the hood. Then I would remove my foot from the gas peddle and start/crank the engine. This procedure fires up the engine right away, everytime without fail.

Now my questions is that if it damages the car when I do that. And can anyone identify that light, low clank/thump sound I hear when I step on the gas/throttle before I turn the key to crank. What makes that sound?

turbosix

could be unrelated but on my turbo buick they have a mode called "clear flood" incase someohow you manage to flood the car, you hold the gas at WOT while cranking and it will not open the injectors until you let off. allows some fresh air to get in to evaporate the extra fuel.

could be something similar to that, no idea. just throwin it out there

Sixdown

My car takes a few seconds to crank up too, but only if left outside overnight in freezing temperatures. I'm not sure if that's normal either. After starting it, the engine makes weird scratching/whirring noises until it heats up.

Dutch

"clear flood mode" is typical of at least OBDII vehicles, thats cool it was on your GN t-type(im guessing). my car does the same thing but i havent had time to diagnose it yet. if i find out b4 you ill be sure to post it

jtc3200

Thanks guys for the response.

This clank/thump is so light I need to turn the radio and the environmental control fan off and wait til the seat belt chime to stop before I step on the gas/throttle so I can hear it. and it happen only once. Then of course I crank the car and it fires up right away. I think the sound comes from under the hood but it also sound like it comes from under the car or back near fuel tank.

I also notice that I only have to step on gas/throttle one time to cause that sound when the fuel tank is full. And it takes a few more times (2-4 times) stepping on gas/throttle to make that clank/thump sound as the fuel tank gets half empty or low.