Can you help me with this? My car cranks super fast when it's cold. (Not outside temp wise but when it hasn't been cranked in at least 3 hours. I had a starter heat shield put on and it didn't make a difference.) Yesterday I may of happened on to something but it may just be coincidence. I had the window down and had car off probably 2 minutes. I turned the key over enough to let the window roll back up and then I turned it further to crank and it cranked snappy. Could it of been "priming the fuel pump"? Do I need to do this all the time? Will it hurt or help anything? Opinions?

 

Fuel pump does prime the first time the ign switch is turned to IGN.
Best troubleshooting trick is try your new procedure several times normally and keep a mental tally of the performance.
No, it won't hurt.

 

Your fuel pump has nothing to do with how fast the starter cranks the engine over, which is what you're describing (unless you're misusing the term "crank"). A weak fuel pump however can affect how long the engine has to crank over until it starts.

 

Yeah, that lol. It's not the starter. You know how a little kid cranks their car? err err err err vroom? lol That's what I got lol. If it's cold, it's a errvroom lol

So if it's a weak fuel pump, what changes there to make it crank real fast after it's sat for a few hours?

 

I am a little confused, if it is not a starter or crank speed issue why did you add a heat shield to the starter?

What you need to do is a fuel pressure test during the extended crank time. Odd are almost even that it could be an ignition/sensor issue hot so a spark tester at the same time would show which the car was missing fuel or spark.

If it is a fuel pump you should assume it is going to just not start one of these times. Think about that every time you shut it down. It is pretty common for fuel pump issue to go from it just started doing "this" to the car will not start anymore pretty quickly.

 

It was suppose to have a heat shield and was missing so it was replaced. Was ruling out why it was doing that. Thought it was heat soaking but it's not. If I just turn the key a little for about 3 seconds, it cranks right up. It doesn't show any fuel pump signs that it is going bad. We've had that before with other cars. Don't mind if it is that, as I'm working on replacing everything anyway just can't do too much to the car right now as we have one in shop with suspected head gasket issue.

I'll get them to check the fuel pump out after the other car gets home.

 

lol....clear as mud now!
You want to check your fuel pressure to see what's going on. You could have a leaky injector(s) flooding the engine a little after you shut it off, which can make for a harder warm engine restart. Sitting overnight gives the flooded fuel time to work it's way into the crankcase and/or evaporate, where it won't affect a restart in the same negative way. A fuel pressure test will show how well (or not) pressure is holding after the pump is shut off. If pressure drops fast, you have a leaky injector, or a bad fuel pressure regulator.