Cherokee starts fast when cold and slow when hot
 

Here's a little something I noticed on my 2000 Cherokee that I thought was odd (and kind of annoying).

When the car is cold (i.e. it's been sitting over night and the motor is completely cool) it starts up super quickly. I mean as soon as you turn the key it starts almost instantaneously.

When the car is warm (i.e. you've been driving around for a while) and you try and start it again it cranks for a good 10 seconds or so before it starts.

I'm trying to figure out why this might be happening? It's more annoying than anything.

The vehicle is a 2000 Cherokee Sport with 150k miles on the body and 20k miles on a completely remanufactured motor.

Any ideas?

10 seconds is a bit long but I am guessing its due to a mild heat soak condition when the fuel in the injectors get hot due to proximity to the intake/exhaust manifolds.

Fuel pump getting weak.

I had the same thing happen with mine. I picked up some heat shield from autozone and put it between the injectors and intake/exhaust manifold. Cured the problem right away. Fuel was getting too hot and turning to vapor I assume

Does it crank slowly, like the starter is struggling to turn, or does it crank like normal?

No, it doesn't crank slowly, it cranks fast. It's just that you have to crank it longer than you do when it's bitting sitting overnight and you first start it.

By the way, 10 seconds was an exaggeration, it's more like 3-5 seconds. It is noticeable though because it starts right up immediately when it's cold.

Hmmm, so putting heat shield between the intake / exhaust manifold is a cheap solution, I'll have to try that.

Fuel pump getting weak? I didn't think about that...

It's also worth mentioning that I'm running the Ford 784 injectors. I installed them months ago but this problem was still there before the injector swap.