It starts when the engine is cold but when the engine is warm it has trouble starting?

NICKMONNER

MEMBER
1971 CADILLAC ELDORADO
V8
FWD
AUTOMATIC
65,000 MILES

I bought a Cadillac 500 C.I. Engine, had it professionally overhauled and installed it in a 1971 Eldorado. It starts when the engine is cold but when the engine is warm it has trouble starting. It acts like the battery is weak. Jumping it helps. The starter and battery were replaced with new ones but there was no change. What is my next step?

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

This is most likely one of two issues. First it could be a crank sensor issue, but this would also cause the engine to cut off when it is running.

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

If the engine is not stalling but just not restarting after it is hot, then more than likely we have a fuel pressure issue.

It could be low when it gets hot, or it could even be too high that the regulator cannot control it properly.

Let's start by doing what is called a clear flood start. This means you need to hold the pedal to the floor and start the engine when it is hot and see if it starts. This will cut the fuel injectors and if the engine starts then that means it is flooded.

However, we should also check the fuel pressure with this guide and go from there.

Please let us know what questions you have on this, and we can go from there.

Thanks