Ok guys,

For a while now I have had an s4 rad in my s5. I have had no filler neck and have always ghetto filled it through the sensor hole and by opening the hose near the thermostat neck and filling. This was ghetto and stupid and I just recently spliced in a fill cap with radiator cap so now everything is good.

Only problem before was I had nothing but water in it because I had to keep filling it maybe due to some leak. Come to find out the water pump went bad, but not before running slightly warm once or twice, no overheating.

Anyways I decided to change the water pump and when going back to restart the car, also after finding out the water pump was bad before I touched ANYTHING it took an hour to crank. I kept trying to deflood it by holding the gas pedal down (s5 vert) and finally I got it to crank. It would run like ****, buck and die and there was no smoke coming from the exhaust like it usually would when deflooded. It would run rough and then clear up and die on me. After a few restarts I could hobble home. I dont see what any part of my cooling system could have to do with any of this.

Anyhow I changed the water pump and it did the same thing, but cleared up. I spliced in the filler neck the next day and it ran like hell as soon as I made any adjustment to the coolant system. Weird as hell. I thought it was an ECU issue.

So here I am. Anytime it is cool or the car has been sitting for a bit it takes sometimes 7-10 seconds of straight cranking to get it to start. It runs rough for a second and if I give it any gas it will die out sometimes. It will clear up for a second then runs like a champ.

How the hell could any of this be related to my coolant issue or adjustments? Could it be my fuel pump and or filter and be totally coincidental? I do remember about three weeks ago when pulling out of burger king the car just died very smoothly, I didnt even know it wasnt running until I hit the gas. It did it again about a week after that. I just thought maybe i bogged it down, but I would have noticed. Sorry for the long *** post. And I am not able to check the compression right now.

Could this be my fuel pump?

 

If it's the fuel pump you can check fuel pressure. If it takes a long time to build up pressure it will crank a while.

 

anyway to check the fuel pressure. More ideas on this?

 

was the waterpump seized, or at the very least, did it eat its bearings? i've had a seized waterpump cause an engine to die after making it difficult to start up (lots of cranking, just like you describe). i don't know why this would affect your engine after replacement, however.

 

You need to make sure your water temperature sensor on the back of the waterpump housing is connected and working properly. if it's not, the ECU will not inject extra fuel for cold start.

 

You drove your car around with no way for it to relieve coolant pressure?

Any number of issues could be occuring but i would be more worried about having driven the car around that way.....