Hard thud from engine during cold start
 

Good morning
weird scenario. Lately my car has been doing this thud/shutter only during cold start just before the car completly turns over on the driver side it feels like. I prime the car once or twice before starting it. I replaced fuel pump, filter, fpr and all the fuel stuff. Any thoughts? Thanks

Is it just a single thud like one big thud or a lot of little thuds?

turning the key sounds like your check valve is going on the pump ,that can go on for long time ,could need a .tune up ,or the starter .?

Kinda sounds like something might be a bit loose but honestly it's hard to say. See if you can get a video of it maybe and let us have a listen. Does it sound like it's coming from under the hood or under the car?

Ill try to get footage but its one of those things you have to feel. Its def coming from under the hood on driver side. Seems like a spark is not happening. I had a tune up done with new opti and all that and the pump is new as well. The fuel pressure holds but i do have to prime after it sits overnight. It does it slightly int he afternoon now that i noticed it but its smaller thuds. I guess you can call it a slight rumble. I think i may try to replace my wires or something and see if that helps. I dont want to do the parts tossing, no codes are showing up either

ya the video will help

sounds like it could be a misfire

its kind of on and off. I cant get footage of the shake. Ordered some better wires and im going to toss them on this weekend and hope that solves the problems. Thanks all

what engine so you have?