Yaris won't start properly/reliably

[lith89]

Originally Posted by SirDigby

...why did they change the fuel filter? I would think the sending unit is not a (normally)serviceable part. usually it's replaced as an entire unit. (unless modifying it) is this a Toyota dealership?

Fuel filter change was part of the service "package". This isn't a Toyota dealership, it's a different independent chain (large one).

Originally Posted by jra

If you smell gas it must be an external leak, could be leaking where pump mounts to tank, or cracked tank or pump housing, where fuel line connects to pump, or could be a fuel line under hood if they had off to pressure test pump and didn't get line back together right.

The gas smell went away after we took it back the second time, sorry if that wasn't clear in my OP.

Originally Posted by CoryM

This is when you find out how good your shop is. Mistakes happen, but it's how they deal with it that matters. Any reputable shop will stand by their work, and fix their mistakes at no charge to the customer. The trick now is to make sure they understand that these issues have been happening only since they were working on the fuel pump assembly. People being people, it can be hard to convince some shops to deal with their mistakes properly. And shops have to deal with customers who think that anything that goes wrong with their car is the mechanics fault, even though it's unrelated to the repairs. So even reputable shops look carefully to see if the problem is actually theirs to fix or not. I've seen people figure we should fix their wheel bearings for free because they suddenly got noisy ever since we replaced the customers very noisy muffler that they had been driving with for months......

Just go back, explain what has been happening and that it's only been happening since they were working on the fuel pump. Hopefully they will be easy to deal with.

Cheers.

Will be taking the car back in the next couple days, thanks for the advice!

(Reworded the TL;DR in OP to hopefully clear up a few things)