Techron to the rescue?

[Duffyjr]

Been having starting issues with car, see sig, here is a typical day.

8am - pops right off, in fact sometimes I feel I can't let go of the key fast enough, immediately reaches normal rpm's.
12 noon lunch - starts but takes 3-4 seconds of turning over and a couple seconds to reach normal rpm.
12:45 back to work - same thing 3-4 seconds of turning over and a couple seconds to reach normal rpm.
5pm leave work - same thing 3-4 seconds of turning over and a couple seconds to reach normal rpm.
5:10 stop at Casey's to pick up a beer and cigs, come out pops right off and immediately reaches normal rpm.

Once started for the day it seems it pops right off up until about 30 minutes of sitting then the longer start time kicks in except when it sits over night. I took it to my mechanic and he couldn't find any problem and said no big deal.

So I decided to try some techron fuel system cleaner not the injector stuff. Didn't notice anything until the end of the tank and noticed it was starting better so I thought I'd run another tank with techron and see what happens. Now I'm almost down to 1/4 tank and it's starting way better, occasionally it will take the 3-4 seconds of turning over but not near as much.

I thought it was a dirty throttle body or dirty sensor but if in fact the techron fixed this and it wasn't some kind of miracle what was the problem?

Let's see if I understand how this works. Gas goes in tank, pump pumps it thru filter then on to fuel pressure reg valve and then to injector, correct or am I missing something?

I use the same E0 gas from same station/pump all the time and no it's not a top tier station, none of the top tier stations here sell E0.

 

[shanneba]

I may have been the injectors leaking down after you shut the car off. The shorter time sitting during the day would have left less time for any gas to evaporate.

It may also be a difference in the gas. I know here in Indiana we have several versions of gas throughout the year.
In fall/winter/early spring the volatility is higher (higher RVP, Reid Vapor Pressure). It is reduced in the summer to reduce emissions from gas evaporating and lessen the emissions when filling the car.

I do not see a Federal requirement for Nebraska.
https://www.afpm.org/State-Motor-Fuels-Specifications/


Indiana RVP requirements:

Here is a map showing the areas in the US requireing differt types of RFG (reformulated gasoline0
EPA RFG Gasoline

 

[bioburner]

Could it possibly be the cars logic controlling the fuel? It senses a cold engine and does a full fuel feed to start, then less fuel for the warmer starts.

 

[Tman220]

Sounds to me, knowing the car and their tendencies, my vote would be a slow to react idle air control valve, or a leaking fuel pressure regulator.

The fuel pressure regulator is a common issue and pretty easy to diagnose if it's leaking. While its running or while the fuel rail is pressurized remove the vacuum line, if any raw fuel is present or dripping from the FPR its bad and needs to be replaced. I had a GM car that acted almost identical with a failing FPR, however there is really no reason I know of that techron could make any difference.

Next idea is a slow to react idle air control valve which is something that could have the possibility of being slightly affected by a fuel additive, however it is located far away from the path of fuel if we are talking about the buick.