LateraLex

This started yesterday. I hold the key over and the engine does not turn over... like da...da...da...da...da...da...da...da...(stall)
Screen is showing OK throughout this.
Then I try again:
da...da...da...da... starts right up like normal.

I noticed it has only happened when I haven't run the engine in a few hours. What is dying?

Carson (K03x2)

There is a check valve in the fuel system to retain residual fuel pressure for easier starting. If the check valve fails, the fuel pressure is lost and the fuel pump has to build up the pressure again before the car will start.

LateraLex

Thanks for the help!

Monkeyboy

First start, cranks but won't turn over. 2nd attempt - fine, never more than 2 attempts. Sometimes it will turn over fine on 1st attempt...@50% of the time. Doesn't matter if car has been sitting all night or if it was sitting for a few hours (usually turns over fine if you stop / start / stop / start.
And what's weird is that when it was winter (cold) - the problem did not happen.
When under warrantee, dealer could not recreate. Been happening for about 8 months now.

I'm too impatient to turn the key to start for @20 seconds, off, then try to turn it over...part of the pre ignition check I believe is to build the fuel pressure.

Some threads got me on the coolant sensor replacement thread...but my coolant temp gauge never acted up - so I left that alone.

I would lean towards lack of fuel pressure as the cause...don't know how to fix it though...

Carson (K03x2)

I'd have to check at work tomorrow to be sure.

quattrorally

on my 1993 90, 12v V6. Finnaly the car just would not start at all.

Luckely this final time happened right under the shop of my mechanic. We got the car into his shop by spraying brake cleaner into the air intake.

Any how, it turned out to be the fuel pump. As far as I remember this ended up costing between $200-$300 CAD.

Audi2ptzero

When you first turn on the key to start the car, the fuel pump will pulse and then turn off. Pressure in the system is around 20psi, the pump wont fully turn on till the car actually starts. Now when you turn that key to start it the injectors spray more fuel then normal. Most of the time when there is a hard start issue it is because the ecu is giving too much fuel. Cold starts are even worse because the ecu is giving more fuel then on a warm start since on cold starts the ecu also retards the timing.

LateraLex

Do you think its the fuel pump or the check valve?

Audi2ptzero

you can try changing out the pump but that might be just throwing money away without really knowing what is wrong with the car. You can also see if you can find someone that can put a fuel pressure gauge on the car to see if your getting any fuel pressure during start up.