intermittent starting problem

[tommyabward]

Recently I have been having problems with my 03 qx4 intermittently not wanting to start. At first it was only happening every now and then and now it seems to be happening at least once a day. The battery seems good and the charging system is working. It'll crank every time, but won't start until the second try.

Again, this only happens sometimes. 80% of the time it starts up fine. Seems to help a little if the fuel pump is primed before ignition. Once it starts, runs fine. No loss of power and no idling issues - so I don't think it's the MAFS.

There was a pending code recently (p1491) for the vacuum cut bypass valve , but it's my understanding from reading the forums that the bypass valve is purely diagnostic and only serves the purpose of delivering data to the ECM - so it's reasonable to assume this probably isn't contributing to the starting issue.

Could this be a fuel delivery issue or a possibly a starter issue?

Any help would be greatly appreciated. Thanks!

[barnaclebob]

When was the last time the fuel filter was replaced? That's probably the cheapest and easiest potential problem to eliminate.

[Densetsu]

You mentioned it helps if it's primed... do you just turn the key to 'ON', wait for a second or two, and then try starting it?

Also, is it harder to start when it's been sitting for a few hours versus if you just popped into a store for 15 minutes and came back out to start it?

If so, it may be the fuel pressure regulator. I have the same issue, but if i prime it by turning the key to ON for a couple seconds everything is fine, so I haven't investigated further. You could also check the fuel pump relay like Towncivilian suggests in this thread.

[tommyabward]

Replaced the fuel filter yesterday, which was severely clogged, and now it starts up like a dream.

[barnaclebob]

Replaced the fuel filter yesterday, which was severely clogged, and now it starts up like a dream.

Nice!