Wimpy Cold Start

[evomaki]

My gen 2.5 has a wimpy cold start. Spins over fine (good battery and starter), and tries to fire right up but is a bit slow to get going. Often I have to turn the key back and start it again to have her fire up. Once warm (like even after two minutes of running) she fires right up. I've searched "cold start" on this site but nothing definitive. Engine runs great once running, even when cold and she finally fires up, it runs and idles well. It's just the starting part. Engine has good compression, new plugs, new crank and cam sensors, and new plug wires. This is a bit of a mystery to me, and defies some of the automotive basics of got spark? Got fuel? Gots both really, and does not feel like an intake leak because it idles perfectly. My guess is some sort of sensor or circuit that is foreign to me. Anyone have any ideas? Thank you,

 

[mudraider]

Fuel pressure regulator maybe? Only on cold start, or sitting for 6 or 7 hours right?

sent from my pretty good Android phone

 

[evomaki]

Yeah, I'd say sitting for 6 or 7 hours would cause it. Not necessarily cold in the true sense of the word. August in Atlanta is not cold. It's like wimpy first start. Then when it runs for even a minute or so and you restart, everything is fine. And even once it fires up its all fine. Idle's and runs great. Just peculiar. Thanks,

 

[Salonika]

Coolant temp sensor?

 

[ljzxup4]

Im have the same problem with my 2.5, any luck with finding the solution?

Sent from my SM-G930V using Tapatalk

 

[shoppingshzhang]

I am having the same issue with my gen 1. I am thinking it could be fuel pump. if I cycle the key to on position a few times before starting, it seems to start better.

 

[cr4x4cruiser]

Fuel Pump is most common culprit, when electricals are in order...

Listen for the fuel pump to cycle, when the key is turned to the 'ON' position [without starting]...

QUIET! Everyone be quiet, please!

It definitely should make noise [whirring] that can be heard within the cabin...

Located in the rear, under the carpet, access panel over top of the tank...

Cheap insurance; replace the inline fuel filter... yeah, when was the last time that was done?

Good luck

 

[shoppingshzhang]

I first thought it was the filter too but it was replaced a week ago and the issue continued. Looks like the pump needs to go. Can't hear the sound when I cycled the key to on.

If the fuel pump is bad, why would the car run and idle fine after starting?

 

[cr4x4cruiser]

I first thought it was the filter too but it was replaced a week ago and the issue continued. Looks like the pump needs to go. Can't hear the sound when I cycled the key to on.

If the fuel pump is bad, why would the car run and idle fine after starting?

Lack of proper pressure, due to a malfunctioning/ dying fuel pump can make starting difficult.

A failing fuel pump becomes a "hit or miss" issue... sometimes it works, sometimes it doesn't.

It may not be the root cause... putting in a shop with proper diagnostics will ensure the issue.

But, it can be reasonably assumed that a vehicle with high[er] miles is due for a fuel pump... no matter, it's a electro/ mechanical device - it can fail at anytime.

We hope this is the case...

 

[IncorpoRatedX]

Coolant temp sensor?

Easy to check, so start there. It's an ohm resistance so all you need is a multi meter. I havent done a gen 2 but i've done a lot of the older ones.

The coolant temp sensor in question is the 2 prong sensor used for cold start enrichment, when this resistor fails, it often fails with the engine thinking it's warm and doesnt add enough fuel for a cold start. You'll often have a truck that will start and run if you give throttle but wont hold an idle and dies as soon as you release the throttle, then once warmed up it runs fine.

If that's the culprit, here's what's going down:
Engine starts - ECU goes into open loop, it's waking up, opening it's eyes and looking around, checking its sensors to see what's going on, is it warm today? cold today? wet? Ecu needs to know these things.
Once it's got all the data it adjusts the fuel and timing to get into warm up mode and once it reaches operating temp, it goes into 'closed loop' the ECU is awake, it's had it's coffee and it's ready to work, the sensor doesnt affect it as much now because it's not asking that sensor any questions.


If it ends up being that, it's an 8-15 dollar part at your local part store and should take you 15 minutes to change and bleed the coolant again.