Truck stalls out on cold start, starts just fine the second time. What do?

alrightay! surprise surprise, a small spray of starter fluid got it going the first time with no hesitation. I guess that implies I have an issue with fuel delivery at first crank. it was 20 degrees out. i wonder if the pressure regulator is malfunctioning or if ive got leaky injectors or what. ive got some techron which is a cheap fix at best, but better than going for an expensive one right away. I'm not sure what else could be causing the problem so I'll start there.

 

Checking fuel pressure is the next thing... I dont know how you would go about checking residual fuel pressure without getting creative.

 

Benson
This wasn’t really in my budget yr or so ago
But
Other seasoned members convinced me to buy. Mainly bc fuel pressure difficult to accurately determine AND critical when diagnosing FP issues


https://www.lceperformance.com/Prod...MIvcHjj_XmiQMV5kp_AB3u1QW5EAQYASABEgLdePD_BwE

 

yall realize it takes all of half a second for the fuel rail to pressurize?

why would it crank and not start but then you stop turn it off and turn it on again and it starts instantly?

 

@johansen That’s what we’re trying to figure out. you raise a good point. It’s not that the truck never starts in the first place, it fires up for just a second before dying, aside from the time I used starting fluid when it stayed running the first time.
When you suggested looking for a difference in fuel injection pattern with an oscope, what problem would that difference in pattern allude to?

 

$20 FPR?

lots of easy tests vids out there

 

I pulled the hose going from the FPR to the airbox and it smelled like fuel, the inna’net said that’s not supposed to be that way. I’ve got a new one coming today, so perhaps that will solve the problem.

 

The oscilliscope will show in milli-seconds the amout of time the injectors are actually opening. If then opening time is the same for both the first and second crank then there appears to be not enough fuel/fuel pressure on inital startup. I underestand the irritation and if this was me I would put a fuel pressure regulator on it and if it fixes it, great, if not, I would live with it.

 

That’s pretty neat technology! I likely will end up living with it if the new pressure regulator doesn’t solve things, at least until I’ve got more time and money to look into the problem.

 

Embrace!!!!

 

Well fellas I guess I’m living with it for now. thank you for the information and suggestions. If I figure it out I’ll be sure to come back to this thread and say what it was

 

It was the IAC valve. To my shame I remained willfully ignorant of its potential failure because I didn’t want to look at the price tag of a new one. It was worth biting the bullet.

 

Great catch... while this is an apple/crab apple comparrison, my 03 Ranger was doing the same thing plus the idle was not right. What I discovered was that not all scan tools are created equally, it is either that or I could not find the duty cycle PID of the Ford IAC in the Snap On scan tools menu. I ended up at a buddys house who has the Ford IDS, that is Fords Factory diag software, and it showed a 60% duty cycle but the valve was not moving. Plug the replacement IAC in and watched the valve operate. Install the new IAC and problem solved. I guess the IAC on cold start goes to full open for additonal air on start. He told me that you can get the same effect by just cracking the throttle with your foot. Live and learn.

 

My IAC going out was the total opposite. Good cold start, and stalled out trying to warm start unless I gave it some gas while cranking.