Long crank and dies on cold start

[HaremStorm]

Curious - what do you call “good”? And where did you check it?

right at the back of the tbi for the high pressure line I have a threaded hookup for my gauge and it ran 10 psi on and a ~14 psi prime

 

[Schurkey]

right at the back of the tbi for the high pressure line I have a threaded hookup for my gauge and it ran 10 psi on and a ~14 psi prime

Kinda strange--I'd expect the same pressure "prime" as running. What is the fuel pressure at heavy load, or with the bleed button pressed so that fuel drains out of the pressure gauge assembly?

How old is the fuel pump and filter?

 

[HaremStorm]

Kinda strange--I'd expect the same pressure "prime" as running. What is the fuel pressure at heavy load, or with the bleed button pressed so that fuel drains out of the pressure gauge assembly?

How old is the fuel pump and filter?

Pump is a year old, did that and rear shocks at the same time with the bed off, fuel filter is less than 3mo old. Always fuel at the same chain of stations bc lots of the gas stations around me are notorious for having water in the ground tanks. As far as under load i didn't test for that, the prime psi may have been my 15 dollar gauge spiking bc i cycled the key or organic operator error as im doing this by myself and being in the cab and under the hood simultaneously isn't really a possibility for me lol.

 

[Sabinoerc]

right at the back of the tbi for the high pressure line I have a threaded hookup for my gauge and it ran 10 psi on and a ~14 psi prime

They say 10psi is within spec. That said, I had a cold start idle problem once with pump ~a year old from Autozone. I couldn’t figure it out and checked fuel pressure. It was 10psi but I noticed it dropped a bit when I blipped throttle. Assumed it was ok and chased my tail trying to fix the problem until I eventually got TunerPro and found that an idle enrichment flag was kicking in/off running my idle up/down. Replaced the pump with AcDelco or Delphi, can’t remember, and fuel pressure was a solid 13psi even when blipping throttle. Problem went away.

So, based on my experience, I wouldn’t assume a new fuel pump is necessarily good and I wonder if on old engines 10psi is really ok. At least, it needs to remain solid with increased demand which is why I assume Shurkey is suggesting watching fuel pressure with bleed open(not something I’m familiar with myself).

Best bet is to get data logging capability but you’d need something which does more than just read codes. You need to be able to look at flags, operational modes. There is no feedback to ECM on fuel pressure so you have to look at what the engine is doing. I’m a newbie at this and others here are much more experienced on what tool does what, etc. It seems either that or shotgun with a new fuel pump and see what comes after that. Good luck!

 

[Schurkey]

What is the fuel pressure at heavy load, or with the bleed button pressed so that fuel drains out of the pressure gauge assembly?

it needs to remain solid with increased demand which is why I assume Shurkey is suggesting watching fuel pressure with bleed open(not something I’m familiar with myself).

Perhaps I should have explained more.

Many--perhaps most, but certainly not all--fuel pressure testing tools have a button on the side to bleed-off pressure. Generally connected to cheap clear vinyl hose that gets hard as a rock with exposure to gasoline, but that's not important right now.
Example:
www.amazon.com/3640-Professional-Injection-Pressure-Tester/dp/B000EVU8NY/

It's a "safety" feature of the gauge, I think. Allows pressure to be bled off into a coffee-can or drain pan, so the fuel doesn't spray all over a hot engine when the gauge hose is unscrewed from the Schrader valve on the fuel rail.

But it can also be used to simulate high-fuel-demand from the engine. Push the button, bleed off fuel...it's just like the engine at idle, is running at high-load (Heavy throttle, high RPM).

If the pump can maintain pressure at high load (or simulated high load) it's proven to have not only good pressure, but good volume.

OTOH, if the pressure drops when the button is pushed, the pump may be lacking volume even if the pressure is OK.

This is not entirely scientific, because different fuel pressure rigs may have differently-sized pressure bleeds. The bigger the pressure bleed, the more volume the pump has to provide to maintain pressure. Ideally, you'd have used the tool on various vehicles and noted how they respond to pushing the button. Otherwise you'd need to measure the volume of fuel released over a 15- or 30-second timeframe, to calculate how much fuel is being bypassed; and then decide if that's a reasonable amount.

 

[HaremStorm]

Heyo, 91 k1500 4.3 4x4. I have a maybe 10-15s crank time then she'll kick off and either high idle for 30 seconds then die (no tach so I would guess about 13-1500 rpm) or it will just right off die. Tried to pull codes off the CEL but just get the system active flashing and I do not have a obd1 reader. New parts include Coolant temp (both) ICM, MAP, Plugs, wires, cap and button as well as new vac lines all over bc rot. Motor was re-sealed and had a timing job less than 8k ago. WTF

Hey all, new day. New issues. Now it's sounding like I'm missing 4/6 cyl on top of my old issues (see attached link) it's really the full package. Spits sputters backfires through exhaust extremely rich to the point fuel is all you can smell in the cab. And more recently stalling. Unplugged Map and it ran "better" still rich and hacking a lung but doesnt stall. Although I may have to attribute that to it being 32yrs old and at 2000ft above sea level trying to run on predetermined map layout. No new codes, still have yet to get my obd1 scanner in the mail. And to wrap it all up I have to get to paducah ky from my area of ND (1400 miles) by the 9th of next month. Can the duck be saved or am I selling it to buy a prius. Sorry to rant I'll be on all night to discuss

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