Engine stalling

**srgould41** · 11-11-2020

Thanks for the reply.

Update: I spent some time looking very closely. I found some issues with the wires to the injectors and repaired them (one had a cut halfway through it). I also found a bare wire at the distributor, the sense return wire which explains the code 42. I replaced the plug and some wire. Since the fuel pressure had been lower then I liked to see I took off the fuel pod. I installed a replacement set of injectors and also took apart the FPR. I rebuilt the TBI (including the shaft bushings) about 3 years ago. What I found inside the regulator surprised me. The spring looked like it had been at the bottom of the ocean for a while. It was crusted over with rust. I bought a "14 psi" spring and put that in there. At the same time I installed an adjustable FPR that I had on my spare TBI. I decided not to tempt fate so adjusted it for 12 PSI. That's as low as it goes.

Took it out for a warm up drive and data logged. It ran normally. The logs looked like previous logs, not greatly richer as I feared. No code 42! Came home and ran through the IAC close procedure, unplugged it then ran the engine. Idle was not perfectly stable, but it was 500-ish. At one point it dropped to 350 and recovered on it's own. Plugged the IAC back in, reset the computer to clear codes and ran it at idle. Mostly smooth at 550 with about 5 IAC counts. Strange how all past data logging drives were 650 idle RPM with lots of IAC counts. I had always assumed that was normal for the engine. I might increase the commanded idle RPM to 575, but later and only if I think the stalling is still there. I might do an 8th turn on the idle screw too, but only if I up the idle in the chip. First I need to get out on a long trip to see if the stalling condition is gone. If it is solved I would not be able to point at any one thing as the root cause since I changed several things at the same time. Since the stalling issue only started after the engine had been running for a few hours I am leaning towards heat soak causing increasing resistance in the dizzy and/or injector wires. Low fuel pressure could have played a role in it too.

I plan to take it out on the 21st or 22nd. Maybe a snow run. Fingers crossed.

**tayto** · 11-11-2020

run it at 14 psi. if the original injectors were on the engine you are better off getting them reconditioned and flowed (for example: witchhunter). i had an '89 9C1 Caprice 13 years ago. someone had out 4.3L injectors in it. i put in a set of OEM good 5.7L injectors. it ran better. swapped in a TPI fuel pump. it ran even better. shortly before selling (5 years later) it i finally rigged up a fuel preasure gauge. 9 psi, in spec but lame. modified stock reg and was able to get 13.5 psi. Ran the best it ever had, better idle, more power, it even ran cleaner emissions.

BTW, stock 5.7L 9C1 injectors actually flow a few pounds more than the "standard" 5.7L injectors.

**tayto** · 11-11-2020

if anything you would want to goto a '7427, it is a TBI pcm with higher data log rate,e-trans, etc. I would personally go with EBL if you dont plan on running an e-trans.

I would check your pickup coil & module. also monitor fuel pressure while the stalling happens. a TPI or vortec pump is a bice upgrade even for a stock TBI system like yours. gm performance sells a whole EFI distributor for a decent price this is the route i have gone a few times before...

**srgould41** · 11-12-2020

No worries on the injectors. I am running 65 lb/hr ones. Flow matched and serviced.

Originally Posted by tayto

run it at 14 psi. if the original injectors were on the engine you are better off getting them reconditioned and flowed (for example: witchhunter). i had an '89 9C1 Caprice 13 years ago. someone had out 4.3L injectors in it. i put in a set of OEM good 5.7L injectors. it ran better. swapped in a TPI fuel pump. it ran even better. shortly before selling (5 years later) it i finally rigged up a fuel preasure gauge. 9 psi, in spec but lame. modified stock reg and was able to get 13.5 psi. Ran the best it ever had, better idle, more power, it even ran cleaner emissions.

BTW, stock 5.7L 9C1 injectors actually flow a few pounds more than the "standard" 5.7L injectors.

**srgould41** · 11-12-2020

I do have a pressure gauge installed under the hood. I would love to have one in the dash, but no way I am running a pressurized fuel line into the cab. I was wondering if I could use an Autometer oil pressure sensor and gauge (electric). I have one I removed for a mechanical set. It would probably only be temporary. Autometer would not comment when I asked :).

**tayto** · 11-12-2020

AutoMeter has fuel pressure transducer. I ran a 100 psi one with EBL many years ago. i have it for sale if you're interested.

**srgould41** · 11-12-2020

I saw their transducer and gauges. Quite over priced like all their other products. :)

I found a different brand gauge/transducer combo that is inexpensive. It's listed for fuel, oil, hydraulic, etc. I just wondered if AM's oil pressure one would work safely with other fluid types. I use their temp transducer with coolant and ATF without issue.

Originally Posted by tayto

AutoMeter has fuel pressure transducer. I ran a 100 psi one with EBL many years ago. i have it for sale if you're interested.