Starting and idling problems

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A fuel system that bleeds off from the regulator not holding , usually causes hard starting until the system reaches proper pressure.
But you want to make sure its not bleeding down due to leaking injectors.
 
89on35s said:
Think about a wiring issue. After swapping parts, it ran good for a while then started acting up again. Maybe a wiring connection in one of the plugs is sketchy?

My background is in Industrial Controls and more often than not I find wiring issues are responsible for erratic behavior.

Cley
Click to expand...

Everything appears to be wired and terminated correctly, however I"ll double check. I'm tending to still think it's going to be injector related at the end of the day, such as either a leaking injector which is leaving some fuel in the cylinder and then upon start up it's already over fuelled causing it to cough and splutter until it sort's itself out and then it idles like a champ.

I'll have a play around tomorrow and do a detailled video.

I'm not sure if the Corvette filter/regulator is meant to
 
On the original truck fuel rails there is a Schneider valve forward on the passenger side. When changing injectors it normally requires scaling the new injector to get them right, The stumble and then smoothing could well be the PCM adapting to the injectors being out of trim. Can you data log and check trims? Mixing up injectors I got no idea how it runs at all.
 
[ame]http://youtu.be/iRDJmX47eRE[/ame]

Hard starting, idles eventually but after a little throttle runs like crap again.
(Fuel pressure gauge mounted on the column)
With Fuel pressure, if I turn the key and let the pump prime the gauge shoots to 50psi. I monitored it over the space of 10mins with a camera and it dropped down to 35 psi. Dropping at the rate of around 1-2 psi per minute. Is that acceptable bleed off for this style of filter regulator? I noticed some systems say it should hold pressure for half an hour then others don't hold pressure once turned off.
 
Redtruck-VA said:
On the original truck fuel rails there is a Schneider valve forward on the passenger side. When changing injectors it normally requires scaling the new injector to get them right, The stumble and then smoothing could well be the PCM adapting to the injectors being out of trim. Can you data log and check trims? Mixing up injectors I got no idea how it runs at all.
Click to expand...

This is a car hemi so the original rails which I still have stored away, don't have a shneider valve from memory. These are the original injectors it came with.
 
The fuel pressure dropping off when it's turned off is not the problem with it running rough. Mine drops to zero after sitting. Just cycle the key twice and it should start right up. Are getting any codes? I have found if it starts and idles ok and then quickly goes to hell, it is the tune or O2 sensor associated.
 
I've thrown a gauge on mine for 3-5 minutes at idle and revs and had Zero drop with the corvette filter/reg, it's like 58-60 dead on. I've never tested it longer, and my gauge was under the hood so I can't tell you about PSI with actual load...

I should add that I run a FAST XFI not the factory ecu, but I would think it would be the same...
 
Sorry brother can't help you with that. But I don't believe you have a fuel pressure problem.
 
Redtruck-VA said:
The fuel pressure dropping off when it's turned off is not the problem with it running rough. Mine drops to zero after sitting. Just cycle the key twice and it should start right up. Are getting any codes? I have found if it starts and idles ok and then quickly goes to hell, it is the tune or O2 sensor associated.
Click to expand...

I was asking as I thought if the pressure was dropping off too quickly once the engine is turned off that perhaps there was a leak (either a leaking injector or a bad o-ring) allowing air in and throwing everything off. When the engine sorts itself out the fuel pressure appears to be steady according to the gauge (58psi). It has the full emissions pack so it has both front and rear 02's as well as the emissions canister and EVAP solenoid. I recall asking hotwireauto if I was to ever disconnect the emissions connections would it effect me running the engine and they said no.

I just re-checked the fuel injectors and there are no blocks and appear fine (not that I'd suspect it since they were flow tested and ultrasonic cleaned recently). I have also connected an Autel Autolink AL319 scan tool to the OBD2 connector but it hadn't flagged anything serious other than 2 codes but they were (unable to see instrument cluster and FAN1) which I'd expect as there's no factory dash or fan system. I cleared those codes but the Fan error returns each time.
 
Well this time I had 8 x 6.1 injectors that were working, put them in and had no real issues. At the 40second mark where I give it a bit of a rev it sounds like after I let off the gas that the engine revs drop below the normal idling point and struggles a little before fixing itself quickly. Perhaps fuel pump is an issue as the regulator seems to be doing it's job. I may have to get an expert in. See the video below. I pressume the rattle/groan from the PCV valve is normal, I had pulled it out recently and wasn't blocked and it still rattled.

[ame]https://youtu.be/KCzZIK23wyE[/ame]
 
I've never had a PCV rattle like that. But I've never run a car manifold. I'd take it out and block it to see if it will make a difference. Your computer might be sensing a change in AFR and takes a little to catch up. I've used magasquirt but not Fast.
 
That engine seems to like those 6.1 injectors in it. I would just leave them in there and run it .
 
I would also think the FAST system needs to cycle a couple of times to adapt to new parameters. My much tuned 03 PCM certainly does....
 
Still having the same dramas, I swapped out the fuel pressure regulator for another WIX one. No change, still primes at 50psi when you cycle the key, even after a few goes. Engine struggles to start, eventually will after stumbling and dieing a few times, it copes with light throttle but if I try to give it a decent press the engine just struggles and sometimes dies.
 
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