Thank you very much...

 

Hello everyone

Update on the corvette. I just replaced the broken vacuum lines with the recommended lines thanks to https://www.corvetteforum.com/forums...rd-tubing.html
I also rebuilt the fuel rail with new o rings, replaced the fuel injectors with bosch III by southbay and installed a cold start injector delete.
Some things to note, while the fuel injectors are installed they seem to wiggle around a bit, anyone else bosch III injectors do that as well? also, I hooked up the fuel pressure gauge tester again. when key is on position it hits 40psi then drops slowly but when the engine is on it holds 42psi. Is there any concern here?
Overall, the engine starts right up and idles fine but I haven't driven it around yet as it is dark and I gotta finish installing the seats since I installed new carpet and added some dynamat. Digital gauges got a rebuild too new LCD screens and a red filter on them.
Besides my concerns, I'll test drive the car tomorrow and eventually smog it. Then post an update.

 

On the fuel pressure bleed down...Most likely the fuel pump's check valve is leaking, no cause for alarm though. It's (leak) all internal, fuel returns to the tank thru the pump. And I'm curious to see how the CSI delete works in cold weather.

 

I started it up in 50F weather like 3 times, no hesitation in the cranking. I also bled air out of the fuel rail through the valve. I believe the CSI is more for like 20F cold starts. Others on the forums claims their car starts fine just takes a second longer in really cold weather.

 

Sounds like you are making good progress, I hope that continues. That slow decline in fuel pressure sounds ok to me as well, and I would agree with 1hotrodz that it is likely a leaking pulsator that is causing the issue. When I was a GM tech way back when, we replaced quite a few of those pulstaors, which on a C4 is not terrible if the bolts on your fuel pump mounting flange aren't rusted away.

 

I'm back from test driving the car, so far the car drives better and no engine codes popped up but I noticed some problems,

• White smoke coming out near the passenger side nearby the motor blower fan. Engine bay
• While idling in park the car idle almost dies then spikes up
• Near the fpr area I smell gasoline again, tried sniffing from the FPR hose but can't tell if its coming from the area around the fpr or inside the vacuum hose

I checked my oil after the drive and luckily it doesn't smell like gas anymore. could my weird idle situation be a symptom of a bad pulsator? If I do replace the pulsator do I buy another or bypass it?

 

Best way to confirm the pulsator issue, is to leave the fuel pressure gauge hooked up and tape it to your windshield - this way you can monitor the pressure while driving under varying conditions. Looks weird but very effective. Not sure on the fuel smell, and I know it is hard to visually inspect that area, so not sure what to say. If fuel is not coming out of the vacuum line attached to the FPR, the diaphram should be ok I would think. Regarding the pulsator - it was designed to reduce pump noise in the system, but some people replace it with a solid fuel line - personal preference I think.

So I will share my experience, as it sounds pretty similar to yours. I bought a 91 L98 6 speed, that sat for several years and was generally rough. I went through and got it idling well, as it used to want to surge and rev up on its own at times. I bought an ALDL cable and used TunerPro RT to confirm and adjust the TPS voltage to around .5 at idle, as that was way off on mine, and fixed several vacuum leaks. So after replacing a few sensors, including the IAC and coolant temp sensor in the front of the intake, it was idling and running well. That is until it got warm, then the intermittent idle condition came back. So I pulled the plugs to run a compression test, and found #2 wet with coolant (30 psi less than the other cylinders). When I pulled the heads a few weeks back, I found that the coolant port in the head had corroded away, and was allowing coolant under the sealing ring of the head gasket..... So what I think was happening is that when the heads heated up and expanded, it allowed the coolant leak worsened and then that cylinder was not firing consistently. That is my current working theory anyway, as everything else is checking good. I share that with you because if you are seeing white smoke near the blower fan area, or coolant burning off from cylinder #7, you may have a head gasket leak there, perhaps leaking internally and externally, but I really hope not. I could never tell mine was leaking coolant from the dipstick, so mine appears to have been going into the cylinder for what it is worth, so was very slight. So a compression test may be worthwhile to rule that out. Fingers crossed - let us know what you find.

 

my car, being an 87 was before OBD. I adjusted my TPS with a multimeter so it should be ok as I watched several videos. IACV I plugged in properly as well. The smell could've been some leftover gasoline while I was bleeding air out of the fuel rail. I'll replace the pulsator soon and drive the car again. Also get a compression test done on the car too. But ya if none of that works might have to dig into the engine again. Also if my car did have a leaking head gasket would it fail smog with high NOX? unless this problem just started appearing of course lol