Howdy all!

A week ago the 2001 base c5 auto started unlike its normal self. I always turn key to on, let pump prime, then turn over and she insta starts like a champ.

Now however, it turns over almost hesitantly. Takes 1-2 seconds longer and feels like a weaker ignition vs it’s typical rocket ship self. Funny thing is once it’s started it runs great. And if I turn it off and restart, it fires up like it should.

I’ve started by checking fuel pressure. Put the tester on, turn key to ignition, and got 50psi. 4 hours later it was down to 40 psi. 12 hours later it’s down to 15 psi.

With such a slow leak I can’t believe it’d be the check valve right? And 50psi should be enough to start the car yea?

My largest concern is fuel pump as I do t have a lift so I’d have to pay to have that done. But with such a slow leak I’m leaning more towards a leaky injector causing a hesitant rich start and slow leak, or the ignition switch itself.

Hoping someone might have experienced something similar. Thank you!

 

Don’t worry about the 4 or 12 hours later !!...per the 2001 FSM you should have 55-62 psi static key ON and should not drop more than 5 psi after 1 minute key OFF or after the 2 second prime !!...if within limits relieve the fuel pressure to 10 psi...if it drops more than 2 psi after 5 minutes the book says replace the fuel pump...that’s it !!...if it drops more than the initial 5 psi we can discuss that (injectors or check valve).

 

yea it didn’t move at all for a minimum half hour after trying. If my FP is low though hmmm that’s something else.

 

You said your static pressure 50 psi so you're a tad low but the first thing I'd check is your battery...12.66 volts is fully charged (11.89 volts is dead and 12.45 is the MINIMUM good charge) so I'd check that FIRST !!...low battery charge can cause a few issues so make sure your battery AND charging system is in top shape. When was the fuel filter ( fuel filter/PRESSURE REGULATOR) changed last ??….my fuel pump (waveform enclosed) on statically with key on draws about 6 amps @ 5300 RPM...you can check current draw with a DVOM jumping between pins 87 and 30...most DVOM's are rated for 10 AMPS max so you should be OK there...another thing is your injectors AND coil packs (coil packs on cold start draw around 8 AMPS EACH) are fed through ignition relay 42 so if the relay contacts become pitted that can cause issues...every so often my '01 takes a few more cranks to start but I don't worry about it...it usually starts on the first crank...give a yell if you need more guidance. Oh, and a failing cam sensor can cause “hard start” issues !!...also if you do think it’s pump related I would clean the pump ground (G401) which is located onboard of the left rear tire on the frame rail.

 

Holy hell thats some serious info right there!

Yeah at 50 it is a tad low but I have no idea how to adjust that up. I miss working on the cars I had as a younger man - idle control screws and such - life as easy!

I went ahead and replaced the battery today with a super start extreme - has extra crankage - we'll see how that goes - thanks for advice!

Fuel filter was replaced 4k miles ago with a WIX - work done best west coast corvettes.

Ive been told that the ignition switch can cause these issues as well. If the battery doesnt solve the issue, I was thinking Id replace the ignition switch next. Then ill have to replace all the plastic bits I break in the process ha!

I have no idea how to get to the pump to check the ground. Im told I can use a jack ( no lift access ) but Ive never lifted the car and Im a bit worried. This is my dream car - Ive wanted this very car all 33 years of my life and now that I have it - Im hesitant to f*ck with it. But I suppose thats why I bought it in the first place. Where do I jack it from, and is there a certain type of jack I should be using?

Thanks for all the info, advice and wisdom!

 

There is no adjustment of the pressure because they call it a “fuel filter/pressure regulator “!!...I can remember a member a while back having pressure issues and it was a bad NEW filter. If you have a DVOM you can do a voltage drop check between battery positive and the fuel pump fuse ( we’re checking for excessive voltage drop across ignition switch)...Enclosed is one video on jacking...there are a few you can find...good luck. If the “hard starting “ is really a concern you can take it back to that Corvette Shop....if they can’t fix it...well, they shouldn’t be fixing Corvettes !!...good luck !!

 

C5 Diag's electrical knowledge on these cars is absolutely impressive and amazing!

Once you get your fuel pressure sorted ( and I bet that will end up being your cause) and you still have the symptom, check for vacuum leaks and maybe replace your fuel filter if you don't have a late model '03 or '04.
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I have the c6 style fuel system and a walbro 450 pump at that....but mine reads 60psi with the pump running and then drops down to about 55 psi and maybe bleeds down to around 50psi after maybe a minute. Either way no cold or hot start issues. I usually do turn the key to "on", let the fuel pump run, gauges do their little startup sweep then, then start it.

Is it possible your gauge maybe just reads a little low and fuel pressure is indeed fine? Might be worth double checking with any gauge or method.

 

It really sounds like a weakening battery. Mine did this recently to. The previous owner let the car sit for basically a year. It was great and fully charged when I got it and the car started fine. After it sat in my garage for a few days not being driven, it hard started. After I drove it a while it was fine, and was even fine the next day. I forgot about it until I didn't drive it for a few days and it did the same thing. Long story short, I put a new battery in it, and now she's fine.