sprint22m

So my C5Z has been giving me some issues since the start of the summer and it's getting worse. When I bought it last summer it never did this once.

When I crank the engine it will start right up then almost immediately stall like it ran out of fuel. I've also replaced the filter/regulator with a new GM part and it didn't help.

Below is Fuel pressure and what I've noted so far.

When it starts fine: At Key up the fuel pressure jumps to 56ish psi and holds once the pump stops its cycle. When I crank it the engine fires right up and fuel pressure rises to 60 psi and all is well.

When the engine stalls: At Key up the fuel pressure jumps to 56ish psi then as soon as the pump stops its cycle the pressure drops to 51 psi and this is when the engine will start then stall every time.

To remedy this I cycle the key several times in a row then crank the engine while the pump is still cycling and usually it will fire up and stay running.

Other than this issue it runs great. I've double checked grounds but I don't see how they would affect fuel pressure anyway. I've been told to put a fuel pump in it as there may be a check valve in it that's going bad? I hate to risk the cost of a new fuel pump if it's not needed. I got the advice from a guy that's not familiar with corvettes so I wanted to double check with you guys.

Bill Curlee

QUOTE"

To remedy this I cycle the key several times in a row then crank the engine while the pump is still cycling and usually it will fire up and stay running.



I have a strange feeling that your ignition switch is giving you issues.


Lets try this. Look at your SECURITY LIGHT on the IPC. When you turn the ignition ON, is it FLASHING or staying On when the car is stalling?

Read and post your DTCs:


READING YOUR Engine Diagnostic Codes



The Diagnostic Display Mode is entered with the following procedure:

1) Turn on the ignition but don't start the engine. NOTE! You can read the DTCs with the engine running and or driving down the road but it can distract you. BE careful! Some DTCs clear themselves when you turn the ignition OFF!

2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.


Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current C code indicates a malfunction is present and active in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except English/Metric (E/M). Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press and hold the RESET button To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5. You can GOOGLE the DTC and also find information on it.




Here is very good site that explains the DTCs:


http://www.corvette-web-central.com/C5DTCcode.html


http://www.obd-codes.com/trouble_cod...d-ii-codes.php



Make sure to include the H or C suffix!!





Bill

Bill Curlee

Forgot to add this: If it is determined to be the switch, here is a do it your self post for you:

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

Bill Curlee

If the pump has electrical issues or shuts down before the engine stops, it will drop pressure. Him cycling the key a bunch of times and that resolves the issues points me to that direction.

Its a great place to start.

Bill

sprint22m

Here's where I'm stuck...

This leads me to believe it's fuel related:
I can watch the fuel pressure gauge and I can tell when it's going to stall. Plus why would it instantly drop 5-7 psi fuel pressure as soon as the pump stops it's short key up cycle? I mean it drops right off from 57 then stops solid at 51 or so psi and that's when I can tell it's not going to stay running. Are they supposed to drop like this and is this enough to make it shut right off? Also when it fires up I can hear from the exhaust note if it's going to stay running. When the engine lights up like a bad azz engine with plenty of fuel and timing should, that's when it will stay running. When it starts up like a worn out old 305 SBC that's when it will die. Ya know... like it's not getting the shot of fuel it needs initially.

This makes me lean towards ignition:
When it does this it shuts off so fast it's like I started it up then shut it right back off. It doesn't sound like it's slowly running out of fuel it shuts right off. Will they do this if they are 5-7 psi low on fuel pressure? I was thinking the injectors would still be puddling some fuel into the intake runners and it would run on a bit like it's slowly running out of fuel but that's not at all what it does... it shuts right off just like you were to key it off.

IDK... I've got some work to do. The codes were just cleared a month ago so I will see what is there and post them if there are any. I don't remember seeing a check engine light but I don't know the system well enough to tell you if I would for every code that's stored?

Thanks for the input guys. I will have to sit and digest all of this... I'm new to electronically controlled corvettes so I’m learning as I go here. I’m no stranger to engines or racing but I’m behind on this stuff so thanks.

sprint22m

Another ignition switch troubleshooting aid is; If the engine will run when you HOLD the ignition switch to the CRANK position but dies when you release the key, the switch could be at fault.

Bill


I read this at the bottom of Bill's ignition switch testing post. Interesting... I'm going to try that. OK dumb question but won't the starter stay engaged too? Or does the "drive by wire" stuff automatically stop the starter once the engine starts?

sprint22m

Update: I've been doing what Bill mentioned by holding the key in the cranking position and the car starts every time. Haven't had the time to pull faults. Before using this method it was doing starting and shutting off on a very regular basis.

C5PEWTER/CONV

Help C5 2001

I seem to have similar problems as sprint22m. The problems varies. Sometimes I have to crank for several seconds then it starts and runs when the engine is hot. Sometimes it starts then stalls immediately when I let off the key. Rarely does it just pop off like it should.

I've read every forum comment I can find but don't seem to get any resolve. They most like culprit seems to be the fuel pump, I will have the mechanic monitor the fuel pressure as we try starting it repeatedly. I will have to take it to a mechanic and don't want to get ripped off. I did have the fuel filter replaced as a cheap place to start but it didn't make any difference. I'm leery of taking out of town trips if there is a chance of the fuel pump failing.

Thanks for any suggestions in advance.

C5PEWTER/CONV

I had the fuel pump replaced this spring ($1000) it no longer starts and immediately stalls but still must crank then let off the key, try again, then it starts especially when the engine in hot. Per my previous post I have already replaced the fuel filter-pressure regulator. ($225)

Any suggestions would be appreciated.

Bill Curlee

Theres a very small in-line fuel check valve in the outlet line from the tank. If it leaks or doesn't function, it allows all the fuel in the fuel line to drain back into the tank after the car sets for a few hours.

Pressurize the fuel line and see if the fuel rail looses pressure in a short period of time.

If it does, replace that part of the fuel line.

mike venth

I had the same problem with my 01 coupe,,, replaced every sensor on the car, fuel pumps, fuse's, relay's, and did the Bill C magic on the Ing. switch... ended up being a bag under hood fuse box.. Bill C could tell ya how to check it.
mike v

C5PEWTER/CONV

Thanks guys. When I have the year end oil changed I will have them look at it.

Any info on the bad fuse box?

mike venth

My 01 would start/die .. s/d.. s/d at first 1 maybe 2 or 3 times then would run fine..
After several months it woulds take 8,10, 12 then run,,but then it would no longer stay running,, noticed it would run if I held the key in start position.. Local Chevy (corvette Citified) tech told me he had seen this on several GM car over the years...He described it like this: When you start the car the (foil) wires in the fuse box acted like a welding rod,,the ark would jump across and fuse the wire back together. Then it would un-fuse when turned off again. So the tech checked the volts on both sides of the fuel-pump-relay on both sides...called me and said " I have good news and bad"!! Good news,, found your gremlin- bad news is; GM no longer carries the part. OOO S&^t.. Went stright to CF and found the Part... After 7 months of chasing the gremlin the Vet was fixed.. OK sure spent a lot of extra dollars,, but now have an 01/66k miles that run and feels like new..CF people were a great help,,,,So a Big WOW and thanks to Bill C and everyone that
aided in my quest to make the 01 coupe do like it is supposed too.. These cars are great
fun,,, Mike Venth

Biotex

01 C5. Start die, Start die, Start die.... Only when hot though. Let the car sit for several hours and starts and runs fine.

From reading this thread I'm leaning towards the under hood fuse panel as the first place to look. Can someone please help me to understand how to check the voltage at both sides of the fuel pump relay?

Also what are the "foil" wires Mike is referring to in the previous post?

mike venth

Pull fuel pump relay out (under hood fuse box cover will show witch one)and check with key on and off for voltage. I used a fine piece wire on each one of the contacts after putting the relay back in. When it shuts down,, CHECK Voltage on both sides of the relay.. Should be HOT on both sides (key-on ).. Could be a Bad RELAY also. They can fail when they get hot. The circuit board that holds the fuses and relays and connected by wires that are rolled, making them into a foil wire-- mine was cracked, but would some times would arch back together,, drove me nuts...

Biotex

Thanks.

C5PEWTER/CONV

Per my previous posts I have replaced the filter/pressure regulator and the fuel pump and still have the extended crank issues but no longer the start then stall.

At the year end oil change my mechanic looked for an "in line fuel check valve" but nothing readily visible at either end.

He then went to a site "IATN" (a tech for pay site) they indicated that the most likely prospect after all this is a Oil Pressure Sender unit at the front of the engine. It senses the oil pressure and if it is out of whack or intermittent, it shuts the fuel off to save the engine.

May try replacing this in the spring. $300

Bill Curlee

Better get a new Tech. The oil pressure sensor (believe it or not) reading ZERO will NOT shut the engine down. Trust me.

Mine read zero after my heads cam install. I had oil pressure but the 5 VDC reff voltage to the sensor failed. The Pressure read zero and the engine ran fine.

We only have ONE Oil Pressure Sensor and its on the back of the engine (Drivers side) behind the intake manifold.

The check valve is inside the fuel line coming from the tank. and giong to the filter. If it cant maintain pressure on the line soem or all of the fuel in part of the line will drain back towards the tank and cause longer than normal cranking before engine run.

Try turning on the ignition to RUN and then turning it off a couple of times before you crank the engine. Each time you cycle the ignition switch to RUN, the fuel pump will run for a couple of seconds to prime the line.

The Oil Pressure sensor is the tall part on the right:



Bill

69

I agree with Bill here

if the electric side of the fuel pump system checks out OK, then you will have to take a look at the mechnix side…

Fuel System Description
Fuel Pump Electrical Circuit
When the ignition switch is in the ON position before engaging the starter, the PCM energizes the fuel pump relay for 2 seconds, causing the fuel pump to pressurize the fuel system. If the PCM does not receive the ignition, reference pulses with the engine cranking or running within 2 seconds, the PCM shuts OFF the fuel pump relay, causing the fuel pump to stop.
Starting Mode
With the ignition switch in the ON position, before engaging the starter, the PCM energizes the fuel pump relay for 2 seconds allowing the fuel pump to build up pressure. The PCM first checks speed density, then switches to the mass air flow (MAF) sensor. The PCM also uses the engine coolant temperature (ECT), throttle position (TP), and manifold absolute pressure (MAP) sensors to determine the proper air/fuel ratio for starting. The PCM controls the amount of fuel delivered in the starting mode by changing the pulse width, or the On time, of the injectors.
As your car takes 3 to 4 attempts for the engine to fire up, this could be an indication that you are losing the static fuel pressure in the fuel feed system over the time the car is parked, (3 to 4 attempts> this equals 6 to 8 seconds of fuel pump run to pressurize the fuel feed system).
Couple of tests you can do to see if you are losing the static fuel pressure with the fuel pump OFF and not activated.
1. Loosen the fuel filler cap in order to relieve the fuel tank vapor pressure.
2. Remove the left fuel rail cover.
3. Connect a fuel pressure gauge to the fuel pressure connection. Wrap a shop towel around the fitting while connecting the gauge in order to avoid spillage.
With the ignition switch, cycle the key from OFF to ON position (NOT START) to pressurize the fuel feed system. Repeat this step 5 times to build fuel pressure. Record fuel fuel pressure on gauge which should be around (55-62 psi). Important: The fuel pressure may vary slightly when the fuel pump stops running. After the fuel pump stops running, the fuel pressure should stabilize and remain constant.
Monitor the fuel pressure gage for 1 minute.
If the fuel pressure drops more than (5 psi) then you have a leak in the fuel feed system.
Components that could cause loss of fuel feed system pressure with fuel pump off (static fuel pressure drop).
Leaking fuel injector(s) > risk low, no DIC codes indicating engine running rich correct? But you can isolate the injectors by disconnecting the main fuel feed line from the injector rail and connect fuel pressure gauge, perform test to see if the fuel pressure drops.
Sticking fuel feed check valve> risk high.
On the Left fuel tank there is a fuel feed pipe that has an integral check valve in order to maintain the fuel system pressure in the feed pipe with the fuel pump OFF. Unfortunately the check valve is not replaceable by itself. The rear fuel feed pipe has an integral check valve in order to maintain the fuel system pressure in the feed pipe and if this check valve is unserviceable, you will have to replace the fuel feed line.
Cheers ,
Goose

C5PEWTER/CONV

Thanks for all the info guys. I'm not much of a mechanic and the car is in storage for now. I will have to revisit this in the spring. Does anyone know a good Vette mechanic in the Minneapolis St Paul area?

Which engine is Bill Curlee's photo, it doesn't look the same as I remember it on my C5?