Hey guys,
Well I left my car for 6 days while we were in New York (great city! very friendly), I got back and it turns over but won't fire up.

It's definitely fuel. Spark is there and when I first cranked it, it fired immediately then died as if it was burning up fuel sitting in the rails, etc. The gauge reads 3/4 and I poured in some extra just in case.

Couple of questions:
- How many fuel pumps does the LT have? I remember reading 2. I hear a hum from the engine bay for a couple of seconds when key is in On position, and after a failed crank. Is this a fuel pump?
I don't hear a hum from the in-tank pump, just a click. I stuck my head under there while someone else turned the key to On and off again. Then again I have never noticed a hum from the rear pump, and I always hold the key in On position for a second or two before cranking to prime it (old habit).

- Is fuel pump failure common on later C4's?
mine's at around 90,000. I found several related threads but they were all 85/ 86 cars. It seems weird that it would be fine when I left it then complete failure after not driving for 6 days. I had noticed it taking longer to start since I changed the plugs and leads recently. It used to start almost immediately on turning the key.

- I want to/ should buy the FSM. It's 120 bucks from the Helm site - anywhere I can find this cheaper? I thought it was more like 50 bucks.

I will try replacing the in-tank fuel pump first. Hoping it's this and not something nasty electrical. At least it's parked at the in-laws where I can work on it

 

The L98, L83, and LTx have one fuel pump. The ZR1 has 2.

Very possible. The hum from the engine bay is probably the fuel pump relay, unless it's located in the car on the LTx's

You can turn the key on and the ECM/PCM sends signal to prime the fuel rail for 2 seconds. After that you will have to wait 10 sec before turning the key on agian before the signal will be sent again. That is the way I start my engine. Wait for a few seconds after turning the key on.

It goes out when it wants to....at any time. The L98's and LTx's cars are pretty similar when it comes to the fuel pump.

You NEED a FSM if you do your own work on the car. The price is about right and you get two books. Look on ebay for a used or cheaper one.


Get a fuel pressure gauge and test the fuel pump before replacing it. Could be something else and you will be replacing a good part. Could also be injector ref pulses. Does the battery have a good charge?

 

Check the fuse to the fuel pump, a failing pump will blow the fuse. If that cures your problem carry an extra fuse next time it blows change pumps.
Yes the pump quits when it wants to. Mine went south at 28,000 miles.

 

A FSM is cheap! Any garage will charge you that much just to say good morning! A fuel pressure gauge is a lot cheaper than a fuel pump. Measure the pressure on the shrader valve at the end of the fuel rail. It should be about 40 psi and when the pump turns off, it should hold pressure for a long time. If pressure falls rapidly you may have leaky injector/s which cause a too rich mixture to start. Unplug one of the injectors and connect a noid light (available at parts stores) or use a low power 12v lamp like a side marker lamp across the injector socket and crank the engine. The light should pulse showing that the computer is pulsing the injectors.

 

Check ebay or http://www.factoryautomanuals.com/ for discount FSM.

 

Thanks for the replies, guys, I'll see if I can find a fuel pressure gauge and let you know how I get on

I forgot to mention I did check the fuses - first thing I looked at. All ok. At least now I know where all the fuses are

 

I replaced the fuel pump today, fixing the problem, and wanted to add to the great info here that was very helpful. Had a little more advice from a friend with a shop too who lent me a fuel pressure gauge and gave me help with diagnosis.
Here's what I did:

-Checked fuel pump fuse, swapped with internal lights fuse (20A), tried to start - no start.
-Bought a voltmeter, pulled an injector plug, checked for volts across plug with key in On position - had voltage.
- Pulled fuel pump fuse and turned over to clear system of fuel, attached fuel pressure gauge to schrader valve, replaced fuse, turned key to On position, checked pressure - zero fuel pressure.

I was pretty sure it was the fuel pump at this point.
Went to local NAPA store, bought fuel pump, pump loom and fuel pump sock. The NAPA guy asked me if it's true what they say about owning a Corvette being a lifestyle. Maybe it was my Vette cap and sweaty dirty face I told him all about Corvette Forum

I the followed procedure in my work manual and on this excellent thread from Frizlefrak here

It was a fairly easy job for a first-timer, I just took my time and tried not to drop things in the gas tank or blow myself up. The hardest part was getting the hoses off the pump assembly. I bought the wiring loom too but decided not to try it after reading I had to splice 2 wires together. I examined the existing wires and connections - they seemed pretty good to not take the risk with my horrible wiring skills!
Pics:


Now turning the key I could hear the pump whizzing up, turned it over and she instantly started up!

Thanks all and see you on the road

 

Nice Photo essay. Thanks for posting pics

 

Thanks for taking the time to document the pics on your FP R&R. That one tension clamp on hose you descrbed as being difficult should have been a snap to remove with needle nose pliers though. Your documentaion will no doubt help others out, and that is awesome! Well done, and nice clear pics.....

Just curious, how many miles did you get out of your old FP?

 

I have read on here that running less than 1/4 tank of gas isnt too good, that the fuel pump is cooled using the gas, so maybe running low on gas a few times caused this, idk.

 

 

The fuel injectors have a coil in them and one wire is connected to 12v and the other coil wire goes to the ECM which pulses that wire to ground according to throttle setting etc., so putting a voltmeter across an injector socket won't tell you much except it will find a blown inj fuse. This is why I recommended using a noid light or a low power 12v lamp across an injector socket and observing if the light pulses during cranking.

 

Thanks for posting the pics. Excellent write up and very detailed pics.

 

Most likely... Ran mine low once, and that pump really let me know.

 

Nice pics of the procedure and glad that you documented the sock position. Word of caution or warning: you indicated that you purchased the fuel pump from NAPA, so it is an aftermarket rather than the OEM. If you are lucky, it will last. But aftermarkets are not manufactured with the tight tolerances of the OEM, so they can cavitate (air into the fuel lines) and are prone to failure. They heat up while in use, so the above post of keeping the fuel tank at least 1/4 full is sound advice. However, since they heat up, the tolerances within the pump change and this is where you get failure. If you have to replace the fuel pump again, get the OEM. In the long run, it is cheaper. Again, thanks for documenting the change out; I've seen it done once on a ZR1.