Greets all... I am a noobie here :rolleyes: , but have a problem with starting my car after its been sitting for a little while. First off it's a 1989 Corvette Targa Top that I purchased second-hand with one previous owner. The problem is when I go to start it in the morning after it's been sitting in the garage all night, it will take a few try's to get it started. When I turn the key, the starter engages, but the car won't start. I'll stop and give it a second or two and try it again with usually the same result. Then, about the third or fourth time I try to start the car it starts up just fine.... However, the idle is usually pretty rough for a minute or so. Once, this scenario plays itself out every morning... the car starts just fine for the rest of the day & works well. ???

The only other issue with the car has just started recently. Every now and then the car will simply shut itself off. The "Service Engine Soon" and "battery" light come on in the idiot light panel and the speedo goes to zero. The car will usually start right back up once I stop and put it in Park, but this is kinda annoying as well! :confused:

Thanx in advance for any input! L8R,

 

As far as it taking awhile to start after it's been sitting, it can be a few things. Try turning the ignition to on but not starting the car. Do you hear the fuel pump cycle for a couple of seconds? If not you're probably having fuel pump relay problems. I believe it's located under the hood, next to the master cylinder.

The fuel pump is driven by oil pressure, so turning it over a few times gives it time to build up some oil pressure if your relay is bad.

 

The fuel pump is triggered for the first two seconds by the ignition and by distributor reference pulses after that. It doesn't have anything to do with oil pressure.

 

Sorry, poor choice of words on my part. Let me start over.

The fuel pump is dependent on the oil pressure switch to run. If the oil pressure is too little the pump won't run. This situation would occur after the car has been sitting.

If your fuel pump relay is bad, it doesn't prime the fuel pump when you start the ignition. You still have very little, if any, oil pressure so the oil pressure switch is telling your fuel pump not to run. This is not a problem if your pump has been primed, however.

Cranking the car builds up the necessary oil pressure and the fuel pump starts to run.

89's may not work this way, but this was the case when I first bought my car. Ignition on, no fuel pump priming, 4 or 5 long cranks then no problems. Replaced the fuel pump relay, instant start and no problems.

But then again, the guy who owned the car before me was a whacko who did all sorts of needless "modifications", so maybe I'm alone on this.

 

Yea... damn, this is an active board :eek: ... sorry, I couldn't check the boards for a couple of days.

Anyways, the fuel pump seems to be functioning correctly. If I simply turn the key a couple of clicks without actually starting the car, I can hear the fuel pump begin to "whirrr" for a little bit and then go quiet. So, that doesn't seem to be the issue.

Also, anybody have any idea on why the car would spontaneously shut itself off at random. It has done this again a couple more times and while it simply starts right back up, its really getting annoying :mad .

Thanx for the help...

 

same problem on my 89.After reading this post,I went out to garage and turned key to on,I didnt hear anything as far as a primming type of noise. Cranked three times before it started,then a rough idle for a few seconds,ok after that.Shut off,fired right up after that. Is this fuel pump relay the one that screws into master cyl? I see two other possibilities that are seperate from M/C, but close to it. :confused: Sounds like this is my problem,tho. Any idea on $$$?

 

The relay should be on the firewall to the right of the brake booster. I have an auto, but if you've got a 4+3 I've heard there's an overdrive solenoid relay in front of it.

It should be cheap.. about 10 bucks.

If this fixes your problem I'd appreciate if you'd share it on the forum, for archival's sake.

 

Thanks very much for the reply! I see the one you are referring to. I will pick one up tomorrow at GM. You know how proud they are of their parts,Probably to the tune of 20.00--30.00 range. Thats OK,I keep it 100% OEM. No problem at all on passing it on to the forum,Glad to do it. :cheers: :thumbs:

 

I may try switching the relay as well just to see if it will fix anything. I can hear the fuel pump "prime" itself when I turn the key to the ON position tho, so I don't know if this is the problem or not. :confused:

L8R,

 

I've got what sounds like a very similar starting problem on my '89 as well - a long cranking time to start when sitting for a long time, followed by a rough idle for a few seconds. Then everything is fine.

It's obvious this is a fuel delivery problem but like some of you, I can hear my fuel pump prime the fuel system prior to startup. So I've ruled out the fuel pump relay, even though it would be an inexpensive piece to replace. I bought a fuel pressure test gauge on the weekend, but I haven't had a chance to hook it up and monitor what's happening. I will try and get to it tonight when I get home. I've heard that it may be a problem with one of the in-tank fuel supply lines, but I won't know for sure until I actually hook up this fuel pressure test gauge and see what's going on.

But I have never experienced the stalling problem that was mentioned. The 2 problems may be related though so hopefully when you solve one, you'll eliminate the other.

I'll post the findings of my fuel pressure test. I'd advise that you get a fuel pressure test gauge as well and conduct the same test. The gauge isn't expensive and well worth the money purely from a tuning/diagnostic point of view. After all, spending $30 on a relay is a waist of both time and money if it turns out NOT to be your problem; spending $30 on a tool that you will not only have forever but that can indicate the REAL problem is worth it's weight in gold - even if it ends up pointing to the $30 relay as being your problem!

 

Hi again,

Well, I just finished doing the fuel system pressure test and here's the results:

1. Prior to startup
Pressure reading:45 psi with fuel pump running (2 seconds)
40 psi and holding with fuel pump off

2. During startup
Pressure reading: 45 psi

3. Idling
Pressure reading: 38 psi with fuel pressure regulator connected
45 psi with fuel pressure regulator disconnected

4. Shutdown
Pressure reading: 45 psi with fuel pump running (2 seconds)
40 psi and holding with fuel pump off

To be honest, I don't know what to make of this. It seems to me that 38 psi at idle is a little low - TPiS suggests that it should be 42 to 47psi; GM states that pressure should only drop 3 to 10 psi below the indicated pressure prior to startup (in my case 35 to 42psi). So it seems that my pressure, at least at idle, is acceptable.

The only thing I can see wrong with the data I'm seeing is that the pressure should NOT drop once the pump stops priming the system. The GM service manual statest that the pressure prior to startup should be between 40.5 and 47psi and hold steady when pump stops. Obviously mine doesn't.

There's a couple of additional tests I can run according to the manual - they involve pinching off fuel supply lines. I will try these next.

But does anybody have anything to add to this diagnosis? I've never done a fuel pressure test and I'm new to it. Any help at all would be appreciated.

Thanks.

 

Sorry, I don't have anything to add to it. I appreciate you posting your results though. This sort of information can prove invaluable when trying to troubleshooting little nagging things.