88vette.hard start,start for couple minutes and die

[JD-vette]

Hi All
I have a problem with 88 corvette.
year:1988
mile:125000

hard start but when it starts the engine sound very normal for couple minutes then die. I was able to pull a code by using the old method that short Pin A & B to obtain the code on information widow. it read 34. so I clean the throtte body,replace MAF relays,check MAF sensor and connectorm,clean IAC,But the same the systom is the same. If anyone have the same problem or idea please help me. I think fuel pump & filter have not been changed. Would it be fuel problem or injector system problem. Or do I have problem with start/ignition problem b/c when hard start, I try to jump and it start so easily. Please help.

Thanks,
JD.

 

[JD-vette]

Please help. any opinions is appreciated.

 

[RedRagTop]

Hi All
I have a problem with 88 corvette.
year:1988
mile:125000

Or do I have problem with start/ignition problem b/c when hard start, I try to jump and it start so easily. Please help.

Thanks,
JD.

JD; Are you saying it often needs assist to start (jump or boost) then runs OK? How are your gauges reading? Voltage?
Did you get the code 34 again?

 

[JD-vette]

No, I never jump. It was just an experiment. No I don't see the code anymore but It might appear again. Thanks,JD.

 

[JD-vette]

It is around 11.5V before start, when it cranks the voltage is aroung 10....somthing. After it starts the voltage is 13.6.... IS the battery bad. I think it is normal.
JD.

 

[RedRagTop]

I think the battery is bad.

 

[vette-dude]

;stupid

Replace the battery. Have the Alt checked too.

Randy

 

[vettenick]

Try disconnecting the Mass Air Flow sensor connector and see how the car runs. If it runs OK, you probably need a new sensor.
When you disconnect it, the computer will run in back up, so it will ignore the MAF sensor. You can also try tapping the sensor with the engine running, if the engine "acts up" when you tap the MAF sensor, that's a dead give away of a bad sensor.
Let me know!
Nick

 

[JD-vette]

Thank you all for your inputs.

Had the battery check and it is good.

It is the same when the MAF sensor is disconnected.

The symtom is still the same, the engine could start good but it die out in 2-3 minutes. When it die it is really hard to start again, wait a while and it could start again easily. Would it be the ignition/distributor/roto/cap/module problem???or electrical problem.

 

[vettenick]

JD... When it dies, have you checked to see if you still have spark to the plugs?

 

[JD-vette]

Nick,

Yes, There is spark when it cranks, I only check one plug thou. I have no clue. It seems I have a semmilar problem (hard start when hot) with all other vettes but mine die out in couple minutes with no hesitation. The engine is very smooth when it can start. Please advise.

 

[vettenick]

If you have spark, then the next logical check is to make sure that the fuel system is working. When the car cuts out, check to hear if the fuel pump runs when you turn the key to the "ON" position. Don't start the car, just turn the key to the on position and listen by the gas tank. You should hear a buzzing noise for about 2 seconds. If that's not happening, check the fuel pump relay for proper operation. If the fuel pump operates, then you must test for proper fuel pressure by using a gauge.
I can walk you through the rest, first check for fuel pump operation.

 

[JD-vette]

Nick,

I think the fuel system is OK. I could hear the pump works fine. Would it be the IAC? It seems the engine can not hold the idle speed properly(I remember I have adjusted the idle speed screw before,according to the repair manual"idle speed adjustment may result n premature failure to IAC vale"). I had removed and cleaned the throtte body and IAC. but I am not sure if I need new IAC.

Thanks,
JD.

 

[vigman]

Is the OIL pressure good?

IF the oil pressure drops BELOW 4 PSI it will shut off the fuel pump...

Something to check...

The next thing would be to VERIFY with a fuel PRESSURE gauge.. that you do not drop BELOW 35 psi on the fuel rail.

Does the car start right back up after it dies?


Vig~

 

[JD-vette]

No, It would not start right up after it dies. wait about 10 minutes or so then it can start right up again. Yes, I need pressure gauge to check the fuel line. so you think this is fuel feeding problem then?

Thanks,
JD.

 

[vigman]

Assuming you can crank & have spark

YES...

the way to tell is to shoot some fuel down the throttle plates.. if it runs THEN you have a fuel delivery problem.. was the car sitting a while?

What is the milage? Is there rust in the tank?


Vig~

 

[JD-vette]

Thank you all for your tech support. The problem with my 88 vette was the fuel pump. After couple weekends checking all related symtoms for code 34, I gave up and had it checked by a mechanic. It turned out to be a fuel pump......Now it runs so smooth and I can feel it faster and more power like a champ(oh-not mentioning that I did clean the throttle body, it is so damp dirty. now it really make a bit different).
But I really wonder why the code read 34 when fuel pump is bad???

Thank you all.

J.D.