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Discussion Starter #1
I have a 1993 d21 with a ka24. It idles fine for about 10 seconds then goes dead. I changed the fuel filter , fuel regulator, ecm, oxygen sensor and air flow sensor. The fuel runs until it builds pressure. The ecm shows no codes. Now what???
 

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It seems to point to a bad fuel pump. When you first turn the ignition key on to the run position just prior to starting the engine, there's a static build up of some amount of fuel pressure which is probably very low. Then after the engine starts up, the fuel pump can't keep up or there's an obstruction in the fuel line.

Tee-in a temporary fuel pressure gauge between the output of the fuel filter and the fuel rail. The readings at idle should be around 34 psi. Anything far less, indicates a bad fuel pump or some obstruction in the fuel line. I would place my bet on a bad fuel pump.
 

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Discussion Starter #3
It seems to point to a bad fuel pump. When you first turn the ignition key on to the run position just prior to starting the engine, there's a static build up of some amount of fuel pressure which is probably very low. Then after the engine starts up, the fuel pump can't keep up or there's an obstruction in the fuel line.

Tee-in a temporary fuel pressure gauge between the output of the fuel filter and the fuel rail. The readings at idle should be around 34 psi. Anything far less, indicates a bad fuel pump or some obstruction in the fuel line. I would place my bet on a bad fuel pump.
Thanks. I will try that. Everything else has been replaced.
 

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Discussion Starter #5
Installed the new fuel pump and I finally got to drive it. But now when it gets hot it won't idle. Now what?
 

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Installed the new fuel pump and I finally got to drive it. But now when it gets hot it won't idle. Now what?
* The fuel pressure may be incorrect. Tee-in a temporary fuel pressure gauge between the fuel feed hose and the fuel rail. The readings at idle should be as follows:
  • with vacuum hose connected to the fuel pressure regulator: 34 psi
  • with vacuum hose disconnected from the fuel pressure regulator: 43 psi
* There may be a major intake system vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.
 
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