# 84 Stanza intermittent problem - fuel system?



## John Yust 84 Stanza (Mar 10, 2005)

Hi, I'm John and I own a Nissan.

I've been having a problem with the engine shutting off suddenly for the last week or so. This is the CA20E engine. When it shuts off, it usually won't start right away. Sometimes this happens in the driveway before the engine has even had a chance to warm up, so it doen't seem to be temperature related. The engine is in good shape mechanically. It has spark at all times. Timing belt is only 10 months old. New fuel filter today. Fuel pressure checks out good, 30 to 35 psi when running.

When it refuses to start, the fuel pump runs on much longer than it is supposed to and it makes a cycling sound. The idle control valve hammers in sync with the cycling of the pump and I even noticed that the code lamps in the ECU both flash with the pump cycle. While this happens the fuel pressue goes up to about 40 psi and cycles up and down about 1 psi. This might happen for a dozen attempts to start the engine, then it will work just right, but only run for a minute or two before it starts all the cycling again and shuts down. From looking at the service manual, it looks like the ECU controls the fuel pump based on inputs form the sensors. The fact that it works right sometimes makes me think the sensors are OK. I'm starting to think that it might be the ECU since everything else seems to check out, but I would like to be totally sure before I lay out that much money. Has anybody seen this before? Any ideas?

Thanks,
John


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## John Yust 84 Stanza (Mar 10, 2005)

*Additional info*

The codes I see from the ECU in test mode are: 22, 24, and 32. 22 is a fuel pump circuit problem. The pump is working, so that only leaves the ECU as a possibility according to the Manual. 24 is the transmission switch and 32 is the starter signal. I don't see what any of that has to do with this. The engine will start when cold. I've seen the ECU flash codes in the past that didn't make any sense, but the fuel pump circuit does make sense this time.

John


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## Gsolo (Sep 11, 2003)

John Yust 84 Stanza said:


> The codes I see from the ECU in test mode are: 22, 24, and 32. 22 is a fuel pump circuit problem. The pump is working, so that only leaves the ECU as a possibility according to the Manual. 24 is the transmission switch and 32 is the starter signal. I don't see what any of that has to do with this. The engine will start when cold. I've seen the ECU flash codes in the past that didn't make any sense, but the fuel pump circuit does make sense this time.
> 
> John


sometimes codes will flash for problems that don't have any affects. Sounds to me like there is something wrong with your fuel pump.


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## John Yust 84 Stanza (Mar 10, 2005)

*Problem solved - dead ECU*

Thanks for the trouble shooting help gsolo. I got a used ECU, plugged it in and the problem is gone. Just in case anybody runs across strange fuel pump problems, the ECU is what controls the fuel pump, so it might be worth looking at that. The used ECU was $75.00. Not a bad deal at all.

John


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## KA24Tech (Feb 2, 2004)

You did a great job on diagnosis because the fuel pump signal is what the ECU thought was missing so it would not send the start signal. The trans code is another without warrant code.

Troy


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