Bordermix Posted June 8, 2009 Share Posted June 8, 2009 Hello, I have a 77' 280Z with a stock L28 and FI system. I have downloaded and read the FI Bible and I own the FSM and I have run all the system checks but I must be missing something! Here is what is happening: When you first start it up the engine runs great, hot or cold but after a minute it begins to run rich and sputter. If you turn it off and start it again it will do the same thing, run great then rich/sputter. Please help............ Thanks in advance, Mike Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted June 8, 2009 Share Posted June 8, 2009 How do you know that it is running rich? It has been a couple of years but I think that this is what happened when I had a rusty gas tank and the rust was clogging the fuel filter. Pull the engine bay fuel filter and see if it has rust, that would be an easy thing to check. Quote Link to comment Share on other sites More sharing options...
Bordermix Posted June 9, 2009 Author Share Posted June 9, 2009 I think it is running rich because of the black soot that comes out of the exhaust and the smell. I installed an inline fuel filter last year right after the fuel pump and I need to check that tomorrow. I also think I need to check the fuel pressure because the more I think about it the more I think it is a "fuel" related issue...... Quote Link to comment Share on other sites More sharing options...
Daeron Posted June 9, 2009 Share Posted June 9, 2009 Is the thermotime switch working right? Is the cold start enrichment circuit turning off like it should, or is it staying on? It sounds like the cold start enrich is styaing on and you should read your Bible to figure out how to test for that. Quote Link to comment Share on other sites More sharing options...
Bordermix Posted June 9, 2009 Author Share Posted June 9, 2009 I checked the thermotime switch and it is within the factory specs, but I even disconnected the connection to the cold start valve and it didn't make any difference. I think I have a fuel pump/rust in the tank issue. When I squeeze off the return line it seems to run better. Quote Link to comment Share on other sites More sharing options...
Daeron Posted June 9, 2009 Share Posted June 9, 2009 okay. There *should* be procedures in the EFI bible for checking fuel supply volume and pressure. If not, then check the FSM for the car. Another thing to keep in mind when doing the electrical checks: Test the component, and then go back and test the component at the relevant pins of the ECU plug. In other words, use the multimeter under the hood, then plug the thermotime switch back in an go unplug the ECU and run the same tests on the switch through the entire vehicle wire harness. This tests the actual reading that the ECU gets, which confirms that your wiring is not the culprit. Testing the component itself is about 98% of the job, but ALOT of problems that drive us shadetree guys nuts fall through that 2% gap. Quote Link to comment Share on other sites More sharing options...
Bordermix Posted June 10, 2009 Author Share Posted June 10, 2009 Thanks for the responses, I won't be able to check the fuel pump and filter till the weekend so I will report back what I find. The good thing is that I KNOW it can run great because it does the first 30 seconds after starting! Quote Link to comment Share on other sites More sharing options...
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