Fuel Delivery issue 74 412

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steve_1125
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Joined: Thu Aug 28, 2003 10:16 am

Fuel Delivery issue 74 412

Post by steve_1125 » Thu Sep 28, 2017 4:09 pm

Hi, the car starts and idles great first thing morning (first video), but any time after that , second video, terrible idle, smoky and terrible mileage, under 10 MPG. Also when weather is hotter

Done so far, fuel hoses replaced, fuel regulator and relay replaced. Could it have to do with the airflow meter on the LJet? Any thoughts appreciated, thanks! Steve

https://www.youtube.com/watch?v=A70-EwsBkT4

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Jadewombat
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Joined: Sat Jun 22, 2002 2:01 am
Location: Houston, TX

Re: Fuel Delivery issue 74 412

Post by Jadewombat » Mon Oct 02, 2017 8:31 pm

Put a fuel pressure gauge on it and watch it as the car warms up. Also, make sure the "sock" in the bottom of the fuel tank isn't clogged. Did you see any tiny rust particles anywhere replacing stuff?

Airflow meters either work or they don't. Not that it isn't a possibility, just not likely. None of the Bosch manuals ever blame the black box (brain) or AFM immediately. Nearly all of them say start with the basics, adequate and consistent fuel pressure, good strong spark, no air leaks, etc.

Then you can start checking other things once you're sure it isn't the above such as the temp II sensor in the cylinder head, airflow meter, wide-open throttle switch isn't sticking, etc.

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raygreenwood
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Joined: Wed Jan 22, 2003 3:01 am

Re: Fuel Delivery issue 74 412

Post by raygreenwood » Fri Oct 06, 2017 5:48 pm

I agree. There are some issues with high miles AFM's....but you cannot check for that until wll else is known to be perfect. No vacuum leaks....none.....allowed. Every hose, seal and rubber part must be checked for cracks and clamped.
Fuel pressure must be correct and stable. Ignition should be spot on.
The terminals in all of the plugs must be clean. The AAR should be open wjen cold and closed....all the way...when fully warmed up.

Start with these things. Ray

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