Question about 1990 Nissan 300ZX

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1990 300 zx starts fine though sometimes rich. Won't restart when driven and turned off. Replaced fuel regulator/fuel damper/plugs & iar filter.Getting fuel & spark.If I restrict(crimp) fuel line car restarts and will run rough and rich for a few minutes. Noticed rpm's @ 1100-1300 when in park. HELP

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Sounds like you have a problem with the coolant temp sensor, could be sensor or wiring. The coolant temp sensor tells the computer how warm the engine is so that it know how to adjust the mixture, a cooler engine needs more fuel. If the sensor or wiring is messed up, the computer gets a signal that the engine is very cold and the computer gives full rich to the injectors.

Posted on Apr 26, 2010


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Sport track 4.0 surges and occasionally stalls at idle as if the tps were faulty.I scanned it and got code po191, fuel rail pressure sensor. I replaced the sensor and it ran great for about 400 miles and...

If you used professional scan tool software, you could look
at the data & maybe figure it out

You can google the codes & read up

All the codes have to do with lose of fuel control & a rich condition

The TPS even with a problem, would not drive your fuel trim so
rich your getting all those O2 Sensor Codes

Look at data
Look at fuel trim
Look at fuel pressure
Look at O2 Switching
Look at TSP Data

Check for vacuum leaks

You could have a lean condition & the fuel system is driven
rich-- thus the rich codes

The 2271 is lack of switch or front to rear bias (only one side- out of range)
There you have to resolve any vacuum leaks,fuel
trim issues,maf issues,ignition problems,etc, then address
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I called a lincoln dealer a couple years ago for someone
on here & they had only used or sold 3 or 4 fuel pressure
regulators across all vehicles in their bays, in a 5 year period

So that may never have been the issue
The code who knows,it's a ford

I have seen 6 or more codes on a misfire & hardly any
had anything of value to use or was even related

Install new spark plugs every 3 years
Only use the factory tip config ( OE style plug)
Measure the center electrode & get it right

Install Front O2 Sensors now & every 100,000 miles

Check for vacuum leaks ( use an Evap Smoke machine)

Both banks are effected,so that tells you something, if you have
a vacuum leak or else you have a MAF problem,doubt it

Dec 03, 2014 | Cars & Trucks

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Expedition 2000 idles rough, stalls, runs rich

Sounds like it is still lean & driven rich by PCM

I assume a repair shop can't resolve the issue !

That seems to be why thousands of people come
to this site & ask questions

I know the MAF is common to both banks, but you diagnose
short & long term fuel trim & perform several tests, before you
replace a MAF Sensor

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Intermittant hesitation and shaking sometimes from idle sometimes while cruising 2001 grand prix

loosen the 2 bolts about at the rear of the exhaust going to the catalytic converter and then try to start the car (highly recommended you wear ear plugs) if it fires up right away your caty is clogged. believe me i just went thru what you are going thru. i replaced everything but the motor. another thing to try is pull the fuse for the injectors. if the car fires up and dies or if its acting like its gettin too much fuel replace the fuel regulator on the fuel rail and then ream out the catalytic converter

Nov 15, 2012 | 2001 Pontiac Grand Prix

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1991 Isuzu Rodeo will start initialy fine but if hot it won't restart.

Improve the FixYa experience for everyone by voting.

It sounds as though you may have a faulty fuel pressure regulator. In order to accurately pinpoint the problem, you will have to perform a OBD-I diagnostic scan.

All the best,


Apr 23, 2012 | 1991 Isuzu Rodeo

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My 1994 villager starts, idles and revs fine After about thirty seconds a white galoline ladent vapor starts pouring from the tail pipe. It gets worse the longer it runs. Compression is good, the vacuum...

Bad head gasket & the white smoke is coolant

The O2 Sensor see the coolant or water vapor
& then PCM adds fuel

So you got coolant & too much fuel out tailpipe

Do a Combustion Leak Test where you put a plastic
container over the radiator cap area & see if the
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Car ships replaced wires plugs o2 sencer sometimes acts like it is flooding run fine on open road.

If it acts like it is flooding while idling, but it runs fine on the road, it could be running too rich and flooding it out due to leaking injectors, bad fuel pressure regulator, or excessive fuel pressure.

I would start by replacing the Fuel Pressure Regulator since it doesn't cost as much as the injectors.
Check your fuel pressure using a Fuel Pressure Check Gauge to see if the fuel pressure regulator is maintaining the proper pressure.

Vacuum is attached to the Fuel Pressure Regulator to control system pressure. When the fuel pressure regulator is not functioning properly it causes the fuel pressure to be above normal operating pressure. This condition causes excess fuel to be injected causing a rich mixture that produces black smoke.

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2000 Mercedes ML430 after driven, it won't start for a while, turns over but wont fire. starts fine when cold


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Starts fine & stops in 3-5 minutes or driving in 1-3 miles.

Did you replaced your whole distributor or just the cap and the rotor? Have you check the pressure on you fuel line it could be your fuel pump.

May 16, 2010 | 1993 Plymouth Colt Vista

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