V6 Discussion and questions about the base carbureted or MPFI V6's and the rare SFI Turbo V6.

fuel pressure readings.

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Old Feb 10, 2012 | 05:41 PM
  #1  
coolrimsatleast's Avatar
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From: Tenino, Washington
Car: 89 f-bird and some others
Engine: 3.4
Transmission: 700R4
Axle/Gears: 3.42
fuel pressure readings.

If I remember, it should be running at 35psi correct? Mine primes at 40 and drops to 38 where it holds for quite a while, but it's running at 30. If I rev it, it'll jump to 34 momentarily. I'll check manual again in a bit when I get back from town.

I have a new filter to install, and I'm soaking the line fittings with PB blaster at the moment. I'll try them again tonight.

Car's been running sluggish lately and sucking too much gas.
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Old Feb 10, 2012 | 06:41 PM
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ex-x-fire's Avatar
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Re: fuel pressure readings.

You might have a weak regulator or an inaccurate gauge.
Check your tune up parts. Clean your maf sensor. Is the engine running cool? It should run at 190-200* going down the road. Faulty t-stat can really cause the engine to run rich.
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Old Feb 14, 2012 | 03:11 AM
  #3  
coolrimsatleast's Avatar
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From: Tenino, Washington
Car: 89 f-bird and some others
Engine: 3.4
Transmission: 700R4
Axle/Gears: 3.42
Re: fuel pressure readings.

Isolated the EGR just in case. Car is actually starting easier, and seems to be running better with the new fuel filter. My coldstart injector line and plug are unhooked due to attempting the ECM swap awhile back, so i have to tap the gas a few times when it's cold. Up until Friday it was taking me to tries to get it started.

Also unhooked the MSD6A and improved the MAF to intake pipe seal.

Timing looked to be 9.5 or maybe 10.

I'll know in about 30-60 miles if I made an improvement in mileage. Operating temp seems a tad higher than before though too.
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Old Feb 14, 2012 | 08:48 AM
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Car: 1973 Datsun 240Z/ 1985 S-15 Jimmy
Engine: Turbo LX9/To be decided
Transmission: 5-speed/T-5
Axle/Gears: R200 3.90/7.5" 3.73
Re: fuel pressure readings.

Fuel pressure should prime at 44 to 45 PSIG. Running at idle with the FLR vacuum line attached should be about 38 to 39 PSIG.
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Old Feb 14, 2012 | 03:33 PM
  #5  
coolrimsatleast's Avatar
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From: Tenino, Washington
Car: 89 f-bird and some others
Engine: 3.4
Transmission: 700R4
Axle/Gears: 3.42
Re: fuel pressure readings.

Since mine primed steady at 41, I guess I might as well do the regulator too. I haven't checked the pressure yet after changing the filter.

Found it in the manuals finally, Haynes says running 34-39, Chiltons says prime 40-47, decrease 3-10 when running.

What's the 'FLR vacuum line'? I'm drawing a blank on that.

*That vac line that hooks to the regulator correct?

Last edited by coolrimsatleast; Feb 14, 2012 at 03:36 PM.
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Old Feb 14, 2012 | 05:50 PM
  #6  
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Car: 1973 Datsun 240Z/ 1985 S-15 Jimmy
Engine: Turbo LX9/To be decided
Transmission: 5-speed/T-5
Axle/Gears: R200 3.90/7.5" 3.73
Re: fuel pressure readings.

That was supposed to be "FPR." Still getting used to this iPhone keyboard. Yes the vacuum line that connects to the fuel pressure regulator.
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Old Feb 14, 2012 | 08:37 PM
  #7  
coolrimsatleast's Avatar
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Posts: 827
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From: Tenino, Washington
Car: 89 f-bird and some others
Engine: 3.4
Transmission: 700R4
Axle/Gears: 3.42
Re: fuel pressure readings.

Well, I either need a regulator, or a new gauge. It's reading 34-5 at idle, and primes at about 44. Better than than before, and it runs better, but not quite what I'm supposed to have. I almost got the regulator today, but it's $85. I'll figure it out tomorrow.
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