My FPR Is Ticking and Fuel Pressure is +3 PSI All The Time, Any Ideas??

[YeaJimi]

I drive my 79 280zx as a daily driver. Its got a little less than 50,000 miles on it. When I got the car, and after driving it 50 miles home, I did some routine maintence including spark plugs and fuel filter. The plugs were white, which I though would be caused by a lean condition. The after emptying the old fuel filter I notice all sorts of rust in the filter.

 

For poopies and giggles I threw my fuel pressure guage on and took a reading. I'm seeing 33 idle and about 38-40 with a blip of the throttle. I've read the specs should be 30/35, so apparently I'm running higher.

 

This would lead me to believe that the engine would be running rich, but the evidence from the spark plugs would suggest there is a blockage somewhere in the fuel rail creating the high on the FPR side, and a low on the injector side. I assume it is the fuel rail because all 6 plugs appear the same way.

 

On another note I have recently replaced the FPR with another OEM unit. I replaced it after seeing my pressure numbers and noticed that the unit was making a "louder than expected" tapping sound. To be honest until I fixed my valve lash I couldn't hear anything. Long story short my new unit is still making a tapping sound. Also the new plugs look white just as the old ones did. I was kinda wishing it was just a blockage at the filter.

 

So does anyone know anything else this could be besides a blockage?

[Tony D]

Your fuel pressure is where it should be, and doing what it should when you touch the throttle.

You are basing this on plug reading alone?

 

They are white at the base, up inside the metal body where the center electrode porcelan contacts the metal threaded body, as viewed through a plug loupe with illumination?

 

If you are looking at the exposed portion of your center electrode, it runs CONSIDERABLY hotter, and will mislead you to the fueling conditions of your engine by up to three jet sizes. Most people who 'read plugs' do it wrong, and as a consequence jet too rich anyway.

 

And this was on a WOT clean cut reading, right?

 

If not, discount your 'readings' and see what happens as you drive. If you are not coughing out the intake and surging while driving along in top gear....likely there is nothing wrong with your fueling....

 

So the answer to the last line is probably best answered by 'overactive imagination, likely'...don't sweat it. If you don't have lean-running symptoms, you aren't running lean. "Reading the Plugs" is universally done wrong...fagedaboutit....

 

Just this past tuesday, I had ALL DAY to kill waiting on another flight out of JFK...sat in the darned hotel all day waiting for the appointed hour, HI Express Lynbrook...right up the street from the Train Store where the guy got Whacked in the 65th episode of "The Sopranos" entitled 'The Blue Comet'...or so the sign in the window said... I had time to play around on Long Island...

[YeaJimi]

Small world I actually live on Long Island. I took a look at every plug. And basically the whole plug is whiten even the ground electrode. That is what started to get me thinking.

 

I'm trying to maximize my gas mileage and also the life of the engine. With gas at $4+ a gallon, I'd definitally like to get more than 20mpg like I currently get.

[jayzrocket]

I talked to a known local mechanic about the fuel stations around here going to 10% ethonal in all grades of fuel, concerned about the stock valve seats and he said that isn't as much a concern as the o2 sensors would be getting a mixed message reading. He also mentioned that the cat may be of more concern, because the ethonal will raise the octain. He also mentioned that this will cause a loss in milage as he has already in his late model ford pick-up and his motorcycle. I am scrathing my head here because in the past Iv'e always run the highest octain in my turbo to maximize my milage, and usually works out that way. So why would the ethonal decrease milage if it raises the octain value? I haven't had my z on the road to test this out yet with the ethonal issue, was wondering if anyone else has any input about this?

[cockerstar]

I'm not exactly sure how the above post fits into the thread, but I'll answer it anyways :S

 

Ethanol has a higher octane rating than gasoline (e85 is around 110-112 IIRC), but gallon for gallon, ethanol has less energy. The 10% blend of ethanol found in lots pumps today improves the burn and makes it more completely as well as cleanly. It reduces power, emissions, and efficency.

[jayzrocket]

Sorry about the mis-thread, but thanks for the reply.

This site has been the best for answering the ?'s that I

have had.

 

Thanks again!

J.