Tabor

When I first started my 1987 944 NA today after sitting for a few days my fuel pressure was 18psi (steady), and then it slowly climbs (on it's own) to 32psi. Holding the throttle at 3k rpm causes the needle on the gauge to shake violently between ~26-30 (it is hard to tell, it shakes really fast).

With the engine off and the fuel pump on it holds steady at 39 psi.

My understanding is that fuel pressure is supposed to be 29psi while the engine is running and 39psi when the engine is off.

Is the 3psi difference between the optimum 29psi and my 32psi enough to cause the overly rich mixture I am seeing in low RPMs (too many hydrocarbons, can't pass emissions)?

Also, is the shaking at 3k enough to indicate a bad fuel pressure damper, or is this amount (4psi) normal?

As always, thanks for all the help.

EDIT- The fuel rail was also completely de-pressurized when I first started the car because I had just installed my new Lindsey Racing fuel pressure gauge.

adrial

I noticed a large difference in how my car drove with only a 3psi change in fuel pressure...so I think its quite possible...

With the cost of a fuel pressure regulator...I think its worth a shot...

BTW When I start my car the fuel pressure jumps to X psi, not X-15psi and then slowly to X. Feels like algebra class huh?

--Adrial

How's your Lindsey gauge fitting under the hood? Or not even gonna try?

Tabor

[quote]Originally posted by adrial:
<strong>How's your Lindsey gauge fitting under the hood? Or not even gonna try? </strong><hr></blockquote>

It is currently under the hood, but I have yet to start the car with the hood down. I don't plan on it either.

Thanks for the help.

EDIT- Until I replace my motor mount with factory units. Right now I have a blown exhaust side aftermarket unit, that only lasted about 10k.

Tabor

Not that I don't respect adrial, but I would like a second opinion from Skip and/or Jason from Paragon Products (since they sell them).

Mainly, do you think I just need a FPR, or also a FPD?

Skip

Start with the FPR - if it's original, it's time. FPD is a completely different design, and *I've* never seen one fail.

PS&gt; Is that CS your friend got Keith Brown's old car? If so, he needs to come up here and give me a push in the AX... Keith and I traded spots quite regularly - that car is quite good!

Good Luck!

Tabor

[quote]Originally posted by Skip:
<strong>Is that CS your friend got Keith Brown's old car? </strong><hr></blockquote>

Yes!

Skip

Autocross Sunday in Bremerton - tell him he's a punk if he doesn't show

Skip (924S killa)

Florida951

My fuel pressure dampener failed and the fuel pressure went through the roof. Hope you fix your problem

Tabor

[quote]Originally posted by Skip:
<strong>Autocross Sunday in Bremerton - tell him he's a punk if he doesn't show </strong><hr></blockquote>

Well, he will be in New York State sunday, so, maybe some other time. I plan to be at PIR on October 4th.

Skip

[quote]Originally posted by Tabor Kelly:
<strong>Well, he will be in New York State sunday, so, maybe some other time.<hr></blockquote></strong>

Okay, I guess I'll accept that excuse

[quote]<strong>I plan to be at PIR on October 4th.</strong><hr></blockquote>

Me too! And Nov 3rd

S

Melchior

Skip, how much for a FPR for a '90 944S2? I don't see a pricing for a stock one on the Paragon website.

Skip

Look <a href="http://www.smartcart.com/Paragon/cgi/display.cgi?item_num=944_fpr" target="_blank">closer</a>