Fuel pressure won't lower.

[TSI4G63TDSM]

Hello, I've read the dsmtuners a lot, but haven't signed up until today. Ok my problem is the my fuel pressure won't go lower than 34psi at idle, I was running and Aeromotive afpr, I got a new professional products afpr today and it acts the same way. Also I've searched for ever on both here, and google. But no answers

Test so far are:
Hooked vacuum gauge to engine, I get 17-19hg on idle.
Made sure there were no vacuum leaks.
Ran return line to gas can (to make sure return lines were good). Pressure remained the same
I've ran one vacuum line from the intake manifold to the afpr, instead of the T fitting and pressure stays the same

Does anyone have any idea's ? Also fuel system is a 255 Wally with stock lines, stock fuel rail, and stock injectors. Pump is re-wired

Thanks in advance.

 

[CrawlinZX14]

Have you tried disconnecting the vac line from the FPR and testing it the correct way? You are supposed to set your base line fuel pressure with the vac line disconnected and plugged ( or just clamped off like most)

 

[TSI4G63TDSM]

Yes. Forgot to add that, I unhooked it and set it to 42psi, then once the line is reconnected it drops to 34psi.

 

[BogusSVO]

Why do you want to go lower than 34 psi?

Most fuel injected cars run 39-43.

I know there is a slight diffrence between auto/5speed and Turbo and NT.

But 34 is a tad low....

I did a quick search and found this...

1. Go to your Misc. tab and click the "turn on fuel pump" box. Once selected you should hear the fuel pump kick on and start pushing fuel through the system. Go out and adjust your afpr to 37psi (1g) or 43psi (2g). Once its good, un-check the activate fuel pump box and it will shut off.
   

 

[TSI4G63TDSM]

When I bought the car from a friend, he had it set at 42 with the vacuum disconnected, and it sat at low 20's. A few weeks ago it started running super rich and wouldn't go below 34. Basically I want it less pressure because that's when it ran best.

 

[NHerron]

Hmm I haven't had any experience trying this but to me your asking the fuel RETURN system to take more pressure, maybe it's too small to return all that fuel? I would think it wouldn't become a restriction so soon but maybe this is the case

 

[BogusSVO]

The AFPR works push/pull
Boost pushes it so it will increase fuel pressure.
Vac pulls it so it will decrese fuel pressure.

Have you checked your vac at idle?

Checked the vac line for leaks?

Do you have bigger cams?

Hmm I haven't had any experience trying this but to me your asking the fuel RETURN system to take more pressure, maybe it's too small to return all that fuel? I would think it wouldn't become a restriction so soon but maybe this is the case

Or got a kink in the return line, ran over something in the road, or some sort of blockage.

 

[TSI4G63TDSM]

Nherron, I ran a line from the outlet to a gas can, and pressure staid the same. So I'm thinking return line is good

BogusSVO, I checked all vacuum lines, I didn't find any leaks. The vacuum at idle was 17-19hg which I've been told was normal. And the car still has factory cams

 

[BogusSVO]

Hook a hand vac pump to the vac line of the AFPR, add vacuume with the hand pumpto 17-19 psi, check the fuel pressure gauge, then hand pump some more.

Could have a blockage at the IM vac port... Its a long shot...

 

[NHerron]

Return line not returning...*

Or got a kink in the return line, ran over something in the road, or some sort of blockage.

Good tips thanks, good things to remember!

Nherron, I ran a line from the outlet to a gas can, and pressure staid the same. So I'm thinking return line is good

Hmm, odd! How are you checking the fuel pressure? Mechanical gauge? Can you try a new gauge in case that one is bad?

 

[TSI4G63TDSM]

Alright I'll try the hand vac now. And a mechanical gauge mounted to the fpr, I'll look I to getting another, but I'm sure pressure is high due to the rich condition

 

[BogusSVO]

Oh... when you checked the vacuume on the engine, On the vac gauge,the needle, was it steady? or did it bounce around?

 

[TSI4G63TDSM]

Went out an hooked a vacuum pump to the fpr, still no change I could only pull 15hg with the pump. I then hooked the pump to the IM line and it showed 19hg, but once hooked up the regulator still sat at 34psi

It was bouncing between 18 and 19 hg

 

[BogusSVO]

How far down did you have to run the set screw to get you 42 w/vac line off?

 

[TSI4G63TDSM]

It's about mid way, 4-5 threads showing.

Does anyone else have any idea's ? I'm at a loss here, and the car is running super rich. It's starting to irritate me not knowing what it could be, thanks for all the help so far.

 

[NHerron]

What size injectors are installed? Are you running any kinda of fuel managment like a SAFC or DSMlink? Coolant sensor plugged in? (2 wire connector on thermostat housing)

 

[TSI4G63TDSM]

It's running stock injectors, No link or any management. Car was tuned using fuel pressure with a logger. Coolant sensor is brand new, could that be it ? I also ran a different vacuum line and different port to rule that out.

 

[TSI4G63TDSM]

Ok so I've been threw every thing I can think of. I've called anyone and everyone I know that is into dsm's. Does anyone have any ideas at all I'm at a dead end

 

[TSI4G63TDSM]

Did more tests today, hooked an electric vacuum pump to it and pressure remained at 34, so it's not vacuum. Took a heater core hose I had laying around and ran it to a bucket and started the car, fuel cams out quickly but obviously not restricted. That rules out the return

So it's not
Vacuum
Return
Regulator

I'm completely lost, surely someone has an idea on this ??

Did more tests today, hooked an electric vacuum pump to it and pressure remained at 34, so it's not vacuum. Took a heater core hose I had laying around and ran it to a bucket and started the car, fuel cams out quickly but obviously not restricted. That rules out the return

So it's not
Vacuum
Return
Regulator

I'm completely lost, surely someone has an idea on this ??

 

[Rsawd95dsm]

When i got my areomotive fpr it had come with two different set springs for it. i tryed the first spring that came with it (because it was already in there and i didnt want to change it) and was the wrong one it wouldnt let me set it to disired pressure, so i had to use the other spring to get correct pressure. Dit either of the fpr come with springs that can be changed out?