FUEL PRESSURE HELP. RELIEF VALVE?

daviddnguyen08

daviddnguyen08

Greenie N00B Member
So after searching and reading some threads, im still confused on what could be causing my fuel pressure to drop. I am 90% sure it is the relief valve that is the culprit but my symptoms are to inconsistent to be sure.

Im pretty much fully bolted, one step colder plugs gapped to .28, with 2 gallons of E per full tank (E15 mix?). Been running autotech internals for over a year now with no problems until now.

Sometimes (not all the time) during cold start, it will idle at 500 rpm with low fuel pressure around 250 psi. After a quick tap of the throttle, everything goes back to normal. Also, ive noticed a couple times during WOT, the car will hesitate at high rpms and studder/pop.

Today, when starting the car, i noticed a bad clicking/clanking from the HPFP. I performed the relief valve test after a cruise to my parents house. I turned the engine off and pressure slowly started to drop to 40-50psi. I WAS SURE it was the relief valve after seeing this. I went back inside my parents house and a couple hours later left to go home. When I arrived home, i decided to perform the same test. However, this time, the pressure held and continued to climb as people stated it normally should.

Does this mean it is starting to fail? OR is it something different like the ITFP or internals?
 
The relief valve should crack at 1850 psi then pressure will drop. Hot motor makes fuel hot and builds pressure. The 60 psi is in tank pressure. I would replace it if it fails the test once if you did it right. Its probably on its way out.
 
I will perform test again today. To confirm the correct testing method of relief valve: just get engine up to normal operating temps, turn off car, Key on engine off, if relief valve is bad, pressure should slowly drop. correct?
I will try to grab some WOT logs today. Hesitant to do WOT until I get everything figured out but I guess logging it would be the only way to narrow down the problem.
 
Can you list your mods please?

Looks like you are hitting some kind of cut by the ECU, Likley Overboost. Take a look at your WGDC’s that the point where the car stutters Time Index 2.658. A little earlier Your Wastegate Dudy Cycle goes from 20’s to 10’s to 5’s then zero. Finally after zero your boost starts to go down, then the ECU Targets 49 WGDC because you are underboosting and you Overboost again and then it trickles back down to zero.
 
5doorsoffury said:
The relief valve should crack at 1850 psi then pressure will drop. Hot motor makes fuel hot and builds pressure. The 60 psi is in tank pressure. I would replace it if it fails the test once if you did it right. Its probably on its way out.
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If after a decent drive.. engine off. But key on...

HPFP climbs to about 1812-1820 then drops down to 1790 then does the same thing.. anything out of the ordinary there? I'm having some fueling issues I cant figure out
 
It's not a fueling issue it's fuel cut. The tune needs to be looked at, and your mods need to be listed.
 
Enki said:
It's not a fueling issue it's fuel cut. The tune needs to be looked at, and your mods need to be listed.
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Let me back up a little.

2012 mazdaspeed 3
97k milew
Cobb downpipe
Corksport injector seals
Cutback exhaust
auto tech fuel internals
HTP 3.5 intake


Pulling a p0089 code off and on. HPFP pressure is perfect at WOT and idles steadily at 400-420

Just got a tune with purple drank. He didn't mention any fueling issues.

Occasionally hpfp pressure will drop into the 80's-90's for about 8-9 seconds car will still run but obviously not to full potential but then it will come right back up to normal operation. This will happen randomly then won't happen for a week. Then randomly will happen again and then return back to normal.

Was thinking about changing a relief valve and or the pressure regulator but haven't had any issues for about 4 days now.
 
In the one log I looked at was obvious fuel cut; everything else looked normal but AFR spiked and load fell off the world in the middle of the pull. Are the other logs any different?
 
Enki said:
In the one log I looked at was obvious fuel cut; everything else looked normal but AFR spiked and load fell off the world in the middle of the pull. Are the other logs any different?
Click to expand...
Ohh no no that was OP not me
 
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