SR20 vacuum leak? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

LtSlayer · 11-12-2020, 02:17 AM

Ok let me start with saying I'm not a complete novice when it comes to mechanic work in general but was a little stumped by this. My car has an s13 SR20DET swapped and it goes through it's ups and downs. I noticed one day the car was significantly down power above ~3k and was leaning out as opposed to running very from earlier that same day and proceeded to replace every coupler and check my previous work with the rocker arms. Everything checked out but when I went to turn on the car I let the fuel pump prime. This is when I noticed the vacuum leak:

The car makes a hissing sound coming from around injector 1/the fuel regulator as the motor primes. I'm no referencing the hum from the pump but an audible hiss from around there. I didn't see or smell gas and soapy water didn't spot it either.

I've read something relatively similar and it was the O-ring on the fuel injector but I swapped this injector 2-3 months ago and never replaced the O ring. Could this really be the problem?

Any other ideas?

S14rebuild · 11-12-2020, 04:14 AM

Why not make a boost leak tester, and pressurize the system in silence (engine not running) to make it easier to pinpoint your vacuum leak

zombiewolf513 · 11-12-2020, 09:00 AM

^ need to do that for the soapy water thing to work

LtSlayer · 11-14-2020, 02:03 AM

Quote:

Originally Posted by S14rebuild

Why not make a boost leak tester, and pressurize the system in silence (engine not running) to make it easier to pinpoint your vacuum leak

The leak is tied to the fuel system, what exactly would I pressurize? I helped fixed 2 vacuum leaks on 2 of my buddies cars last weekend but this is different since its tied to the motor being primed. What part of the motor would I pressurize?

LtSlayer · 11-14-2020, 02:05 AM

Quote:

Originally Posted by zombiewolf513

^ need to do that for the soapy water thing to work

I was seeing is pressure leaking out from the fuel system would make the bubbles but I'll try that soon. There's a T joint that runs to my boost gauge, I'll pressurize that. Since it's when the fuel pump primes its pretty quiet anyways.

S14rebuild · 11-14-2020, 05:43 AM

Cant be a vcuum leak is its hissing when the car is not running and only when then fuel pump primes

LtSlayer · 11-14-2020, 09:25 PM

I'm saying it's easy to hear before the motor hides it. I took it apart to check the valvetrain and replace all the couplers. After trying to use soapy water to find the leak I'm hesitant to start her up again, if you saw my wiring harness you would be too. I'll fire her up on Wednesday fs. My question is, what could cause a hiss from around the intake manifold when the fuel pump primes?

LtSlayer · 11-14-2020, 09:26 PM

Quote:

Originally Posted by S14rebuild

Cant be a vcuum leak is its hissing when the car is not running and only when then fuel pump primes

I'm saying it's easy to hear before the motor hides it. I took it apart to check the valvetrain and replace all the couplers. After trying to use soapy water to find the leak I'm hesitant to start her up again, if you saw my wiring harness you would be too. I'll fire her up on Wednesday fs. My question is, what could cause a hiss from around the intake manifold when the fuel pump primes?

zombiewolf513 · 11-14-2020, 11:35 PM

replace the o rings on the injector you replaced

LtSlayer · 11-15-2020, 12:01 AM

Quote:

Originally Posted by zombiewolf513

replace the o rings on the injector you replaced

I'm getting lazy to go to the parts store as it's miles away. I did put Vaseline on it tho to help seal. I may need the car to go back home in a week or so as well. It ran but would run lean under load. wont it run rich once the turbo spools? i didn't want to force it so I didn't get to see. I can do a balancing act and keep my eye on the gauge. It's 5 miles of street 95 of highway

LtSlayer · 11-19-2020, 10:00 PM

I bought a complete set to replace every intake gasket, I'm going to put new rings and the thick rings that keep the Injector centered. Is Vaseline or silicon grease better to set these in? I used Vaseline with install of the same rings months ago and see no pitting. I'm going to replace all the vacuum lines since I'm pulling the entire intake manifold anyways and I'm going to paint everything to make the bay look a bit cleaner.

Any suggestions while I'm in there?

zombiewolf513 · 11-20-2020, 01:08 AM

Clean the iacv

LtSlayer · 11-20-2020, 01:36 AM

Quote:

Originally Posted by zombiewolf513

Clean the iacv

That could very well be dirty since a rocker arm was broken earlier and the exhaust cycled into the intake. Would that make the vacuum leak hiss we all love so much?

zombiewolf513 · 11-20-2020, 02:32 AM

engines make clicking and hissing noises. i cant tell you where its coming from bc im not there. is the motor having any issues running and driving other than making a hissing noise from somewhere?

LtSlayer · 11-20-2020, 04:04 AM

idle hasn't been noticeably affected, only AFR underload or over 3K with an audible hiss/sandy scratchy sound. No fuel leak and hardly smells like fuel at all.

nmerriw · 04-30-2021, 12:17 PM

I know this is an old thread, but for anyone having similar issues this sounds like a failing Fuel Pressure Regulator to me, the hiss is probably the fuel flow through the regulator into the return line, as there is no vacuum generated without the engine running

11-12-2020, 02:17 AM	#1
LtSlayer Leaky Injector Join Date: Jul 2020 Location: Norco Posts: 69 Trader Rating: (0) Feedback Score: 0 reviews	SR20 vacuum leak? Ok let me start with saying I'm not a complete novice when it comes to mechanic work in general but was a little stumped by this. My car has an s13 SR20DET swapped and it goes through it's ups and downs. I noticed one day the car was significantly down power above ~3k and was leaning out as opposed to running very from earlier that same day and proceeded to replace every coupler and check my previous work with the rocker arms. Everything checked out but when I went to turn on the car I let the fuel pump prime. This is when I noticed the vacuum leak: The car makes a hissing sound coming from around injector 1/the fuel regulator as the motor primes. I'm no referencing the hum from the pump but an audible hiss from around there. I didn't see or smell gas and soapy water didn't spot it either. I've read something relatively similar and it was the O-ring on the fuel injector but I swapped this injector 2-3 months ago and never replaced the O ring. Could this really be the problem? Any other ideas?

04-30-2021, 12:17 PM	#16
nmerriw Leaky Injector Join Date: Feb 2018 Location: SC Age: 26 Posts: 119 Trader Rating: (0) Feedback Score: 0 reviews	Fpr I know this is an old thread, but for anyone having similar issues this sounds like a failing Fuel Pressure Regulator to me, the hiss is probably the fuel flow through the regulator into the return line, as there is no vacuum generated without the engine running

11-12-2020, 04:14 AM	#2
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,495 Trader Rating: (8) Feedback Score: 8 reviews	Why not make a boost leak tester, and pressurize the system in silence (engine not running) to make it easier to pinpoint your vacuum leak

11-12-2020, 09:00 AM	#3
zombiewolf513 BANNED Join Date: Mar 2011 Location: AZ Age: 36 Posts: 1,682 Trader Rating: (6) Rides Gallery: zombiewolf513 Feedback Score: 6 reviews	^ need to do that for the soapy water thing to work

11-14-2020, 05:43 AM	#6
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,495 Trader Rating: (8) Feedback Score: 8 reviews	Cant be a vcuum leak is its hissing when the car is not running and only when then fuel pump primes

11-14-2020, 09:25 PM	#7
LtSlayer Leaky Injector Join Date: Jul 2020 Location: Norco Posts: 69 Trader Rating: (0) Feedback Score: 0 reviews	I'm saying it's easy to hear before the motor hides it. I took it apart to check the valvetrain and replace all the couplers. After trying to use soapy water to find the leak I'm hesitant to start her up again, if you saw my wiring harness you would be too. I'll fire her up on Wednesday fs. My question is, what could cause a hiss from around the intake manifold when the fuel pump primes?

11-14-2020, 11:35 PM	#9
zombiewolf513 BANNED Join Date: Mar 2011 Location: AZ Age: 36 Posts: 1,682 Trader Rating: (6) Rides Gallery: zombiewolf513 Feedback Score: 6 reviews	replace the o rings on the injector you replaced

11-19-2020, 10:00 PM	#11
LtSlayer Leaky Injector Join Date: Jul 2020 Location: Norco Posts: 69 Trader Rating: (0) Feedback Score: 0 reviews	I bought a complete set to replace every intake gasket, I'm going to put new rings and the thick rings that keep the Injector centered. Is Vaseline or silicon grease better to set these in? I used Vaseline with install of the same rings months ago and see no pitting. I'm going to replace all the vacuum lines since I'm pulling the entire intake manifold anyways and I'm going to paint everything to make the bay look a bit cleaner. Any suggestions while I'm in there?

11-20-2020, 01:08 AM	#12
zombiewolf513 BANNED Join Date: Mar 2011 Location: AZ Age: 36 Posts: 1,682 Trader Rating: (6) Rides Gallery: zombiewolf513 Feedback Score: 6 reviews	Clean the iacv

11-20-2020, 02:32 AM	#14
zombiewolf513 BANNED Join Date: Mar 2011 Location: AZ Age: 36 Posts: 1,682 Trader Rating: (6) Rides Gallery: zombiewolf513 Feedback Score: 6 reviews	engines make clicking and hissing noises. i cant tell you where its coming from bc im not there. is the motor having any issues running and driving other than making a hissing noise from somewhere?

11-20-2020, 04:04 AM	#15
LtSlayer Leaky Injector Join Date: Jul 2020 Location: Norco Posts: 69 Trader Rating: (0) Feedback Score: 0 reviews	idle hasn't been noticeably affected, only AFR underload or over 3K with an audible hiss/sandy scratchy sound. No fuel leak and hardly smells like fuel at all.