Fueling & Injection Fuel Pumps | Injectors | Rails | Regulators | Tanks

how to test for leaky injector besides ohm

Thread Tools
 
Search this Thread
 
Old Nov 13, 2011 | 09:30 AM
  #1  
purple98haz28's Avatar
Thread Starter
TECH Enthusiast
iTrader: (5)
 
Joined: Oct 2005
Posts: 525
Likes: 0
From: Sulphur, LA
Default how to test for leaky injector besides ohm

Let me start off saying car is a 98z28 152k mile tr230 cam only most supporting mods m6. it is on the factory fuel system as of now. Recently when I come to a stop after driving a distance my RPM will only come down to 1500 rpm for around 20 seconds before dropping to 800 or so. My oil has a slight gas smell. Car performs good other than that. Gas in the oiil scares me as i know it can wash the cyl's if diluted too much. I did search on here and found to ohm the injectors my results were 12.3-12.6 on all cyl- that should be good right? I also read about a noid test but don't have the tool(where and how much for one)- this only test voltage right? I thought about removing fuel rail with injectors and priming up pump to see if they leak..any other easier less messy way? I also need a fp guage. How do i test the fpr since its in the tank. PLEASE HELP WHERE SHOULD I GO NEXT thanks-Brandon
Reply
Old Nov 13, 2011 | 04:13 PM
  #2  
FICINJECTORS's Avatar
FormerVendor
iTrader: (30)
 
Joined: Sep 2008
Posts: 1,274
Likes: 0
From: Cumming, Ga
Default

Originally Posted by purple98haz28
Let me start off saying car is a 98z28 152k mile tr230 cam only most supporting mods m6. it is on the factory fuel system as of now. Recently when I come to a stop after driving a distance my RPM will only come down to 1500 rpm for around 20 seconds before dropping to 800 or so. My oil has a slight gas smell. Car performs good other than that. Gas in the oiil scares me as i know it can wash the cyl's if diluted too much. I did search on here and found to ohm the injectors my results were 12.3-12.6 on all cyl- that should be good right? I also read about a noid test but don't have the tool(where and how much for one)- this only test voltage right? I thought about removing fuel rail with injectors and priming up pump to see if they leak..any other easier less messy way? I also need a fp guage. How do i test the fpr since its in the tank. PLEASE HELP WHERE SHOULD I GO NEXT thanks-Brandon
hi,with that many miles you should have your injectors serviced.
its $15 per inj.service includes internal ultra sonic cleaning,flow bench test,measuring of all 8 injectors flowing together and all new filters,o rings, pintle caps etc.
Reply
Old Nov 13, 2011 | 06:39 PM
  #3  
purple98haz28's Avatar
Thread Starter
TECH Enthusiast
iTrader: (5)
 
Joined: Oct 2005
Posts: 525
Likes: 0
From: Sulphur, LA
Default

i agree and that sounds like a great deal until i upgrade injectors with some heads...but this is my dd right now until i get my yukon engine swap done how fast is the turn around. Also come on other peeps what else do i need to do to troubleshoot and find what my problem actually is. BTW I only drive it 6 miles each way to work.
Reply
Old Nov 14, 2011 | 05:33 PM
  #4  
purple98haz28's Avatar
Thread Starter
TECH Enthusiast
iTrader: (5)
 
Joined: Oct 2005
Posts: 525
Likes: 0
From: Sulphur, LA
Default

not many people read in this section huh...please help me troubleshoot
Reply
Old Nov 19, 2011 | 02:42 AM
  #5  
Pony Exp.305's Avatar
Launching!
iTrader: (6)
 
Joined: Mar 2010
Posts: 267
Likes: 0
From: Lake City, TN
Default

change new fuel filter?
Reply
Old Nov 19, 2011 | 06:39 AM
  #6  
Old Geezer's Avatar
TECH Senior Member
iTrader: (3)
 
Joined: Jun 2004
Posts: 5,639
Likes: 71
From: GA, USA
Default

1.Start with a data log, and see what shows up.
2.A noid checks for inj pulse, can be purchased at most ap stores, not much $.
3.An ohm test will show inj coil issues, if any.
4.A fuel psi check is done at the rail, not the tank. The test results can then be looked at to see what's up w/ the system.[55-58psi is OK.]
5.Hanging idle can be caused by several problems.[Refer back to item 1].
Reply
Old Nov 22, 2011 | 06:02 AM
  #7  
purple98haz28's Avatar
Thread Starter
TECH Enthusiast
iTrader: (5)
 
Joined: Oct 2005
Posts: 525
Likes: 0
From: Sulphur, LA
Default

thank you for the help. i will follow your list. where can i go about getting a data log as i only have a basic code reader?
Reply
Old Nov 22, 2011 | 10:24 AM
  #8  
ZL1Killa's Avatar
TECH Resident
iTrader: (17)
 
Joined: Sep 2004
Posts: 3,747
Likes: 0
From: NC - Charlotte area
Default

Originally Posted by purple98haz28
thank you for the help. i will follow your list. where can i go about getting a data log as i only have a basic code reader?
find someone who has hptuners/efilive/or something that can do so. or pay a tuner shop to ride in your car while you drive and do the logging.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Nov 22, 2011 | 11:01 AM
  #9  
C5kid's Avatar
TECH Regular
iTrader: (12)
 
Joined: Mar 2003
Posts: 453
Likes: 0
From: Hershey, PA
Default

why not just pull off the injector rail w/ the injectors and prime the pump? this is how we found a leaky injector on a friends car.

as long as you have the stock rails that clip the injector to the rail you can just pull it up and prime the pump a couple to times to see which one is leaking.
Reply
Old Nov 22, 2011 | 11:15 AM
  #10  
Pocket's Avatar
TECH Addict
15 Year Member
iTrader: (22)
 
Joined: Apr 2009
Posts: 2,656
Likes: 149
From: NC
Default

Be sure to unplug the injector connector prior to that test

If you have billet rails, pull the whole intake and prime the system
Reply
Old Mar 1, 2016 | 11:21 AM
  #11  
Snorkelface's Avatar
Launching!
 
Joined: Jul 2003
Posts: 258
Likes: 0
From: Rancho Cucamonga, CA
Default

Which injector connector would I unplug before doing this test? I'm trying to diagnose if I have a leaking/stuck open injector.

Thank you!

Originally Posted by Pocket
Be sure to unplug the injector connector prior to that test

If you have billet rails, pull the whole intake and prime the system
Reply
Old Apr 10, 2016 | 05:43 PM
  #12  
Pocket's Avatar
TECH Addict
15 Year Member
iTrader: (22)
 
Joined: Apr 2009
Posts: 2,656
Likes: 149
From: NC
Default

All 8

If the connectors are still hooked up, priming the system will result in each injector squirting a small amount of fuel. With them unplugged, the pump will pressurize the system without the injectors firing. If you have a leaky injector, it will spray/dribble out even with the connector unplugged. Dont be afraid of a small drip or two from good injectors, if you have a leaky injector, it will be obvious
Reply
Old Jun 29, 2016 | 02:21 PM
  #13  
taws6ali's Avatar
Teching In
10 Year Member
 
Joined: May 2011
Posts: 49
Likes: 0
From: michigan
Default

hey guys I have a 1999 trans am and I am having major fuel problems. car and mods after upgrading my ls1 block with ls6 heads cam springs etc) ended up with the fuel leaking down into my crank case and oil and out the exhaust..which lead to throwing a rod through my ls1 block. well that's history at least for now. it was my first attempt at an engine build EVER !!! even though I went 100% by the book I figured I might've did something wrong right?... 7k dollars later I bought an ls3 crate engine with all proper adapters, extensions and conversions (Lingerfelter crank and cam conversion box, I am using my ls1 MAP sensor, ls1 knock sensors (relocated to the side of the block), ls1 oil and temperature sensors) I start the car only to find out that my ca is leaking fuel out the exhaust ... only thing I didn't do is get it TUNED (but would that cause excessive fuel leakage ? and I'm not convinced a fuel relator could be the cause of this since I get 60psi at idle and it stays constant without changing
Reply
Old Jun 29, 2016 | 04:14 PM
  #14  
Pocket's Avatar
TECH Addict
15 Year Member
iTrader: (22)
 
Joined: Apr 2009
Posts: 2,656
Likes: 149
From: NC
Default

With all the old sensors reused, it sounds like you're running the old PCM on the new engine which absolutely will run super rich untuned. Stock 24/26lb injectors LS1 vs 42lb injectors LS3

Its doubtful your new injectors are leaking, you are simply getting too much fuel into the cyls and there isnt enough air to burn it all. Get it tuned
Reply
Old Jul 7, 2016 | 05:17 PM
  #15  
stevieturbo's Avatar
9 Second Club
 
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Default

Originally Posted by purple98haz28
Let me start off saying car is a 98z28 152k mile tr230 cam only most supporting mods m6. it is on the factory fuel system as of now. Recently when I come to a stop after driving a distance my RPM will only come down to 1500 rpm for around 20 seconds before dropping to 800 or so. My oil has a slight gas smell. Car performs good other than that. Gas in the oiil scares me as i know it can wash the cyl's if diluted too much. I did search on here and found to ohm the injectors my results were 12.3-12.6 on all cyl- that should be good right? I also read about a noid test but don't have the tool(where and how much for one)- this only test voltage right? I thought about removing fuel rail with injectors and priming up pump to see if they leak..any other easier less messy way? I also need a fp guage. How do i test the fpr since its in the tank. PLEASE HELP WHERE SHOULD I GO NEXT thanks-Brandon
High rpm is highly unlikely to be injector related.

Why do you "need" a fuel pressure gauge ? What problem is there that you need to check this ? And you check pressure at the rails, near the injectors.

If it's your daily, stock injectors and you really do think there is an injector problem, then just buy some replacements, they'll be cheap anyway
That means no downtime.

High idle could be any number of ecu related issues, someone competent at tuning etc should be able to take a look and ensure everything is normal when this is happening.
Reply
Old Jul 9, 2016 | 08:52 AM
  #16  
Pocket's Avatar
TECH Addict
15 Year Member
iTrader: (22)
 
Joined: Apr 2009
Posts: 2,656
Likes: 149
From: NC
Default

Originally Posted by taws6ali
I love you bro no (homo) i was told they are the same psi (ls1\ls3) do you know what can i do to make them work with my car so just a tune up?
No, they're quite a bit bigger

Just a computer tune, any dyno shop should be able to handle it. Id avoid driving it very much because running that rich will wash the cyls down and cause pre-mature ring wear. Would seriously suck to have low compression in your new crate engine over something simple
Reply




All times are GMT -5. The time now is 03:26 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE