Testing for leaking injectors..?
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,218
Likes: 117
From: San Antonio Texas
Testing for leaking injectors..?
As suggested by a few here on this forum, I might have a stuck/Open/ leaking injector. I was wondering if any of you know how to test a Bosch III injector. I can't take the rail off with the injectors hanging and fire up the pump, because the Bosch III's don't have the rail retaining clips like the Multechs have and the fuel pressure would blow them right out of the fuel rail. Other than maybe just a visual inspection for a drooling one, is there any active way to test a Bosch III for a stuck open or leaking injector? Any electrical test to hear or see the injectors valve operating or something?
I'm growing weary of working on this thing, so I'm stepping away for a few days and going to the Good Guys Show in Ft. Worth for the Week End to chill out and regroup my thoughts.
I'm growing weary of working on this thing, so I'm stepping away for a few days and going to the Good Guys Show in Ft. Worth for the Week End to chill out and regroup my thoughts.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
If an injector is leaking , there will be gas in that cylinder ..After turning the key and charging the fuel rails a few times , if the pressure leaks down quickly, pull the plugs, turn the engine by hand, and look for gas to come out... You have made sure it's not the diaphram leaking or maybe the valve in the pump ..Right??....WW
Last edited by WW7; Oct 1, 2015 at 07:04 AM.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,218
Likes: 117
From: San Antonio Texas
Had a super rich flooding condition. Had trouble w/ temp. sending unit & it's loose connector before so changed that + its harness and also put on a new fuel pressure regulator. No change. :-(
Race Director
Joined: Oct 2011
Posts: 16,091
Likes: 819
From: Dallas Texas
2025 C4 of the Year Finalist - Modified
I've wondered the same, since I have the same injectors. I've read that if you do a fuel pressure test, and it goes down slowly, most likely it's a leaky injector. But I like to see it visually falling from the injectors. Wonder if Jon(FIC) would know how to?
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,218
Likes: 117
From: San Antonio Texas
I had done a pressure test once a while back, and it held pressure for a long time after shutoff. This time it dropped like a rock when the pump shut off. Have to figure out where it's going!
Melting Slicks
Joined: Jul 2011
Posts: 2,605
Likes: 202
From: Trinity FL
If the pressure drops quickly after you shut it off it is going somewhere. If you don't see the fuel on the ground it is obviously winding up in the cylinders. Whether this is from a leaking injector, some fault in the fuel system, or the PCM somehow keeping a few of the injectors open is beyond me. But I think it is a good idea to step away from C4 for a little bit and send the injectors out to john for testing. He does have a jig setup to pressurize the injectors to see if any fuel spills out. It wouldn't be a bad idea just to rule this out, and would also give you some time off. I can't imagine him charging you for testing them if you bought them from him.
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Melting Slicks
Joined: Jul 2011
Posts: 2,605
Likes: 202
From: Trinity FL
Also wanted to add I'll be watching this thread closely as I just installed Bosch III 24# injectors myself. No problems at all and the car does seem to run smoother. I bought them used from Mike92LX in the for sale section. I ordered the rebuild kit off ebay for around $15 and replaced the strainer baskets and all the o-rings. They work like a champ.
Really looking forward to see what you come up with.
Really looking forward to see what you come up with.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,218
Likes: 117
From: San Antonio Texas
I got these injectors from Jon & they've been great. What ever happened to this engine happened suddenly at the top of 3rd gear. Engine fell off power & started running rough/flooding. Thought I'd found the trouble a couple of times. Torn gasket on MAP sensor, bad temp sensor connector, acted like fuel pressure Reg. So did one of those too. Threw another opti on it because I had one.... Nothing has helped yet. Hope I didn't ruin those injectors somehow. Saw he's offering LT4 injectors now. Maybe I can trade up if I find out what's wrong.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,218
Likes: 117
From: San Antonio Texas
Haven't done that yet but I guess I will when I get back home. I was wondering if there is a way to apply voltage ( how much?) to an injector to hear it click or something to indicate if it is opening & closing? I for sure wouldn't want to smoke one trying to test like that not knowing how much voltage or for how long! I know they operate VERY quickly when theyre running, way less than a second.