Does 3 bad injectors cause no start on 5.2? Possible to test injector wires? - JeepForum.com
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Unread 12-17-2012, 04:52 PM   #1
Rynfw100
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1993 YJ Wrangler 
 
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Does 3 bad injectors cause no start on 5.2? Possible to test injector wires?

Hi, I'm doing a 5.2l swap into my YJ and I'm trying to get the beast started for the first time. Problem is, it seems to be getting fuel and it is getting spark, however a no fire.

I tested all 8 of my injectors on my fuel rail and 3 did not "click" when I took a 12v battery and used two wires to connect to the injector's terminals. Would this cause a no start? I'm using a fuel rail off of a 92 dakota in order to keep the fuel pressure regulator on the rail instead of in the gas tank, if that helps at all.

Also, I would like to test the injector wires and make sure they're getting a pulse from the PCM (which also could be faulty) Is there a procedure to test and make sure that I'm getting a pulse from the PCM on the injector wire connectors?

Thanks!

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Unread 12-17-2012, 05:01 PM   #2
Foundrydude
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3 cylinders not getting fuel, it's probably not gonna start. Almost, but not quite.

Bout the only time a V8 will run when it's down 3 cylinders is if it's already running and warmed up, and has dropped down to that many cylinders. Getting a cold V5 started is not so easy.

good luck
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Unread 12-17-2012, 05:07 PM   #3
Rich93ZJ
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There are many other factors/scenarios that can cut the pulse to the injectors. What ECU are you using for the swap, 5.2 I hope. I would also use the factory fuel rail just to help eliminate some gremlins. Sounds like a good project but remember, the electronics suck in the zj to begin so it sounds like you will have a lot of research to do. Get a schematic at the very least..Good luck
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Unread 12-17-2012, 05:31 PM   #4
LordHobbit
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to test if injectors are getting a signal, rent a noid light.
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Unread 12-17-2012, 05:48 PM   #5
dusterdude
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Quote:
Originally Posted by LordHobbit
to test if injectors are getting a signal, rent a noid light.
I sold a guy a noid light kit last week,first one ive sold in years.was surprised he knew what it was.
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Unread 12-17-2012, 06:28 PM   #6
Rynfw100
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I'm using the 92 Dakota rail because it has the fuel pressure regulator on the rail and it has a return line which is just like the YJ. Also the ECM is from a 1994 Dodge 1500 with a 5.2L and manual transmission. I'm replacing the 3 injectors with the injectors from the ZJ rail that I have because all 8 passed the clicking test. Will the noid light connect into the harness and tell me if it is sending the right signal?
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Unread 12-17-2012, 09:37 PM   #7
AVR2
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Quote:
Originally Posted by Rynfw100 View Post
Will the noid light connect into the harness and tell me if it is sending the right signal?
A noid light will tell you if the control signals are going to an injector. Unplug the connector from the injector, plug in the noid light and crank the engine. If the signals are reaching the connector, the light will flash. Basically the same sort of deal as a spark tester.
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Unread 12-18-2012, 02:35 PM   #8
Rynfw100
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After renting a noid light locally, I found that I'm getting signal from all 8 injector wires, I replaced 4 injectors because one more didn't click after all, and still a no fire. After trying to turn the fuel pump on a couple times, then cranking it, I held down the fuel pressure release valve on the fuel rail and I got nothing out of it. So I've narrowed it down to two things, my fuel rail, which I didn't notice until now, has a kink on one of the fuel line connectors on the fuel rail. Or it could be the fuel pressure regulator which is located on the fuel rail, operated by vacuum. Since I'm not getting any fuel into the rail, but I know the fuel is in the lines (ask me how I know ) I believe it's either of these two culprits. If the fuel pressure regulator is bad, would it cause no fuel to get into the lines?
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Unread 12-18-2012, 02:43 PM   #9
ratmonkey
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it'll start and run on 5 cylinders. won't be pretty but it will.

the pressure regulator can leak all gas past it into the vaccuum line if it's bad.
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Unread 12-18-2012, 03:03 PM   #10
Rynfw100
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That's what I figured... It should still belch and bubble if it is getting some fuel, but it is not.

Would or should fuel spray out of the fuel pressure release valve when you're cranking the engine and you're holding the valve open? Even if the fuel pressure regulator is bad, or there is a gnarly kink in the fuel rail connector?

I'm thinking that if I get a new fuel pressure regulator, and still a no fire, I'll buy yet another 92-93 Dakota fuel rail and just swap my new regulator on the replacement rail... It may be a lot of work, but I really want this beast to fire :/
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Unread 12-19-2012, 05:41 AM   #11
ratmonkey
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Check fuel pressure with a gauge, they're cheap.
It needs 40psi.
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'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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Unread 12-20-2012, 08:35 AM   #12
Rich93ZJ
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Are you positive you have spark? Spray some carb cleaner down the intake and see if it will fire. It should at least stumble if you have good spark.
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Unread 12-20-2012, 09:03 AM   #13
Rynfw100
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Absolutely positive. I did the spark test (Stick phillips screwdriver down the plug wire, get close to metallic object in engine bay ie. headers and if it sparks it has spark), and when we shoot starter fluid down the intake, it will grumble, but wont continue starting.

I'm getting 0 fuel into the rail. I've already gone ahead and am having another shipped to me... I'll figure this thing out soon
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My 5.2L V8 swap and Jeep build:

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