# Dual questions: Testing injectors & dash/tail lights out



## dukhunter322 (Aug 2, 2009)

I just got back from a 400 mile trip with my Z24I 1987. I have had injector problems since I replaced them. I think one is holding open because it is sucking the hell out of fuel.

How do you test and injector for proper function?

Second, During the trip, I stoped for gas. Truned the lights back on and bam, no dash lights or tail lights. Fuse is good. What the hell? 

By the way, I put this truck through some bad mud holes hunting and it performed surprisingly well. 

Thanks.


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## zanegrey (Dec 5, 2005)

when you first put the key in the ign and then turn the key to the start position but not engaging the satarter the fuel pump charges and primes the injectors..

this u should be able to hear...it should charge and then stop..does your s do this or do the injectors stay on the whole time ?

check codes...

clean and or replace headlight switch..


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## dukhunter322 (Aug 2, 2009)

Just like we discussed weeks ago, they do not continuously run. they are primed and you can hear them stop. What makes me think it is a bad injector is when I stop and shut it off, get out for 5 min, if I touch the pedal, it will not start until i press it to the flor and balck smokes comes from the pipe, then it clears.

I will clean the switch. One other thing. I took off the fuse panel and sprayed contact cleaner on the back and front of it to get the dust off-thought there may be a bad connection causing the dome light not to work. After this is when the dash-tail light went out. Was I a dumb ass?


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## zanegrey (Dec 5, 2005)

n e time some one ask me if they were a dumb ass.. my answer is hell yes..

but you were just trying to mantain ur truck so do not sweat it..


it sounds like the injectors are still stuck on .

when you hit the pedal it opens the butterfly which lets all that gas go in at once ..kind of flooding the engine..

so when you open the pedal all the way to get it to start you are just increasing the air .

and then the black smoke which is unburnt gas..

read the codes again ..

make sure the o2 sensor is good .
check the temp sending unit is good and making good contact..

this is a 720 so check the fuel pressure reg and or replace it..

check egr for function and proper vacumn sequence..


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## dukhunter322 (Aug 2, 2009)

this is a 10/86 truck so is it still a 720? I will go and pull the seat again and read the codes. Are you talking about the water temp sending unit?


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## dvdswanson (Nov 6, 2005)

check your TPS


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## dukhunter322 (Aug 2, 2009)

I read the codes. the lights are flashing together, not separate. Mine is yellow and green. I got a 23, 24 and a 51. that is it. I replace the exh sensor and same 51 code. I am lost now.

Here is what is funny, I pulled both relays off fuse box and took loose the fuse block. I turned on the key and wham, I had tail lights and interior lights. I though ok, just a gremlin. So, I put both relays back on and screwed the block back down and bam the lights went off. I cut the key off, thought about it, pulled one relay off, turned lights back on and they were on for 2-3 seconds and went back out. 

I dunno???????????????????


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## rogoman (Dec 16, 2004)

dukhunter322 said:


> I just got back from a 400 mile trip with my Z24I 1987. I have had injector problems since I replaced them. I think one is holding open because it is sucking the hell out of fuel.
> 
> How do you test and injector for proper function?


First try to isolate the bad injector by removing the spark plugs after letting the engine idle for a short time. If you notice a wet or blackened plug, then that cylinder has the bad injector. 

If that doesn't show anything, then unbolt the fuel rail from the intake manifold and pull off the entire assembly. Keep the fuel hoses still connected and don't remove any individual injectors. Also keep the electrical connectors on the injectors. With the assembly now away from the intake, turn the ignition key to the run position WITHOUT STARTING THE ENGINE. Now observe each injector to look for leaks. There should be no drips.


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## zanegrey (Dec 5, 2005)

z24 i does not have a fuel rail


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## dukhunter322 (Aug 2, 2009)

zanegrey said:


> z24 i does not have a fuel rail


You beat me to it. 

Zane, I am out of suggestions. 

Am I reading the codes correct?


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## zanegrey (Dec 5, 2005)

aside from the color .. i think u r reading it right..

u do not have to worry about 23 or 24 and the 51 is injector circuit..

the ecm is telling u the problem..not the injectors but the circuit..
so uncover the injector wires back to the ecm..and hope it is not in the ecm..

i know ..that is a lot of work.. i am thinking you have lost the pulse ..

so the injectors ,when on ,are on all the time instead of pulsing..

this pulsing happens faster then we can see it so you will have to check it electronically..

the the relay and the ecm control the inj via a negative ..


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## dukhunter322 (Aug 2, 2009)

Well, it may be me, but after I put in the new EGR sensor, it seemed to run a lot better and stronger. Does the EGR control the richness/leanness of the injectors? 

Also, I removed the light-turn switch. Looked at it and sprayed cleaner. I also removed the two relays on the fuse panel. Aftetr this, I turned on the light switch and the tail and dash lights came on for a few seconds and sent off. 

Bad relays or switch?


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## rogoman (Dec 16, 2004)

zanegrey said:


> z24 i does not have a fuel rail


Oops, My bad!


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## dukhunter322 (Aug 2, 2009)

I need two GOOD injectors. W/O paying a right testicle for.


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## zanegrey (Dec 5, 2005)

i will see what i can do...


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## dukhunter322 (Aug 2, 2009)

zanegrey said:


> i will see what i can do...


Thanks. I am going to order some off Ebay if I cannot find some.


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