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post #1 of (permalink) Old 12-24-2001, 02:01 PM
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injectors?

ok, here's my scenerio. i have spark, and i definatly have fuel. when i crank the engine, i am gettnig fuel pouring out of the drivers side exhaust manifold? injectors staying open at all times? when i check the injectors for power, i turn the key on, and i have power at both sides of the injector plug, even when i take it off the injector. now, this sounds wrong to me. shouldnt one side have power, and the other be a ground, which controls when the injectors fire? i have tried two different computers, and two distributors, and am still having the same problem. from visual inspection, all wires appear to be fine, though 90 percent of them are coated and covered, i dont see how something could happen to them under there. please, any help, before i push this truck off a cliff to get rid of it.

Dominic


dont worry, i am sure i will just unbolt all the injection crap and put a carb on before i do any crazy such thing.

"MUD BUCKET" 1984 bronco, 88 302, 32x11.5 , I am at screen name iskybantilus on instant messenger.
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post #2 of (permalink) Old 12-24-2001, 02:16 PM
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Re: Injectors

The injectors are grouped into 2 banks, but not the same as the banks of cylinders. To open the circuit, you have to pull ALL the injectors from a bank, identified by the second wire's color. All injectors have a common power wire (Tan I think), and each bank has its own ground, which is only grounded intermittently by the computer to open the banks of injectors. When you pulled 1 injector, the power was still going thru the others in that bank, giving you power on the ground side.


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post #3 of (permalink) Old 12-24-2001, 02:34 PM
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Re: Injectors

ok, good point steve. i didnt think that they might not be banked the same as the cylinders are. gonna go check that out. i left my manuel down at school, so i am kinda stranded currently without u guys.

Dominic

"MUD BUCKET" 1984 bronco, 88 302, 32x11.5 , I am at screen name iskybantilus on instant messenger.
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post #4 of (permalink) Old 12-24-2001, 03:27 PM
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Re: Injectors

ok, i believe the injectors are getting power to properly fire. could the injectors leak down because of improper fuel pressure? if so, what is the easiest way to check fuel pressure? i was gonna go get a gauge, but dont see anywhere to easily hook it up. hmm, this is getting more and more peculiar by the moment. if it turns out to be pump, anyone got a spare high pressure pump?



Dominic


"MUD BUCKET" 1984 bronco, 88 302, 32x11.5 , I am at screen name iskybantilus on instant messenger.
post #5 of (permalink) Old 12-24-2001, 05:17 PM
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Re: Injectors

Theres a schraeder valve on the fuel rail you hook the guage to but if you had TOO much pressure, i think i would suspect a defective pressure regulator(on the rear of the rail) before the pump.

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post #6 of (permalink) Old 12-25-2001, 04:40 AM
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Re: Injectors

Even with the rail pressure regulator unhooked (max press), the pump can only develop a certain amount of pressure, which shouldn't be anywhere near enough to damage the injectors OR cause their malfunction. A fuel pressure gauge at Sears (lifetime warranty [img]/wwwthreads_images/icons/smile.gif[/img]) is less than $30.


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post #7 of (permalink) Old 12-26-2001, 05:19 PM
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Re: Injectors

well, i got the fuel pressure gauge this morning. hooked it up, hmm, was getting 9 or 10 psi, and after pump went off, immediatly went down to zero. checked the oil .. hmm, extremely high, and smelling like gas. plugged off the return line, no difference. pulled the four plugs on the driver side, cause thats where i could see fuel leaking out of the manifold, and number 8 was spraying fuel right out the spark plug hole when i try to crank. went and picked up my set of spare injectors. just put it in, but its dark and i could barely see, and when i turned the key, the gauge didnt even move, so i called it quits for today. any thoughts or ideas? i am hoping just that injector died, and that the one i put in is good.

Dominic

"MUD BUCKET" 1984 bronco, 88 302, 32x11.5 , I am at screen name iskybantilus on instant messenger.
post #8 of (permalink) Old 12-27-2001, 01:07 AM
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Re: Injectors

That's not nearly enough pressure. I'm not sure about the specs off the top of my head, but it seems like it's 40-60 psi. Look into the possibility of a bad hi-pressure pump (the one on the frame rail), or leaky fuel system between the tank & the HP pump, or even a bad lo-pressure pump not supplying fuel to the HP. Then there's also the possibility of the tank filter being fouled...


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post #9 of (permalink) Old 12-27-2001, 10:49 AM
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Re: Injectors

ok, i have now tried 3 spare injectors, with the same results. i am reading absolutly no fuel pressure, and i am getting fuel pouring into cylinder 8.?! if i am not building enough fuel pressure, could this happen? i dont understand it, whatever it is. and if before i was reading 8 or 9 psi, imediatly droping, the gauge doesnt even move now? :\ i am sure these pumps are not cheap, so i cant afford to just replace them to find out. anythoughts on testing them?


"MUD BUCKET" 1984 bronco, 88 302, 32x11.5 , I am at screen name iskybantilus on instant messenger.
post #10 of (permalink) Old 12-27-2001, 01:25 PM
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Re: Injectors

well, that eliminates that possibility. the fuel pump is delivering good pressure, both before and after the fuel filter. yet at the rail, still no pressure, still all leaking down into number 8. as unlikely as it seems to me, i guess i will buy a new injector, but i dunno, seems weird to me, and i dont wanna throw 80 bucks down the drain. hmm, getting a bit discouraged, any thoughts? i dunno, i guess everythign points to the injector, but 3 bad injectors, talk about bad luck, between spares and all the work to replace them.


Dominic

"MUD BUCKET" 1984 bronco, 88 302, 32x11.5 , I am at screen name iskybantilus on instant messenger.
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