5.3 swap issues..
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5.3 swap issues.. Alright so I finally got around to swapping a gen 3 5.3 into my k5. For the harness I reworked a complete truck harness and made a fuse block all according to lt1swap.com. Have it all wired and hooked in to my car and I go to start it...it cranks over but doesn't fire. When it cranks it sounds like I don't even have the coil packs hooked up, like there's no compression or even a hint of trying to start. I checked the plugs though and it is sparking so thats not the problem. Fuel pump is fine and pumps for 2 seconds before start and is pumping fuel through it and it's getting up to the rails. Popped one side of the rails up to check the injectors and they're dry. Why wouldn't the injectors be pumping fuel? If it was VATS wouldn't it start for a second or two then shut off? The injectors are wired to go on with the coils and the coils are working so the injectors should be working....?
VATS disables the injectors. Its supposed to work for a few seconds, but sometimes they don't fire at all.
Make sure you have power to the injectors. Then check to see if the PCM is pulsing ground (a test light works fine if you don't have a noid light set). If you have no ground pulse, suspect VATS.
A little starting fluid can rule out compression or timing issues.
Make sure you have power to the injectors. Then check to see if the PCM is pulsing ground (a test light works fine if you don't have a noid light set). If you have no ground pulse, suspect VATS.
A little starting fluid can rule out compression or timing issues.
Teching In
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From: pontiac, il
I had problems with mine also. turned out to be a couple of things. One make sure all your power sources are hot while cranking i had one that was hot with key on but while it was cranking it lost power. The second was that if the injectors have been sitting for a while they get stuck closed. I had to let them soak all night in injector cleaner and tap on them lightly with the key on to get them all unstuck. it's a common problem i've read. worked for me good luck.
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Sprayed a little starting fluid in it and it fired right off.
I'll check that pulsing ground and see if it is or isn't, in the meantime I'll try cleaning the injectors out since they have been sitting around awhile so theyre probably stuck. Thanks guys!
I'll check that pulsing ground and see if it is or isn't, in the meantime I'll try cleaning the injectors out since they have been sitting around awhile so theyre probably stuck. Thanks guys!
Agree with JBorders. Make sure that any 'KEY ON' power sources have power WHILE cranking.
Jon
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Jon
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Well each bank of injectors is wired with that same bank of coils to the same fuse and the coils are sparking so they should be getting power while cranking but I'll have to check today
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simple check, helps to have a spare injector connector.
hook each injector directly to 12v+ and ground for just a brief moment, listen for a click noise. If each one does not click, they are not flowing any fuel.
do not hold power to injector, just tap power to it just as quick as you can apply and release , listen for the noise.
-Brendan.
hook each injector directly to 12v+ and ground for just a brief moment, listen for a click noise. If each one does not click, they are not flowing any fuel.
do not hold power to injector, just tap power to it just as quick as you can apply and release , listen for the noise.
-Brendan.
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Verdad Gallardo Power comes from your fuse/relay setup. The PCM provides GROUND to activate the injectors. All VATS does is prevent the PCM from grounding the injectors. If you only see 6 volts to the injectors while cranking, you have a weak battery or bad wiring somewhere. It has the data to pulse the injector properly at 6 volts, but anything under 9 is generally to low for the engine to fire. I doubt 6 volts to the starter would even make it turn over.
You said the coils are wired to the same 12v source? Are they only getting 6 volts? What is the battery at while cranking?
You said the coils are wired to the same 12v source? Are they only getting 6 volts? What is the battery at while cranking?
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I'll have to check fri/sat when I'm back around it again. The battery has been sitting around a few months so that could be the problem but we'll see how it all goes then and report back
