No crank

[Blake1999]

Hi I have a 5.3l out of a 2001 Tahoe swapped into a 1985 c10. I have a painless engine harness all wired in and the pcm is completely stock. I have talked to a few people and I have heard the engine should crank but not run. Well when I turn the key the fuel pump cycles as it should and then nothing. I'm getting it tuned soon but I'm trying to figure out why it won't turn over before I take it somewhere to get tuned and then it won't run. So my plan is to check the starter and then grounds. Is there anything else that could cause this problem? Also how many and where should my grounds be for this swap I know Ls are ground sensitive so I just wanted to make sure it is grounded properly to avoid future problems anyone have any advice or auggesrions? Thanks!!

[ls1nova71]

The grounds depend on your harness, aftermarket harnesses often have them tied together so there's only one. Not cranking usually has nothing to do with the harness unless it includes a starter relay which most do not. How do you have your starter wired? Did you use the original purple starter wire from the 1985? If so, it should be just like it was. Make sure it's in park, check your battery cable connections for being good and tight. Is the battery good?

[Blake1999]

No the original chassis harness is actually replaced with a painless harness as well but that wire is there on the s starter post. I need to check the voltage on it when I get home. And it is in park and battery is brand new. As for the major grounds like battery to engine engine to frame isn't that how it should be?

[mongocanfly]

Has your ecm be unlocked? I've got "told" a lot of things when I did my swap..one of which it "had" to be unlocked to crank...lsnova is right ..if you wired your ls starter like your original it should at least spin the engine...
Just so you know...ground to engine..engine to frame ..engine to body..is the way mine is

[Blake1999]

Ok thanks for clarifying the grounds and No it hasn't been unlocked yet I'm gettjng it unlocked and tuned soon. I will test the starter and all the wires tomarrow. Thanks for the help from you guys!

[davepl]

I don't know how you wired yours, but when I wired mine I used the factory purple wire from the ignition key, that originally triggered the starter solenoid, to trigger the starter solenoid.

What do you have connected to the solenoid? How does your key activate it?

Sounds to me like you're supplying power to the ECM and expecting something to happen, but if you don't actually crank the engine, nothing is going to crank it for you, as it were.

[68c10airstream]

My painless harness for my 5.3 for the 2001 engine that went into my 68 c10 had 2 ground eyelets. I installed them at the back of the cylinder heads. My harness had a total of 4 hook ups. The 2 grounds mentioned earlier, 1 hot all the time, 1 hot with the key on. This harness came equipped with it's own fuse/relay box. It did NOT contain the starter circuit.
Good luck!

[Blake1999]

What did you have to add for the starter circuit if you've dont mind me asking?

[68c10airstream]

I did a ministarter (powermaster, $200.00 i think) because of the good cranking hot, smaller size, indexable, and i used the organ donor starter/battery cables (oem is good quality). Works great with headers also as i run 3/4 length sanderson headers for a ls in a 68 and up nova application from 6 years ago.
Found the box, powermaster part#9509
I didn't have to change anything, used the stock neutral safety switch mounted on the auto column and stock wiring purple wire i think!

[68c10airstream]

Sorry for the broken multi edited earlier post (phone call). The 2 small gauge wires for the stock 60's,70's gm starters had a bigger gauge and a smaller gauge wire going to the starter solenoid. The bigger gauge wire you will use, you may need to solder/crimp on a different eyelet and i believe it's purple and was installed on the "S" terminal. The smaller gauge wire was on the "R" terminal and went to the old style coil and you don't need it for an ls swap. Good luck!
P'S, my painless harness was a fuel injection stand alone self contained harness. As an example if you had a engine stand you could use this harness completely to run the engine, provide a fuel pump and fuel piping, supply a starter and it's circuit. The harness was designed to work with a gm engine controller #411 and even included the charging circuit for a gm alternator. Hope this helps!!

[mongocanfly]

Its not going to fix your spin the engine problem but I recommend you go ahead and take your ecm to your tuner..they can unlock it and set it up with a base tune..theyr going to have to do that anyway...at least that way you can actually crank it and let it run before the final tune...so you can work out any bugs...and make sure its a dyno tune...worth every penny

[Blake1999]

What did you have to add for the starter circuit if you've dont mind me asking?

[mongocanfly]

I'm not sure what your asking about adding a starter circuit..but on my starter its wired just like my smallblock starter..hot from battery to center lug on solenoid and the wire from the key to the small lug on solenoid and another wire from center lug of solenoid to terminal block on firewall..this wire powers all the orignal truck components.. mines a manual trans and there's a clutch switch that won't let the engine spin until you mash the clutch..as stated before your ls harness only needs 4 wires to work..1 constant hot...1 switch on hot...and 2 grounds..outside of the switch on hot you have 2 independent electrical systems..if you have your starter hooked up correctly it should at least spin the engine..you should have a neutral safety switch of some sort..if you rewired the whole truck you may have missed something..

[davepl]

Originally Posted by Blake1999

What did you have to add for the starter circuit if you've dont mind me asking?

I'll try this once more because maybe I wasn't clear, pls forgive me if I sound pedantic here but I want to back up and go at it from the basics.

Your ECM has NOTHING to do with the engine cranking. It never gets involved. If the starter motor spins the engine over, all the ECM knows is that it's turning, but turning slowly. So it'll add fuel and spark and try to light it off.

But the ECM is otherwise not involved in cranking it at all. You could use jumper cables and a screwdriver to crank the engine over at the starter, and it'd all be the same to the ECM.

So right now I think you didn't wire up anything to crank the engine over. You need to do that.

There is a purple wire that comes off the ignition key. It normally is thick and runs through the neutral safety switch on the column, and then to your old stock starter's "solenoid".

At the solenoid you have two wires. The big one from the battery and the purple one from the key. You turn the key and it fires the purple wire, starts cranking, and the ECM now sees a tach signal and starts doing its job.

Unless you have that purple wire connected just like it was 1968, however, nothing will ever start that motor.

[Blake1999]

Yes the purple wire is there. The purple wire has a5v reading before going into the neutral safety switch and after has 0v so it must be the neutral safety switch correct? What could cause it not to give a current other than being faulty?

[Blake1999]

IT CRANKS NOW I unplugged both sides of the neutral safety switch and wired them together just to see, and it worked!!

[Blake1999]

So I cranked to over a few times to see if oil is flowing a d it's not even getting to the filter Any ideas?

[BR3W CITY]

Oil pump o-ring?

[Blake1999]

I used the oil ring that came with the aftermarket
High flow oil pump I also have the chevy performance oil pan so it's a different oil pickup tube than stock what color O-ring should I use?

[homemade87]

If you put a dry pump in you will not get that pump to prime with just cranking on it . Best to put a little grease in the pump . This helps priming considerably but does not guarantee you will see pressure at the gauge while cranking . I have never had much luck priming an ls engine with the starter .

I would consider making you a priming pump from a garden sprayer to get some lube in the pump . Easy to build . There is a few videos on youtube to show you how . Pretty inexpensive also . There is a oil pressure sending unit at the front drivers side to attach it to . At this point I would just crank it and watch the pressure gauge . You should see pressure pretty quick .

[Blake1999]

Alright i got tge oil flowing but when I crank it smoke or vapor or something comes out of valve cover area what could this be? Is it just becaus if the brand new engine?

[davepl]

Yeah it's pretty much impossible to prime an LS motor with the starter. We use a spare small block oil pump in a little box with a driveshaft that we spin with a drill. You can also buy pneumatic setups to prime them.

How much smoke or vapor are you talking about? All engines have SOME blowby. Shouldn't have a lot though. Take a video maybe?

[BR3W CITY]

Video might help.
Even if you used the right o-ring, its possible to pinch it or have it misaligned during installation.

When I did my engine the first and second time, I didn't use a priming tool FWIW. I know some folks have issues getting prime, but I always had it within a few crank. I prefill the oil filter, put a quart under each rocker cover (reattach obsiously), then fill the rest of the engine and crank a few times.

[Blake1999]

Im getting 30psi now when cranking but still don't have a time so I can't start it does anyone have any mail order tune places they suggest I'm in the Dfw Texas area.

[68c10airstream]

check with terry at "lone star dyno". He's been great to deal with. Straightened out my tach issue. Double checked it with 2 different tachs before sending it back 2,000 miles!!