Good evening everyone, I swapped a 5.3 into a jeep wrangler and I cannot for the life of me get it running.

Tldr, chevy 5.3 won't stay running after starting. Will run for a few seconds with a gas soaked rag over the intake. Injectors are new and it has run before, but not anymore. New fuel pump as well. Novak adapters worked my harness.

I replaced the injectors with new injectors from Amazon. They do spray and has been confirmed.

Walbro 225l fuel pump, 55psi at the rail.

If I start from cold, it will run for probably 2 - 3 seconds before dying. Firing on all cylinders so it seems, then dying.

If I immediately try to crank after that, it will fire on maybe 4 cylinders, then not crank.

Then, if I just continue to crank the engine, it will fire every few revolutions on one cylinder as if it's trying to start, but won't.

Bonus information, if I put a gas soaked rag over the air filter, it will start for a few seconds longer, then die as if it's slowly being choked out.

Additional bonus information, I only have open headers on it with no 02 sensor bungs. This problem has occurred without 02 sensors and with them plugged in just dangling.Pcm has been flashed for vats and is from an 06 silverado.
Here is a link to it running.
https://youtu.be/nFFmlB9kKAU

The battery is now dead and I haven't tried to start it in a while. I'm just getting back into this build with new energy.

What should I look at first to diagnose this?

The MAF sensor was throwing a code prior it being put on hold. I cleaned the sensor, cleared the code, and put the sensor back on. If the MAF was bad, could this cause a no start?

 

Are you SURE that he turned VATS off?

Because this sounds like a VATS problem.

One time that happened to me; tuner made all the changes I wanted, but forgot VATS.

EDIT: Any codes?

 

I'm going to be real with you and tell you I'm not sure. I had it tuned through the guy on LT1 swap.net and had him remove the vats.

Would it run this long if VATS were turned off? This was it's first start up.. it also took like 5 minutes of cranking to get it to actually start like this the first time.

You Tube

 

It's been sitting for about a year, so as of right now, no codes. I will see if the battery will hold a charge to try to see if I can get some codes.

 

Is it maintaining fuel pressure when it struggles to run?
What do the spark plugs look like... brand new, dry, sooty black or wet?

 

I took them out when I was originally diagnosing this problem. They were sooty black. I cleaned them off and reinstalled afterwards.


I remembered a smell of gasoline as well.

When I had the fuel pressure reader hooked up, I believe It kept pressure when cranking. I don't think I ever actually got it to run with the gauge connected

 

I've got the battery charging now

 

Need to let us know:
-Fuel pressure while cranking
-Fuel pressure when running
-Where you are measuring fuel pressure.
-Whether or not fuel pressure regulator is vacuum referenced.
-How plugs look after a few minutes of running (or attempting to)
-Battery voltage while running
-Part number for the injectors being used
-What ECU/vehicle the engine was originally from.
-AFR if you have a wideband.
-Oil pressure if you have a way to read it.
-If it runs better by unplugging the MAF.
-Anything on the engine thats modified.

Seems like a lot, but that will clear up 95% of the possible causes.

 

Can you tell us more about the engine? Did you rebuild it/ freshen it up? If not, did you ever hear it run before?

Because I was thinking about this today, and when you mentioned black plugs, it made me think that there might be some kind of pressure leak into the intake.

Ex: Intake valve not sealing

Exhaust valve not sealing BADLY

EGR valve stuck open (but I doubt you're running EGR)

I bring this up because over the last few weeks, I've had a few vehicles come in with mechanical problems like that.

Try the simple stuff that AwesomeAuto said first, then try a compression test on all the cylinders. If you get one really low, or zero compression, there's your problem.

 

I actually rebuilt it myself. I did run a compression test a while back and they all came back within spec.

I've never rebuilt an engine before this one. What a task!

You're right, I'm running an 06 intake to delete the EGR.

I watched this video mentioning that the computer will notice the 02 sensors seing regular air and then dumping fuel because the computer thinks it's running lean. Then it keeps thinking it needs to dump fuel and won't start again after an initial start. I'm going to get the exhaust put on and troubleshoot further if that doesn't magically fix it.

 

O2's hooked up and dangling in open air?

 

Yes.

Jeep is at the exhaust shop now.
Spoke to the guy and he told me people drive their cars to his shop with open headers and no O2 sensors some times and have no problems running.

Meanwhile here I am.

Let's start from the top everyone. What should I check?

 

You need a code reader.. If you want a nice little tricky one that plugs in to the OBDII port look at Ultragauge, its like a mini glass dash and can clear many codes.
Without some telemetry off the system your chasing gremlins .. The reader will also show a code if vats is killing the engine. Basically you can spend forever hit and miss or just get
straight to the right tool for the job.. (We've all done it... )

You can actually burn up Heated O2 sensors running them in open air,, minimum of about a foot of pipe after them to be safe..
If they are that bad they will throw a hard code on the ECU.

 

So I've got a code reader. I'm running home to get the battery on the charger. That way, once the exhaust is hooked up, I can plug the battery in and see exactly what's going on. I probably should have written down the codes it was reading Oh well. I've got new motivation to finish this and we will get it done!

 

Will this code reader be sufficient?

 

Have you messed with the crank sensor?

 

I have not. What symptoms would a bad crank sensor cause?

 

Just thoughts on how I'd start,, you may have already covered it...
You will likely need to run it to get the codes.. if its had a dead battery for a while.
Based on the post timing history your fuel is probably bed if you haven't drained it..

That reader looks like its strictly a code display, you might look at a cheap cable or USB that can connect to a android or iPhone and run the torque app at some point down the road.. Or the Ultra gage.

Check how the oil looks and smells, if it got gas in the oil you'll want to drain that too.

 

Oh,, ANY time I get run ability issues,, I check all the sensors on the bench if its not triggering a obvious code.

CPS, TPS, IAT, Cam sensor, CTS... Trust nothing.. They go bad both hard and intermittent, new ones can be bad all too often.

 

P0030
p0050
P0053
P0059

ECT MAP IAT TPS all seem to work as they are reading on the code reader.