5.3 swap ready to start.. no run.

[Windsma]

This is the Email i sent Brendan at LT1swap.com around midnight last night. (he reprogrammed the PCM)
Maybe you guys can help, yesterday was miserable and this was the icing on the cake.

Having an issue with the 2001 5.3 swap. (into a 1972 C10)
Cranks wont run, no sputter or anything.
Also the OBD2 scanner port wont link to the PCM (green data wire, has cons12v and grounds)

Crank angle sensor is plugged up, pretty much left every sensor plugged in
Block is ground to the battery using the 5.3 batt cables neg, other is ground to the frame, rear block ground is attached to the firewall
Coils are getting 12v, just me, so i cant see if they're actually firing
Fuel pump kicks on to prime the system every key cycle, has pressure
I have 12v to the injectors. (The engine only sat 2mo)
All 4 fuses have power

Side notes,
My main trans connector is smashed from the wreck, but i drove the 01 truck into the shop.
o2's are not plugged up at all
Pins were removed per the site guidelines
F11 and E3 neutral safety switch signal are open and not attached to anything. ?

I triple checked all my connections before hitting the key. I was certain it would fire first shot. Nope..
I would think there's a power/ground issue with the PCM but the Fuel pump relay signal is working.

[truckdude239]

okay runa ground wire to teh case of your pcm and and see what it does mine did the same thing and ran the ground wire and it fired right up

[Windsma]

Will do. Thanks. I live in HighPoint and have to run back to Burlington to the shop.
I am not using the truck PCM mount. I put it in a C5 vette mount. If that makes a difference.

[truckdude239]

i used an s-10 mount on mine and bolted it to the fendor, and mine wouldn;t start but soon as i hit a ground to the pcm it fired right up, high point not the far from me i live in lewisville and work in winston salem

[Windsma]

Brendan is awesome, very quick reply.

The engine harness grounds need attached to the engine block, NOT the firewall. This however should not prevent starting.

There are 3 ground eyelets on the 5.3L harness, 2 behind the intake, attach to top of block, or back of the heads. (Not Valve Covers) There is 1 more engine block ground for the coils behind the power steering pump that attaches to the engine block just above the oil pan rail, in front of the motor mount on drivers side. Make sure that is connected.

When you turn on the key, and the fuel pump runs, bump the starter over with the key and leave key ON, does fuel pump run another two seconds when you do this? (It should if it reads the crank sensor) Also, make sure your KEY HOT power to your injectors and coils stays hot when you are cranking over the engine. Some KEY HOT wires go dead when key is in CRANK position.

Let me know what you find....

-Brendan.

[truckdude239]

umm my hanress did not have any ground on it ummm

[Hart_Rod]

Do you have power to the coil/ign wire while you are cranking the engine? If you have it connected to an accessory wire, the power goes dead while you are cranking. You can hot wire it to the battery just to check.

[Windsma]

Injectors and coils have power during cranking.
All grounds are connected as they should be.
Just dropped the starter to look at the crank sensor. Its plugged up and not damaged.

Brendan asked if the Fuel pump comes back on during cranking. It does not.
He also said never ground the PCM case.

[ls1nova71]

Who did your harness work? If you drove the truck it was in less than 2 months ago, then it's not the engine or injectors, so I would say you've missed a wire somewhere. What wire are you powering up the LS harness with? Also, how are you checking to see if coils and injectors have power while cranking?

[Windsma]

I reworked the harness, its my 2nd.
Checking the pcm pins and crank sensor now.

[truckdude239]

You shouldn't have to ground the pcm but in my case that's what solved my issues I've read it else where on here that people have had to do the same thing. I had no start no fuel pump running and no obd2 commutation I tried a crap shoot of grounding the computer and it fired right up

[Windsma]

Brendan

If you don't see any power from fuel pump control when cranking, than either the PCM is loosing power when craning, or the PCM is not reading the crank sensor. The PCM will command the relay back on as soon as you crank or engine runs. So since its missing, its not reading crank sensor.

You might check PCM connections, make sure bolts are snug. You might remove the plugs on the computer, make sure no pins are pushed back into the PCM.

So started Crank Angle Position sensor Trouble shooting.

No voltage at sensor..
Great.. I tucked the PCM away very nicely so had to take a few things apart to get it out.
Voltage at the PCM connector. Blue#2... but none at the sensor..

Threw on my test leads, Dad stopped by for 3min.. told him to hit the key.

It fires right up..

So now i start cutting my nice pretty harness up to trace the CAPS green wire..
and find this.
Not sure how it happened. I cut all deleted wires off at the loom.

[ls1nova71]

Broken wire, yep, that's your problem!

[Windsma]

Well.. I just took off the wire loom..

Seems that the wrecked donor truck did some internal damage to the harness.. Gonna be a long night.

[oldman3]

Glad you found the problem...Jim

[solidaxel]

Another success story for the site!

[nstp71]

Yeah guys I know this is a older thread, I have a 71 c-10 with a 5.3 ls swap. The engine turns over with the key, but the fuel pump won't turn on. Any hey would be appreciated.

[Windsma]

Originally Posted by nstp71

Yeah guys I know this is a older thread, I have a 71 c-10 with a 5.3 ls swap. The engine turns over with the key, but the fuel pump won't turn on. Any hey would be appreciated.

The fuel pump is controlled by the ECU
It will pump for a few seconds when you turn the key. If not you have an ecu/wiring issue.
If it runs for a few seconds when the key is turned to on but, not while cranking.
You have a crank posistion sensor / wiring problem
Posted via Mobile Device

[nstp71]

Thanks I'll give a once over tonight and let you know the outcome.

[nstp71]

Hey guys I figured out the no fuel issue, it was a bad crimp connection on my in-tank fuel pump. "duhhh!!!" runs fine first startup. Thanks for all the help.

[atownsend]

I have been talking to Brendan also, and he has been a great help. I got my swap running yesterday, Monday, and today, it will not stay running, again. Nothing changed from yesterday, but, it will not stay running. I have checked the wring, all is the same, checked gas to make sure that it has gas, checked fuel pressure, fuel pressure is great.

Any ideas, folks?

someone please tell my how to terminate the cols and fuel injectors to keyed and run position hot?

I want to activate/make active the coils and fuel injectors when the key is in the start and run positions. Thanks.

[mongocanfly]

Check your maf if it cranks and dies instantly...do you have fuel pressure

[atownsend]

Yes, have fuel pressure, power on the coils and injectors at start and run, and I have about 3/4 tank of gas. It was running on Monday just fine. I took the wiring harness off to do some clean up, and today, the engine won't keep running.
I checked the wiring again, and I need to dedicate wires from the BCM:

C1 - Orange, Hot at all times
C1 - Pink, Hot at start or Run
C1 - Brown, Hot at Run
C1 - Black Grounds.

The PCM was flashed by Brendan.

I need to confirm the power wiring. I had the Pink on keyed power rather than power on Run.. That might be my problem. So, we will see tomorrow.

[ls1nova71]

Do you have a way of checking for codes? I just had a bad wire on a MAP sensor keep one from running, so it could be a number of things, but my bet is it's in the wiring you messed with since it was running previously. I would double check the harness.

[atownsend]

Okay, I checked harness again, and everything seems to be proper. I purchased a fuel pressure tester. I got 50 psi when I turned the key to the Run position, and I did hear the fuel pump. The pressure immediately dropped to 45 psi, and it would not and still will not keep running when I finally get it running. I have to use starting fluid to get it running. It will keep running when I get it running with starting fluid.

I left the fuel pressure tester on to see how much the pressure drops. Within 2 minutes after turning the engine off, the fuel pressure drops to about 30 psi.

History: I used the Suburban fuel lines and had to use pressure fittings to cut and piece the fuel line (both main feed and return) back together. When I found that the fuel pressure was not holding, I tightened my fittings. Well, the fuel pressure dropped faster than before. I suspect that I am loosing pressure within my hack fuel line job.

So, I ordered some proper fittings (nylon) and nylon fuel line from Summit. I will attach the correct fuel fittings and fuel lines and re-check the system for proper fuel pressure and see if I can start and keep the engine running. I will do that as soon as my parts come in.