initial start after swap

[rodstored-72]

hi, I have a 2013 4.8 LS I am wanting to know what I need to do for the initial startup after the swap? it is a stock engine/trans package. all factory computer, electronics and fuse box. the equipment is original to the O.G. truck from swap.
IE - any computer (laptop/software) conn. needed?
- do you conn batt and then crank over?

thanks

[LS short box]

Assuming everything is connected correctly I connect the battery and look to see if I any smoke coming out. Kidding a bit. Then if everything looks good I pull the fuse for the fuel pump and then crank the engine looking for oil pressure. When I see oil pressure I put the fuel pump fuse back in. Then I just crank it and it should start but be ready to shut down if you have a fuel leak. If everything is good you will be shocked how quickly it will start and run. Good luck.

[Davidf]

What I did: primed the oil system from plug on side of block/oil galley. Connected battery and looked for leaking smoke. Felt all the power wires for warmth. All good, then did a few key on fuel pump cycles. Yep, pump cycled and showed me all the leaks (I had a few). then I bleed the air out of the line via the Schrader valve on the fuel rail. I turned the key to start and it fired up instantly...My so was amazed as was I.

I should note that when I first connected the battery and saw a spark, I was worried. Only reason it should spark is because there is load or current draw. Hmmm, what could it be? Oh yeah, the headlight switch was on from installing the gauge cluster. Reconnected the battery, still a small spark. Dang, what now...oh, the door was open...sheesh.

[rodstored-72]

Thanks for the replies. I would guess that if all listed is good then connect to the port & check for any codes?? I wasn't sure that if the ECM was not being "read" during initial startup if it might not "agree" to start....
SOOO. I guess the "order" is to check/get oil pressure and then fuel pressure, once the electrical fires are put out...LOL

[rodstored-72]

bringing back to the top... I have tried to fire it up and I am not getting enough fuel pressure at the rail. fuel makes it past the regulator/filter, but I do not see any pressure at the rail, I can hear the pump turn on and fuel comes out of the hose after the "corvette style" reg./filter..

reminder: this is a stock 2013 4.8 with stock fuse box & electronics in a stock '86 swb with duel tanks. the pumps are AC DELCO EP381 in stock '87 "baffle" tanks

[LS short box]

Double check your connections at the FPR. It's easy to get the inlet and return connected backwards.
You could "hot wire" the fuel pump and then see what's coming out of the FPR.

[rodstored-72]

LS shortbox,
Thank you for the reply. I had a friend help me with the issue over the weekend & he indicated that the FPR is connected correctly, we also noticed that the return line was still dry - no fuel was in it while we were trying to start the truck. I THINK it might be a issue with how I connected (assembled) the fuel pumps in the tanks. I am guessing that my next recourse is to drop the tank(s) and then see what is going on in there??? this was my first time working with fuel pumps...... aarrggg

[Accelo]

I had the same issue with mine. It turned out the pump was wired incorrectly, backwards!
I had to pull the pump from the tank to check it. The manufacture switched the wires at the keyed plug. No quality control anymore, you are the quality control. Depending on your wiring set up you may just try switching the wires. Mine was also grounded at the tank so switching the wires wouldn't work for my set up.
Cheers.

[rodstored-72]

accelo, thank you for the reply... it sounds possible to me. would you be able to detail more on how you checked for that & what I am looking for? again the pumps are the AC DELCO EP 381 pumps. I am planning on dropping the tank(s) this weekend to see. I guess I should be hopeful that is the issue??... either way the dropping of the tank & undoing all my work at the tanks needs to happen..... aarrggg!

[Accelo]

Aren't the AC DELCO EP 381 pump 18psi pump made for TPI? My search says the output is 18psi.
You will need 58psi for the LSX motor. Better check that as I only did a quick search.
It the output pressure is that low the fuel may not be getting past the regulator.
That would explain the no fuel in the return. If you have fuel in the supply its not the pump rotation.

Typically the OEM's don't make wiring mistakes like my China built pump.
Slightly better quality control. Yours may be made in Mexico.

[rodstored-72]

ACCELO, hhHHMMM... I am not sure on the pump pressure. I used the 381's because they were used multiple times on different builds (on here) and no mention of lack of pressure output. I hope that is not the case... I do not want to have to buy 2 new different pumps!

[Rich84]

ep381 is the correct pump.

[Accelo]

Must have been "I heard it on the internet" stuff I shouldn't have repeated.

[ls1nova71]

TPI's run at 45psi, so the EP381 will work fine. That's the pump I used way back before I knew any better and that swap has well over 100k miles on it.

If you're hearing the pumps come on, but not getting any pressure, a lot of times it's the hose between the pump and the pick up tube is leaking, come off, or has had a hole blown in it. I wouldn't think it would happen on 2 pumps on a new build at the same time though.

What brand of filter/regulator are you using? I have seen many off brand ones bad straight out of the box. If it isn't an AC Delco or a Wix, I would change it.

Also, what are you using for a switching valve? Are you sure fuel is getting past that?

[rodstored-72]

LS1nova71,
thanks for the reply, I do hear the pump come on, it just does not pump the PSI needed. I am planning on dropping the tank this weekend & re-check the hoses & pump situation. the reg/filter is the "typical" corvette reg/filter that I have seen used a bunch... I have a picture of it in my build thread, but I do not remember the specific name (wix??) a friend has looked at that part of the fuel system & indicated that is is connected correctly, not "reversed". the dual tank setup is a factory setup with all laid out as from stock GM. I am getting fuel past everything, but the pressure is not able to "build?" enough to get to the engine, the gauge connected at the rail does not read any pressure. I am guessing that your suggestion about the connection(s) in the tank sounds pretty likely, unfortunately I have to drop the tank(s) to recheck/redo them
.....aaarrgg!

[Accelo]

To clarify my pump was connected correctly electrically.
I even pulled the pump and everything looked good. The factory connections were labeled - and + and connected correctly. Still the pump ran backwards.
Only way to confirm it was running backwards to actually reverse the wiring and see the functional results. It would be weird to have Delco pumps with the same wiring error.

(friend has looked at that part of the fuel system & indicated that is is connected correctly)
I used the same Wix filter/regulator. I looked up the connections on the internet and plumbed it that way.
When I could tell the pump was dead headed by the sound, I looked up the connections again to confirm.
I found the two different connections on my internet search.
I reversed the plumbing and that solved my issue.

I didn't mention that I had to pull the tank a second time because the location of my regulator ended up right next to the muffler.
I had to extend the stainless lines to get the regulator away from the heat.

Seems everything that could go wrong did.
Cheers

[rodstored-72]

accelo. thanks for the additional info. and clarification. I am planning/hoping to figure out/fix the issue this weekend....

I didn't mention that I had to pull the tank a second time because the location of my regulator ended up right next to the muffler.
I had to extend the stainless lines to get the regulator away from the heat.

Seems everything that could go wrong did.
I am feeling that way now..... and I am just starting...

[rodstored-72]

update:
I removed the bed & lowered the tank to get access to the pump & connections. I unhooked feed line from the tank (to the engine) and turned on the pump... the pump ran fuel, but it did not "look" to be pressured.. it ran out like if a garden hose was just turned on at hose bib. not sure what to "look" for now?
...everything appears (to me) to operate correctly, except for pressure??

[Rich84]

Triple check the fuel filter. As said by Accelo, I remember seeing incorrect information on the internet (go figure) regarding the connections.
I didn't have to deal with switching valves. I only have one tank. That would seem like a good place to look as well.
How about voltage at the pump??

[Accelo]

fFow and pressure are two different things.
Put a gauge on the line with it deadheaded and see what it reads.
You can also measure the volume over time against the pump specifications.

[rodstored-72]

accelo, thanks! so if I understand correctly the pressure straight from the pump out of the tank should be around 58PSI? if it is not then my issue is the pump connection to the sending unit? if the pressure is 58PSI then my issue more than likely is the filter/regulator connection?

[Accelo]

The pressure straight from the pump should be higher than 58. Out of the regulator it should be around 58PSI.
Confirm you are not loosing fuel to the second tank. I.E. no backwards flow is possible.

[LS short box]

I bought a Harbor Freight fuel pressure tester. It has adapters for fuel line and the valve on the fuel rail. My current project isn't quite ready yet but I always check the fuel pressure after the FFR when its running at the fuel rail.
I haven't run dual tanks on my LS projects but do you get the no/low fuel problem from both tanks?
I know I'm guessing but have you confirmed you have a full 12 volts at the pumps? Good grounds for both pumps?

[rodstored-72]

update:

SHE RUNS!!! it appears to be an issue with my tank selector valve?? I ran a line directly to the FPR & the truck fired right up! the driver's tank gets power & operates correctly. when I "dash switch" the tank selector, the pass F.P. has no power. I am in the process of re checking my wires at the tank selector valve.
....thoughts??

[LS short box]

I'm happy you got it running but I'm no help on the selector switch.