jordanpierce21

Hey guys new here but really hoping for some solid advice on my swap.

Background:

01 4.8l and 4l60e
Computer reflashed deleting vats and emissions by lt1swap.com
Wiring harness done by myself of lt1swap direction this is only my 2nd harness but the 1st one is running my buddies 5.3l buick apollo no problems.
walboro 255

1980 2wd chevy Luv

Issue:

First day swap was complete truck fired and ran fine 2 or 3 times the final time was for 15 or so minutes then i shut it off.

About a week later got driveline made installed attempted to start and it would just fire and die repeatedly. Once every quite a few attempts to start it will fire and run just fine. When take truck for test drive it well rev all the way out but has no power at all like stock geo metro.

I can then park it and try and fire again and it will fire and die. Sometimes it will attempt to run and idle at like 400 rpms and die.

Things i have tried:

Only code is p0101
Changing maf, iacv, tps, pcv, water temp sensor
Providing constant power to fuel pump
pressure checked off rail while running(not moving) at 60 psi
adding more battery to chassis and motor grounds using multiple sets of jumper cables

I ordered a sump kit to sump tank hasnt came yet but luv tank only has 1/4" pickup in tank but is than -6 to the front both feed and return dont know if this could cause lack of power and hard starts.

All in all though Im really at a point where i dont know what it could be or to try.

76larkman

Have you try to clear computer and let it relearn itself to see if runs any different? Check all wiring connections and plugged in. Vacuum leak?

jordanpierce21

Definately reset by undoing the battery. No vacuum leaks. Could crank sensor do something like this?

shanex25

iTrader: (3)

IM pretty sure it won't ever start if it crank sensor. You do have the cam sensor plugged in? It's at the back of the motor by the factory oil pressure sensor under the intake. I think it could still be fuel pressure issues that only fluctuate while driving.

jordanpierce21

Yes cam sensor is plugged in. So ur saying fuel could cause lack of power but not my fire and die issue. Also i have tach signal when it fires ig that rules any sensors out.

shanex25

iTrader: (3)

Yes, make sure you have a good power and ground for your fuel pump. I had very similar issues at first but I had my fuel pump power lead temporarily twisted together for start up and first drive. Once I soldered and heat shrinked it, problem was solved. Walbros are very voltage sensitive.

jordanpierce21

http://youtu.be/l7l4PtNlcOY

jordanpierce21

This video shows it start and die. it also shows how sometimes when you give it barely any throttle and fire it it will rev up and then die you cannot give it anymore gas or it will die instantly

This is also with tank sumped now.

rpturbo

iTrader: (47)

Do you have any way to check your map sensor?

jordanpierce21

Im sure i can is there a sticky on how to test?

jordanpierce21

Now when I hits harder valve barely any fuel releases. Could my fuel pump just be shot and giving just enough to fire.

jordanpierce21

*NEW UPDATE*

Used a seafoam machine with just gas truck ran fine and revved smooth on 3 different start ups which ruled out injector things and stuff like that so thought walboro was done for.

So i changed to a carter p5000 and have the tank sumped.

Well turned out that day was a fluke too. Truck did same thing again so i went back to the seafoam machine and truck will not run again.

Also not sure if it matters but sometimes on attempted start up the tach flashes real high on cranking like 2-4k

I really need some advice here guys... Could it be my computer? Wiring? Sensor? Myself and multiple mechanic friends are out of ideas and who wants a ls luv going to waste

jordanpierce21

So the start and die ended up being a faulty map sensor the truck now starts every time idles great. But when I go to drive it after about 15-20 seconds in gear it begins to load up really bad and will barely pull its own weight. I can put in neutral coast shut off and restart truck it will run and drive great again for another 15-20 seconds then do the same thing. What could cause this it has completely washed out the plugs.

trozfan

I will chime in, and I may be wrong but sounds like the trans is in limp mode?

aknovaman

iTrader: (7)

Does it set any obd2 codes now?

If you have no codes and you have 58 psi fuel pressure at the rail, it could be sticking injectors.

jordanpierce21

So tried pulling codes multiple times today and every time there are no trouble codes. I will put a fuel pressure gauge on it next as i do not have one. I have tried 2 different fuel regulators though is it possible the p5000 just isn't moving enough volume?

jordanpierce21

Tried to seafoam the **** out of the injectors no change. What could cause it to cycle and run perfect then peter out continously over and over everytime...

jordanpierce21

k guys tried other injectors and it stopped cutting out but was still down on some power besides on start up. drove it for probably 30 mins and got just as bad as before or worse. is this just injectors clogging up or am i looking at the wrong spot... really need help on this. also put another walbro in it and same result...

Bowtie316

iTrader: (1)

I would take a look at the o2 sensor voltages and fuel trims. If you get the o2 sensors wires installed on the wrong banks it will act somewhat like you describe. It might start up fine in open loop, but when it goes to closed loop one bank will go 25% rich and the other side 25% lean.

Do you have any codes at this point?

ijimmy

You need 3/8s fuel supply lines to the rail ,, 1/4 inch is not big enough