sdetweil

I am putting a 5.3 truck engine into a custom 56 ford truck.

I got the engine/harness/computer all together, had lt1swap reprogram out the emissions, etc..

I personally modified the harness, built the fusebox and relays.

using a Walbro 392 fuel pump.. cranks but will not start.

spray some starter fluid in the manifold and it starts and runs.. til you cut power.. so the injectors are firing, the coils are firing and the fuel pump/regulator are working.. turn it off, and won't start, but cranks.

I disconnected the EGR from the exhaust manifold (replaced with headers)
but did not disconnect it from the intake.. my 'assumption' is that the EGR is closed by default.

also the throttle body is a replacement from the way the engine came.
It came drive by wire, I purchased a used cable TB.. the engine responds to throttle changes. (yes I added wires to the ecm to support tps and iac

so, what am I missing?

no codes are thrown while running.

when running it is at high idle.

here is the project
http://www.ls1.com/forums/f70/gm-gen...0/#post2705795

Sam

mmmchickenboy

My guess is 1) injectors not firing during cranking or 2) fuel pump not getting power during cranking.

Chrome_Rust

iTrader: (4)

Leaning towards fuel pump no power while cranking.

Try running the pump full time then crank it. Or check fuel pressure while cranking.

Charlie

sdetweil

k, will check. I was going to replace the fuel pressure regulator last night, we have a 99 silverado that had a failed fpr... and it was always on cold start it had a problem..

when I popped the retainer, I got sprayed with fuel.. so at least the regulator is working.

why wouldn't the fuel pump be on when cranking? doesn't the ecm control that?
the fp does cycle for the 2 second preload

I also put a test lead on the #2 injector control line, while cranking, and don't see my testlight flash.. but maybe this is too short a signal..
the other lead has solid power at key on and during cranking

Sam

sdetweil

Ok, replaced the fuel pressure regulator, and set the pump to full time power..
no change..

sprayed a little starter fluid.. fired right up and runs, responds to throttle.

got a P0102 code, for the MAF, which is plugged in, but laying on the ground (til the pipe comes this week)

So, I agree, looks like the injectors are not firing during crank.. but the plugs are.

which controls the coils? cam or crank sensor?

Sam

ghettocruiser

iTrader: (17)

All of the pink wires, or power wires for sensors/coils/injectors need 12v while cranking. It sounds like your injectors arent spraying.

Also...its VERY easy to break a power circuit on these harnesses. I was very careful cleaning mine up, and I still managed to snip one little bridge somewhere, and caused a few major components not to work. Since the pink power wires are all spidered together. Not sure what all you did with your harness though, so you'll have to start checking things out. But I suspect that its just a matter of getting things 12v while cranking.

J.

sdetweil

thanks.. all the injectors have +12 on the pink wire during cranking. just checked that. the coil pack connectors have +12 on pink, the o2 sensor plugs have +12 on pink (no o2 sensors installed yet),

and clearly they work once the engine is running.. so the problem is not power leads.

something is telling the ecm that no fuel is required.

Note: I am NOT using the standard in tank fuel pump, and am NOT using a separate fuel pressure regulator, only the one on the manifold.
this is the LM7 intake with return style fuel rail.

Sam

garys 68

iTrader: (1)

On some older ignitions, the crank position does not provide voltage to the original coil. That's provided from the starter solenoid to bypass a ballast resistor.
Check your keyed voltage to ecu while in run and crank position.
Also is your pump wired thru the ecu or just to the ignition? Same issue may exist there.

sdetweil

on the harness, I converted a truck harness to a car shape..
removed all unused wires, extended wires where required. all changes were twisted, soldered and heat shrink wrapped, at different positions on each harness segment to keep the harness bundle size down.

the ecm is now 6 ft back of the manifold, instead of on the drivers side front of the engine. The passenger side wiring is unmodified except for the extension of the pink +12 and routing that to the new fuse block.
(see lt1swap.com http://lt1swap.com/fuseblock_obd2port.html)

this was a DBW setup, converted over to drive by cable.
the ECM was reprogrammed to remove any VATS, DBW, the after O2 sensors, EGR, ...

Sam

sdetweil

thx..

the fuel pump is relay controlled, fed directly from the battery.
(see my prior post on the fuseblock setup).. I am using an aftermarket ignition switch..

which has only 3 connectors

B -- hot in
I -- run
S -- start

Sam

sdetweil

I went and got some NOIDs from Autozone.. unfortunately not one for the truck EV1 injectors.

but I also tested the fuel pressure.. solid 54psi at the manifold, even while cranking.

so, we are still at, the injectors are not firing..

my son said, this is a typical 'flood start' issue..

what makes the ecm think flood start (no extra fuel needed)..

Sam

Chrome_Rust

iTrader: (4)

Check TPS voltage. If the ECM is thinking the throttle is 100% or close to it, it might be thinking it needs to clear a flodded engine. unplug the TPS and see if it will start.

sdetweil

thanks..

well, I didn't try that.. I disconnected the IAC..

looking back thru my work on the harness mod, I missed two sentences.. from LT1swap..
Throttle Position Sensor (using oil pressure sensor plug)

LT1Swap ==> If you don't switch the black & gray, the TPS will work backwards.

I am using a real TPS connector.. doah

Sam

sdetweil

Houston, we HAVE ignition!!!..

and yes, it would have started if I had unplugged the TPS...

Sam

Ksths2

iTrader: (1)

great job! glad you got'er figured out

Chrome_Rust

iTrader: (4)

Glad to help!

sdetweil

got her in and running nice.. covers really make a difference

Sam
| added front view center pic

Ksths2

iTrader: (1)

those covers do help convering all that crap up, I'm thinking thats what i'll do with my 6.0 project as well. Where did you get your covers at? Cost?

chuckd71

iTrader: (23)

Good to see you got it running. Random gremlins are the worst.

Ksths2- The covers are part nos 12598332
12597908
12574573

and run about $20, $20 and $35 from gmpartsdirect and etc, plus their usual insane shipping. I ran the same ones on my old engine. https://ls1tech.com/forums/14822747-post150.html They really do cover pretty much everything, and I might still actually have them sitting around the garage somewhere if you are interested.

sdetweil

all this was to save converting to the car intake, and front accessories, only to put covers over the valve covers anyhow.. I had already spent >$150 to come up with a manifold and fuel rail/injectors, but had to spend more money to change injector plugs, and move the truck idler pulley and waterpump, and... to allow the cable driven throttle body to work.. .

and its on a truck, so the better torque down low was another reason not to want to change..

I found them cheapest at GM PartsGiant, www.gmpartsgiant.com
both sides come with the screws to hold them to the valve covers.


12597908 COVER 1 drivers side
12574573 COVER ASM 1 - passengfer side
12598332 COVER 1 center - vortec max
(they don't make the escalade center cover anymore.. removable emblem)

12561510 RETAINER 1 (top of manifold)
89017380 BRACKET KIT 1

I did the retainer cause mine was broken ($4) and the bracket cause I am going cable driven ($17!)

$80 plus shipping.. which started at 13, and then they whacked me another 17 cause they are lousy packagers.. 2 on top of each other and one on end from there, making the box too long, requiring extra charge..

Nalley GMC has the best online parts diagrams..
http://parts.nalleygmc.com/showAssem...=0&modelYear=0

Sam