LS3 crate motor will not start

[ari666]

what RPM is it reading while you crank?

does it get a nice strong 12V signal to the ecu while cranking? (i.e. ecu circuit is taken before the starter circuit)

 

[07GTS]

if its got fuel pressure then just need to make sure injectors are pulsing if yes then its getting fuel, then check spark and if its getting spark also then something is not right should be firing or at least trying too, check the inj like ari666 mentioned with the led then u have a visual u can see, alot of multimeters may not respond fast enough to see the ms pulse of the injector

 

[52Chev]

E67 ECU, 60 psi at the rail waiting, 160 rpm on crank, but no pulse at injectors or spark? Thanks again for your help so far.

 

[ari666]

good solid voltage to the ecu while cranking?

dunno if your ignition key is the same as my 66' but "acc" switches off when cranking, so make sure youre not using that to power the ecu, coils or injectors. on my impala the "acc" is a thick brown wire so its misleading. the one i used i think was pink and was very thin, i ended up hooking up a 60A relay and a 60A fuse to the pink wire to drive my ecu, otherwise it wouldve burned out that wire in no time.

acc is only used for the ciggie lighter, wipers, radio etc and it powers off when the starter is kicking so the acc dont drain watts.

 

[52Chev]

Solid 11,8v during crank. Yes my acc drop out during crank but there is no drop in voltage to the ecm. It has to be in the ecm I think ari666?

 

[ari666]

if the PCM is getting RPM then i cant see why it isnt outputting that RPM to the coils. have you done the injector test? are the sparkplugs wet when you pull them out?

is this a deadhead fuel system or a return?

far out i dunno man. im guessing the PCM came with the engine, so all the settings should be already done... would have to be wiring.

 

[52Chev]

I get the rpm indication from the odb plug so you would think that is thru the ecu. Dead head fuel system. Noid test failed as there was no light. Plugs dry. I am at a loss as well ari666.

 

[ari666]

ok so deadhead system, im running out of ideas so: is the deadhead maintaining pressure while you crank?

doesnt explain the spark...

so thats a stupid idea. sorry.

 

[ari666]

now youre SURE that the coils and the injectors + rail is getting voltage while cranking? theyre a seperate + to the ecu + and if theyre acc, theyll switch off.

 

[ari666]

see diagram:

yo can see the + supply isnt the same as the ecu, so even if the ecu has a nice 11.8, if youve hooked up the coils to acc, theyll switch off while you crank. so all the sensors will still function cos' they get +5v off the ecu, theyll send a - trigger to the coils and injectors, but if the + isnt there, then nothing will happen.


without hooking it up to hp_tuners to check sensor operation, im totally stumped.

160rpm while cranking is about right, so your home and trigger sensors are both workiing and reporting and the starter is turning it fast enough to fire.
voltage at the ecu is 11.8V so the ecu has plenty of power to drive all the +5v triggers
60psi at the rail is PLENTY
it MUST be a voltage issue.

unless the PCM just isnt setup for something on your engine. whether the input parameters for "crank low res" is wrong, or VATS is somehow fragging it. but if the ecu came with the engine, then the odds of that are very very low.