No start. Injectors?

[explict]

Hey guys, it's been a long time!

Anyhow. Car wont start. Turns over, very random sputter once every 30 seconds cycle. I am attributing that to my evap purge valve being broken, but I could be wrong.

Tried starting with pedal to floor, as well as pumping it.
On diablosport tuner, INJ1F through to INJ8F all read no when car is off , key in on, and when turning over.
Fuel pressure at fuel rail is at 42psi. Even if I take out the fuel pump relay it doesn't drop.
Injectors read 12v with key on.
Tried starting with each one unplugged, and a combo of two unplugged.

What would cause my injectors not to fire? Crank position sensor? camshaft position sensor?
Any thoughts?

 

[explict]

Sorry, I should also elaborate.
Its a 4.6L Aluminator with BBR stage 2 heads. MSD COP's Siemen Deca (I think) 48lb injectors, Whipple 2.3L supercharger amongst other things.

 

[07 Boss]

How are you sure it's the injector? Have you tried starting the car with starting fluid or ether?

 

[explict]

I will go try now.

 

[07gts197]

Sounds like the crank position sensor but it would throw a code immediately.


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[explict]

Ya, no codes.

Also. starting fluid never started it. It just sputtered some.

Also, I ordered a new crank sensor and EVAP purge solenoid, will be here Monday.

 

[Anti]

Did you check spark then? You can literally make the car run for a moment with no fuel and only starter fluid.

 

[07 Boss]

I'm just not sure how you have narrowed it down to injectors. From what it sounds like it could be more ignition related. Have you pulled the plugs after trying to start it. You gotta do the basics when diagnosing. Guessing usually never works. Pull the plugs. See if they have fuel on them after cranking it. Or pull your fuel rail off and see if you get fuel out the injectors while cranking. See if you get spark from your plugs. There could be a bunch of reasons why it doesn't start. Fuel is only one of the components.

 

[explict]

So what your saying is, the fuel rail can hold pressure if the fuel pumps are disconnected and I'm cranking it over? So many people are saying ignition related, but there is 0 fuel exiting the rails.

 

[07 Boss]

So what your saying is, the fuel rail can hold pressure if the fuel pumps are disconnected and I'm cranking it over? So many people are saying ignition related, but there is 0 fuel exiting the rails.

Why are the fuel pumps disconnected? How do you know there is no fuel exiting the fuel rail? I'm a little confused. What steps have you taken to check if fuel is coming out of the injectors? Never mind, I see what you did.

 

[07 Boss]

I'm looking over your original post. When you crank it with the pedal on the floor it actually cuts the fuel. If you have a bad purge valve it might be causing a vacuum leak but I think it would still start. Injectors should see 12v with the key on. Have you tested the injectors for resistance? Do you have a multimeter? Once the rails are pressured up they should still hold pressure, at least for a short while. Oh I see you unhooked the pump to see if fuel pressure would drop with the injectors going and no added fuel. How long did you crank it without any loss of pressure? I still think you should pull a plug just to make sure. Do you have any data logging capabilities? I'm not sure data logging during start up will tell you much but you ought to be able to see if there is a signal going to the injectors.

 

[freeloader1969]

Pull the plugs and make sure they're not fouled. You may have fouled them now by attempting multiple starts without success. Will the car start without the MAF sensor hooked up?

 

[explict]

Put in new Crank sensor as well as the EVAP canister, started like a champ.

 

[bmeaggie]

Did you swap one or both of the new items back out to confirm which was the culprit?

A little extra trouble but would be beneficial to know which was root cause next time this happens to someone.

 

[Juice]

Did you swap one or both of the new items back out to confirm which was the culprit?

A little extra trouble but would be beneficial to know which was root cause next time this happens to someone.

There is no way any evap issue will keep the car from starting.
Injectors will not fire without a crank signal.
Thus, It WAS a bad crank sensor.

 

[bmeaggie]

There is no way any evap issue will keep the car from starting.
Injectors will not fire without a crank signal.
Thus, It WAS a bad crank sensor.

Makes sense to me... thank you!

 

[explict]

Yes, sorry I should have specified. The crank sensor was the culprit. The evap was causing other issues. Rough idle, ran like crap when it was cold etc..

 

[Joel W Bergma]

Hmm I have same issue. Maybe swaap crank sensor. Is there a way to check crank sensor with voltmeter.