roppa440

The fuel pump fuse checks out OK.
I swapped the horn and fuel pump relays around. The horn still works and the engine still cuts out. Still not a drop of fuel from the Schrader valve. Not a drop. I can hear a faint very high frequency tone when I switch the ignition on but can't say I can hear a fuel pump working at all.

roppa440

Getting somewhere I think.
When I turn on the ignition there is a high pitched tone that lasts a few seconds. By quickly running around the car it seems to be coming from the TPS. If I pull the plug on the TPS the noise stops.
Is this noise normal or am I getting closer.....?

C5 Diag

I've never heard my TPS make any noise but we also may have a fuel delivery issue too...MMMM ???....you can see if you have 12 volts on pin 87 with key on with pump relay removed...this is the load feed...the other pin should be ground...I think the ground point is G105 I believe...jumper pins 30 and 87 at the relay (you are jumping the load side) and the pump should run continuously...if it runs then we might have the "control" side of the relay missing power from the PCM (it is power side switched) or a bad control ground....just make ABSOLUTELY SURE you are jumping the right pins...go to the back on the left wheel well and see if you hear the pump running.....I wouldn't suggest popping the Schrader open with the pump running to check to see if any fuel is coming out...get a pressure gauge...they are not to expensive. It's a little difficult getting to the pins if your DVOM or test light have thick tips !!

neutron82

that's why I asked if the car was modded, my car is speed density tuned and doesn't use the maf and if the battery is disconnected, new tune file is flashed, or anything like that it must fail the maf in order to go into speed density and the car will turn on and shut off just like you are describing until that code is failed which sometimes takes 10 or so starting attempts... this probably isn't the case here but that's my reason for asking

roppa440

Sorry for not responding to that question. But no its all factory stock except for headers and a few home mods. Been running fine all summer. Ran a 12.95 @ 107 on my annual quarter mile outing. The water pump is a high flow replacement as I am trying to keep the engine temp steady and it shoots up at low rpm and idle in traffic.

roppa440

Well that gives me something to do. Getting dragged out to dinner by the wife now so that's if from me for today. :-)

Walt G

Fires and quickly dies sounds to me like air can't get into the intake manifold.. it fires as it's pumping the air out of the intake manifold, but then can't get any more air. I once put an engine on a dyno and forgot to remove a 'cap-plug' from the charge-air-cooler before hooking up the hoses. That led to the same thing you're experiencing... fire, very short run before any air that leaked in was pumped out and the engine would die.

Given that the throttle was disconnected during your water pump replacement, it sure seems to me like something is messed up there (throttle not opening).

I can't really explain why you are not getting faults for this, but perhaps the circuits have continuity (passing), and then the thing won't stay running long enough for the more complex monitors to set a fault (actual position not matching desired position might take a little while of engine running to set)???

Does anyone know if the 'clear flood' mode (holding pedal to the floor while cranking) actually opens the throttle all the way during cranking? If so, he can try that and have someone look at the throttle blade to see if it is actually opening.

I think even during normal cranking one would see the throttle move open a little if things are working correctly, and I would expect the control logic to open the throttle as the engine is stalling in an attempt to recover.

Another thought: try disconnecting the vacuum line at the brake booster... if the engine runs that way (possibly too fast), I think that would point to a intake throttle that isn't opening.

Bill Curlee

Actually MEASURE the voltage on the fuel pump fuse.. On top of each fuse are TWO TEST POINTS. Measure each one to chassis ground with the key ON. Should see full battery voltage on each test point.

Bill

C5 Diag

Bill Curlee

That noise is most likely the syncrous motor that moves the throttle blade. IF,,,,,,,,,,,,,,,,,,, The throttle by wire system has ANY issue, it would for sure set a DTC!

Couple of test:

Remove the air bridge.. See If the throttle blade is erect when key on. Thenunplug the motor connector when you hear the noise. Then see If you see a DTC for that motor..

BC

C5 Diag

Mickeyrx70

roppa440

Hi guys.

Thanks for all this. Other things are getting in the way of me getting any time in the garage so I might not get much done until the weekend now.

However I have checked the wiring to the TPS and it has continuity. I took the throttle body off and inspected it carefully. Seems completely fine. It might be a good idea to check the motor is actually operating but the engine should still start and idle as the default throttle blade position is open enough.

I need another pair of hands really. So the weekend will be the best to try and really bottom this out.

Thanks for everything so far. I will report back when I have done all the suggested checks.

Roppa

roppa440

I'm back.

I have 12v each side of the pump fuse.

If I short out the relay pins 30 and 87 the car fires and runs, It also revs normally showing the TB must be working even though I could not get it to open by holding the throttle down with ignition on.

I can hear the pump running with the relay shorted and have plenty of pressure at the Schrader valve. But still have that low oil level warning.

I cleared all the DTC's and tried starting the car without the relay shorted out. Cuts out after initial firing as before. No codes have come up. Only that continuous Low Oil warning. Even though I had plenty of oil pressure showing on the gauge and there is plenty of oil in the block.

I have already swapped relays so the fault must be with the circuit that energises that relay I assume?

roppa440

Oh and I checked the relay with a regular 9v battery. It works as it should.

C5 Diag

C5 Diag

Engine oil level switch is on that ground also (105) !!….you probably have a bad ground !!!....I forgot you swapped relays...never mind !!!....check pin 85 with a 12 volt test light connected to battery POSITIVE....light will light if ground is good...I did a quick resistance check and I get .03 ohms between 85 and engine block !!

roppa440

I get just less than that between that pin and the block...

roppa440

Which is ground 105 anyway?

roppa440

And with the ignition on I get 12v between pin 86 and the block too.