'04 VZ SV6 Fuel Pump

[ToastMalone]

Hii, I have a 2004 VZ SV6 (LY7 10H7C) with starting issues which I'm hoping someone can shed some light on, Car cranks but just wont fire


Tested spark: Good spark
Sprayed some aero start down the guts and got some backfires
Couldn't hear fuel pump so checked fuse/relay which turned out to be in working order then decided to purchase a new fuel pump and assembly,
after installing this and putting the tank back in to my surprise the fuel pump still wasn't priming, Me being me didn't think to use a test light at the pump before putting it in

Still cant hear the fuel pump priming

Cluster shows system ok! then it shows service vehicle soon

Not very mechanical minded but after some research people with similar issues went in the direction of replacing camshaft position sensors (i believe there is 4?) and some mentioned the oil sensor/switch

Upon inspecting my oil pressure sensor it looks brand new from the outside and seems to be intact, no oil around it at all

The camshaft position sensors (2 near the PCM and 2 on the other side (pretty sure im looking at the right sensors) they were pretty oily so i cleaned them up with some contact cleaner(hope thats not bad)

Everything else on the car seems to still work fine, keyless entry, radio, lights etc

My old man has a cheap diagnostic tool, I will run a scan later tonight and update my findings, in the meantime does anyone have any input on what I could try? I have a test light but no multi-meter (looked at them in the shop but no idea how to use them and didn't want to do further damage)


Cheers, Toast.

 

[krusing]

Firstly, Welcome

With your test lamp, check to see if there is power at the fuel pump, "Just as you turn the ignition switch on",
Being they normally prime the fuel rail and switch off,
and when the engine fires, they start and constantly run.
Check the loom to the fuel tank under the car.

Check to see if you have power at the Relay socket, if so
Swap the fuel relay with one that you know is ok,
Could even be a corroded ground connection.

 

[krusing]

I forgot to mention,
Did you put the fuel lines on the correct barbs/fittings, as they look pretty much the same.
as I have read, as member replaced his tank unit, and put them on anywhere, and he couldn't get his car to fire,
and then he dropped the tank and worked out his error, connected them up correctly, and it fired up ok.

Secret to remove anything, it to mark it accordingly.

 

[Fu Manchu]

Be careful shoving test lights into pins on harness plugs. It can be enough to push a pin open and have it become a loose connection.

Very fine pins in the back of the plug. Careful not to have them touch. Crocodile clip connecting to multimeter leads.

If a test light is used, only lightly touch the pin without pushing it into the harness plug.

 

[Fu Manchu]

It’s not the cam sensors that cause this. It has been know to be the Crank Angle Sensor. That is located back from the right hand header. 10mm bolt.

Test the control side of the fuel pump relay. I don’t have the details of which pin on the relay at hand.

Get that scan tool onto the car to see if anything comes up. I doubt a cheap tool will give any clues as to why the SVS is on or be able to see every thing or interpret the codes correctly. However have a go. Use what you have.

There will be something not being switched. Fuel seems likely. Might be something like getting the keys reprogrammed to the car. Or it could be a faulty PIM or just a glitch. A lot of possibilities.

 

[ToastMalone]

With the cheap diagnostic tool it found these?:

PT0118 - Engine Coolant Temperature Sensor 1 Circuit High
P2229 - Barometric Pressure Circuit High

Thankyou so much for the replies, weather wasn't on my side so couldn't do the tests mentioned above today, will get them done tomorrow and post any updates.

 

[Fu Manchu]

Both easy fixes.
The Barometric pressure sensor is a repurposed MAP sensor mounted behind the intake plenum. Super easy to sort out.

Off the top of my head, not sure about testing. They are cheap and easy to do.

The coolant sensor really needs more specialised equipment to test the circuit. You don’t have that. Replacement can be done, but easily may not solve the problem. High voltage condition is often caused by a wiring/connection fault. Let’s hope it’s a faulty sensor.

Voltage will be high when cold and low when hot.

They are easy to change and cheap to buy so maybe give it a go.

 

[ToastMalone]

Awesome, I will grab those tomorrow and replace those anyway, could they have anything to do with the fuel pump not powering or are they additional bonus issues lol

I checked the fuel pressure in the schrader valve earlier and literally not even a drop

 

[Fu Manchu]

Who knows. With out any supporting data and the tools to get the required data you are spinning the choccie wheel.

I will suggest that with so many issues at once, go through the engine harnesses and clean all earthing surfaces. Disconnect the negative terminal first from the battery.

There are quite a few. Even minor corrosion in the threads or mating surfaces of the earth’s will cause no end of gremlins throughout the cars system.

This is something that costs nothing to do, unless you count a cheap brass brush for a couple of dollars and some metho at a stretch.

I guess I should do a thread on that for VZ one of these days.

 

[Fu Manchu]

I’m going to suggest there is no control/trigger voltage at the fuel pump relay when you turn the key.

Don’t shove a test light into the relay pins. You’ll bugger the pins and that’s not a fun repair. Better to use a sewing pin connected to a multimeter for a ghetto solution.

Get a multimeter.
Get a decent bi-directional scan tool
Start watching diagnostic videos to get a grasp of what’s involved to fault find what’s happening.

That is a significant cost outlay. So start with the cheap stuff and that’s cleaning the earths.

You need a factory manual. There are multiple links to download it. A bit of searching. You need a computer, the factory manual won’t work on a phone or iPad.

You’ll also go on a steep learning curve.