2 new fuel pump relays, wont turn over

[Widowmakr]

So I've been having weird intermittent start issues over the past couple of months.

To begin as of this post, I have all brand new:
- spark plugs gapped
- all new coilpacks
- new oem ignition switch
- new oem crank position sensor
- walbro 450 fuel pump
- new belt tensioner
- new serp belt
- all new fuses

So after replacing all of those, I was ready to start driving my car again. One morning, the car would not turn over, like it was being starved fuel. Weird as the previous owner installed a brand new walbro 450 fuel pump and the car has previously shown no hesitations. Keep trying to start the car and no luck. I then grab a voltmeter and a brand new fuel pump relay from the dealer just to eliminate that right off the bat. Plug the new relay in, no luck in starting, so now my guess is the fuel pump is bad

I test the connection of the fuel pump relay in the trunk and cannot hear it turn on when the ignition is in the "on" position - I test all 4 pins individually with a key turn every time I test a pin, no voltage. At this point I'm like well that's weird, I should be getting a signal at least back here as I have a brand new oem fuel pump relay. I plug the old relay back in and I'm getting signals at all pins, try to start the car and after a few cranks the car turns over - fuel pump is completely fine (should be as its less than half yr old)

Go today to the dealer to grab another fuel pump relay and throw that thing in there - same thing, no signal and no turn over - I don't hear the fuel pump turn on. So now I have 2 brand new oem VW/Audi fuel pump relays that will not turn my car over, but an old relay that will. The old relay takes a couple of cranks before it finally turns over. Whats going on? I'm not receiving any codes at the moment

The old relay is missing its cover, so I'm assuming the previous owner popped the cover off an had known about this issue. I'm just confused why 2 new relays wont start the car. With the old relay, if I turn key to crank over it'll take a couple of cranks, and when I release the key the car will turn over. the 2 new relays, the car does not turn over.

One thing to note as the car has not always started like this, the turning cranking over started to get worse and worse as timed passes. So Im confident I have some sort of issue with relays here, just not exactly sure what I can do except enlarging my stockpile of OEM fuel pump relays lol.

Also no fuses are blowing with all of this

Very stumped here

[Austonwerner4]

With the car in the ON position, the pump will not stay running. It turns on for a quick second.
Disconnect the line in the engine bay, place it in a bucket and make a relay jumper and see if you get a solid flow.

Have you scanned your car at all with VAG? Check the connections at all 5 locations. The trans sensor could be bad/dirty.

[Widowmakr]

With the car in the ON position, the pump will not stay running. It turns on for a quick second.
Disconnect the line in the engine bay, place it in a bucket and make a relay jumper and see if you get a solid flow.

Have you scanned your car at all with VAG? Check the connections at all 5 locations. The trans sensor could be bad/dirty.

I've scanned the car with vagcom and I am throwing an o2 sensor code p0150 which should not I'm assuming is related to this problem lol

I realized your first sentence and had a friend turn the key to on individually to check every pin with both new and old relays. Every pin at the fuel pup connection was giving me no feedback with the 2 new relays, but I did get feedback with the old relay.

One thing, I checked at the fuse too as well. The 2 new relays did not give me any readings when checking at the fuse as well, but I did get feedback with the old relay

Everything to me is pointing to maybe a difference in the relays? Maybe i have an old relay and the new ones for some reason are not compatible after a part update?

Which locations are you speaking of? So far Ive checked the fuse panel, relay panel, fuel pump conenction

I really appreciate your help

[Austonwerner4]

What I mean is get a 6" piece of wire and crimp on flat spades on to each end.
And with the relay removed, feed line in a bucket and key in "ON" you insert the jumper you made into the relay panel

You'll have to look up which two you insert them in. I'm on vacation and I can't find the picture I took. I used this method to check for fuel leaks when I upgraded lines, but this method will check the flow of the pump.

[Austonwerner4]

But with the relay removed or not, it should still crank.

Check each connection. 2 on each head and one near the front driver side of the trans

[Widowmakr]

But with the relay removed or not, it should still crank.

Check each connection. 2 on each head and one near the front driver side of the trans

The car does still crank with relays removed

Are you saying the slow crank could still be due to a fuel pump on its way out? Or maybe fuel pressure/flow is weak?

I guess I need help in understanding how that could be, as all of my symptoms are pointing to something faulty with the relay/relay area

I'm going to try your suggestion tomorrow and see what happens

[Zba]

A slow crank is most likely due to your battery, not fuel related. When you rank it does it go wrwrwrwrwrwrwrwr or wr....wr....wr...

[Widowmakr]

A slow crank is most likely due to your battery, not fuel related. When you rank it does it go wrwrwrwrwrwrwrwr or wr....wr....wr...

I should've mentioned, the battery is brand new. Nothing is indicating (lights, codes, lack of power/voltage) it's a bad battery/alternator/starter. Those all have been tested and are fine

It's not a slow crank, just a continuous never ending crank with new relays, a couple of cranks then a start with old relay.

Could it be a fault within the relay panel?

[Zba]

Very odd for the car to start with only the old relay.

Do as others have suggested and check for actual fuel while cranking. Do this by disconnecting the fuel feed line at the rail

[christianb5s4]

If the fuel side is good, next thing I'd look at is the crank position/speed sensor. Intermittent starting issues are a classic symptom.

[Monty23]

While turning the key to "start", does VCDS show a few hundred rpm or does it stay at zero? Has the motor/trans ever been removed before (by you or the PO?). I'm suspecting the crank position connector may have been tugged while pulling the motor and the wiring could be torn/messed up which could cause your intermittent issue.