URGENT! No power to fuel injectors!

[mylittlemonster]

I'm getting fuel delivery to the fuel rail, but when I try and start (with the injectors out) they are staying bone dry. I very recently replaced the fuel pump relay (could it be faulty). Fuses #34 and #32 are both fine. Someone please help!

[mylittlemonster]

bump

[mylittlemonster]

To add: I'm getting pressure to the rail. It's just the injectors that aren't getting power.

[mylittlemonster]

Anyone got any ideas?

[guy022077]

what year/motor car?

[mylittlemonster]

2001 1.8t

[Seerlah]

Crank position sensor?

There is a sensor on the front of the head. Follow your injector harness, and it is the only sensor on the harness after the fuel injectors. If this sensor is faulty, car won't start. Not sure what it prevents though, and may be the fuel injectors from spraying. Just a guess!

[mylittlemonster]

I'm now not getting fuel to the rail. Fuel pump replacement?

[mylittlemonster]

When a pump goes, does it work in spastic bursts and then die completely?

[Seerlah]

Take out the fuel pump and test it with a 12v source and ground/negative. I use my car battery when I do stuff like this. If the pump is fine, then check your fuel pump relay.

If the pump is bad, I have my stock one I can sell you for a decent price.

[mylittlemonster]

How exactly do I do that test? I've got a spare already, but I appreciate the offer.

[walky_talky20]

So you have no fuel pressure, and no supply voltage to the fuel injectors? Sounds like the fuel pump relay isn't closing.

Easy test:

Connect with vag com to the ECU. Start Output test mode. The ECU will close the fuel pump relay during the entire procedure. Click Start/Next and step through the tests until you get to the fuel injector tests. Make sure they all click.

BAM. You just tested ECU control of the fuel pump relay AND the injectors. You also tested that you have a good fuel pump relay, you have power to said relay, the relay is successfully delivering power to the pump and injectors, and that all your wiring is good. And it only took you like 30 seconds. Cool, eh?

Sidenote: The Crank sensor is located on the side of the engine block, very near the oil filter location. Failure of that sensor will prevent fuel injector pulse and spark (but will not prevent the fuel pump form running). The CAM sensor is the one on the front of the cylinder head. Failure of that sensor will not prevent anything in particular. It will (in a random fashion) prevent the fuel and spark from happening at the correct timing, but that is all. Even with it unplugged, you will still get fuel and spark in the cylinders.

[mylittlemonster]

I don't have the full version of vag-com. I can't run the output modes (unless I'm mistaken and I was looking in the wrong place). Is there any other way of testing these things?

[walky_talky20]

How about a test light or a multimeter? Do you have one of those?

During cranking, check for power on fuse #28 and #32 during cranking (check both sides of each fuse). And then get a screwdriver and check for spark.

[mylittlemonster]

I don't have either. Is there any other way to test this? I do have spark on every cylinder. Those fuses aren't blown, but I don't know if they're getting power.

[Seerlah]

Whoops, sorry about naming wrong sensor.

But when I tested my pump I took it out of the tank, and clamped wire onto the negative and positive terminals on the battery (be sure not to let these cross, and basically treat them as if they were jumper cables). Simply place them onto the pump (positive on positive and negative on negative), and see if the pump turns on or not.

[walky_talky20]

Well, if you have spark, then you're crank sensor and ECU are OK. So I'm going to assume you are getting ground pulse to the injectors. That means that it's highly likely there is nothing wrong with the fuel pump or wiring, and that your entire problem is the fuel pump relay not closing.

1st thing: Have someone put their ear directly above the fuel pump while you crank the engine for a second or two.

Thing 2 (if 1st thing results in no pump activity): Remove fuel pump relay and install a jumper wire (or alternatively, remove plastic cover on the relay and close it manually). Fuel pump should run constantly, listen for it again. The car may start now, give it a try.

[mylittlemonster]

I'm not hearing any pump activity. I'll do the relay thing.

[mylittlemonster]

Here's the other thing. I've been testing/working on this for a while now and I've heard the pump run. I've also disconnected the fuel line at the rail and I've gotten pressure there before, but now I'm not getting anything. The previous owner took it to a mechanic that really mistreated the car and screwed the owner, so who knows the last time the pump was replaced. Is it possible that the pump was just getting weak and now it's shot? That it was just never enough pressure to get the car started?

[Seerlah]

When was the last time the fuel filter was changed? A situation could be that the filter was clogged, and causing the pump to overwork itself, in turn compromising the longevity of it. Just a scenario, and not saying that's what happened.

[mylittlemonster]

Replaced fuel pump: problem fixed. Thanks for the help guys!

(I replaced the filter as one of the first things when this first happened and I think that's exactly what the problem was)

[walky_talky20]

That's great. Thanks for updating with the fix.

[tcarrier92]

I'm having a similar issue. 03 audi a4 Quattro 1.8t (B6). Replaced the valve cover gasket and now I have 3.5v going to every fuel injector connector. It ran completely fine before. It runs for about 5 seconds then dies now. Stripped all the wiring back to every fuel injector connector and as far back as I could on the harness. Found multiple exposed wires. Fixed all of the breaks AND replaced the pigtails and still have 3.5v per connector. Pump is turning on and has proper voltage. Tested every fuse and relay I could find after hours of research on locations and they're all good. Tested cam and crank sensor and they're both good. Crank sensor was a b*tch to get to. Codes are every cylinder misfire and a lean code. I don't have vag com. I'm about a day away from buying a cable. Any advice where to go from here for me?