Murray

My 89 S4 was running fine till last week. Now it wont start. here's some background...

It stalled once when my wife was driving, but started right back up. The next day I took out for test drive. It was very low on fuel and stelled when I accelerated hard around a corner. I thought I had just starved it of fuel because it was low. It started right back up and ran fine. I fueled it up. The next day I took it to work. Ran fine on the way there. On the way back home it stalled once again when I floored it getting on the highway. Thankfully it started up again after a small wait. I drove gently home. However, when I was almost home it died one last time and would not restart.

As diagnostics I have done the following:
1. Has spark - will start and run when I spray some quick start in the intake.
2. Fuel pump relay functions - have put in a known good one
3. When jumping the fuel pump relay I can hear the fuel pump running.
4. The car does not start even with the jumper in place.
5. I checked the vacuum lines to the fuel dampeners and there is no smell of gas.

What should I do next?

Thanks,

Murray

Mrmerlin

after verifying the flow pressure and the quantity use the WSM for reference
you nay need to check/ replace the fuel filter and the fuel pump
also swap out the 4 running relays,
ignition, lh, ezk, fuel pump

WallyP

1) In a quiet place, open the hood, turn the ignition switch on, and listen for the injectors clicking at random. If you hear them clicking, the LH ECU just died.
2) If there is no clicking, have a helper operate the starter while you listen to the injectors - there should be regular clicking while the engine is turning.
3) If there is no regular clicking during starting, swap a known-good "53" relay into the LH (injection) relay socket, then the EZK relay socket.

Let us know, in detail, what you find at that stage.

Murray

Thanks for the feedback on next steps. I'll check those things after work today. Is there a write up on Rennlist regarding how to access the fuel pump and filter in case I need to change them?

auzivision

Hi Murray,

Not sure how you check/monitor the fuel pressure, but you might see if Autozone or the likes has a free loner tool program if you don't have a guage.

Some great Dwayne photos on the subject found here:

https://rennlist.com/forums/928-foru...re-w-pics.html

Sounds remarkalby familiar regarding the on again off again, jumpering pump relay 'listening' to pump routine. Ultimately, replacing the fuel pump on mine fixed this.

Hope to see you Hell.

Murray

Weird I only seem to have issues before a trip. Maybe it's trying to tell me to stay home....

Assuming I can get this all sorted out in time I will definately be going to Hell. The boys and I will be tenting it again.

Thanks for the link. That helps a lot. God Bless Dwayne!

Murray

SteveG

"Floored it" is the batt secured, connections?; regardless, replace ground strap if it is original.

outbackgeorgia

My first issue with symptoms like yours was the crank position sensor.
Follow Wally's procedure. If no clicking, check the CPS connector.
Also, watch the tach, it should move during the starting process if it is normally operative.
If it does not move, it is likely the CPS or possible the LH. I had both fail, CPS first, then the LH.
Good Luck,
Dave

BerNard94

Cheers.

Murray

Other diagnostics done so far:

1. listened for injectors clicking with just ignition on - no clicking heard
2. listened for injectors clicking with starter engaged - injectors heard clicking but they didn't seem as loud as they do when its running.
3. swapped out EZK, LH and ignition relays - no change

4. I don't have a fuel pressure guage so I just loosened on of the fuel lines and watched it for flow while the engine was cranked. A small amount of fuel came out but not much in the way of flow.

So at this point do we think it's the fuel pump? Tomorrow I will expose the fuel pump and try reversing the current to see if something has just gotten jammed.

Murray

Mrmerlin

warning dont make any connections at the fuel pump where your touching the wires to complete the circuit use a wire for ground and touch it away from the pump its easy to spark a fire at the pump needless to say dont open any hoses to check for flow.
If you have an internal fuel tank pump that it has probably failed and swapping in a fuel trainer and omitting the intank pump will probably make things work

Murray

Is there a way to test the in-tank pump? let me rephrase that...What is the easiest way to test the in-tank pump?

Don Carter

Autozone usually has a set of noid lights you can rent to check that the injectors are firing. A short in the injector wiring can kill all of them. On my 89 the wisdom about the tach needle jumping while cranking did not hold true. Surprised noone has mentioned IMS yet. Check for LEDS lit up on control module next to fuse panel.

928 at last

Murray,
Forget testing. The hose is probably shot anyway, and they're a known failure point in the system.

Sounds like you've sucked a load of crap into the pump/filter by running to the bottom of the tank. At least that's my first guess. I could "hear" my pump when it was jammed. The first option would be to briefly reverse the pump in hopes of clearing the jam. There's lots of detail here on the forum on this.

I've got the noid lights if you really want to check the injector firing.
If it's not starting at all though.....

If the pump is indeed done, (it probably needs a filter in any event),
I'd lose the in-tank pump and replace with the late-eighties unit that's designed to operate without the in-tank unit. The part number is on here in a post by Greg Brown. I wouldn't recommend the 040 pump unless you're planning some serious mods in the future.

NOTE: the crush washers in the fuel system are ONE USE units. You can try to anneal them if you're up for that sort of thing, or just order what you need X2, then you're covered.

NOTE II: Counterhold everything on disassembly and reassembly. The hardline between the pump and filter will twist easily and then be an attractive wall-art conversation piece.

Everything is accesible at the rear of the car - on the passenger-centre there's a hatch that's easily removed for access to the external pump and filter assembly. I've done my set-up twice with minimal jacking required.

Once you figure out what you want to do, call Roger. He's got all the bits you're going to need.

Podguy

I am surprised that more people do not have fuel pressure gauges. This is the first thing to try when it looks like you have a fuel problem. Lots of places sells then including a reasonably set from Harbor Freight.