merope

Hi All,

My FPDs were leaking so I got OEM replacements (86.5), both front and back. I checked to make sure they were screwed in tight by jumping the pump and all seemed ok. She was sitting for a month.

Now, after doing the surgery, she is not starting. Although the older dampers were leaking previously, she had no trouble starting before. I checked to see whether I may have killed the relay when removing it, by just jumping the fuel pump to start the car, to no avail. I always disconnected the battery when touching the fuse panel. I hear the pump running so I am quite certain she is getting fuel. The new dampers are OEM and I doubt they are at fault. I can hear fuel circulating in the rails when the pump is running.

What's next to check?

Thanks

Bertrand Daoust

Did you remove (or change) the FPR too?
Edit: Is your car ('86.5) is like the S4, 2 dampers and 1 regulator?
I'm asking because on the S4 it is possible mix the FPR and the front FPD.
I did that mistake and had the same problem. No start...

Kevin in Atlanta

Check the Bosch part numbers - if you got a FPR by mistake no fuel will make it to the rails.

merope

Front one as read off the part: 928.110.202.23
Rear one, as read off the box: 93011060230

These should be the correct ones for an 86.5.

At this point, my guess is that the car is flooded. When running the pump, without the engine running, I hear a lot of swooshing and whirling noise. I assume it should be relatively quiet, once at pressure. Could it be that one (or more) of my injectors are leaking into the cylinders?

-Andras

merope

Yes, it is an 86.5. I got the correct parts. Double checked. FPR was changed to OEM like 4-5 years ago and looks fine, I didn't touch it.

Kevin in Atlanta

You should hear the fuel pump slow down when the rails are pressurized.

Swooshing suggests the fuel is going right back to the tank.

merope

Even jumping it? I thought that would continue to circulate it.

Kevin in Atlanta

Fuel returns to the tank once you have 45ish PSI on the rails. The fuel pump should sound different. But, without hearing what you're hearing I can not be totally sure. You need a fuel pressure gauge.

merope

I have one. Will test for leakdown as well. I didn't hear a change in the pump sound, but either it is leaking or full already with pressure. But it did sound like fuel was being released somewhere, but I didn't see it spraying out anywhere. My feeling is that one or some of the injectors are leaking into the cylinders, causing flooding, which is why it didn't start.

If so, any recommendations on how to rebuild the injectors or where to get new ones?

-A

Mrmerlin

NOTE if you suspect leaking injectors,

I would pull the plugs then use a bore scope to confirm your leaking injector theory,

NOTE dont crank the engine over with the starter till this has been done

merope

Unfortunately, I don't have access to a bore scope.

Why the no start? Overfilling cylinders and fuel compressing? I should do a quick fuel smell test on the oil dipstick.

I tried to crank her quite a few times yesterday.

-Andras

merope

Ok, I didn't realize how cheap these boroscopes have become. Ordered one. Thanks for the tip.

Kevin in Atlanta

If you say the car ran up until the moment you swapped dampers then the car should still run. Nothing changed.

So, that begs the question did it run the same day you before swapped dampers?

I get the feeling there's something missing from the car's history.

Pull the plugs see if they are wet.

merope

Well, I didn't run it for like a month prior to swapping. But she never had issues starting after a long sleep. What did change was me running the fuel pump for an extended period checking for leaks. The last time I swapped fpds I didn't do this test, just started the car and checked for leaks while the car was running.

Plug pulling and checking is next on the list. Per Mr Merlin's advice with a boroscope. Curious.

hwyengr

Once the air/fuel ratio gets to a certain point on either side of lean or rich, the atmosphere in the cylinders isn’t volatile anymore. It’s the same as being able to drop a lit match in a full gasoline can. There’s too much fuel in the air to be explosive.

For the short period of time I drove my 928, it flooded by looking at it funny. The one time I got stranded, it only got running by pulling the fuel pump fuse and cranking with the throttle wide open for a while to clear the cylinders. Then VA-ROOM.

But if enough liquid fuel condenses, you do risk hydrolock. How much cranking have you done?