draco's keeper

I've been going thru WSM and every fuel pressure/injection thread but I'm still not sure I'm on the right track. My car started right up after reinstalling charged battery and a short prayer! Then promptly idled real rough and shut off, wouldn't restart unless I depressed pedal to floor. I smelled gas so I knew it was flooded,removed plug and they were black/fouled,cleaned them and reinstalled. Car will fire right up and shut right down,no fuel pressure after shut down.When I jumper fuel pump relay I get 40 psi, no pressure when jumper is removed.FPR holds vacuum and so does dampers.Filter was changed and known good relays installed. From other posts I'm thinking fuel injectors (they are original and look like they've never been disturbed) can these be gummed up to the point they are not closing. I don't want to start taking the FI harness apart because I know that will lead to intake R&R,powdercoating etc. etc. Any expert opinions would be appreciated!

Leon Speed

How long has it been in hibernation? Did you put in fuel stabilizer? Did you swap the fuel pump relay? What model year?

draco's keeper

It was out of service 3 months I did have stabilizer in fuel and battery disconnected,I have known good relay for fuel pump and good spark.It is a 87s4 5spd x-pipe/ no cats and RMD. I will never put this car up for the winter again!

Leon Speed

Did you try unplugging the MAF? Does it run roughly or not at all? Can you hold rpm until the engine warms up?

Bill Ball

What model year?

JHowell37

It's not the fuel injectors. You'd have to fill them with tar to get them to stop opening and closing properly. When fuel injectors get gummed up, their flow is reduced/compromised, but nothing in them will stick open.

Basically your car doesn't run unless the fuel pump relay is jumpered. This is indicative of a LH failure which is common on the S4. Go here to see if this describes your problem, and for more info:
http://www.jdsporsche.com/23fiecu.html

draco's keeper

It won't run even with fuel pump jumpered, I did that to confirm fuel pressure because by the time I'm out of car there is no pressure (rail mounted gauge).This is a 87 s4, what is the best way to disconnect MAF take it loose from boot or disconnect in place.Also is it normal when fuel pump is jumpered to hear fuel rushing back thru return hose? Best test for FPR?

Leon Speed

Take the air box off, unplug MAF, leave it in place, replace airbox (leave 10 mm nuts off for testing).

JHowell37

If you're not building fuel pressure, then leave the MAF alone. That's not causing your problem. In addition the car will run with a bad MAF. It will run like ****, but it will run.

The reason you get fuel pressure when you jumper the relay is because one of the two terminals is hot at all times and you're basically wiring the fuel pump directly to the battery. When you do this it is normal to hear fuel rushing back down the return line to the gas tank.

In my first post I misunderstood. But nonetheless, the car doesn't run with the fuel pump jumper, however the fuel pump will operate.

With the relays back in place and everything hooked up, can you hear a clicking sound come from the engine compartment when the key is turned to the "on" position?

I still think it's the LH.

Mrmerlin

is there anything in the aircleaner box?
Has the car been sitting outside was it getting wet?
is the CE panel wet or do you see water tell tales of water dripping down from the blower box?
www.928gt.com for a fuse chart, pull every fuse and check for corrosion, pull every relay any with corroded pins should be opened, clean the hot post and 14 pin connector with the battery disconnected

draco's keeper

There is nothing in the air box, car was in a heated garage,normally I'm working on something so it gets started every week or so but this winter but this winter due to circumstances I couldn't do the work I planned to do.There is no sign of water inside near CE panel,I did clean/reseat X3 every fuse and relay and went over ground points(which were done last summer).I'm going to do the WSM test for fuel injector harness short and test again to see if injectors are firing wildly after it shuts off.

draco's keeper

This was my first and foremost fear after reading about my flip wing S4,that it would lose its brain! I did some more tests and you definitely hear a high pitched whizzing sound after it shuts down. When I place a long screwdriver on injector bodies they are all buzzing like crazy, classic LH failure! Now to make some calls! Thx for everyones opinions.

Leon Speed

Seems a lot of LH's are failing lately..or is it my imagination??

Rich9928p

more info on no-start and brain related failure here: www.electronikrepair.com

Rich9928p

There are 3 relays that must be operational:
- fuel pump
- LH
- EZK

For your model, you can swap the horn relay with these relays.

A few weeks ago friend's 86 Euro wouldn't start. He tested the fuel pump relay and it was OK. But he didn't test the other relays. I checked for spark, there was none, we jumpered the EZF (older type spark module) and it started.

SO FIRST THING - check all 3 relays.

For all of you - the fuel pump only runs 1 second when the ignition key is turned on. It will not start running again until the engine RPM reaches about 50 RPM. So just because you don't hear the fuel pump run when the key is on - that doesn't indicate a problem.