Ok so I am still having problems getting my 1990 S5 convertible to start.
I have tried deflooding techniques, new fuel pump, new fuel filter, new pressure sensor, new spark plugs, has spark, has a full tank of gas, has oil, new pressure regulator control solenoid valve, it has pressure up to the fuel rail, but still wont start.
When I use a jump wire on the yellow plug to test the fuel pump it comes on but doesn't prime and shut off.
I can hear the fuel pump relay under the dash click when I have the key on without the jump wire and then the fuel pump shuts off so I think that is working properly. The main relay also clicks like it is supposed to.

What I'm thinking now is that the fuel pressure regulator is not working so the fuel is just running in a circle back to the tank when I use the jump wire. If the regulator doesn't stop the fuel and let it prime and flow into the injectors it wont start, right?
I can't figure it out and this is the last thing I can think of.
Does anyone have any idea or maybe let me know if I am right or on the right track?
I'm really just sick of guessing and would love to get my car back on the road.

 

I understand why you are sick of guessing. You have to sart with the basics of ignition, not with parts. If your timing and compression haven't changed (they probably didn't), all you need is the right amount of gas and good spark. Pull a plug or two and check them for spark. After you crank, you should smell fuel in the cylinder you pulled the plug from. You are probably missing one completely if you can't start at all.

Any recent changes?
Symptoms last time it ran?
How long since last start/run?
Crank strong?
Any ignition at all while cranking?

The only part I throw at higher HP and forced induction motors is spark plugs. I have fouled them fast before. Beyond cleaning.

Don't forget a coil can give a reliable but weak spark. It should be bright and snappy. Not dim!

 

Try a second or two at the most of starter fluid into the intake duct and see if the car fires up for a few seconds at least. This will help to verify if you have spark.

 

I tried deflooding, checking for spark and fuel before I started with parts and everything seems like it should run. I replaced the plugs so they are not fouled and all coils seem to be working really well.
Basically everything seems like it should run but it still wont which is what led me to believe something went out.
It ran perfectly fine up until I went to start it and couldn't get it to. And it has been almost 2 months since it has started.
I should have posted this in my last thread instead of starting a new one just to specify what all is going on. But basically I have done all of what you stated and Im still guessing haha
thanks for the replies though I can use all the help I can get.

I have a multi meter that I have been using to check different relays and things.
Does anyone know how to use a multi meter to check the fuel pump resistor relay?

 

If you're getting fuel pressure then the fuel pump relay must be working to a degree. Have you yet to try using some starting fluid to isolate your problem to a solely fuel related issue? And have you been able to measure the fuel pressure?

 

I used a pressure gauge and it has plenty of pressure but when I use a jump wire on the plug near the air box to prime it the fuel pump just keeps running and returning so I dont think my injectors are opening.
Is there something that controls the injectors that could be failing?

 

If you are testing w/the key to on and the engine not turning over then the injectors will not inject any fuel unless they are leaky to begin with.

 

Does anyone know how many ohms I should have when testing my main relay?

 

In the four wire relay plug, the Black/White wire and the Black/Yellow wire should have 12 volts w/key to on.

 

Thanks Satch!

 

Also does anyone know if an s4 main relay will work on an s5?

 

Have you isolated the problem as it relates to the Main Relay? Do both the B/W and B/Y wires in the 4 wire plug have voltage w/key to on. If one or both don't then the problem could be caused by other factors besides the relay itself.

 

Neither have voltage but I got an s4 relay from a friend that I was going to try if it would work for an s5

 

The other two wires ( White/Blue and White/Red wires) in the 4 wire relay plug should have constant voltage w/no key. Do they?

 

It didnt get any voltage with the key on or off.

 

Those wires should have voltage all the time and are powered by the EGI fuse in th engine fuse box. Besides the EGI fuse being blown the other two possibilities are the wires w/no voltage (White/Blue and White/Red) are loose from its connection to the fuse or the wire from the battery which powers the fuses in the engine fuse box is loose (least likely of these two scenarios especially if the headlights or hazards work).

 

Fuel, air, spark. You need to check which one you're not getting. If you think it's your fuel injectors, try to find someone who can bench test them. You can also try testing them on the car, but be careful with the spraying fuel.

-Don

 

Does the car crank like it wants to start? If there is no cranking going on at all it could be a starter related problem. It kind of sounds like fuel is not getting to the injectors for some reason or low fuel pressure.

 

The fuses are all good and my headlights/hazards do work but I can check those wires.
It has air and spark. the fuel pump runs and has plenty of fuel pressure but when I used a jump wire to prime it the fuel pump just runs and never shuts off. It just passes through the fuel rail but doesnt seem to be running into the injectors. Its like it just keeps returning to the tank. Thats why I thought it would be something controlling the injectors more likely than all my injectors failing at once

 

When you jumper the fuel check connector and turn the key to on the fuel pump will turn on and stay on til you either disconnect the jumper or turn the key off, until then it stays on.

The primary injectors are used during start up and idling and not the secondaries.

If you have a spare CAS you can plug it in and spin it w/the key to on and the primary injectors should click. If you do this unplug the electrical plugs to the coils to limit the clicking sounds to just the primary injectors.

And the starter fluid thing.

 

If u think its a fuel issue try spraying it with starter fluid. If it starts them u know its a fuel problem.

Check fuel pressure.
Check voltage at injectors.
U are probably on the right track either the relay
At the front of the car there is a place to check voltage to ur pump relay. Ill have to look at my car to give u a better description. Check it or voltage and then again at the pump