Startproblem e24 -83

[asoderstroms]

Hi guys new here, i hope u will help me with a problem with my car.
I try as good as possible to write in correct english ( Im from sweden).
Now to the problem, i bought me a 635csi 83 that was standing in a garage in about 20 years and it don´t want to start anymore.
I cleaned up the tank and fuelsystem, then i tried to start it up and yes it work in about 1-2 seconds then it died again....
I looked if the fuelrail got fuel and yes the fuel pumped as it should but i don´t know if the injectors open because i tried to start with start gas and then the car run as long i put start gas in it.
Have you any ideas? can i check if the injectors got signal? Are they controlled by a relay or something?

Thank's for the moment!

[rlkrlk]

Perhaps the fuel pump, or fuel pump relay? I think you need to measure fuel pressure or be certain the fuel pump is working. And there are 2 fuel pumps, at least in the M635. One in-tank pump and one external. Have a look at the fuel system diagrams at realoem.com.

Good luck!

Ray

[CW6er]

Check out my post (scroll down) on this thread for the main reasons a car will start and then stop:
http://bigcoupe.com/phpBB2/viewtopic.php?t=20071&

[Dash01]

Do you have a mechanic's stethescope? Get one. Have someone turn the key to start, while you listen to the fuel injectors. Also while you listen to the fuel tank and the external fuel pump.

Take the cap off the fuel relay. Push the contacts together with your finger, and watch the fuel hose at the fuel pressure valve. Does it jump a bit when you push the relay contacts together? If so, you are getting pressure to the fuel rail.

In your car, is the fuel relay the same kind and color of relay as, say, the horn? Swap the relays, and tap the horn, to test the relay that was in the fuel socket in the relay box.

I went through all this on my son's E28. Problem was moisture in the distributor cap. 2 hours in the kitchen oven at 180 degrees F, moisture was gone, car started immediately.

And, after being parked for so long in a cold, moist climate, the fuel flowing may not be fuel. It may be water. Find out.

[tandersn]

you can get a cheap $1.50 12v diode from an electronics hobby store. Remove one of the injector plugs (careful, the plastic will be brittle and it is easy to break). Put the diode in the plug, and crank. You should see it blink. Try it both ways, Diodes only work one way.

[pgh880]

Hi ,

It happened to me also. There was no pulse signal from the ECU going to the injectors. Replaced the ECU then problem sold!

Pgh880

[CW6er]

The Bentley shows how to make a LED tester for the injectors (page 1-15). They use a 1/4 watt, 330 ohm resistor on one leg of the LED.

Remember, the car starts up but then stops, so everything is initially working and then changes. Follow my link above for the main reasons.

[tandersn]

The Bentley shows how to make a LED tester for the injectors (page 1-15). They use a 1/4 watt, 330 ohm resistor on one leg of the LED.

Remember, the car starts up but then stops, so everything is initially working and then changes. Follow my link above for the main reasons.

I think what they are saying, is that it only started with starting fluid (Start gas). So not necessarily is everything initially working.

[asoderstroms]

The car only got a fuelpump under the car, and like i said got a lot of fuel to the fuelrail when i turn on the key with the fuel line released so i don´t think it´s the problem?
And i don´t have a stethescope to listen if the injectors open i should look if i can find some.
I don´t really know were i find the ECU and coldstart valve also the speed sensor that you talked about in your post CW6er?
There is a lot of relays in the fusebox but i have not located that which of is the fuel relay?

It´s a lot of questions but i have never ever held on with this cars before hope u will understand.

[CW6er]

I think what they are saying, is that it only started with starting fluid (Start gas). So not necessarily is everything initially working.

Ah ...... Thanks tandersn! You are right, I missed that!
But on reflection, I don't think it makes a difference: If the Speed sensor shut off the fuel pump it could continue to run on the starting fluid? If there was a vacuum leak, the starting fluid might well compensate. So I still think he needs to work his way down the list, most of the test apply anyway.

- - - Updated - - -

By the way. Welcome aboard! :cool

The first thing to do is check out this Posting for links to Factory WorkShop Manuals, Wiring Diagrams (ETM's), Factory Parts Catalogs, parts Suppliers etc. and get to know what is available:
http://bigcoupe.com/phpBB2/viewtopic.php?t=10410

Download the free wiring diagram (ETM) for your year car right a way, you really can't work on the car without it.

What model year is your car? You say you only have the one pump (no In-Tamk pump)? Some of the early Euro cars only had the one pump, so we need to make sure if it is Motronic, not L-Jet fuel injection? All of these suggestions have been for Motronic I believe?
_____________


The car only got a fuel pump under the car, and like i said got a lot of fuel to the fuel rail when i turn on the key with the fuel line released so i don´t think it´s the problem?

Well, no. Just getting fuel to the rail doesn't mean anything. You need to test the fuel pressure. The fuel pump must supply 43psi (3bar). If the pump were only supplying 10psi then fuel would still gush out with the hose off but would not run the car. You need to test the fuel pressure. Work your way down the list in my previous link and when you get to item (3b) it has links on how to make a fuel pressure gauge. Or buy one from the auto parts store.


And i don´t have a stethoscope to listen if the injectors open i should look if i can find some.

You should hear the injectors "ticking" even without a stethoscope and they should be vibrating a little bit also. But the valves also tick, so if they are loud, it can be hard to separate the two sounds. You can try putting a screwdriver against an injector and then putting your ear to the screwdriver to help. A "noid" light from the auto parts store or the homemade LED tester will tell you for sure.


I don´t really know were i find the ECU

It is the least likely to be your problem unless water has leaked into the car on the right side. Has it been stored in a dry place? I'd leave it until last to check, but it is located inside, above the glove box .


and coldstart valve

Again, not likely the problem. It shuts off when the key is released from the start position and isn't needed to keep the car running.


also the speed sensor that you talked about in your post CW6er?

The Speed and Reference Sensors are located in the rear brace that runs from the cylinder head to the intake manifold. I just saw that the illustration for testing them is missing on my post so I just uploaded it and will post it here also. Be careful! the plastic plugs get brittle with age and can crack. Also there is a wire locking bail around the bottom of the plug that you have to release to unplug it.

http://bigcoupe.com/phpBB2/files/testing_ref_sensors_216.png


There is a lot of relays in the fuse box but i have not located that which of is the fuel relay?

Well, the Main and Fuel Pump relays are on the outside of the fuse box and they can be hung in different positions, so that is why you have to Identify them by the color of the wires going to them. That is why you need to download the ETM first thing. Click on "Power Distribution" in the PDF menu bar to go to the fuse box diagram. hen click on "Injection Electronics" and scroll down until you find the fuel pump relay with the wire colors shown.

http://bigcoupe.com/phpBB2/files/relay_jumpers_193_114.jpeg

[Dash01]

Rather than jumper the relay, you can pry its plastic cap off and just push the contacts together with your finger. Watch and/or feel the fuel hose at the fuel pressure regulator as you do this: If it jumps or stiffens, the external high pressure fuel pump is working to pressurize the hose.

If you have another relay of the same type as the fuel relay, swap them and see what happens. (I'm not sure about the E24, but in the E36, the fuel, horn, and rear window defroster relays are the exact same type, so it is easy to swap the horn relay into the fuel relay socket, and vice versa. Do this and tap the horn: If the horn is silent, your swapped-in fuel relay was faulty.)


However, if the in-tank fuel pump is not working and/or the filter or line is clogged, the external high pressure pump may be starved of fuel, in which case the car may not start, or if running, may not develop full power. Sometimes when the tank is full, the car starts and runs fine because gravity pressure overcomes the line friction to the external pump. But when down to, say, 1/4 tank, there is inadequate gravity pressure to feed the external pump, so the car may not start or run properly.