Hi, I'm rather new here and really appreciate the help. I just bought an 89 560 SEL. The engine wants to turn over but all I hear is the motorized sound of an engine trying to fire up. It almost sounds as though it's not getting spark. Seems like it's either not getting spark or fuel. I want to guess it's a spark issue. Just makes the whirring sound of a motor. Any suggestions? It was running fine up until very recently. Thanks!

 

Most common cause is the fuel pump relay. Try starting it with the air filter off, and if the air intake flap (big round disc) drops a long way as you crank it, then you have a fuel pressure problem.

Also listen at the back of the car for a hum or buzz as you try to start. This noise will be the fuel pump. If you don't get this noise, check the fuel pump relay.

Search the forum for more info, I'm sure it has come up recently.

 

pull out one spark plug cable.
put a spark plug on it and ground the body.
crank the engine and see if you got sparks.

 

Thanks again. I listened for the pump when the key is turned... nothing. I jumped the #7 & #8 pins and still no pump noise.

I do get spark.

I'm thinking he pump might be bad. Sound logical?

I'm trying to take the pump off and the end where the fuel leaves the pump, toward the engine, is giving me a hard time. So far I only have the fuel line (from he tank into the pump) off, the power disconnected of course, and the very outer hex nut removed. The hex nut on the inside of the outgoing fuel line is giving me trouble. Any suggestions?

-mike

 

UPDATE - I took out the pump, hooked it up to a battery. It works fine. The 7 & 8 jump did nothing. I am stumped.

There are 2 pumps. could one be dead and blocking the other from getting power or would it be passive?

 

I'm not sure which connections 7 and 8 are, but if you look on the bottom of the fuel pump, you will see the numbers 30, 15, 87, 50, etc, you need to bridge pin 30 which is battery voltage to 87, the consumer, in this case the fuel pump. Terminal 15 should have power with ignition on, but the wire to the relay isn't really thick enough to run the fuel pumps, it is just a trigger.

Let me know if this helps.

 

Thanks. I have a couple of questions:

1- are you saying that bridging the #7 & #8 pins but still not getting the fuel pump to kick in wouldn't prove anything? Do you think the relay might be the issue?

2- it reads like you're diagraming hot-wiring the battery to the fuel pump. I did check the pump direct to the battery and it worked like a charm.

I want to think (hope) the relay is the problem. A few people mentioned bridging those pins and then turning the key. I assume I'm supposed to leave the relay OUT and just bridge those two pins. Of course I can be an idiot, so tell me if I'm wrong.

I appreciate the help.

-Mike

 

Ok Mike,

the bridging of the pins is done with the relay out, and yes, it is "hot wiring" the fuel pump. If this works, it is 99.9% of the time that the fuel pump relay is faulty.

Unfortunately, I don't have anything with me now to work out what pins 7 and 8 are, I always look at the terminal numbers (30 & 87) to work it out.

But you might need to check and make sure that you have 12V at the pin marked 30. Preferably use a test light to check this.

The other thing you can do is just open the fuel pump relay and look for a dry solder joint, which is usually under the relay on the cicuit board

 

OK, I have the fuel pump working. The relay is OK, there's spark and the car SOUNDS like it wants to start. MUCH better life than before. But it's not starting. The chances that the fuel pump wasn't working (it wasn't), AND something else is wrong all of a sudden are very slim.

Do I have to prime the engine in some way to get it to start? It seems like it wants to start, I pumped the gas pedal (because there probably wasn't much fuel near the engine since the fuel pump wasn't operational for months). I'm thinking I need some starter fluid or something. What do you think?

 

Try cranking the engine with the air filter off and watch the round flap in the intake. It shouldn't drop right down. About 1 inch is ok, any more and you still have a fuel pressure problem. You may need to remove your spark plugs and check that they are not wet. This indicates flooding. If this is the case, dry the plugs, refit them and crank the engine with your foot flat to the floor.