1989 300e starting problem

[gbvette98]

1989 300e (109k miles) won't start. If I pull the fuel pump relay it will start and run until it runs out of gas ( about 5-10 seconds) I then put the fuel pump relay back in, and it wont start, after a few cranks I pull the relay out and it starts again until it runs out of gas again (5-10 seconds)

Is this a bad relay? I have second one I got from a junk yard from a 300e with 150k miles and it does the exact same thing?

Any ideas?

Also, what is the other relay behind the fuel pump relay for?

 

[television]

1989 300e (109k miles) won't start. If I pull the fuel pump relay it will start and run until it runs out of gas ( about 5-10 seconds) I then put the fuel pump relay back in, and it wont start, after a few cranks I pull the relay out and it starts again until it runs out of gas again (5-10 seconds)

Is this a bad relay? I have second one I got from a junk yard from a 300e with 150k miles and it does the exact same thing?

Any ideas?

Also, what is the other relay behind the fuel pump relay for?

First thing to do is to make sure that the fuses are making good contact,use a good switch cleaner / lubricant.

Malcolm

 

[television]

Maybe Nick knows if the alarm isolates the fuel pump relay

malcolm

 

[gbvette98]

Malcolm,

thanks for the quick reply. All fuses are in working order, I have metered all of them.

Any other ideas

 

[television]

Malcolm,

thanks for the quick reply. All fuses are in working order, I have metered all of them.

Any other ideas

When you meter them use the contacts not the fuse, this must come down to the alarm,later cars used a starter lock out.
I am thinking about it. malcolm

 

[gbvette98]

When I metered the fuses I did use the copper contacts not the fuses themselves. so.. on to this alarm thing.

How would I go about diagnosing the alarm? and by alarm I take it you do mean the car alarm, correct?

 

[television]

When I metered the fuses I did use the copper contacts not the fuses themselves. so.. on to this alarm thing.

How would I go about diagnosing the alarm? and by alarm I take it you do mean the car alarm, correct?

There is a relay on the output of the alarms that is in series with the fuel pump relay.

Is it the Scorpian alarm Malcolm

 

[Bolide]

Why not run a temporary 12 v feed to the pump and try starting it? That should get you closer to knowing where the problem is

The OVP relay seems always to be suspect on older cars. And older W124s always seem to have bad starting due to fuel rather than ignition problems

Nick Froome
www.w124.co.uk

 

[gbvette98]

Malcom, do you may if I call you or you call me.. I would PM you but this forum wont allow me for some reason. I'm losing my mind with this car.. I've been messing with it for over a week now.

My personal email is
gbvette98@comcast.net if you want to contact me with your phone number or ask me for mine.

 

[gbvette98]

nick

the OVP is fine.. one of the first things I have checked... but I will try the bypassing the relay idea

thanks

 

[gbvette98]

nick,

now say that I go ahead and bypass the relay and the car runs, what is that telling me? bad relay?

 

[television]

I will email you the 6 pages that i have printed off for you in the morning

Malcolm

 

[gbvette98]

Thank you malcom

 

[television]

They were a sod to send,sent 6 Emails or I lock up and freeze, this computer will go out of the window next

Malcolm

 

[Bolide]

Gbvette: if it works with the relay bypassed, remove the bypass and put an old-fashioned voltmeter (with a needle, not a digital display) on the pump feed. Then observe when the feed cuts (assuming it does). This should tell you at what key position the feed is being cut (assuming it is)

If it still dies after starting with a known-good temporary bypass voltage feed to the pump (watch the voltage via a meter) then, logically, it's not a problem with the electrical feed to the pump. Then I'd look at voltages elsewhere, at the HT system, at the fuel pressure and the cold-start enrichment system

Does it start OK when warm?

First things first: bypass the relay and go from there. And maybe put a voltmeter on the battery during cranking to see what the voltage drops to

Television: time to buy a Mac


Nick Froome
www.w124.co.uk

 

[television]

Gbvette: if it works with the relay bypassed, remove the bypass and put an old-fashioned voltmeter (with a needle, not a digital display) on the pump feed. Then observe when the feed cuts (assuming it does). This should tell you at what key position the feed is being cut (assuming it is)

If it still dies after starting with a known-good temporary bypass voltage feed to the pump (watch the voltage via a meter) then, logically, it's not a problem with the electrical feed to the pump. Then I'd look at voltages elsewhere, at the HT syste, at the fuel pressure and the cold-start enrichment system

Does it start OK when warm?

First things first: bypass the relay and go from there. And maybe put a voltmeter on the battery during cranking to see what the voltage drops to

Television: time to buy a Mac


Nick Froome
www.w124.co.uk

Hi nick, I have sent him all of the fuel pump relay diagrams so he should be able to short it out to test.

Re computer dont know anything about MACs though.

Malcolm

 

[gbvette98]

I want to thank you guys... but unfortunately I still have the same problem

I went through all the steps in that paperwork you sent me malcolm and it all tests out good. I had already metered the OVP on the bench but just checked the socket to make sure it's getting juice, which it is and it is clicking when you turn the key to the on position, so I believe the OVP should be ruled out.

Nick, When I bypassed the fuel pump relay, the fuel pump does turn on constantly ( doesn't cut out) but she doesn't start but if I remove the feed she starts until it runs out of gas, back to square one . What is that telling me?

I appreciate your time as I'm pulling my hair out over here

 

[gbvette98]

I also noticed that there is no power to the cold start valve at any time (key on, key off, cranking so on).

I metered the pump feed with the relay in and when key is on, it gets 12v for 2-3 seconds and you can hear the fuel pump kick on momentarily, it then gets 12v while I crank and stays at 12v during the cranking.

What is the HT system and cold start enrichment system?

Thanks again guys, I think I'm going to be bald by tomorrow if I don't solve this problem.

 

[television]

I still think it is an immobilzer problem and some circuit are grounded or open circuit.

It is not alway a good idea to run +12volt feeds back into the system as these things have semi condutors in them.

I was hoping that somone with a 124 wouls have joined the thread.

Your enrichment devices come from the Key.

Malcolm

 

[television]

Dont forget the engine rev limiter is in this relay its effect is to cut the fuel pump your fault could be there.

Malcolm