I haven’t started the car in at least a year, but when I did then, it ran fine. Today I tried and it would run 2-3 seconds and quit. First guess is maybe the fuel pump cuts out. Can I run the pump directly by bypassing the relay? If so, where is the relay located? Guess I’ll have to fire up my old XP laptop that has a copy of WIS.

Hi,
I'm not an Auto Elec, but.. don't try & bypass the Relay. It's there for a good reason, so as not to burn out your electrical system, see, it act's as a separate switch, thus reducing the Current, or load on the switch/s.

Any spark or ignition point around the fuel system, would be a catastrophic event!!

Unfortunately, any vehicle which sits for a year will be plagued with a number of faults

Poor battery current/voltage, OVR,(over voltage relay) & or fuse, the fuse box it's self, fuel relay, any earth straps, all usually attributed to poor contact & or corrosion. Hence no running engine.

A quick test for battery power, is put your headlights on high beam, and if not bright, especially while cranking the engine, that would be a good place to start with.

If unable to drain the fuel tank, then at least fill it up with fresh fuel. Fuel is usually only good for up to 4-6 months, depending on the type, your environment, etc. Don't worry if it doesn't fire up straight away, it will take a short time to purge thru.

When the ignition switch is turned on, a wirring sound should be audible. If not, fuse or pump,or relay and fuel filter could all be possible causes. If problem persists, suggest you get a qualified technician to assess the situation.

Don't forget about the engine oil change and filter change, cause a gummed up engine and or valve train won't help your situation, as by now, oil / water & fuel contamination will be present!

So once again, check the battery and terminals fill up the fuel tank with fresh fuel, change your engine oil and filter, and you will have to work, one step at a time from there.

Get back to me once this is done if you still have problems.

Hotwired the relay connector but no change. Still runs a few seconds then quits so the fuel pump works although I don't know the pressure. Battery is fine if it starts. Will check the plugs next and maybe the fuel pressure.

Hi there,

Glad to hear that your battery is ok.

I have a question for you re: checking your fuel pressure etc.

As I'm sure, you know that in order to complete the fuel diagnose of the Bosch / KElec fuel system, you will have to have a Fuel Flow / min meter, Pressure gague, a return to tank gauge and a Lambda tune up machine, also a Fault Code reader, for your particular model.

If you have access to these, and the technical data knowledge, to support the model of your vehicle, and nessesary experience in said, then I guess you can proceed accordingly.

However, this said, if not, perhaps the inspection and any fault diagnosis should be performed by a MB Technician, or a Fuel Injection expert, to avoid any confusion & or great expense to your fault finding diagnosis.

Here's wishing you luck.
Regards

Is this still CIS?

If so it sounds like the start valve is operating but there's a fuel delivery problem for the other injectors. These injectors do tend to gunk up if they are not used. Sometimes you can free them up if you force through some fuel with a pop tester but if you're not from the diesel engine world I guess it is unlikely you have one of those. A bit of time in an ultrasonic cleaner might help - but the fastest way is to replace with (borrowed?) known to be good injectors.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Just one more thing you could may need to do, is IF you have a engine immobiliser, disconnect it,and try, they usually will cause the Ignition Coil to cut out. Check if you have more than the usual number of wires running to it or it's connector.

And i would check all fuses ,give them a turn in their holders

Yes!!
Even though they may seem Okay, they wear a Ring around the contact points and difficult even to check the continuity with a meter.
May seem fine, but the Copper points wear out and... The units on that line,can be an intermittent problem.
Good one!

Its the fuel pump. Connected a pressure gauge to the test port and hot-wired the pump at the relay connector. I can hear the pump working but the gauge barely moved.

No CIS on W202's or post '93 W124's

Before you change the pump, change your fuel filter. It maybe so clogged up the pump can't get any fuel through it.
You also may need to remove the injectors and clean them out. You can buy kits for the seals and the injector filter.
At the minimum I would run a bottle of techron through the fuel system.

This can be either the pump or the regulator itself, if the fuel pressure regulator is not allowing pressure to build up the injectors will never fire.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

It was actually out of gas. Coulda swore the gauge showed some and that it ran 2-3 seconds probably threw me. Removed the pump and thought something wasn't right when no gas poured out as I removed the supply hose from the pump. Then I fired up the pump and felt suction on the intake side. So I put the pump back in and added 4 gallons gas. Powered up the pump and the pressure gauge showed good pressure. Thought it would run, but now it don't seem to have ignition. Not only won't it run the 2-3 seconds as before, but even starting fluid has no effect. Had a similar no start issue on another C280 a few years ago posted here, and bypassing some relay behind the instrument cluster got it running again. Will have to search on my old posts.

It was a battery issue. I was using just a jump box to start it which I've done with many other cars with no problems. Put in a regular battery and it started up fine.