Starts but won't keep running...HELP!?

[wedgeinald]

Recently aquired a 280i Wedge that hasn't seen the road since 1996!!

The car is in generally sound condition despite being layed up for so long.

Current problem is we are trying to re-commision it so we can get it MOT'd and see whats gonna be needed to get it on the road.

The engine will start but dies after about 5-10 seconds. It makes no difference if you boot the throttle/no throttle or hold the starter in all the time. We are 99% certain we have ruled out an electrical fault.

We think its a fueling issue, it seems that while the car is in "cold start" mode the engine runs fine (It will start with no throttle and tick over nicely for those few seconds), but dies when it switches to "normal running" mode.

Anyone on here had this fault and can point us in the right direction for what to check first? Thought we'd ask just in case its something simple before we rip the fuel system to bits.

Thanks in advance

Norman

[jeff m]

The 280 has a ballast resister which means the 12v for the coil comes from the start position of the key. After key is released the 12 passes through the resister (A big thick blue wire) and results at 8-9 volts at the coil.

Cold running, there is a thermotime switch which operates the "extra" injector for starting. This operates on physical heat and on electrical current running through to disable it.
Cold engine, starter operated, it will squirt.

After it has started it relies on the Aux air device. When the engine is cold it allows extra air into the plenum and as it is CIS, extra fuel.

Once hot, the WUR takes over and controls the fuel pressure.

Take hose off the ADD and see if you see a hole. There is a half moon thingy that closes off the hole when engine is hot. My guess would be this thing is gummed up. Easy to take it off and give it a good spray. Heat it up to test it moves before replacing it. (Hold over the gas while wife is out.)
Cold it should be open.

Also clean the bypass under the butterly.

EDIT. AH...butterly = butterfly, sorry about that

Edited by jeff m on Monday 5th October 12:44

[jeff m]

I would get a new fuel filtre on that and some techron in the new gas you have put in the tank after draining the 1996 stuff too.

[wedgeinald]

Some good stuff there Geoff...just the sort of insight I needed. Sounds like you know the injection system on the V6 quite well?

Will have a play with those bits when i get chance (might not be till at least next weekend) but I'm in no huge rush to get the car running as it will soon be winter but would be useful to get that darn'd MOT sorted ASAP so I can maybe get the car running properly for spring 2010.

[Wedg1e]

There's a kill switch in the airflow meter that stops the fuel pump if the engine stops. If it's adjusted incorrectly or stuck then it could be preventing the fuel pump from operating - there's an over-ride feed while the car is cranking to prime the fuel system.
Try giving the pump a temporary 12v feed and then start the car; if it keeps running it could be something this simple.

[wedgeinald]

That sounds like you might have hit the nail on the head.....certainly that would cause the type of symptoms we have.

I'll check it out and reply here cheers.

Norman

[jeff m]

Wedg1e said:

Try giving the pump a temporary 12v feed and then start the car; if it keeps running it could be something this simple.

Or swap the cream coloured relay with a regular relay, from wipers headlamp etc.
Does the same thing but w/o getting underneath.
Ignition on.....listen for pump.

[MJG280]

or as on mine there is a wire plugged into the top of the injector box on the wing. I have to have mine unplugged for the engine to run after the start.

I have a TIF of the injection and ignition system scanned from my TVR manual if you want it. E-mail on my profile. Same for anyone else if they want these.

[benebob]

Mine did the same thing. Again it sat probably as long as yours did. Ran a new relay set up for the fuel pump when I deleted the the Fuel injection computer. Make sure you clean out that tank good, clean and replace all the rubber hoses.

[Wedg1e]

jeff m said:

Wedg1e said:

Try giving the pump a temporary 12v feed and then start the car; if it keeps running it could be something this simple.

Or swap the cream coloured relay with a regular relay, from wipers headlamp etc.
Does the same thing but w/o getting underneath.
Ignition on.....listen for pump.

Hmmm, that's a point, I was forgetting that the later injection acquired a bit more in the way of electronics... I think one of the modules checks to see if the sparks are firing and uses that instead of the airflow meter kill switch to control the fuel pump.

[jeff m]

Wedg1e said:

jeff m said:

Wedg1e said:

Try giving the pump a temporary 12v feed and then start the car; if it keeps running it could be something this simple.

Or swap the cream coloured relay with a regular relay, from wipers headlamp etc.
Does the same thing but w/o getting underneath.
Ignition on.....listen for pump.

Hmmm, that's a point, I was forgetting that the later injection acquired a bit more in the way of electronics... I think one of the modules checks to see if the sparks are firing and uses that instead of the airflow meter kill switch to control the fuel pump.

Correct it's op'd from the low side of the coil, those electricicals op the WUR and AAD too so you can just check the 12v up on top as it's the same feed as to the pump. Although of course there's Murphies Law which requires one to squeeze under the bugger with a test lamp and a hammer.

[wedgeinald]

Just a quick thank you to everyone for their helpful suggestions.

I hope to have a look at the car again (Once I've got all the test bits i need sorted) maybe this weekend if the weather is ok or one weekend soon.

Thanks again for your helpful replies.

Norman