400SE FUEL PROBLEM

[tivfan]

Can anyone help? My 400 would die but would restart after about 15mins, i checked the fuel pump out of the car, it worked i put in back and it wont run, i have Steve Heaths "the tvr wedges" vol 1 but cannot find the fuel pump in the wiring diagram, i'm no car mechanic but thought i might be able to follow the diagram through and check out all relevant components. it seems there are several components that would switch off the pump but not knowing where the pump is in the diagram has really stumped me, has anyone a diagram that shows the pump on a 1990 400se?, or has anyone had this problem and knows how to resolve it.
Thanks
Dave

[350matt]

The pump should only run during cranking and then when the engine is running, if you suspect problems with its supply I'd check this by running a feed directly from the battery.
Otherwise change the fuel filter , check fuel pressure etc

Matt

[jmorgan]

My hotwire primes up on ignition on. Under the impression that the hot wire primes on ignition on and the flapper on cranking?

[rev-erend]

Can you tell us if it's a hotwire or flapper airflow meter ..

My suggestion is to take the fuel pipe off at the fuel rail (follow rubber pipe from drivers inner wing)

Put put pipe into an empty milk bottle (or container you can see into) - then have a friend crank the engine over.. might even be worth taking off the coil lead..

You will see if you get petrol or not..

[h2dca]

As noted the pump only operates during cranking/engine running and has no on/off pressure switch. If the pump was running OK off the car then I would suggest the actual fuel system ie tank to injectors is OK.

Out of interest when does the car cut out, is it at full operating temp or above and do the cooling fans cut in at the correct temp.

Reason for asking is that the fuel system has a temp switch and at hgh temp switches off the fuel system and then after cooling will reset and the engine will run.

[briantvr350]

Dave,

if it's a flapper system, checking the fuel pump is running is quite easy...

Take of the lead from the coil (just to be safe)
Take the large hose off the air flow meter
Switch on the ignition

reach in to the airflow meter and move the flap...

fuel pump should run and be audible...

If you want to be sure that fuel is present take the fuel hose off the cold start injector on the plenum chamber direct it into a suitable container and activate the pump as above...

From memory, there is a relay on the relay panel and a seperate fuse on the fuse panel both required to be present and intact for pump to run.

If it's a "hotwire" version... haven't a clue sorry.

Regards,

Brian (and a Red 350i) with flapper fuel injection

PS... wouldn't be the first time a dodgy alarm or immobiliser has caused problems, the fuel pump circuit is a favourite to intercept.

[GreenV8S]

h2dca said:

Reason for asking is that the fuel system has a temp switch and at hgh temp switches off the fuel system and then after cooling will reset and the engine will run.

Does it really? Sure you are not confusing this with the fuel temp sender? This is used by the ECU to trim the injection times to match viscosity changes in the fuel, but doesn't have anything to do with enabling or disabling the pump.

[tivfan]

"wOW"
Thank's guy's, I did'nt expect this sort of response.
Have got to be at work till late today so wont get chance to try any of the solutions till tomorrow, really appreciate the help, will post outcome asap.
Many thank's
Dave

[h2dca]

GreenV8S said:

h2dca said: Reason for asking is that the fuel system has a temp switch and at hgh temp switches off the fuel system and then after cooling will reset and the engine will run. Does it really? Sure you are not confusing this with the fuel temp sender? This is used by the ECU to trim the injection times to match viscosity changes in the fuel, but doesn't have anything to do with enabling or disabling the pump.

Perhaps confusion here, I was suggesting the fuel system not the pump as the car starts, runs, then stops and after 15 mins it will restart, hence the suggestion of a possible temp related problem.
However the switch I am referring to is the thermo time switch where if the coolant temp is in excess of 35 deg C this will inhibit the injectors.

I had exactly the same problem on a previous TVR albeit a 400 Griff and though the car did not overheat the switch for the fans was operating at a slightly higher than normal temp due to scale on the switch and the engine would just stop in traffic.

After new coils, leads etc etc etc at the TVR factory the penny dropped and it was an engine temp issue.

Regards
Hamish

[GreenV8S]

As I understand it, the flapper systems would have a thermotime switch which switches on an extra injector in the plenum. This is supposed to run for a set period after cold start to provide warmup enrichment. I think if it ran for too long the engine would run very rich and might get a bit unhappy, I wouldn't expect the engine to simply 'switch off' but it could run roughly or stall. I seem to remember a comment from Mark Adams that advised disconnecting this because it delivered way too much enrichment. I guess this is what you're thinking of? By the way the hotwire engines (V8S onwards) don't use this system, the cold start enrichment is handled by the ECU using the normal injectors.

[adam quantrill]

Hmm - try changing the ECU temperature sensor - these can go wierd and give funny readings, I had one that went open circuit at around 60 degrees C and totally confused the ECU.

Have I said this before???? ;^)

[GreenV8S]

adam quantrill said:

Hmm - try changing the ECU temperature sensor - these can go wierd and give funny readings, I had one that went open circuit at around 60 degrees C and totally confused the ECU.

That's a good point, why oh why didn't you tell us earlier?

[TIVFAN]

Thanks for all the info guys, i eventually had to call out an electrician he's changed the engine management relay's which he said were working but faulty, it appears to have cured the fault for now.

many thank's
Dave

[TIVFAN]

PS
For your info it's hot wire and primes on ignition.
Dave

[tallbloke]

Thanks for following up on this thread Dave, it all helps build the knowledge base.