3.9 efi HELP Calling PH Bods

[Mrs Fish]

James here;

Really need some pointers. My brother has a 3.9 efi rangerover which has decided to run PERFECTLY when started however when starting both cold and hot it turnover and struggles to catch and requires 5-10secs of turning over with throttle pumping to start...once going is perfect.

We've changed HT leads, Plugs, Distrib Cap, Coil...the only thing we can think of is the cold start temp sensor but it still wasn't happy when left for 30mins from hot so diubtful this is the cause...

ANY SUGGESTIONS PLEASE

James

[CatherineJ]

Check the EFI until under the seat for signs of corrosion.

[Mrs Fish]

Will do but the fact that it runs foine once started is suggesting sensor etc?

[CatherineJ]

The reason I am suggesting it James is the experience we had with an EFI Classic about 5 years ago. I ended writing an article in LRO about it. It was a total nightmare and was down to corrosion. It had similar problems as the car you are talking about.


The garage spent fortune (billed to me) trying to rectify the fault. If nothing else it is worth checking the condition of the unit for future reference.

Edited by CatherineJ on Thursday 27th July 21:01

[Mrs Fish]

What was the result a new EFI?

[Mrs Fish]

Sorry re read my post didn't wish to sound off hand...Interesting to see a corroded ECU, will suggest. If corroded why does it run fine when started?

[CatherineJ]

A reconditioned unit. I think it cost me less than the other parts and labour that they wasted their time over.

[Mrs Fish]

Will go through with my brother soon. Cheers

[CatherineJ]

James I meant to say, that you need to physically remove the unit, not just a visual inspection from behind the seat.

[Mrs Fish]

Okay..

[Pigeon]

Cold start injector not working? (Take it out and see if it squirts; if not, squirt a bit of petrol in the hole, replace the injector, then try starting)

Fuel vaporising in the pipes leading to a delay while pressure and liquid build up? (Bridge out the fuel pump relay so you can run the pump for a bit before you try and start it.)

[Fish]

Anothers cheers

[convert]

Is there an ECU temp sensor at the front of the inlet manifold (might be 2; one is a thermotime switch possibly, if so the ~ECU sensor is the rearmost one).

Try disconnecting this

[eliot]

There's no cold start injector on the 3.9efi - as it's should be the later hotwire system.
"Pumping" the throttle on an efi doesn't put more fuel in it, just more air. take a look at your idle stepper - remove it and inspect it - check that it moves then you turn the igntion on. Its the thing bolted to one end of the plenum with a 4 pin connector and a hosepipe sized hose going between it and the throttle.

[chassis 33]

We have a similar problem on our hotwire disco. From cold or warm it never really makes much difference, I've found a get around is to turn the ignition one and off twice allowing the fuel pump to prime before trying to start, it doesnt always work though, and like has been said pumping the throttle seems to help matters.

I've checked the stepper several times doesnt help. When you get to the bottom of it let me know!!!

Regards
Iain

[GreenV8S]

eliot said:

"Pumping" the throttle on an efi doesn't put more fuel in it, just more air.

It *should* produce accelerator enrichment on every petrol engine. I could keep mine running on the hotwire setup by pumping the throttle when the AFM died.

[eliot]

GreenV8S said:

eliot said:

"Pumping" the throttle on an efi doesn't put more fuel in it, just more air.

It *should* produce accelerator enrichment on every petrol engine. I could keep mine running on the hotwire setup by pumping the throttle when the AFM died.

Agreed, it reads the TPS for accel enrich - but during cranking?

[Graham]

I'd change the temp sender as a matter of course they telll the ecu all sorts of weird thing when they dont work properly and are only about 12 quid... i've had a number fail.

change that and then unplug and reconnect the ecu to reseat, another goody is the earth connections on the engine bay loom. depending on the exact loom there will be either a bindle of black wires or a single black wire.

Edited by Graham on Saturday 29th July 10:58

[Pigeon]

eliot said:

GreenV8S said:

eliot said:

"Pumping" the throttle on an efi doesn't put more fuel in it, just more air.

It *should* produce accelerator enrichment on every petrol engine. I could keep mine running on the hotwire setup by pumping the throttle when the AFM died.

Agreed, it reads the TPS for accel enrich - but during cranking?

Yeah, should still work during cranking, I've used it successfully to compensate for a defunct cold start injector.

[Fish]

My bro is away climbing mountains till Sunday will talk it through then, anyother suggestions usefull.

Cheers everyone James