3.9Efi starts and dies - Fuel pumps Qs?

MattMatt · Mar 20, 2011

I've just spent the day finishing up wiring up the 3.9Efi which now fitted to my 88" Series. It was a 200TDi before. Got all the relays clicktying and good spark at t plugs. Fuel in - fuel pump ticks - turn key - BINGO......

Then it died....

Tried it again and again - it fires - runs for a few secs - then dies.

From what I've read here and there this is typical "air leak in the inlet system" stuff but before I go tearing it apart I have one or two questions for all those wise people who know much more than me....

The fuel system is pressuresed to 37psi? Really? That seems very high! I have a red top Facet but that only pumps to 8psi. Do I need a new pump?

Also.. do I need the road speed sensor and where does it connect? Would this effect the engine running

Your help would be greatly appreciated.....

jamesmartin · Mar 20, 2011

pump needs to produce 34 psi to run, have you connected wire to coil for efi to know its supposed to be running

MattMatt · Mar 20, 2011

Yep - I read up on everything before I did this so I know the wiring is right. The coil has a constant supply and the ECU is powered. I did have a small problem with finding the earth wires but that is ok now.

What kind of pump produces 34 psi?

jamesmartin · Mar 20, 2011

efi in tank pump ,can use early type that goes in sender size hole, wont run properly without high pressure

classic kev · Mar 20, 2011

MattMatt said:
I've just spent the day finishing up wiring up the 3.9Efi which now fitted to my 88" Series. It was a 200TDi before. Got all the relays clicktying and good spark at t plugs. Fuel in - fuel pump ticks - turn key - BINGO......

Then it died....

Tried it again and again - it fires - runs for a few secs - then dies.

From what I've read here and there this is typical "air leak in the inlet system" stuff but before I go tearing it apart I have one or two questions for all those wise people who know much more than me....

The fuel system is pressuresed to 37psi? Really? That seems very high! I have a red top Facet but that only pumps to 8psi. Do I need a new pump?

Also.. do I need the road speed sensor and where does it connect? Would this effect the engine running

Your help would be greatly appreciated.....

Yes you need the high fuel pressure.

Road speed transducer is required on 3.9 efi system, the transducer tells the ecu to switch on/off the idle speed control, it may well be the case that your ecu is not stabilising the idle speed so the engine dies instead of idling properly. There should be a connection in to the efi loom for the transducer, it is a 3 pin plug IIRC.

If you do a bit of searching you should find a few threads about problems other members have had when doing this conversion so you can double check you've got everything in the right place etc.

MattMatt · Mar 21, 2011

I have done loads of searches and read almost everything I could before I attempted this. I haven't found anyone mention this problem before so if anyone has got some previous experience I would be grateful for some advice

classic kev · Mar 21, 2011

MattMatt said:
I have done loads of searches and read almost everything I could before I attempted this. I haven't found anyone mention this problem before so if anyone has got some previous experience I would be grateful for some advice

Search this forum, there are 9 threads that are related. Search for "speed transducer"

e4yob · Mar 21, 2011

HI, I used an external fuel pump when I did my conversion. I first tried an old facet red top fuel pump I had lying in the garage but it wasn't powerful enough so I got one simular to this on from ebay.
V8 EFI external Bosch type 4FP Fuel Pump ROVER V8 TVR on eBay (end time 30-Mar-11 17:56:19 BST)
I never got round to wiring my road speed transducer up for about 6 months after I did the conversion and to be honest i haven't noticed any difference now that it is wired up, although some people do say that they have suffered from stalling problems with it not connected. I now need a speedo cable to go from the road speed transducer to the speedo so i can reconnect the speedo. it's a bit of a pain trying to guess my speed all the time. It was deffinately well worth the time and effort doing the conversion.

MattMatt · Mar 21, 2011

Thanks for the reply - just what I wanted to hear

BTW I have found and excellent site about installing the EFI including some bits I didn't know about tuning TuningTheRoverV8 by Eliot Mansfield. Some really good info

jamesmartin · Mar 21, 2011

how many times betore you believe you need high pressure pump

vougese39 · Mar 21, 2011

Totally agree with James pump is the first port of call
Yes you need to connect the road speed transducer use a range rover speedo cables to connect the transducer to the speedo head

MattMatt · Mar 21, 2011

jamesmartin said:
how many times betore you believe you need high pressure pump

Aw don't be mad - just getting all the info that's all

I've put one on order - just hoping it will cope with sucking the fuel out of the tank as don't have room for an additional pump and a swirl pot

vougese39 · Mar 22, 2011

the pick up in the tank has a 1/2" deep swirl pot but if you are doing major off road with big side slope angles then you will always need to keep the tank above half full of you will get running faults.

just anoth idea to throw in the smelting pot went to a customer a while ago who had done this conversion and the pump sucked all the ****e up and blocked all the injectors hope this is not your fault too

MattMatt · Mar 22, 2011

Dont think so - tank was cleaned out when I changed from the Tdi and I've got a big filter inline before the fuel pump

3.9Efi starts and dies - Fuel pumps Qs?

MattMatt

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