Thread: VN fuel pump progress

Aaah the bulgy fuel hose. If it's burst the pump may be still working.

Yeah the rubber bits aren't used. The Disco pump has a small base and rubbers that you re-use.

Well got it all in with lost of thanks from input here...fired up on petrol and all seemed good. Put the gas tanks back in and that worked fine...all seemed good then the next time I went to start I could here the fuel pump running but it wouldn't fire..finally did and seemed ok. I noticed that it was running rough and chuffing black smoke, ok when booting it but holding the throttle in any one spot ran rough and rich. Took it for a fang on the open road plenty of power up to fourth , never has had much pull in top..back home still rich . When I flick to gas it increases its revs by 500rpm and drops the same when on petrol..I think this may have been happening before but as the pump was so hit and miss mainly used gas....any thoughts? Gary

Commonest causes of rich running are 1. fuel pressure regulator vacuum hose fallen off the back of the manifold 2. ECU temp sender disconnected or faulty, its a 2 wire plug next to no.2 cylinder inlet tract. and 3. MAF faulty/left unplugged/incorrectly wired and ECU in limp mode.

Start the engine on petrol, do not switch to gas, see how petrol runs. If you then switch to gas and back to petrol while running, and this induces the staggers, your ECU is probably going into limp home mode because the MAF power supply was disconnected with the injectors. Peel back the boot on the MAF, test the brown/orange stripe wire for voltage. If it is the same as battery voltage on petrol but zero on gas, you need an alternative supply for it from before where the injector power was cut.

ECU limp home mode cancels if you restart with the selector on petrol.

Originally Posted by bee utey

Commonest causes of rich running are 1. fuel pressure regulator vacuum hose fallen off the back of the manifold 2. ECU temp sender disconnected or faulty, its a 2 wire plug next to no.2 cylinder inlet tract. and 3. MAF faulty/left unplugged/incorrectly wired and ECU in limp mode.

Start the engine on petrol, do not switch to gas, see how petrol runs. If you then switch to gas and back to petrol while running, and this induces the staggers, your ECU is probably going into limp home mode because the MAF power supply was disconnected with the injectors. Peel back the boot on the MAF, test the brown/orange stripe wire for voltage. If it is the same as battery voltage on petrol but zero on gas, you need an alternative supply for it from before where the injector power was cut.

ECU limp home mode cancels if you restart with the selector on petrol.

yes I have seen gas systems wired that way. Couldn't tell them though...'we're the gas experts, not you'.... eventually it dawned on them that a MAF cut will induce a limp mode....like I said to them a week earlier. Still, it was their workshop (unchargable ) time wasted, not mine


JC

Thanks heaps, just as you said power to the brown/ orange on petrol and non on gas..it ran great starting on petrol, same on gas and crap when switching from gas back to petrol....I've found where they cut the org/blk in the main loom and have wired through a relay, these two joins are live, whether it is on gas or pet, the yellow wire from the relay goes to the gas/ pet SW in cab, but the same yellow wire has a brown wire running off through a diode and to earth,.
Where in need your input ....is your comment " I need an alternative supply for it from before where the injector power was cut"
I really apreciate your help so far, and am sorry to keep bugging you..knowledge in my parts of the world is light..and as you can see even the " professionals " don't seem to know either ..I've included a couple of pics that might help...also what kind of gas conversion is mine?? Thanks again Gary

The diode and earth is a surge suppressor used to prevent switching spikes in the relay. Most installers use a suppressed relay instead, but there's nothing wrong with your setup.

As for the MAF, cut the brown/orange feed wire about 100mm from the MAF, connect a new wire to the MAF side and then connect that to the always live side of the relay wiring. Dead easy, I learnt this on my first D1 conversion over 15 years ago.

Converter says BRC, not that the system has to be all from one manufacturer.

Edit2: Still not a "nameable" system, it's basically a "simple" mixer system as opposed to a "complex" mixer system, such as Impco, OHG and other brands. Basically a BRC converter can be used on hundreds of different vehicles with the appropriate mixer. (And it can be replaced by a dozen different brands of converter without changing the system type.)

So am I right to beleive that VN Commodore onwards fuel pumps fit in place of the stock one on Disco's? Does that include late Range rovers as well?

Originally Posted by Vee_que

So am I right to beleive that VN Commodore onwards fuel pumps fit in place of the stock one on Disco's? Does that include late Range rovers as well?

What do you call a "late Range Rover"? All 3.9 litre RR (up to 1994) are essentially the same as the D1 in the fuel system design. GEMS injected P38's (1995-8) can also use the same pump AFAIK as they run a recirculating fuel system. 1999-on D2's and THOR engined P38's run a different pump altogether, higher pressure.