Thread: Relability carburettor 3.9 how to?

Dunno why you think the EFI is particularly unreliable, carry a spare fuel pump and an ignition module and that's 99% of their common problems covered. All the working parts of an EFI system can be carried off a wrecked donor vehicle at little cost. Back when they were new they cost a lot more because second hand wasn't available much.

Anyway there's no way I'd ruin a 3.9 with a Holley, I'd get a set of standard carbies and manifold off an earlier Rangie, they work well and you carry a couple of diaphragm kits for them. It won't be legal of course. The EFI harness is almost completely separate from the rest of the harness, not hard to remove.

But if you're into wholesale removal, I suggest you remove the motor too and fit a diesel from a Disco, now there's reliability and double the fuel mileage too.

While it is certainly not difficult to put a carby on that engine, there are a few things you should consider before you do.

For a start - legality. You wouldn't be legally able to take that year model back o a carby as it wouldn't meet that years emissions requirements. If you needed a RWC or insurance, etc, that could be an issue.

Aside from that the easiest way would be to bung a manifold and carbs off an older 3.5 but those carbies may not suit your needs. The Holley is not suited to offloading and will starve the engine of fuel when going up and down hills. The Edelbrock would be the same.

Wiring would be easy, just unplug the ECU, and ditch all the wiring oing o the injectors and sensors. The starter wiring is independent of the ECU, so that's done and then you just make sure the ignition supply to the oil is still maintained.

i agree with Bee Utey - the EFI is far more reliable than carbies in the longer term. If you have concerns get second efi bits from wreckers and carry them.

Also agree if you do go crabs but on the standard 3.5 strombergs - much better than the holly and arguably more fuel efficient.

Garry

easy,

remove the 3.9s inlet manifold, bolt on a 3.5s with a pair of cd175's

rip out the electonic dizzy and drop in the guts of the dizzy from the 3.5 add the coil and your basically done.

last thing to do is to add a fuel pressure regulator and maintain the in tank fuel pump or rip out and shred the guts of the fuel pump assembly and install a facet pump to run the cd175s

not difficult but also not worth the effort, the main killers of the landy EFI are about the same as the killers for the carbies, blocked filters and stuffed pumps.


personally in your situation the most frequent engine stopper is the spark electronics, sort that out and the vehicle is good to go.

Starting to think carby is the way to go as well

My 1994 Rangie 3.9 averages 40l/100k. Motor done less than 190,000ks Absolute joke.

Replaced-

ECU temp sensor
dizzy
coil
plugs+leads
new air flow meter
stepper motor (was faulty)

Checked there is no vac leaks. Brakes are free. My old 1990 used to average 20l/100k and I thought that was bad!

I'm out of any other ideas apart from ripping it all off and throwing a carby on. Or give up and sell cheap.

Camo

Originally Posted by Camo

Starting to think carby is the way to go as well

My 1994 Rangie 3.9 averages 40l/100k. Motor done less than 190,000ks Absolute joke.

Replaced-

ECU temp sensor
dizzy
coil
plugs+leads
new air flow meter
stepper motor (was faulty)

Checked there is no vac leaks. Brakes are free. My old 1990 used to average 20l/100k and I thought that was bad!

I'm out of any other ideas apart from ripping it all off and throwing a carby on. Or give up and sell cheap.

Camo

Leaking injectors, high fuel pressure (dodgy regulator), etc... Are you just swapping parts hoping this will fix it ?? I would be checking for example the temperature senders readings at the computer, not at the sender. This also tests the wiring as well. There's no point replacing a temp sender if the wiring from it back to the computer is dodgy etc...

I'd be driving everyone on here insane trying to getting wiring schematics and locations of the various components so I could do some fault finding. I always refuse to change parts unless I can verify they are no good. For example, why would I change a temp sender if I chucked an ohm meter on it and found it's resitance was within spec.

seeya,
Shane L.

Originally Posted by DoubleChevron

Leaking injectors, high fuel pressure (dodgy regulator), etc... Are you just swapping parts hoping this will fix it ?? I would be checking for example the temperature senders readings at the computer, not at the sender. This also tests the wiring as well. There's no point replacing a temp sender if the wiring from it back to the computer is dodgy etc...

I'd be driving everyone on here insane trying to getting wiring schematics and locations of the various components so I could do some fault finding. I always refuse to change parts unless I can verify they are no good. For example, why would I change a temp sender if I chucked an ohm meter on it and found it's resitance was within spec.

seeya,
Shane L.

Yep everything checks fine on the laptop. At first the ECU temp sensor was not working and thought was an easy fix! didn't do anything:-(

Also forgot I put a new vac advance on as well.

Where is the fuel pressure regulator?

Originally Posted by Camo

Yep everything checks fine on the laptop. At first the ECU temp sensor was not working and thought was an easy fix! didn't do anything:-(

Also forgot I put a new vac advance on as well.

Where is the fuel pressure regulator?

It'll be next to the fuel rail somewhere ... Mines too old to be injected. All you need is a fuel pressure gauge anywhere in the fuel rail to check it. Have you checked none of the injectors are leaking? Also check the cold start injector if it has one (to check these I just pull the fuel line to them and blank it off).

seeya
Shane L.