Early RRC Fuel Tank Connections

[drover81]

Hi All - I'm trying to correct a few issues and it appears as though the spill return line has been plumbed into the fuel tank breather (and vice versa) - yet I can't locate anything to verify.

Hoping someone can check theirs and advise.

I have an early RRC Fuel tank (external fuel pump) - like this one:
Range Rover Classic Fuel Tank | Rimmer Bros (https://www.rimmerbros.co.uk/Item--i-GRID009260)

Spill return is plumbed up higher on the same side as the fuel tank level indicator (can't seem to locate a photo on the net of that side of the tank).

Breather is plumbed to the outlet coming out from the bottom of the tank (visible in the above link).

Is the plumbing back-to-front?

Thanks.

[Meccles]

Sounds wrong. Breathers should be up high, returns can be low.

[350RRC]

Hi,

The return line goes on the nipple / pipe that is right in the middle of the Rimmers image next to the the front mounting bracket.

They can get closed with rust so check that, or drink more fuel.

DL

[drover81]

Hi,

The return line goes on the nipple / pipe that is right in the middle of the Rimmers image next to the the front mounting bracket.

They can get closed with rust so check that, or drink more fuel.

DL

OK - sounds like it is back-to-front.

Thanks.

[drover81]

So I've started scoping what I need to fix the problem. Can anyone advise what the spill return fittings are? (AN4?)

The PO cut the original spill return line the engine bay and I need to plumb the 3/8 fuel return into it (the car is running a Holley pro-jection system). The projection system requires less than 4psi pressure in the spill return too...

[350RRC]

I would say that it's been plumbed the way described in the first post is because the puny return line and (possibly rusted) spigot into the tank was creating more than 4 psi of pressure.

Also if the tank is full the return would be pushing fuel back in against more fuel if using the stock spigot.. 4 psi is not much at all.

I'd start thinking some sort of tee fitting for return / breather from the breather source.

DL

[drover81]

I would say that it's been plumbed the way described in the first post is because the puny return line and (possibly rusted) spigot into the tank was creating more than 4 psi of pressure.

Also if the tank is full the return would be pushing fuel back in against more fuel if using the stock spigot.. 4 psi is not much at all.

I'd start thinking some sort of tee fitting for return / breather from the breather source.

DL
Yup, my backup plan is to tee into the fuel filler breather and plumb the tank vent into it. It might be a bit of a bugger considering the fuel filler breather is about 15mm ID, but possibly the nearest way to fix the problem.

[350RRC]

Hi,

Given the modded breather / return set up and the modded injection set up.......... what is the problem that you're actually trying to solve?

DL

[drover81]

It seems under certain conditions, the tank vents fuel through the spill return. Also appears as though the charcoal canister is plumbed to the carb on one side and on the other, fresh air.

Sent from my Mi-4c using AULRO mobile app (http://r.tapatalk.com/byo?rid=78345)

[Meccles]

This is a comment about the Holley Pro Jection system in a Jeep forum that might be of interest. Thread was about what makes Pro jection suck. consensus was that it didn't but needed correct tuning.

I'll agree w/ everyone, and say that they are a bitch to tune but seem to run well after you get it right. The closed loop kit is a definite must have, as it allows the ecu to make corrections to the mixture automatically. Also fuel pressure (https://www.ebay.com/sch/i.html?_nkw=fuel+pressure) is key, the correct inlet pressure and little to no return pressure.

[Meccles]

Apologies the quote had a link in it which is what posted. Try again. I suspect there aren't many RRC running this system, so may not be massive amount of knowledge wrt to how they work on RRC

"I'll agree with everyone and say they are a bitch to tune but seem to run well when you get it right. The closed loop kit is a definite must have as it allows the ecu to make corrections to the mixture automatically. Also fuel pressure is key, the correct inlet pressure and little to no return pressure"

This is from Jeep forum dated 2004

I'll agree w/ everyone, and say that they are a bitch to tune but seem to run well after you get it right. The closed loop kit is a definite must have, as it allows the ecu to make corrections to the mixture automatically. Also fuel pressure is key, the correct inlet pressure and little to no return pressure.

[bee utey]

It seems under certain conditions, the tank vents fuel through the spill return. Also appears as though the charcoal canister is plumbed to the carb on one side and on the other, fresh air.

Sent from my Mi-4c using AULRO mobile app (http://r.tapatalk.com/byo?rid=78345)

Sounds like whoever plumbed the EFI system reused the tank to canister line as the return line, not realising the canister needs to function for the tank to vent correctly. Personally I would dismantle the filler neck and fit a bulkhead fitting (nut on the inside) into the filler and plumb your new return pipe there.

It's quite easy to make your own bulkhead fitting, get a 30mm long 12-14mm mild steel bolt and nut, drill it through to 6mm ID or so, grind/machine off the thread for 15mm for the return hose to go on, then assemble the bolt and nut from inside the filler pipe with sealing washers.

[drover81]

Sounds like whoever plumbed the EFI system reused the tank to canister line as the return line, not realising the canister needs to function for the tank to vent correctly. Personally I would dismantle the filler neck and fit a bulkhead fitting (nut on the inside) into the filler and plumb your new return pipe there.

It's quite easy to make your own bulkhead fitting, get a 30mm long 12-14mm mild steel bolt and nut, drill it through to 6mm ID or so, grind/machine off the thread for 15mm for the return hose to go on, then assemble the bolt and nut from inside the filler pipe with sealing washers.
I think you're on the money - that's what I'm finding with this RRC. Somewhere in its history, there's been a lot of 'well, it kinda, mainly works!'

Cracking idea about the bulkhead too.