P6 V8 manifolds and loss of power

Going to get head back on mine tomorrow if it doesn't rain...started cleaning painting heater pipes as had new hoses to put on decided electric fan housing needed a lick of paint that made the wiring look tatty...see where I'm going with this lol...good luck!

Hope it goes well! My heater's not even connected ... no doubt the matrix is full of holes or something! Just refurbed the Ninety's heating and it works (as well as a Landy heater ever does anyway!) now so that's one job ticked off. Hope your paint is tougher than mine - bought some Simoniz 'Tough' Satin black and Red Oxide, scrapes off with almost no effort at all, so will all probably need redoing, but it'll get me a couple years while I sort out some of the other issues

Managed to snap the pump's outlet barb off (brittle plastic didn't like me pulling the nasty (?)PVC hose off) so have ordered a new one with built in pre-filter and one-way valve - it's got a 1.2m header rating so won't have problems at all fitting right in where the old one was. New filter and hoses are in place so fingers crossed the pump shows up soon! Never mind, gave me the chance to put the Ninety's wing mirror back on after a quick spruce-up, and look up how the cold-start cable / switch / light system works, so not wasted time.

So, on request, an update! I've finally had time to go and at least fit the pump, had to mess around as it was a different setup (inlet/outlet at opposite ends rather than beside each other) but I think it'll work. Thing needs to be mounted at 45 degree (presumably to avoid airlocks in the pump body itself?). Photo to follow shortly. That was yesterday, unfortunately it started peeing it down (remember, doing all this on the roadside) so that was that. Hopefully tomorrow'll be nicer and I can get the wiring and hose all hooked up and give it a go!

For anyone who reads this later (for posterity innit) I finished installing the pump, but it wasn't that. Next step drilling a hole in the fuel tank and installing a fuel return pipe and line from the carbs, still working on the assumption it's flooding for now!

What does it have for an air filter ?........I'm wondering if your having carb iceing problems ..........it feels just like fuel starvation

Nick666 said:

For anyone who reads this later (for posterity innit) I finished installing the pump, but it wasn't that. Next step drilling a hole in the fuel tank and installing a fuel return pipe and line from the carbs, still working on the assumption it's flooding for now!

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Do I get a hint from this you've sorted it? But don't want to let us know cause of your new thread!...if so I'm intrigued and can't wait for an update...never seen a v8 dip stick like that before by the way...

Moron said:

What does it have for an air filter ?........I'm wondering if your having carb iceing problems ..........it feels just like fuel starvation

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The PO put them in just before I picked it up, he'd been pretty good with the oil changes and whatnot so I haven't replaced them yet as it's not done more than 400mi since - so I don't know for sure! But I'm told they're two of the Rover P6 air filters. Which given that's what the engine's from makes sense. What makes it slightly more interesting is that the P6 airbox doesn't look like that. Another mystery to solve!

Shippers said:

Do I get a hint from this you've sorted it? But don't want to let us know cause of your new thread!...if so I'm intrigued and can't wait for an update...never seen a v8 dip stick like that before by the way...

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No, not sorted! So I'm looking forward to a solution as much as you are
Dipstick? Hey presto.

How much fuel is getting delivered to the carbs? Disconnect the pipe just before the 1st carb and run the pump (with a jar to collect any fuel) if its only a trickle, try running the pump with the fuel filler cap off. If the air hole is blocked then air can't get in the tank to replace the fuel the pump is trying to remove, it might be partially blocked so the pump can pump just enough fuel to allow it to idle but not enough to refill the float chambers when pushed harder. I had this problem with a V8 in a 90 once - took me ages to find it.

It's certainly easy enough to check that, and I wouldn't have thought of it, thanks v much!

You found the problem to your power loss yet?

Not yet! Been waiting for a female 7/16" UNF to 8mm hose connector (arrived today) so I can fit a hose to the return. Going to test it out into a jerry can first so I don't drill the tank for nothing. Hopefully this weekend (although have a stack of other jobs to do as well so ....).

Sorry meant to add, I did have a go with the fuel cap off but didn't seem to be the key. I'm going to keep it in the back of my mind though, might be a combination of things after all...

Good luck with your search and let us know when you find it.

Nick666 said:

Not yet! Been waiting for a female 7/16" UNF to 8mm hose connector (arrived today) so I can fit a hose to the return. Going to test it out into a jerry can first so I don't drill the tank for nothing. Hopefully this weekend (although have a stack of other jobs to do as well so ....).

Sorry meant to add, I did have a go with the fuel cap off but didn't seem to be the key. I'm going to keep it in the back of my mind though, might be a combination of things after all...

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Where are you going to fit return...the pic i posted from my setup on your other thread shows return is much smaller than 8mm and is the last connection to the fuel system...the engine is the original LR install for 101 as the left rocker cover has the extended oil filler...and the fuel pipe set up is as the diagram in the MD supplied repair manual that came with it

Modification as per the attached. The internal diameter of the new hose nozzle is significantly smaller than the other ones I have, interestingly enough, although the OD is the same.

Brief update here for future reference - wasn't the fuel return on its own anyway, although I think that's improved things slightly. I'm going to replace the distributor / coil / leads in one with the SimonBBC kit, given (having tested it) the vacuum unit isn't working anyway and it'll tick a few things off the list. Also the carbs almost certainly need rebuilding which I suspect may be the biggest culprit - new floats at the same time. The gauze on the pickup pipe isn't as-new but certainly doesn't look clogged or like it has had anything blocking it so that's good at least. Will update as and when I find anything!

My 1974 88 has a Rover P6 auto in it and doesn't have a fuel return. It has a Facet fuel pump and an in line filter after the pump (just a generic 2 inch round job (you can see it to the right of the airbox) but you can see the fuel in it so a good indicator that you're getting a good feed). Your plugs should be short reach not long reach (did I read that?) - i use NGK BP6HS (they are the right colour) but I think original should be BP5HS. Mine has a Simon BBC electronic dizzy now as the 1971 original was worn and I don't really like points and condensors. My airbox is like this except there is a silion hose coming off it into a stainless 90 degree pipe with a K&N filter on the end (by the radiator) and the 2 original filter removed.
[GALLERY=]

Yes I think yours is the proper P6 airbox - not sure what mine is, seems odd to be off-centre like that but hey, it works. Marked as made by 'AC'. It's been sat since I last updated as haven't had the time (or cash) to do anything with it - will probably try a SimonBBC distributor next as the vacuum unit is shot at the very least. Hopefully end of the month although might have to be July! Oh and have just seen Sunny's wheels are a bit knackered so probably have to get new ones first (since at least Sunny runs!). Sigh.

Having read through this thread I agree with Shippers in the earlier post - I think you're trying to over complicate the issue. I don't run a return on my 3.9 with SUs and Facet copy pump. If fuel is coming out of those vents then the fuel shutoff valve is not working or the float is stuck. Fuel shouldn't come out for any other reason. So as long as you have fuel coming into the carbs at a reasonable rate at around 3psi (any more will overpower the fuel shut off valve -you could fit a Sytec regulator to compensate) the SUs should work fine if in good condition. I think your's might need some TLC

If you are going to rebuild your carbs with a kit from Burlen beware of the Stayup floats as the are handed left and right. I've also had problems with them jamming the fuel cutoff valve if the tab is not level so really test them before fitting the carb back on the manifold as they are a pig to get on an off (I've rebuilt loads of these)

BTW - I do have clear pipes from the vents that empty below the sump just in case the valves stick as it doesn't get started every week and you don't want fuel washing around your inlet manifold. Turn the pump on and see if anything is coming out of the pipes - if so whack the carb bottoms LIGHTY to free up the floats/valves

No there's no fuel coming out of the vent pipes. I'm pretty sure my carbs do need an overhaul, but the distributor is a bit knackered too, so I'm going to start with that for now since I still haven't done anything irreversible e.g. drilling holes in the fuel tank so I can just put the plug back into the fuel return at the moment. Then tune the carbs and see how that goes. If it doesn't work, then I'll look at rebuilding them (not really looking forward to that mind!). Got it started today though and it seemed happy enough idling with just a bit of pressure on the pedal which it hadn't before. I've been giving all the linkages springs etc liberal doses of 3in1 and they all move a lot more smoothly than before.