chris r Posted March 14, 2017 Share Posted March 14, 2017 A friend has just got a link for his car and I downloaded the software to have a look/play. Does anyone have pointers/tips or want to give me a walk through. I can bumble my way through but would prefer not to fuck his car. Wont be touching timing maps or fuel as dont have a wideband & its not my car to fuck Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 I'd have thought Link would have a fairly helpful help section or forum? I don't know Link ECUs at all so I cant help. Ok people of EFI.. I need some advice/help with surge tank plumbing. For ages my current fuel pump arrangement has been like this... But for ages it has always been a bit noisy especially when its hot outside. One time when arriving at my parents place in Blenheim on a stinking hot day and moving the car about on their hot asphalt the engine started idling lean. I felt the surge tank and it was really bloody hot. What I figured back then was that the hot fuel returning from the fuel rails was going back into the surge tank and the engine was not drawing enough at idle to bring in fresh cold fuel from the tank. This is possibly compounded by the fact that the surge tank is filled by a low pressure high volume Carter pump I had been using when the car had the Rotary. So on that day I ended up making the fuel table richer at idle to compensate and that worked fine for when the day was hot as but usually it just means the idle is too rich. I finally had got around to putting the Viva up on the hoist and having a look at things. I decided to add a tee to the return line went from the regulator on the rail to the surge tank. I then ran a line direct to the the return on the main tank and connected the overflow from the surge into the spare input on the tee. This did not work. In fact the pump was way noisier and engine ran lean. So I tried running the return straight back into the main tank and blocked off the overflow. I figured the surge tank would still fill up as any air would get drawn through. But no.. air does not sink... So that didn't work either. I've connected it back the way it was as I was in dire need to go for a strop over the hill to show off the car to my cousin. I took a photo and this what its currently like- you can see the brass tee I'd added when mucking about... After doing more research (that would be looking at stuff on google..) I have noted that almost all surge setups are like mine. So they all have the same potential issue of rising fuel temps within the surge tank. To me it makes more sense to have the return to the main tank.. so long as you have a lift pump that will always keep up with demand and keep the surge tank full. But the surge will still require a overflow to purge air out and that needs to go to the same return pipe on the main tank. Am I right? I don't think I can run the return from the rail into a tee on the overflow line that goes from the surge to the tank because the higher pressure would override the lift pump pressure and prevent it filling the surge. Man that's a tricky one to type..or picture. I figure I could add a second return into the main tank and run the rail return into that? All I know is that I need to stop the hot fuel going back into the surge. I dont really require a huge surge tank as the car does not see any D1 hardcore action. But if the main tank is low its nice to know I wont get any starvation out of a tight set corner heading up Takaka hill etc. Obviously newer cars have in tank pumps with sumps etc so they don't starve nor do the pumps get hot. I'm not keen on having to build a whole new tank nor do I have a heap of room where my current setup is mounted. Not at all keen on a setup in the boot as my boot space gets filled with bikes or camping gear often and I dont want added clutter. Ideas? I might sleep on it... P.s.. Also I am wondering about the effects on fuel pump pressure when the voltage from the alternator goes up and down. If my car bogs down at idle due to my idle not being perfect (due to above hot fuel issues etc) I note that the fuel pump sound changes..like its struggling from the low voltage the alternator is putting out when the engine bogs. Does this voltage change actually make much difference to pressure at the injectors or is there enough leeway from the fuel rail pressure regulator to compensate? Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted March 19, 2017 Share Posted March 19, 2017 What about a larger return from surge to main tank? It might let the lift pump.flow more cool fuel to the surge tank by letting more warm fuel back out Edit. Also what about a speed controller for the high pressure pump No idea on current needed but jaycar has good PWM speed controllers..You could set it to half speed and use an output from the MS to flick a relay and supply full pump power when throttle or rpm or something dictates Quote Link to comment Share on other sites More sharing options...
Yowzer Posted March 19, 2017 Share Posted March 19, 2017 Why not fit a fuel cooler? Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 It just seems odd to have to fit a fuel cooler when it should be getting fresh cool fuel from the tank anyway. Plus lack of room, hassle of having extra crap under car. Yeah Nathan, I was wondering about pump controllers. But spendy plus if it was plumbed right it shouldn't need one. I think. Im mean the performance is fine except this hot fuel issue. Oh and the problem with fitting larger return from surge to main tank is the weakest (smallest) link will be the small 6.5mm inlet into the tank. That will always be the restriction. If I bother to make that bigger I'd rather just add a second return inlet into the main tank instead - run one from the surge overflow and one from the rail return. hmmmm 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted March 19, 2017 Share Posted March 19, 2017 I had good success with insulating my fuel rails, with plastic washers under the bolts. Rather than steel bolts going into hot head > rail directly. I actually bought a fuel cooler to help address this problem but didnt need to after that. Previously the whole thing would be too hot to touch if I had say 1/4 tank or less on a hot day. 2 Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 My rails are cast alloy and already have plastic washers fitted ( superior mazda technology...) I think it's heat soak from sitting in the vee and the fact that warm petrol just circulates at low revs. Is your return straight to the tank ? 1 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted March 19, 2017 Share Posted March 19, 2017 Bentley uses the A/C system on some of its cars to somehow cool the fuel Could it be that the pumps are heating the fuel? Maybe do a test with the lift pump running for 30 min by itself and then with the EFI pump running by itself and see if either one of those is responsible somehow? Just seems odd to me that the lift pump itself can't supply enough cool fuel. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 The lift pump won't run the engine but I think you mean run it through with engine running? I highly doubt the presure pump would or could create this sort of heat though.. especially in a recirculating system. I can disconnect the lift pump and the system will still work.. I discovered this early on one of the first drives over to Blenheim where I'd stopped to just check the setup for leaks and realised I'd not reconnected the leads to the lift pump. I think those commy external pumps can suck enough to work that way. It really needs to bench tested I reckon. Might do that. Wondering if the sound at idle, a high pitched gurgling sound, could be cavitation? Only noticeable at idle but then again once moving it would be hard to note any sounds over road noise. It's annoying as its the loudest aspect of the car. I'll certainly add more rubber mounts than I have to try and quieten things. Quote Link to comment Share on other sites More sharing options...
fletch Posted March 19, 2017 Share Posted March 19, 2017 Fuel pump controller? My skyline had one and I think some other efi cars I have messed with have had them. Gives the pump lower voltage unless pedal is mashed. I think there are a bunch of diy pwm controllers out there now. Quote Link to comment Share on other sites More sharing options...
kws Posted March 19, 2017 Share Posted March 19, 2017 I would have thought this would be he best way to run it. Return to tank, and a separate overflow back the tank. *not my image, but makes sense. Hot fuel goes back to tank and doesnt go anywhere near surge. 3 Quote Link to comment Share on other sites More sharing options...
Rookie Posted March 19, 2017 Share Posted March 19, 2017 A fuel cooler is definitely not needed for an application like this. As for how to fix it, my bet would be running another fitting into the fuel tank and plumbing the return in there. Your MS should also be able to control the fuel pump with the built in PWM so hook that shit up too, as it makes a diference on over pumped cars. Also to answer your question about fuel pump voltage making a difference, yes, it makes a huge difference and will effect your fuel pressure significantly, which you should be logging is you aren't already. Use the technology Alex! 2 Quote Link to comment Share on other sites More sharing options...
kws Posted March 19, 2017 Share Posted March 19, 2017 My Rover is old school as fuck, it just runs a big resistor on the power feed to the pump, to drop the voltage. Its factory like that, and apparently to reduce noise, lol. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 Technology scares me Dave.. it was a bold step going this far. But yeah- actually I never realised my MS has a pwm to control the pump. I'm pretty sure all my outputs are used plus are the pwms able to handle the current of a fuel pump? I need to learn more. The pump was is a Fuel miser(misery) replacement for a commy, V6 I think, so should be about right. Anyway... I think I may well have found a major contributor to the problem. Please see here in photos.... Crikey. That was a lot of shit. In bench testing the lift pump was barely skirting out a dribble. Fuck knows how the main pump was able to even get anything let alone run the engine!!!! Removing the pre-filter and the lift pump went from a dribble to a bloody good flow. Hannah will pick up a new filter today and while this lots out Im going to add another inlet to my tank so I have another return option. I think there may well be some re-mapping coming up..... 4 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted March 19, 2017 Share Posted March 19, 2017 Good outcome! Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 Yeah its always awesome when ya find a proper fault and an easy fix. I honestly don't know how it managed to run like that..but no wonder the main pump was making all sorts of sucky cavitation sounds. Glad I'd fitted a filter but the maintenance man needs a kick up the bum.... Still going to play about with fitting a return back to the tank and see if it drops the temp however I bet with good flow now the surge might stay cooler. Plus interested in digging out more info on pump voltage stabilisation and that 'proper width monkey' stuff Dave was talking about. Moral of the story is..don't rely on your cat to maintain your fuel system because it obviously doesn't work. 2 Quote Link to comment Share on other sites More sharing options...
Ned Posted March 19, 2017 Share Posted March 19, 2017 wonder if thats why my china 044 is loud as fuck... /nah, will just be because china 3 Quote Link to comment Share on other sites More sharing options...
Rookie Posted March 19, 2017 Share Posted March 19, 2017 Also, I might have jumped the gun, I forgot you are running a MS!, so I don't think it can do PWM fuel pump control, soz babe. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted March 19, 2017 Author Share Posted March 19, 2017 I was wondering.. bloody poverty spec ecu. .. But I reckon I could still fit a 12volt stabiliser to the pump feed before the relay. Have it so the pump always sees a set voltage must surely help in consistency ? Quote Link to comment Share on other sites More sharing options...
Rookie Posted March 19, 2017 Share Posted March 19, 2017 But Good job on checking the simple shit first. Quote Link to comment Share on other sites More sharing options...
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