Wiring Questions For Intank Fuel Pump Upgrade

[kingtube69]

I think you've got the wrong idea...

SSR takes the trigger from the same trigger wire that comes out of the ECU to the relay at the back of the car.... do not use the output of the OEM relay to trigger your SSR because of the OEM relay dies you're f'd.

Hmm, this is what I understood was to be used based on the diagrams on the fuel pump rewire.. I thought that would leave the FPCM in tact therefore if the engine stops it wont keep pumping fuel. Are you able to draw a diagram or explain in greater detail?

Are you talking about the trigger wire on the ECU in the kick panel itself (run a wire to the back of the car etc etc etc)?

Used this as a comparison and it looked ok with the exception of the SSR

http://www.sau.com.au/forums/topic/234796-re-wiring-your-fuel-pump/

Edit edit edit (third time now )

I think I see what you mean, maybe I'm reading it wrong.

The SPST relay is an additional one I ran as per the link above. The SSR would go in before this and power up the SPST relay which is recently installed.. Does this make sense? To me its no different to the setup in the link but with the addition of the SSR to trigger the magnetic SPST relay instead...

Edited September 18, 2015 by kingtube69

[Dose Pipe Sutututu]

FPCM only controls the -ve, once you've snipped and earthed your pump the FPCM is bypassed

[kingtube69]

FPCM only controls the -ve, once you've snipped and earthed your pump the FPCM is bypassed

Hmm but that's not recommended right?

I have the grey wire which I'm assuming is the earth going to my relay in addition to the blue wire so going by what you said, its not bypassed right?

EDIT: Mine is like Cals on page 14 of this post

http://www.sau.com.au/forums/topic/91993-fuel-pump-direct-feed-rewire/page-14

Correct me if I'm wrong looks to be fine though

Sorry OP for hijack.

Edited September 18, 2015 by kingtube69

[GeeDog]

What John is saying is the the FPCM is originally connected between the grey wire from the fuel pump & earth - it simply switches a voltage dropping resistor in & out to reduce the voltage across the fuel pump. By earthing the grey wire, you have already taken the FPCM out of the circuit - it doesn't matter if you leave it plugged in or not. Don't confuse the FPCM with the original fuel pump relay, which provides the +12V to the fuel pump when the ECU decides it wants the pump running.

[kingtube69]

I'm still trying to wrap my head around it all but It seems to be fine to me. I just need to confirm the voltage but the priming works (senses no crank so only primes and doesnt run on)

I've spoken to Scotty and he confirmed that what I intend on doing is how it needs to be done.

I just took the car out for a drive and it runs as expected (normal)

Thanks for the help guys!

[scotty nm35]

There are many ways to run the relay wiring, but most of them seem to fail with these 460's in particular. The relays I use are Jaycar 70 amp, as the 30 amp ones don't last long. Even these 70 amp relays fail. I think it's just a lack of voltage to the coil, hence the contacts aren't pulling in well against the spring creating a high resistance joint. The higher current caused does the rest, blowing 30 amp fuses and melting plugs. Bypassing the resistors will bump the voltage up, but I also suggest the ssr as that diagram will work on any vehicle's pump wiring, no matter how it's setup, and would be easy to fit without modifying the stock circuit at all. Just a shame there isn't an SSR integrated into a relay, not that I have found anyway.

The ssr should supply a strong 13V source to pull the 70A contacts in hard, and switches on at the low voltage supplied by the stock pump wires, no earthing to the body required. (I always earth to the battery, just a habit of mine.)

Interesting some use the 30 amp relays with built in diode protection to stop back emf, not sure it's needed on such a small coil but perhaps they have had issues?

Pump signal straight from the ecu might be a better option, bypassing the stock relay, but with no current going through surely it would be more reliable anyway? Certainly a lot harder to run the wiring.

[sonicz]

Kingtube, I don't think its necessary to to do any Mods other than install the new pump in the factory location IF YOU have a need for it. If the stock pump is working fine, it is probably just perfect for you, so just leave it. Can I ask why your upgrading the fuel pump? If you don't have a exact purpose to do so for OTHER " upgrades" you are doing to the car, spend your time instead installing a fuel pressure gauge and regulator, that is much more helpful than a new high flow pump you probably don't need and especially one that is rewired for moah poaw!'

Heres why.

-Your stock pump is probably flowing enough, even good for up to 350hp.

-If you drop in the new pump you will probably be flowing too much, running rich causing crazy AFRs confusing the computer and possibly causing damage to engine, injectors, fouling up cat etc.

-If you drop in the new pump and earth out the grey wire you will be flowing even more and running richer. It not only bypasses the hi/low voltage switch but it raises the total high voltage output to the pump as well. I have 100% proven this with my own testing.

-If you drop in a new pump and do a direct battery rewire you will probably be flowing even more way to much.

So if you are upgrading pumps for the same reason I did, which was being told "these pumps are now 20yos old you don't want to risk leaning out and frying the engine.." Don't do it Its not good advice. Especially since you are never told anything about over fueling because the "stock FPR is fine and will handle it" and also that "the stock wiring is inadequate you need to do a direct wire".

Not only are you possibly trying to fix a problem that isn't there but you are making a problem out of nothing and spending time and money in the process. So check your fuel pressure under boost and if it isn't dipping, what need would you have for a new pump? You wont.

I stupidly replaced my stock fuel pumps on both my skylines and THREW them out out mind you on cars that ran perfectly and now I have been having all sorts of problems getting the right flow with an aftermarket pump. I have tried differing wiring tactics, different FPRs, the car is never happy any more. I was running 80psi off pressure through the injectors without knowing and neither did the car because it thought it had 43psi for years. This was ALL on the stock wiring just a high flow pump. Nothing has burned out, just ran stupidly rich and no matter what i do I cant get the pressure below 50psi unless I go look for a used factory pump and do all that effort to swap back out.

[kingtube69]

Kingtube, I don't think its necessary to to do any Mods other than install the new pump in the factory location IF YOU have a need for it. If the stock pump is working fine, it is probably just perfect for you, so just leave it. Can I ask why your upgrading the fuel pump? If you don't have a exact purpose to do so for OTHER " upgrades" you are doing to the car, spend your time instead installing a fuel pressure gauge and regulator, that is much more helpful than a new high flow pump you probably don't need and especially one that is rewired for moah poaw!'

Heres why.

-Your stock pump is probably flowing enough, even good for up to 350hp.

-If you drop in the new pump you will probably be flowing too much, running rich causing crazy AFRs confusing the computer and possibly causing damage to engine, injectors, fouling up cat etc.

-If you drop in the new pump and earth out the grey wire you will be flowing even more and running richer. It not only bypasses the hi/low voltage switch but it raises the total high voltage output to the pump as well. I have 100% proven this with my own testing.

-If you drop in a new pump and do a direct battery rewire you will probably be flowing even more way to much.

So if you are upgrading pumps for the same reason I did, which was being told "these pumps are now 20yos old you don't want to risk leaning out and frying the engine.." Don't do it Its not good advice. Especially since you are never told anything about over fueling because the "stock FPR is fine and will handle it" and also that "the stock wiring is inadequate you need to do a direct wire".

Not only are you possibly trying to fix a problem that isn't there but you are making a problem out of nothing and spending time and money in the process. So check your fuel pressure under boost and if it isn't dipping, what need would you have for a new pump? You wont.

I stupidly replaced my stock fuel pumps on both my skylines and THREW them out out mind you on cars that ran perfectly and now I have been having all sorts of problems getting the right flow with an aftermarket pump. I have tried differing wiring tactics, different FPRs, the car is never happy any more. I was running 80psi off pressure through the injectors without knowing and neither did the car because it thought it had 43psi for years. This was ALL on the stock wiring just a high flow pump. Nothing has burned out, just ran stupidly rich and no matter what i do I cant get the pressure below 50psi unless I go look for a used factory pump and do all that effort to swap back out.

Hi Sonicz,

I ended up going the bigger pump to get prepared for E85 - My goal is to get between 275 and 300 KW on pump fuel and over that on 85 in the near future.

I straight away had issues with how the car is running (would miss and so on). I then went out and got a Nismo FPR and gauge etc. Modified the flow to be 43PSI base but the car is still running a bit how do you do on boost.

It will be going for a tune in the next month or so and it hardly gets driven so I'm hoping it should be fine up until then. Once tuned I would guess that it will be back to normal/running right again.

Thank you for your message, I should have held off putting the pump in and left it to the tuners to do if I had known earlier

[sonicz]

What pump did you end up going with, and what was the fuel pressure reading? How far out is your screw on the nismo FPR to get a base pressure of 43PSI?. Make sure to set the base pressure of 43psi with the vacuum hose unplugged. Have you done a drive test and seen the fuel pressure as you hit boost and back down?

Yea when you are making drastic changes like fuel its a huge influence on the way the car runs. People just change fuel pumps willy nilly because of the "regulator" but its exactly the same as throwing in a new set of injectors without reprogramming the ECU. Actually its even worse as it delays the firing of the injector solenoid and sometimes the fuel delivery goes up, sometimes it goes down, sometimes spray pattern is altered etc, or all 3 at once.

And as you say with the new pump even when you bring the fuel pressure back down to where it should be, it still acts as you put it a bit "how do you do" under load. I think an aftermarket pump has different flow characteristics and different pressures and so it just isn't what the ECU expects.

What fuel pressure gauge did you use?

Edited September 28, 2015 by sonicz

[s2d4]

I am going to ignore whatever sonicz says.

[tridentt150v]

Whatever happened to the "only thing you need to do for a Series II was provide a proper dedicated earth lead nearer to the pump" tip. A very simple and easy mod that works, no real need for any other modification for a replacement in tank pump.

[sonicz]

Whatever happened to the "only thing you need to do for a Series II was provide a proper dedicated earth lead nearer to the pump" tip. A very simple and easy mod that works, no real need for any other modification for a replacement in tank pump.

Yup that would be good advice for light mods to the car. It would increase the voltage to the stock pump and provide a bit more flow for no cost and little work. The problem is people replace the stock pump with a high flowing one AND also do the wiring mods. This leads to way too much pressure in the system.

[tridentt150v]

If you could call pushing 300kw and a walbro pump with no issues....................light mods, then yeah I guess.

[scotty nm35]

Only when you have a restriction in the return, or if your chinese reg isn't up to the task.

I don't have an issue with my SX reg and 6an teflon braided return...

[kingtube69]

Whatever happened to the "only thing you need to do for a Series II was provide a proper dedicated earth lead nearer to the pump" tip. A very simple and easy mod that works, no real need for any other modification for a replacement in tank pump.

Heuh - I didn't know about this until now

My opinion was that the bigger pump would draw masses of current so it was worth doing the wiring upgrade - no?

Regardless my car running "how do you do" seems to be caused by other issues not the reg but I'll test that theory tonight when I get home

[scotty nm35]

My opinion was that the bigger pump would draw masses of current so it was worth doing the wiring upgrade - no?

The stock wiring is definitely not up to the task of running a single 460L. I have seen them draw over 25 amps at full load.

A 255 Walbro perhaps.

[tridentt150v]

I purchased the Walbro 400, an in betweener that is supposed to be the ducks guts for turbo cars blah blah.

http://www.full-race.com/store/fuel-systems/fuel-pumps/walbro-400lph.html

like this but I didn't buy it from these guys, they just had a nicer pic and blurb.

[scotty nm35]

The 400 is a good cheap pump, just don't run any ethanol through it. I would even be worried with e10 98.

[tridentt150v]

Can't get it out here, I use 98 sometimes, but mainly 96. I have WMI and don't go for or need anything with rotten vege juice in it!!!

Had a Nismo pump before [from Nengun so assume it was genuine], was getting very noisy, so I reckon it was on the way out - surprise really cos it hadn't done that much work, probably 40,000km max.

[scotty nm35]

Not sure on the specs on your premium fuels where you live, but I would be surprised if it doesn't have ethanol added at certain times of the year. Just making you aware, would be a shame to ruin another pump in a few months because you cheaped out on a few bucks to buy the ethanol compatible version.