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Read Symptoms: We Suspect Fuel Pump. Make Suggestions To New Fuel Pump

SargeRX8

By SargeRX8,
in General Maintenance

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SargeRX8 Grand Master

SargeRX8

Posted
Posted (edited)

Hey all,

Well I just got my car back from the tuners. When it was there(advan) peter was telling me he was finding it hard to get a good 'cruise' tune as the AFR was erratically jumping up and down and he initially suspected some sort of compressor surge. He took it for a drive and it was responding well on the street. Today though I was having issues. The car would not want to start on me when it was warm. I'm not saying it doesn't do it when cold but when it was warm it was being a pain. It would turn turn turn for about 30 seconds and still nothing. After I did get it to start the PFC hand controller showed a knock read of 54. It didn't rev past 1400. Fuel pressure was checked and tweaked accordingly yesterday. One thing I did notice was the fuel pump doesn't sound like its priming. When I explained the symptoms to him over the phone he immediately suspected the fuel pump and he now thinks it was affecting tuning yesterday.

When revving the car in neutral and holding say 3krpm the revs splutter and sound like arse. Revving to 4krpm the revs splutter and drop by a couple hundred rpm. He is almost certain its the fuel pump. He told me if its not priming its a sure way of knowing its on its way out. The injectors are brand new nismo 740cc injectors coupled with the standard fuel rail, a nismo fuel pressure regulator and a brand new ryco fuel filter.

What do you guys think? Under boost and load it drives perfectly but now I am very cautious as I don't want it to lean out on me. Any way to test the fuel pump?

Can confirm fuel pump IS NOT PRIMING!

Edited by SargeRX8
shaund Enthusiast

shaund

Posted
Posted

First easy thing to check is the vacuum line to the fuel pressure reg. Make sure its a) there and b) giving vaccuum/boost. while idling with no load, pull the vacuum line off the reg and stick your finger over it. You should feel a bit of a suck. Ideally, a T piece and a mechanical boost gauge here goes well.

If the fuel pump is suspect, check the wiring and use a multi meter and check for voltage at the pump while its idling. Make sure terminals are clean and solidly attached - a bit of CRC is a good idea too. Check the workshop manual for the expected voltage. It may be in the range of 10-14V. The best thing to do after checking the electricals would be to attach a fuel pressure gauge to the incoming fuel line just before the rail. Any good tuning shop should have a gauge on hand. All it takes is a T adaptor and some small EFI clamps. 30 minute job max if a useless apprentice does it. This will show immediately any problems with pressure. At idle you'll get a reasonable idea, but a run on a dyno would be ideal. Standard fuel pressure while not on-boost is 3bar, and fuel pressure should increase linearly with boost, ie, 0.5bar of boost, fuel pressure should be base 3.5bar.

If you suspect flow isn't enough pull the pump out, get a clean bucket, fill it with say 2L of fuel, submerge your pump and pump it out into another clean bucket. Time it and compare to specs you should be able to find online for flow at whatever voltage you can drive it from (car battery with jumper leads?). Just make sure you don't get any sparks when connecting or disconnecting power. fuel will go bang with an electrical spark. Listen for noise when the pump is running. It should sound reasonably quiet and smooth. If its the original pump, it may have shagged bearings, or may have been damaged (can be rust on the outside as an indicator) by race fuels or corrosive additives.

If what you mean by "not priming" is that when you go from ignition "off" to "on" and you dont hear the pump running, its likely you're already at pressure and no priming is required.

If you turn the key from off to on (not start) and you hear the pump run for a few seconds and then stop, you can turn it back to off, wait a few seconds, turn it back to on and it will not prime as the system is already at pressure.

What fuel pump are you using? what duty cycle are you seeing on the injectors when you're seeing the problems? Perhaps you're running out of fuel because your pump can't keep up? A factory pump isn't big enough for 740cc injectors if you hope to use them beyond about 50% (in a GTR - GTS-t is less).

Good luck, and don't set yourself, your car, or your house on fire testing your pump :)

SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted

Hey man, cheers for the response. The pump is getting power its just really hard to start and when it does it splutters alot. The tuner also had alot of problems getting the afr right on cruising speeds and rpm levels. I've had this pump for about 2 years now and the sound it makes is very distinct. now I don't hear it do anything but a thud in the tank. I'm abit worried about doing that bucket test but I'm going to yank the pump out today and see what is up. The pump is a bosch 040. They are louder then stock, very audible. I can't hear it at all. the car always used to prime just not anymore. ill try give it direct power when its in tank and see what happens, if it primes, pumps or what not. regardless of that I do have a new pump on the way.

shaund Enthusiast

shaund

Posted
Posted

Does your car still have the pump speed regulator? It could be thats fried too and doing funny things too. Perhaps wire it direct and bypass the module and see what happens.

You hear a thud in the tank? Under what conditions? You shouldn't hear a thud :O

SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted (edited)

It thuds when its going onto ignition. It used to be a click and then the buzz now its a clunk thud sound. I took it to advan he just touched the throttle and hes like its leaning out badly and will pop and choke and only get worse under boost. He said the pressure regulator was fine but because of the thud in the boot and it being hard to start indicates hardly enough pressure and the fuel pump could be on its way out. He told me change it then go from there.

What is a pump speed regulator? Is that the standard regulator on the rail? Ive got the Nismo FPR on the car. I don't have a fuel pressure tester but can get and install a gauge to check the pressure.

On the drive to the tuner I noticed as soon as I come onto boost it gets alot worse. At 4800rpm my injector duty cycle was on 41%. Seems a little high for 740cc nismos.

Edited by SargeRX8
R.3.2.G.T.R Grand Master

R.3.2.G.T.R

Posted
Posted

look up fpcm (fuel pump control modulator).. i think its behind the driver seat side panel.. what voltage were you getting at the pump.. you can ground the fpcm and it wont switch between high/low depending on whether u at idle or not

SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted

look up fpcm (fuel pump control modulator).. i think its behind the driver seat side panel.. what voltage were you getting at the pump.. you can ground the fpcm and it wont switch between high/low depending on whether u at idle or not

I have done this as I was told when the car primes it only gets 7v and with this grounding point it gets 12v. I can hear the pump priming now but it still kicks in the tank and still pops and splutters. It really is undriveable and unfortunately doesn't look like aus posts guaranteed next day express post is guaranteed...

DVS JEZ Grand Master

DVS JEZ

Posted
Posted

As in the other thread. How is it mounted? I have had issues with the hose clamp around th body of the pump being too tight. But that was with a fresh pump.

Do as shaund said and try it out in a bucket of fuel or water.

Check the wiring inside the tank to the pump too

Otherwise just get a new one and see.

SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted (edited)

This pump has seen about 40000km of use maybe a little more. It hasn't had any issues in my old car(although my old car would always lean pop when cruising and touching throttle). Its just started after the tune.

I'm going to pick up an electronic fuel gauge tomorrow and fit it in. Should I still be seeing the standard 42psi when running a nismo FPR and nismo 740cc injectors on the stock rail? I'm also running about 10psi low/12psi high boost for about 230rwkw low boost/245rwkw high boost.

It sounds like its working after grounding the negative terminal but it doesn't feel like its working correctly. It sounds like misfire but its not misfire, its just a very quick, random sequence of lean popping. I can get a video but I don't want to risk damage...

It does it on idle so I very much doubt its misfiring. I'm running .7 gap on bcp7res with yellow jackets. They were fine on 1.1 gap on standard boost and turbo but with this turbo they were losing spark as soon as I came onto even 6psi of boost so peter gapped them to .7

Edited by SargeRX8
SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted

Take the fuel line off at the rail and check there is sufficient flow.

How old are the inj? Did u get them flow tested if theyre 2nd hand?

Injectors are brand new, never been installed until we fitted them in the rail. I'm going to go autobarn or some shit and buy a fuel pressure gauge. I just called up a spare parts shop they have a GTR fuel pump for $120 fml I wouldn't have bought the 040 if I knew and I could have gotten it today. I guess I can and keep the 040 spare. The GTR pump will be a more suitable lift pump for the surge tank too. If I do get a fuel gauge, do I install it between the filter and the fuel rail? What fuel pressure should I be reading for what I'm running? 43 on idle? Maybe if its on the downside I can adjust the regulator to compensate for the lazy pump or is that a bad idea?

SargeRX8 Grand Master

SargeRX8

Posted
  • Author
Posted

Just fitted in a GTR fuel pump, the problems are gone. Low down its still shit because the old pump was failing and the tuner can't get a straight afr so its still rich then lean then rich then lean. But f**k yeah, it starts now, I can hear it prime, it runs just fine under boost and holds power all the way. f**k yeah lol.

Should I run the fuel pump with the negative line grounded to run it at full speed all the time? My brother suggests I do so I did for now.

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