No Voltage At Fuel Pump

[Craved]

This is awesome, i have been using a manual fuel pump switch for both std and external pumps as i was not getting power to the std pump relay..

have printed this out and hopefully able to repair it all , then use the std power feed as the trigger for my dual relay setup.

cheers for keeping into your thread, nice to see someone complete their progress and post the results.

Nice Work Govich

[dk_fabiosantos]

I didn't actually find the FPCM. I've grounded the negative terminal of the fuel pump just outside the tank and this bypasses all the varying ground shenanigans and gives the full voltage at all times. I looked for it for about 30minutes before realising i didn't have to anyway.

edit: and yeah it is just basically a variable resistor

So basically you have no fpcm right?You only have a pin 104 coming from the dashboard fuel box to the relay and from the realy to the (-) and battery(+)?Cause on r32gts the fpcm is wiring connect to fuel pump too.

Thanks for the infos!

Edited October 2, 2007 by dk_fabiosantos

[govich]

So basically you have no fpcm right?You only have a pin 104 coming from the dashboard fuel box to the relay and from the realy to the (-) and battery(+)?Cause on r32gts the fpcm is wiring connect to fuel pump too.

Thanks for the infos!

I do physically have a FPCM in my car, and Pin 104 from the ECU still goes to it, but its operation is bypassed by having a chassis ground on the fuel pump negative terminal. Electrically the FPCM may aswell not be there as there is negligible current running through it compared to my chassis ground. ie. if the FPCM wasn't in the car, the car would perform the same, except maybe the ECU would throw out an error code for FPCM malfunctioning (not sure if there is one).

Hope that helps, i might draw up a diagram if you'd prefer. Don't have time now though.

In other news, my fuel system is AOK 100% but the car won't start again, this time it sounds like it isn't firing (i wish i could run the car off the fuel pump because it sounds so damn loud and eager), so i have to diagnose the whole spark side of the system. There's no blown fuses anywhere either. I think this car is playing with me, because it splutters into life and then turns off just as quickly on the first try after leaving it resting for a while, but then won't even fire after that. I've checked the whole fuel system, tried the direct battery feed to fuel pump positive, makes no difference. Might even be a blockage somewhere, but i'm pretty sure the motor is getting fuel, and the fuel pump isn't straining.

edit: the problem here ended up being a hose coming loose from the idle air control valve assembly, the engine started fine with a bit of assistance on the gas pedal.

Edited March 14, 2008 by govich

[Tao]

Did you ever find the solution to your no-start issue? I'm having almost the exact same problem with my r33 gts-4. I was not getting any voltage to the fuel pump. It does pump wonderfully with a direct feed though. I've ran a direct ground to the negative terminal on the battery. It also randomly starts when I try, I can hear the pump prime when it does start. However, I ran the pump directly off of the battery and the car refused to start anyway. Is it possible that this is related to the AFM or any other part? When it does start, 1/2 the time it runs perfectly, the other 1/2 the time it likes to cut out. It acts like there is a vacume leak after the AFM.

[govich]

Did you ever find the solution to your no-start issue? I'm having almost the exact same problem with my r33 gts-4. I was not getting any voltage to the fuel pump. It does pump wonderfully with a direct feed though. I've ran a direct ground to the negative terminal on the battery. It also randomly starts when I try, I can hear the pump prime when it does start. However, I ran the pump directly off of the battery and the car refused to start anyway. Is it possible that this is related to the AFM or any other part? When it does start, 1/2 the time it runs perfectly, the other 1/2 the time it likes to cut out. It acts like there is a vacume leak after the AFM.

To me it sounds like something (wiring, relay, etc) might be loose somewhere and is intermittently losing contact. Is it blowing any fuses? To be honest though, there's a lot of things it could be. You could try checking if there's any fuel pressure in the lines straight after it cuts out, to see if failure of the pump causes it to cut out from starvation..

These days whenever i read cut-out the first thing that jumps to mind is loose AFM contacts. Here is a thread on repairing the AFM.

Intermittent problems where there are no real traces of the problem are probably the most annoying, so good luck.

Edited March 12, 2008 by govich

[Tao]

To me it sounds like something (wiring, relay, etc) might be loose somewhere and is intermittently losing contact. Is it blowing any fuses? To be honest though, there's a lot of things it could be. You could try checking if there's any fuel pressure in the lines straight after it cuts out, to see if failure of the pump causes it to cut out from starvation..

These days whenever i read cut-out the first thing that jumps to mind is loose AFM contacts. Here is a thread on repairing the AFM.

Intermittent problems where there are no real traces of the problem are probably the most annoying, so good luck.

It is possible that it is the wiring/relay. I tried the Air Con relay in place of the fuelpump relay. No help there. There was a parking assistant that was installed. They had spliced into the wiring behind the fues box. I'll try fixing that today, although the wiring seemed fine yesterday when I took it out. the AFM is also on my list, I already re soldered the connections to the plug, I think I'll try pulling it out and re soldering the points behind the copper plate today. It is terribly annoying, I'll post back up and let you know how it went. Thanks a million.

edit: Almost forgot. No fuses have been blown

Edited March 12, 2008 by Tao

[Tao]

I fixed it. It was a loose ECU plug. Thanks again for the help

[dangerman4]

hey guys

just to clarify a couple things.

if you have no power to the fuel pump relay it may be because the engine control fuse under the steering wheel has blown.

this is generally caused by the wires to your O2 sensor in your dump pipe earthing out on your brake lines.

with mine i found that some of the insulation on the wires had cracked off due to heat and then the wires were earthing out causing the engine control fuse to blow. this also powers the idle control solenoid, and also the pfc boost controller.

worth checking.

[bahanthich]

i may have missed something, but i cant see where you mentioned what the problem is if you keep blowing the 15amp fuse for the fuel pump in the boot?

I have installed a walbro fuel pump (is mounted securely), (highflow version 255l/hr - apparently) and about a week after i installed it. I blew the 15amp fuse. About 10 minutes after putting another fuse in (15amp), i blew it. I used a 20amp fuse to drive it home, but dont want to leave it like/drive it this until i can fix it. I had to use a crimp to connect the positive and negative cables of the fuel pump (supplied with the fuel pump) to the factory wires.

Ive seen a few posts about walbro fuel pumps being installed, and this fuse blowing but couldnt find a resolution except possibly replace the wires?. Do upgraded fuel pumps need bigger fuses? In another post http://www.skylinesaustralia.com/forums/fu...ump-t76328.html it says generally max current for a fuel pump is flow/hr divided by voltage. so with the walboro flowing 255l/hr / 13v is around 20amps. does anyone know what the stock wiring supports (i presume its probably 15amps because thats what the stock fuse is). Should i replace all the stock wiring for the fuel pump, and then install a larger fuse (or keep the 20amp fuse).?? Does this mean the relay also needs to be replaced with one which can support more amps?

[racingr33]

Hi Govich

I have a 1996 R33 GTS-t manual modified.

I know you posted this a long time ago so I hope you are still online.  I am having a similar problem however I don't have an A/T fuse. To give some history I left the car sitting for a long time and the fuel pump seized (Walbro) and I have it earthed properly bypassing the FPCM etc. When I found it was seized I tried fixing it by pouring rust remover in it which cleaned the rust out and that got it moving slightly so I plugged it in for 30 seconds and tapped it but it wasn't working so I removed it but noticed it was warm. I then decided to check if there was power to  the pump but there isn't. I have traced it back to the trigger wire from the FPCM ie if I earth that wire I get power to the pump. I can't figure out why it isn't triggering but Is it viable to just earth that wire from the FPCM so that the pump will run continuous as soon as the ignition is turned on?