Omg Month Long Fuel Pump

[Damo Monster]

OK, so to give you a short version of the story:

I was cruising along in my R32 GTS-t do around 100km/h when all of a sudden it tried to stall/die on me about 5 times.. I wasn't on boost or anything, just cruising..

.. So I took it to the mechanic, who changed the fuel filter and ordered a fuel pump for it as he said the pressure out the the factory one was very low, indicating it was probably stuffed..

.. THREE WEEKS later he finally got some cheap looking no/name brand and fitted it.. When I drove the car after that, it tried to die/stall EVERY time it hit boost.. So I took it straight back..

.. He seemed to think maybe the pump was faulty or the wrong one.. At this stage I had really had enough, so I went on the net and had a 500hp Walbro pump delivered the next day.. Took it into him, and got him to fit it..

.. The car now seems to run sweet, wether cruising or boosing.. BUT.. if it comes to rest or idle, it now stalls/dies.. OMFG!!!! After fitting the pump that he supplied, I reset the ECU, other than that it had had the fuel filter changed, and I got an oil change while I was there.. Other than that, the car is fairly factory other than a turbo back 3" exhaust and a KN Panel filter. Also the car is an auto and is still running the factory RB20DET...

If anyone has any ideas what could possible be causing this, PLEASE let me know as I really miss my car and I'm not really sure this mechaninc knows what hes doing anymore

Cheers,

Damo

Edited February 23, 2010 by Damo Monster

[payback21]

Damo, try cleaning your AFM or changing it with another to try.

[Damo Monster]

Damo, try cleaning your AFM or changing it with another to try.

cheers for gettings back to me.. i dont think i have any hope of finding another afm anytime soon, so how do i clean the one i have? could i pull it apart and use contact cleaner or something? cheers

[BASHO]

cheers for gettings back to me.. i dont think i have any hope of finding another afm anytime soon, so how do i clean the one i have? could i pull it apart and use contact cleaner or something? cheers

Take it out and spray contact cleaner on it , try not to touch the wire with anything , just give it a few hits, read the instructions on the can they're pretty helpfull.

[boostn0199]

In regards to the stalling , is the type where u pop it into netrual and the revs just drop and car dies when you stop , if its that then that sounds like the blow off valve issue or afm dirty or the throttle body needs to be cleaned

[Adriano]

Take it to a mechanic who knows what he is doing. Start with a diagnostic check

[Damo Monster]

In regards to the stalling , is the type where u pop it into netrual and the revs just drop and car dies when you stop , if its that then that sounds like the blow off valve issue or afm dirty or the throttle body needs to be cleaned

no it seems to be the type where i slow down at an intersection, car still in drive with foot on brake to decelerate and once the cars comes to a rest, the revs drop right off and it dies.. if that helps isolate the problem?

[Damo Monster]

Take it to a mechanic who knows what he is doing. Start with a diagnostic check

lol.. yeah its funny how much faith we put in people sometimes.. i dont know anything about car repairs, but im starting to think i might as well have had a crack at it.. anyway, he has some bloody expensive scanner computer thing that he attached to the car in the beginning, but everything lit up as ok.. he also put a fuel pressure guage on the fuel lines near the engine, and thats when he said the factory pump was putting out very low pressure, and was probably the cause of all the probs.. the thing i cant figure is the change in the three pumps.. the factory one would cause the car to try and die whilst cruising at 100ks.. the second one he supplied would cause the car to try and die everytime the turbo came on.. and finally this walbro one seems to make it run sweet once its going, but cant seem to idle.. and come to think of it, im sure that car had a backfire when i was booting it a bit to test the car out with this walbro pump fitted.. it only happen once, so im not sure weather it was a backfire, or perhaps maybe i just hit a rock or something..

.. is there any chance the walbro pump would be poking far to much gas at the engine causing it to flood when trying to idle?

[scotty nm35]

The airflow meter needs to be swapped with a know good one. Its probably the issue. While you are there check for leaks and tighten all hose clamps, make sure all hoses go somewhere.

The plug pins where they go onto the circuit board of the AFM may have broken, these can be repaired with a re-solder.

[Swiper the Fox]

lol.. yeah its funny how much faith we put in people sometimes.. i dont know anything about car repairs, but im starting to think i might as well have had a crack at it.. anyway, he has some bloody expensive scanner computer thing that he attached to the car in the beginning, but everything lit up as ok.. he also put a fuel pressure guage on the fuel lines near the engine, and thats when he said the factory pump was putting out very low pressure, and was probably the cause of all the probs.. the thing i cant figure is the change in the three pumps.. the factory one would cause the car to try and die whilst cruising at 100ks.. the second one he supplied would cause the car to try and die everytime the turbo came on.. and finally this walbro one seems to make it run sweet once its going, but cant seem to idle.. and come to think of it, im sure that car had a backfire when i was booting it a bit to test the car out with this walbro pump fitted.. it only happen once, so im not sure weather it was a backfire, or perhaps maybe i just hit a rock or something..

.. is there any chance the walbro pump would be poking far to much gas at the engine causing it to flood when trying to idle?

These pumps need 13.5V to operate properly.

Did he wire in a new voltage feed and relay for the new pump?

The std wiring has a resistor circuit that is switched in at idle...starving the pump of voltage and starving your engine of fuel.

lol at the AFM people...he says it runs fine whether cruising or boosting so why say its the afm when it appears to be metering the air nicely.

Edited February 23, 2010 by DiRTgarage

[Damo Monster]

These pumps need 13.5V to operate properly.

Did he wire in a new voltage feed and relay for the new pump?

The std wiring has a resistor circuit that is switched in at idle...starving the pump of voltage and starving your engine of fuel.

no, he just did a straight swap on the pumps.. as in factory one out, new one(s) in to factory wiring.. didnt know about the resistor circuit stuff.. is it easy enough to bypass on the r32s?

[Damo Monster]

The airflow meter needs to be swapped with a know good one. Its probably the issue. While you are there check for leaks and tighten all hose clamps, make sure all hoses go somewhere.

The plug pins where they go onto the circuit board of the AFM may have broken, these can be repaired with a re-solder.

will try and examine the existing afm tomorrow.. as i said before, finding a known good one will be pretty much impossible for me to do, short of blindly buying a new one from nissan (which is probably worth more than the car )

[Swiper the Fox]

no, he just did a straight swap on the pumps.. as in factory one out, new one(s) in to factory wiring.. didnt know about the resistor circuit stuff.. is it easy enough to bypass on the r32s?

cut the earth going to the pump from the FPCM and attach it to a suitable earth somewhere on the chassis/body.

[Damo Monster]

cut the earth going to the pump from the FPCM and attach it to a suitable earth somewhere on the chassis/body.

oh god, im gonna sound dumb here, but i have to get this right so i can relay what to do / do it myself tomorrow.. what is the FPCM? would i be right in assuming that you are refering to the wiring loom that goes to the top of the plate where the fuel pump live under (i seem to recall it ends up being about five or six spaced out terminals)? and would i be right in assuming the the resistor is attached/switched on the ground wire, hence cuting the ground wire to the pump and simply earthing it to the body will result in it getting 13.5v full time?

thanks so much for the help!!

[Swiper the Fox]

oh god, im gonna sound dumb here, but i have to get this right so i can relay what to do / do it myself tomorrow.. what is the FPCM? would i be right in assuming that you are refering to the wiring loom that goes to the top of the plate where the fuel pump live under (i seem to recall it ends up being about five or six spaced out terminals)? and would i be right in assuming the the resistor is attached/switched on the ground wire, hence cuting the ground wire to the pump and simply earthing it to the body will result in it getting 13.5v full time?

thanks so much for the help!!

FPCM = Fuel Pump Control Modulator.

The earth can be grounded behind the drivers side boot trim as it runs up here to the rear drivers side under the trim where the FPCM lives.

Doing this wont give the pump 13.5V but it will run it so it will behave at idle. The factory wiring drops up to 2V with the increased load of running the larger fuel pump but in some cases ive seen it as low as 10.5V with the earth wire mod. done.

Edited February 23, 2010 by DiRTgarage

[Damo Monster]

FPCM = Fuel Pump Control Modulator.

The earth can be grounded behind the drivers side boot trim as it runs up here to the rear drivers side under the trim where the FPCM lives.

Doing this wont give the pump 13.5V but it will run it so it will behave at idle. The factory wiring drops up to 2V with the increased load of running the larger fuel pump but in some cases ive seen it as low as 10.5V.

fantastic, that seems to make a lot of sense.. it didnt occur to me that the new pump could draw more power (at least at the time lol).. i brought the walbro 341 cause i was told it was a straight replacement for the factory one.. thinking the mechainc should be able to manage with it i hoped i was doing the right thing..

i'll get a multimeter onto that pump tomorrow and see whats happening with the voltage! i take it that you had to do this mod before?

[GTScotT]

OK. i havent read all posts, but sounds like the mechanic had grounds to blame the pump. now if he checked fuel pressure inline at the rail, he could have possibly overlooked the fuel reg.

to test, find a way to clamp the hose after the reg. to do this i usually use vise grips. DO NOT drive the car like this for long, it will kill the pump and/or spring a leak.

I know this is a very crude method people, but it will overcome the possibility of the reg, i recommend you try.

[GTScotT]

double post FTL

[Damo Monster]

FPCM = Fuel Pump Control Modulator.

The earth can be grounded behind the drivers side boot trim as it runs up here to the rear drivers side under the trim where the FPCM lives.

Doing this wont give the pump 13.5V but it will run it so it will behave at idle. The factory wiring drops up to 2V with the increased load of running the larger fuel pump but in some cases ive seen it as low as 10.5V with the earth wire mod. done.

yikes, just re-reading your post.. you have seen the pump drop to 10.5v WITH the earth mod done?! i hate to think what they are dropping to with just the factory wiring on their own.. they should warn people about this in BIG print on the box lol!

[paulr33]

physically inspect the fuel pump

is it installed and mounted correctly onto the factory bracket on the roof of the fuel tank?

or it sloshing around in the fuel tank (common botched installation)

should take 5 minutes to check with a torch (no naked flames as tank is exposed)

you can open the tank from the top on the parcel shelf, square panel, 4 bolts