R33 Stalling Problem..

[sfitzy]

Have you changed your plugs lately? VuDuDoc?

[Guest VuDuDoc]

dont believe its that. ive had a problem like this before with the same car just different engine. plugs cant be the reason.

[sfitzy]

At least if you change them, then you can eliminate it from the list of possible causes..... So far I have....

Changed the plugs

Changed the battery

Adjusted the idle

Changed the fuel filter

And it hasn't stalled yet... (in the last week or so) It's come close a couple of times but hasn't stalled.

[Guest VuDuDoc]

i have done all that on a previous engine though they were in the same chassis. I have a fresh engine and teh same problem is there as with the first motor. Now this leads me to believe that if the problem hasnt been fixed buy the other fixes..then i have to trouble shoot further into the car. and i think many with this problem are dumping alot of money playing hit or miss.....i hope to have a solution.

[sfitzy]

What didn't you change with the fresh motor?

[Guest VuDuDoc]

the whole motor is different. i swapped a KA24e out of my 240sx and put in the rb20det. there for everything is different except for cabin wiring and the fuel system. i took a multi meter to a bunch of stuff and been trouble shootin the system. though alot of the components are checking out good so what else is there.....nowat i mean. im at a point where im looking at wat stayed in the car. the question is the about the voltage on the fuel pump varying and wat components are in the loop after warm up that would cause our symptoms aside from tune up items and the obvious. if it were obvious we wouldnt have these problems. god i love chasing a gremlin.

[sfitzy]

Sounds like you got one two...

Assuming that everything in the fresh motor is fine, no air leaks and such. Then it must be something related to what was not changed.

Are you using the stock ECU for the RB20DET?

Are the fuel pumps the same capacity for a 240SX and a RB20DET? We don't have 240SX'x overhere... They run the same engine as in the Bluebird don't they?

Anyway because if the pumps aren't the same and when you run at idle the ECU would expect a certain amount of fuel which it is more than likely not getting and would adjust have time to adjust.

However if you are driving the car and come off the gas (which used to make mine stall). The ECU would start to response by sending its 'normal' voltage signal to the pump, however the ECU may not have enough time to increase to signal to the pump. The engine then is starved fuel and stalls.

Why some skylines stall is because that the pump is getting older... many of our cars are 8-12 yrs old, they just aren't efficient as they once were. Same with alternators, batterys etc. I am gradually replacing all these items and I reckon the car will run just fine.

Also, I thought of grounding the pump to make it run at full capacity all the time, but what I think is a better option is to put a variable resistor in this ground line to dictate the minimum current to the pump. Thereby allowing you to adjust the minimum flow of the pump and allowing the ECU to control it during normal driving.

I think this sounds logical, anyone else out there with an idea?

Sorry about the long post....

[sven laptop]

My R33 is completely stock & had the same problem (never had the tank close to empty, so it wasn't being starved of fuel).

It never happened when cold, only when up to full running temp.

It was fixed by raising the idle speed.

It now idles at about 800rpm, instead of around 600 as it was before.

[Guest VuDuDoc]

BINGO!!!!!!!!!!!!!!! This is wat im talking bout!!!!!! Both of you hit it on the nose. now what would be the base values on a pump at idle.....this would be something out of a FSM. now my pump is fairly new but was exhibiting this with the old pump. almost as if a switch was flipped that left it idling. i went from 650 to 800 and it wont vary but to try and stall comming after comming to a stop.i have about 4-5 wires to my FP. so i have to figure out which or how the voltage is varied. someone told me this was BS though i beg to differ.hopefully there is a way to rig it with a new relay and hardwire it. i saw this done on a 3000gt where there was a drop in voltage and it worked but to apply it to our cars is the trick. something to think about

[sfitzy]

There is a thread around that outlines the technique invovled to hardwire it.

[Guest VuDuDoc]

thx for all the help. hopefully there can be a solid answer to the stalling. I hope its a standard solution.

[sfitzy]

This was the thread I was talking about...

http://www.skylinesaustralia.com/forums/sh...light=pump+wire

Instead of hardwiring your pump a variable resistor in an easy to reach position in the grounding line would allow you to vary the minimum current to the pump! Can anyone with an electrical backgroup back this up?

[Guest VuDuDoc]

yeah i read that string. the question is boot area? wheres that. im gonna research more on tracing the ground. my ground goes into the seatbelt module so hopefully nothing is fried in there.

[sfitzy]

The boot area refers to the area in a skyline where the battery lives... You access the fuel pump/tank from a cover next to the battery which is pretty much under the rear parcel shelf in a Skyline. You need to take off a foam/chip board cover to get at it.

[Guest VuDuDoc]

ok so that procedure mentioned has to do with relays or just grounding at the pump. reason being for 200sx(240sx) the pump lies intank in the trunk(boot) and runs its wiring through the seatbelt module. the ground lies under the left side seat and the wiring continues on through to ecu and then out to the engine bay where the relay lies. have you done the procedure mentioned? one method i saw was rewiring the relay and running all new wires from the engine bay back(could this be what i was reading?

[sfitzy]

From what I have read they have just grounded the pump... But I wouldn't do that, you pump will be forced to run at 100% capacity all the time! I think putting a variable resistor in this grounding wire would allow you to set the minimum current to the pump at all times. The ECU will still be able to increase the flow during hard driving, but when off the gas the new set-up would maintain a pump pressure high enough to hopefully stop the car from stalling! I think this could be a better option!

[predator]

...rising rate fuel pressure regulator

[sfitzy]

Any news VuDuDoc? is the car still stalling? cause I haven't stalled in ages! But I still think that the pump is on the way out... only going to get a new one once the old one packs it in!

[Guest VuDuDoc]

nope been hella busy doing another motor swap. i changed out the relays in the box and the car is much better. i think it was egi or the grey relay. ill write more on it this is just a quick blurb

[Guest VuDuDoc]

alrighty i tested the fuel pump at the connection (in trunk) and registered 12.01 at idle then when throttle depressed it dropped as low as 11.3. noticing a considerable bog in engine performance. now i changed out the relays and although they did help alittle this is ridiculous! any ideas. OBTW this is a RB20det in an 89 200sx....so there isnt a fcm...at least not that im aware of.