madsteez

Well ive started to take everything apart and replace it,but have gotten no where to having my car run right.

Now im going to list a few things i have encountered and i want everything to say what is best to do next.

My car currently has a walbro 255 liter per hour fuel pump,but with stock injectors and stock fuel pressure regulator.

Now a few months ago when i blew my first motor i came across a problem with having the car cut off when i would rev it,come to a stop,or if im crusing and put the car in neutral.

I then got the motor tuned up at dyno inc,and tim got it to idle fine again by adjusting the air/fuel mixture. I thought it was because i was running larger injectors(440)

Now the problem is back and i see no sense in getting a stock azzzzzz mini me tuned.Ive asked other boards if they think the fuel pump is the issue and they said no. That the stock fpr wont let the fuel pressure change. Then i read on a site:

The idea of a higher flowing pump is not necessarily to increase fuel pressure. In fact, if all other components remain the same, the fuel pressure does not rise with the addition of a new pump. As fuel demand increases, with higher rpms, the fuel pressure can drop but the flow increases. If the pump cannot support the required flow, the engine will run lean.


Ive begun to think that this is the issue,seeing how all my plugs are coming out looking like charcol(ive gone through about 5 sets of ngk)
Ive also read that the stalling of my car would be from the car leaning out at idle,and therefor not supplying enough fuel to basically over power the amount of air thats being sucked into the engine.

Sorry that was really long but i figured if i got into detail i could get honest opinions before going and spending 200+ on a new fuel pump and strainer.

Fabrik8

Yeah, you have no reason to need 440 injectors or a 255LPH fuel pump. Neither will give you an extra ounce of power because you're not even touching what the stock setup will flow. Going bigger doesn't get you anything when stock is plenty big. You're not running lean because of the pump; that fuel pump can support probably 3 or 4 times the amount of power you have right now. I'm guessing you have a sensor problem or something like that, such as having a dirty idle air control valve or mis-calibrated throttle position sensor, or a bad MAP sensor. You haven't really given much symptoms or information other than your hunch... Did you make some change right before the problem came back?
What mods do you have, you said you have a stock mini-me but are there any mods such as a lightened flywheel?

When you say your plugs look like charcoal, is that raw charcoal (black) or ash (white)?

madsteez

They are black,i didnt want to go into great detail because i have another thread explaining the issue. The car was at one point making 200whp,not much but you can see the need for the fuel pump since they are needed to support around 230whp safetly.As of now the car has a stage 4 6 puck clutch,9 pound flywheel,light weight crank pully.I have replaced the dizzy,tps,fitv,map sensor,iat,iatv and the ecu all about 2-3 times with known good ones and have gotten no where. Im getting a new engine harness tomorrow,and that ONLY leaves the fuel pump left.

https://www.vadriven.com/forums/tech-talk-9/need-help-asap-car-wont-start-231897/

Fabrik8

If they're black you're running really rich, that black is soot. So too much fuel. You might have a coolant temp sensor problem.
A flywheel that light will often affect idle, the RPM drops to idle so fast that the IACV can't catch it and keep it there without overshooting and stalling. It's a common problem.
If you're running that rich then there is even more of an issue trying to keep idle because enough air can't get into the engine to offset that much fuel.
You've just been blindly replacing stuff it sounds like, you need to start actually troubleshooting in a methodical way. This shouldn't be too hard to track down, but just replacing everything in sight to see if it fixes it is a big waste of time and money.

madsteez

Well i have boat loads of parts in my shed,so i have everything at hand,except the ecu's.

And holy crap your right,it first started this when i did install the flywheel,but it didnt do this in the car it was on before me.Are you recommending i get a adj. fpr to lower the pressure,my injectors do pulse really fast,but i thought i was running lean,hense the plugs sparking with no fuel causing them to turn black.

I did read that a few with 255lph pumps bumped the fpr from 35-41psi.

Fabrik8

Lean plugs are usually white and chalky looking, really lean plugs have little silvery specs of aluminum on the electrode.
If the fuel demand isn't high enough, the regulator may not be able to regulate the line pressure with that much fuel flow from the pump. That depends on the type of fuel pressure regulator though, there are different types of fuel systems. Return-type fuel systems can be overpowered by too much fuel flow, which I'm assuming is your problem. Tuning will solve this, because the tuning will adjust for the new (different) fuel pressure with the higher flow pump. So your tuning may be off if you've changed anything on the engine since it was tuned last.

There are a few reasons that it may not have been doing that on the other car, mostly a different combination of variables (part mods, etc), sensor health, and tuning. Also, if you have different types of accessories (aircon, power steering, etc) from car to car, the parasitic accessory drag will be different.
Different types of clutches are different weights too, which can add or subtract from the problem, so if the clutch in the other car was different.. It's possible that there is a little amount of clutch plate drag too, but I would doubt that's a problem.

If the plugs are that black, the light flywheel might have thrown the ability to regulate idle off enough to have problems. There isn't any reason to not use a light flywheel, but you need to find what is actually making the engine run that rich.

madsteez

Thanks alot for spreading your knowledge, I think im going to put in a stock fuel pump less i can get my hands on a adj fpr asap. I hate how it runs flawlessly when the engine is cool and then will not hold idle when its warmed up. But to answer your question yes it has a fuel return line,which i just recently replaced the hose running to and from it.I do NOT want to pay 150.00 to have my sohc tuned it honeslty just isnt worth it. Again thanks alot!

Fabrik8

The ECU's idle regulation is different cold than warm, and the fast idle thermo valve plays a part also. Cold idle is higher RPM and more aggressively regulated, with ligher power output at that RPM, so the flywheel weight isn't really as big of a deal.
Again, there isn't any reason that it can't idle just fine with that flywheel, it just has to have components that the ECU can use in stock form, or it needs to be tuned. If you want to drop a little money, a wideband O2 sensor might be a nice investment to really tell you whats going on when you make fuel system changes.

thermal

On the stalling out at idle issue, I can almost guarantee that the culprit is all coming from all that "lightened" aftermarket parts you have installed. As briefly explained up top, some drag on the rotating assembly is actually helpful on the idle.

madsteez

Alright well im putting stock crank pully on,and getting a adj. fpr today.

If that doesnt work im going to dyno inc. to have them tune into my air fuels.