Is the stock fuel pump made by Denso?
 

So my car was being tuned yesterday and for some reason it went lean. My pump was replaced with a denso fuel pump. This one in fact....

http://img36.imageshack.us/img36/8056/img6894j.jpg

I was going to list my stock FD stock parts for sale when I noticed my old pump also said denso on it.

Here is a pic of my old pump.......

http://img25.imageshack.us/img25/814/img6893u.jpg


Did denso make the pump or was my pump already replaced when I purchased my car??

Now this brings me to a couple of other questions. Sorry I am still new to this.

If the following have been replaced/new
Fuel pump
Fuel filter
injectors

What else could cause me to lose pressure? The stock fuel pressure regulator?

And finally I need an AFR/wide band gauge in my car that is for certain. I know some gauges will flash or beep at you when it hits a certain point. Is there any thing out there that will shut down the boost in lean conditions?

If I am flogging the car I don't want to wait for me to see or process a flashing light or some beeping sound. I want it shut down immediately! Any suggestions?

Yes the stock pump is a Denso.

The voltage could be dropping at the pump at high RPMs, there are several threads on re-wiring it for constant 12V. You did not mention what you were using to tune the car. Do you have a PFC? How much boost were you running when it was going lean? How much power was it making? You could just need a better tuner.

The tuner is good. I didn't mention all the information cuz I was not sure it was relevant but I suppose it's better to supply more info than not enough :)

Here are my mods

street ported motor
intercooler
1300 secondary injectors
high flow cat
rb exhaust
down pipe
hks twin power
fidanza light weight flywheel
Bully clutch
denso fuel pump with fuel mod
fluidyne rad
greddy profec b 2
BNR stage 3 turbos
battery relocated to the trunk
power fc
Have a cheap water/meth kit but need to replace it. ( This is off while being tuned, once I buy a better/reliable unit it will be tuned with AI ).

Things were going fine. Started out with pretty low boost, and he was working his way up. 13psi on our way to 16psi. It got to around 14.5 psi when it kind of leaned out a touch. I think it was 11.8 afr perhaps 11.5 I can not remember. He added a bit more fuel and tried again. Then for some reason it went lean very quickly at transition so he stopped. We shut the car down, let it cool and hooked up a fuel pressure gauge.

At idle the car was around 42 . We started the run again and the pressure went up to around 58 but again at the secondary transition the gauge showed the pressure dropping to around 45-50. All the supporting stuff he uses showed the car went lean again.

I do not really know what he is using in terms of tools. Data logger, wide band, intake temperature gauge, lap top, my pfc, and I some other stuff ( If I knew how to tune I would know what this stuff is or might be able to do it myself :dunno: )

Anyway, we were only around 312HP ( mustang dyno ) when this accured so we were not pushing it hard.

Verify there is a good seal between the fuel pump and the hard line. I had a very similar problem and it turned out the o-ring inside that little bell shaped connection going over the pump outlet was letting fuel blow by after it hit a certain pressure. I fixed it by cutting that bell off and just using high pressure fuel line to make that connection.

That said, you may be close to running out of fuel pump. Not sure which Denso pump you have but if it was stock replacement I would upgrade to something a little higher flow.

Your pump is the real deal, high flow Denso which is a direct replacement MKIV Supra pump. There is no o-ring bypass issue because the connection was done via the supplied hose from the pump outlet directly to the hardline. Make sure your 1300 cc injectors actually flow as specified. They'd be bored out 850s and the success rate can vary. I've been bitten by them in the past.

I'd recommend some top feed 1600s or 1680s (depending on what you get), which will of course require a secondary fuel system mod. Then you'll have plenty of fuel, which will help you benefit from your BNRs a lot more reliably.

It's not the injectors since the fuel pressure was dropping when it would start to lean out. My current guess is either OEM FPR or the FPR solenoid. The FPR solenoid should be ditched to remove a failure point.

thewird

Also as mentioned get the fuel pump rewired. Could be the stock wiring isn't up to the task. Fuel filter, and fuel pump sock are also things to check. As far as a wideband that lowers boost, i've never seen or heard anything like that. Afr's change so much depending on throttle, boost and personal tuning that it would be tricky making a system like that.

The fuel pump is wired directly to the battery all the way to the pump. Fuel filter and pump are pretty much new as well.

thewird

Anyone have an answer on this.........


I need an AFR/wide band gauge in my car that is for certain. I know some gauges will flash or beep at you when it hits a certain point. Is there any thing out there that will shut down the boost in lean conditions?

If I am flogging the car I don't want to wait for me to see or process a flashing light or some beeping sound. I want it shut down immediately! Any suggestions?

I don't know of any widebands that flash or beep either. The problem with that is devices that flash or beep are simple and based on a particular number that you set. If you set the thing to flash or beep at anything over 11.5 for example, then every time you're sitting idling, cruising, or letting off the gas it would flash/beep at you. That would be annoying. The only way to do it is to have a gauge that also inputs a boost signal and compares the boost to the AFR and I just don't think anyone makes anything like that. The best you're going to get is different colors. Usually green yellow and red. If you see any color other then green under full throttle then you need to lift off.

You can always do preventative mods. Make sure your map sensor and wastegate line are secured well. Add some form of aux injection, keep an eye on your boost, AFR's, knock and water and air temps.