2000 Gt High Fuel Pressure

[Clayton302]

Hello, I have a 2000 GT with a Kenne Bell 2.1 and my fuel pressure get up around 60 psi once the car gets up to temp (open loop). When its in closed loop (before operating temp is reached) the fuel system works fine, goes up to 55-60 under full throttle like it should with the boast a pump. Once it reaches temp it idles at 50-60 and goes to 65-70 under full throttle. It finally threw a code P0172 bank 2 rich. Any ideas would be helpful.

 

[usaf_branham]

maybe your boost sensor switch (i think its called a hobbs switch) that activates the BAP is getting stuck open

 

[Clayton302]

Its worth a try, I guess I could disconnect it and see if the fuel pressure rises under normal driving after temp is reached. Ill try it to day and report back. I keep seeing all these threads with related issues but once the issue is addressed they never follow up. Thanks!!!

 

[Clayton302]

Its not the hobbs switch. I tested it by disconnecting it and driving around normal and reaching operating temp. Fuel pressure was still high 50+ at idle.

 

[trinity_gt]

Hello, I have a 2000 GT with a Kenne Bell 2.1 and my fuel pressure get up around 60 psi once the car gets up to temp (open loop). When its in closed loop (before operating temp is reached)...

I think you've got your terminology backwards: At "operating temp" the car will be in closed loop. When it's first started and cold, it will be in open loop. As well, the fuel system will go into closed loop far sooner than the coolant will reach operating temperature.

the fuel system works fine, goes up to 55-60 under full throttle like it should with the boast a pump. Once it reaches temp it idles at 50-60 and goes to 65-70 under full throttle. It finally threw a code P0172 bank 2 rich. Any ideas would be helpful.

The additional fuel pressure you see under full throttle is a function more of the PCM, FRPS and FPDM than it is of the BAP. The BAP simply generates 17V so the stock pump can actually move a decent volume of fuel at increased pressure.

You should verify the vacuum line connection from the blower manifold to the fuel rail pressure sensor (FRPS). Did you install the damper disc under the FRPS during the blower install? If not it's possible the sensor has been damaged...

 

[Clayton302]

Trinity-gt, Thanks for you reply. I have verified the vacuum lines and they are all functioning properly with out any leaks. I have not checked the damper disc or even knew of this. I read about it on the kenne bell site. Once i check it i will reply with an update. I will also do some checking with a volt meter to check the FRPS if i can find the procedure i will updoad it. Might be in the manual.

 

[Clayton302]

BTW my terminology was backwards. Thanks for catching that. Closed loop until the o2's reach temp and open (MAF, ect..) until o2's take over. Can I turn the o2's off and run in open all the time? Maybe I'm getting ahead of myself here. I will try verifying the FRPS (fuel rail pressure sensor) is functioning properly before moving on. I found a cool explanation of closed vs. open loop http://www.modularfords.com/f149/definition-closed-loop-vs-open-loop-58339/

 

[Clayton302]

I'm pretty sure it the FRPS i will verify once I have a chance to check it. I will also include some instruction from a different forum on how I did the check.

 

[Clayton302]

well guys the problem is holding its ground. I'm starting to think it may not be to much of a problem. some cars with similar fuel systems run upward for 80 psi all the time. I would still like to see it lower.

Things I've notice:
1. When the cars is first started and for about the first 10 minutes of driving, the fuel pressure is fine.
2. When it gets to operating temp it starts to climb. coolant temp (not the o2's or in closed loop)
3. if i drive on the freeway or if i can get the coolant temp to drop down to about 180 the fuel pressure starts to drop again like the computer was over fueling to cool the engine or something.



The car doesn't run hot. It never runs hotter than it should (190 to 210). I'm starting to think I should mess with the parameters related to coolant temp on the tune (What temp the fans come on to keep the car cooler). Don't think i can get to any adjustments for the thermostat, Just a thought.

 

[BrightBlue00GT]

My 2000 GT's fuel pressure at times gets into the 60's when the ambient temp is really hot. At start-up and under 'normal' ambient temps regardless how long I drive it (about 50 miles each way city and highway) it stays around 40ish, but in the afternoons driving home while in the city it will spike in the mid 60's at times, jumping rather than a slow creep. Once I'm on the highway it comes back down, but the autometer gauge does seems to bounce around a bit anytime the temps are hot, even when not going that high it still bounces around. I'm used to it and it hasn't failed so I just live with it. 148K miles on her now, almost 100K since installing the KB.

 

[wmburns]

Just wondering how much boost is being made at the time the fuel pressure jumps so high? Remember that many external fuel pressure gauges are NOT intake vacuum referenced. The boost pressure will ADD to the Delta fuel pressure. So with 20 PSI of boost, 60 PSI gauge would be the expected pressure.

Would also like to know what the PCM "thinks" the engine coolant temperature (ECT) and input air temperature (IAT) is.

 

[BrightBlue00GT]

If happens when not even in boost, just normal city driving.

 

[runningONfumes]

Being no one has posted on this in a bit I guess its not much of a problem anymore, but did you install the Kenne bell yourself or was it already on? kenne bell superchargers use a boost a pump application for them, and takes over control of your stock of other installed fuel pump.

Sent from my SAMSUNG-SGH-I727 using Tapatalk 2

 

[Clayton302]

Yeah it happens under normal city driving and is still a bit of concern for me but. I have driven about 3000 mile with it doing this and have check the oil for excessive gas odor as well as and rich codes on the ecm. I have also checked the plugs for indications of a rich condition and it doesn't seem to be a problem. I guess there are some others out there with this same issue but haven t heard too much on it. I have checked just about every thing I can think of as far as supercharger install and fuel mods install Everything is above average on the install and is installed correctly. The boast a pump may be going bad or have some weird issue that crops up when the car get up to operating temp. If i drive on the freeway and get the temp down (180 ish) it drops the fuel pressure some (within factory spec) which would leave me to believe it is an effort to cool the car by the ecm?? Not a lot of knowledge behind that last ECM statement. Anyways one might think its the tuning software I'm using which is sniper, but the guys there are confident its not, I have tried just retuning with their base tune and no change. Also the car does not run hot around 185 to 200. Its southern utah so is 105 + average here in the summer. As for now I'm just leaving it.

 

[Clayton302]

all this is just normal driving not under boast. under boast it sometimes gets up to 70 for about 1 sec under WOT but just for a sec then goes back to 60ish for the rest of the rpm pull. I have also tried changing the Hobbs Switch.

 

[Clayton302]

Just looked through some Data logging that I took while down at the drags in Vegas and notice that it is very erratic the timing is jumping from 13° to 37° under full throttle and when this happens the MAF, load %, Kg/Hr, and other jumps large amounts as well. This is happening about every 5 to 20 data points. The RPM's, speed, coolant temp, Intake Air Temp don't jump. I think this issue could be tune related. When I bought the car the owner had lost the real stock file so i got a new one based off the computer code he gave me and I'm wondering if they gave me the wrong stock file to start with. Is there a way to get the computer reflashed to stock from Ford to start over with?