I have no idea what may be causing this, so bare with me. This does not happen all of the time, only when I am cruising on the highway for some reason. Even on the highway, it does not always do this(seems to be when I cruise for a prolonged preiod of time). This also only happens in 2nd gear but does not happen every time I am WOT in 2nd...only when it drops to 2nd.
When I am cruising around and decide to go WOT, my car drops into 2nd and the fuel pressure drops to the baseline(~42psi, will be normal once the tune). Sometimes it will instantly drop straight to the baseline and sometimes it will gradually drop to around 45ish psi before it gets to 3rd. Once the car shifts into 3rd...fuel pressure is right where it should be(1psi for 1psi boost.)
If I go from a dig, then there is no fuel pressure problem at all...only occasionally when I drop into 2nd when crusing on the higway.
Any ideas? I thought the fuel pump might not be getting enough voltage, so I put my volts booster back on that activates after 70% throttle or something like that and it still has the problem. Thanks for the help in advance.
What about the fuel pump itself? I just reaplaced mine with a high flow pump, it fixed all kinds of KR and funky things my car has been doing for a few months.
Well I think the pump might be going bad, but would like a couple of opinions. My fuel pressure now drops through all gears and seems rpm dependent. It will drop from a dig or roll. Last time I switched the fuel pump, there was some black crud on that white boot on the pump. Could my pump be clogged?
It will hold appropriate pressure, just not under WOT conditions where rpm's will be high.
I am also hoping to get this fixed asap! I changed the fuel filter just under a year ago...but I am changing it for the tune here.
I don't know what is going on any more...today my fuel pressure will not drop at all. I tried to make some runs and scan the voltage and a few other things while under WOT, but my pressure is rock solid and so was the voltage...13.3 solid.
I guess if I am getting it tuned and it does this...I will turn my car off and back on and it might not do it. All I know is today, that fuel pressure was rock solid and did not drop at all.
I will try a bit harder on some highway runs here later, so we will see if when that pressure drops the volts drop as well. If the volts are still solid and the pump is losing pressure then I am assuming it is fuel pump related. I still don't know why it only does this sometimes. Last night was the first time I saw the drop in 1st.
Sounds like you should just replace the pump. My oem pump was funky some days it would be hard starting and other days it would start fine but not have enough fuel for WOT and once in awhile it was completely fine.
Just replace the pump before your dyno tune so Brian can work his magic.
yeah, I think the pump is going to need to be replaced...
I did some highway runs and the voltage stays solid...but my fuel pressure would gradually drop down to idle level when I went WOT. Does this inconsistent behavior seem like a fuel pump problem? A couple more good opinions is all I need to replace it.
I was hoping that the walbro255 I have would work longer than 6 months...but maybe it won't. I just replaced it not long ago, but who knows. $150 just sucks for something that may not fix the problem. And if it turns out to not be the pump after I have bought it and installed it then that tune might not be in reach for me. If I have to spend more money to fix the problem, then it isn't looking good for that date coming up.
I am going to change the fuel filter tonight and see if that does anything...I am not a religious guy but I wouldn't mind a few prayers thrown my way.
I was asking the same thing to some of my co-workers and they all agree fuel pumps are often funky like that when they are dying.
I put a new pump in my car recently only to tear back into the tank in less then a week, after being stranded 5 miles from home; I feel your pain. But I'm sure you could find another 255LPH pump that doesn't cost $150 my TRE pump only cost me $70.
Well Ed I am going to take your advice on this one. I just replaced the filter and still the same problem occurs. Do you have good things to say about your fuel pump? If so, where is the best place to get one? thanks a lot man, Andy C.
To be honest I've only been running this pump for about 2 weeks now, it fixed alot of my KR problems and such I was having. The pump carries a 1 year warrenty which beats what the Walbro's. There is a handful of us Bonneville guys running this pump thats labeled for use in a Mustang:icon_lol:
thanks a lot Ed, I will have to find out what specific pump works with my car. In the past the original one we put in wasn't compatable...so we had to use a different style. the wrong style pump is not good news...fuel pressure would drop to about 20psi
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