Fuel Pump Cavitation?

[KINGSUN_33]

Hello everyone, new here. Searched the site for any answers but couldn’t find anything.

Here’s my issue, during an auto x event I was experiencing a cut/hesitation in acceleration. Rounding a corner applying throttle to power out've the turn then all engine power goes out then springs back to life. Grabbed my laptop and recorded a log. Come to find my fuel pressure dropped to 2 psi in that moment (bad) sent it to Lito for overview and he thinks my pump may be caveatting or sucking air as all other data supports the pump being okay. Essentially cars acting like I’m running outve fuel.

Fuel filter only a year old. New pump strainer. No visible leaks, no codes runs and drives fine under normal conditions. Only when working the car hard. 3/4 tank at time of issue and cross over is connected I triple checked it.

This happened day 2 of racing and day 1 there was no issue present. I highly doubt its fuel sloshing around as I’ve never had that before hand and I had more than enough fuel.

Anyone have ideas on what’s going on here? Going to dig into it this weekend. Attatching picture of log. (FP GREEN) (RPM BLUE) (TPS RED)

-Car build: 07GT stick, P1sc, dw340, 39lb injectors. 91 octane

 

[StockishS197]

Looks like cavitation to me. There is an old TSB out there so it’s a known issue if you are still running the original pump
Edit:

FORD TSB ARTICLE # 06-9-9
Issue
Some 2005-2006 Mustangs may exhibit a hesitation on acceleration after a long cruise. After coming to a stop from a highway type cruise, some vehicles may experience a hesitation when the customer begins to accelerate. Air bubbles can form around the fuel pump during a long cruise and can be ingested into the pump on acceleration causing a hesitation.

On top of that, maybe fuel isn’t transferring from each saddle tank so perhaps there could be some fuel starvation since it seems to be happening on during cornering?

 

[KINGSUN_33]

Thank you, I’m running the stock hat but swapped out the pump for a higher capacity one. So I wouldn’t think it would cause that but maybe the pump is. I’m leaning towards fuel starvation even though I had 3/4 fuel and I’ve gone below half so it has to be transferring fuel but it could’ve just been angry for some reason. I haven’t found anything yet that supports either

 

[JC SSP]

Wasn’t there a factory issue with the fuel starving from one side of gas tank saddle to the other? The cross over hose was kinked or disconnected?

 

[07 Boss]

I believe my Whipple manual says not to do wot pulls with less than half a tank as it may lean out due to possible fuel starvation from the tank. I've always filled up with 100 octane before going to the track so I have no idea if this is true or not but I remember the warning. I also seem to remember a few issues with cavitation on 05-06 cars after long sustained cruising. I sent my old pump to someone who was having this issue.

 

[KINGSUN_33]

I did exactly that, was at 3/4 tank for sure and filled before said race. Gauge could be reading inn correct but has be right every day before and after. Not really sure what to think but I guess I’ll just keep my eye on it if it keeps happening

 

[Joe dee]

My 2006 mustang v6 4.0 gave me the same problem. I put a fuel pump pressure gage on it had to let it run for 20 or so before I found out it was running at 28lbs then for one second it would drop to 5 or6 lbs then back up to 28 or so lbs when it should be 30 or more lbs. I changed the fuel pump runs fine now at 34lbs at idle. Ordered new fuel pump through home depot for 160.00 its a Delphi pump

 

[KINGSUN_33]

That’s interesting. I think I’ll pull my pump out and take a look for anything sticking out

 

[KINGSUN_33]

Have an update, pulled the pump out, took a look. Didn’t find anything outve the ordinary, no tears in hoses, everything secure and tank was clean. So I don’t think it was the pump. I have a FP gauge hooked up on my fuel rail and my prime pressure was 55 ish psi. I could watch the needle drop to 0 which took about 5 minutes, seems like it should hold no?

 

[JC SSP]

I would have replaced the pump but that’s me…

 

[07 Boss]

If the pump and filter are good I would be looking at the rail pressure sensor or the control module for the pump. Have you recorded the signal to the pump to see if it's commanding the pressure drop?

 

[KINGSUN_33]

I agree with you there, couldn’t get a new pump in time. Want to ensure it’s not anything else first.

 

[KINGSUN_33]

If the pump and filter are good I would be looking at the rail pressure sensor or the control module for the pump. Have you recorded the signal to the pump to see if it's commanding the pressure drop?

What would that be under the log? I also checked the vaccum system for gas and had nothing.

 

[07 Boss]

What would that be under the log? I also checked the vaccum system for gas and had nothing.

Not sure as every manufacturer may use different terminology but look for something like "commanded fuel pressure" or "target fuel pressure." If I remember I'll open up my HP at home and see. But when you do just compare the two as they should directly correlate with one another. If the actual pressure doesn't keep up with the commanded pressure that would indicate an actual mechanical issue with the pump or delivery. If the pressure is commanded to drop that would indicate a bad sensor, module or wiring.