Fuel Pressure Drop

May93

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I'm currently experiencing fuel pressure drops with my 2007 GT500. Its upgraded to a 2013 Trinity Blower and Injectors, 10% lower, stock upper pulley, dual fan heat exchanger, Dual BAPs (VMP P&P), off road H-Pipe and nGuage with ZT2 for data logging. The problem I'm encountering isn't the tune so I'm not mentioning the name of the Tuner.

Basically the problem started as I was data logging to see how the car was performing on a hot day. This to send to my tuner as a reference to how the data log looked on a hot day. I figured if it ran good on a hot day it would be ready for the track. So I take it out and in 4th gear at about 5800 RPM it noses over. This happened again at a lower RPM so I knew I had some type of fuel problem.

Fortunately I was data-logging when it happened and was able to verify the problem when reading the data-log. Sure enough around 5800 RPM the fuel pressure dropped to 9lbs. It then periodically increased when letting off the gas. Check engine light came on and codes PO148 and P1234 were present.

So after some troubleshooting I found what I thought was the issue. When I installed the PAP's I wasn't paying close attention to the directions where it said take the 25 Amp fuse from the # 66 position and place it in the # 6 Fuse position on the strut tower. I didn't do this and when I checked sure enought he 15 Amp fuse was blown. I replaced it and also checked all other fuses to include both the 40 Amp BAP fuses and all were good.

So I take the car out and its definitely running better while doing a data-log up to 5000 RPM's. I couldn't feel any stumbling but after I got home and checked the log sure enough the fuel pressure at one point briefly dropped to 16lbs and then back to as much as 70 at times. I also rechecked all fuses and all were fine.

Tomorrow I'm replacing the fuel filter to see if that helps but I'm leaning towards a fuel pump being bad. Anyone have any suggestion? I'll try and attach the data-log.
 

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fullboogie

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Have you been in the tank at all prior to now? I've seen a number of threads about guys finding the Y connector broken, or a hose off, after messing with the pumps. Worth checking while you're in there.
 

May93

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Have you been in the tank at all prior to now? I've seen a number of threads about guys finding the Y connector broken, or a hose off, after messing with the pumps. Worth checking while you're in there.

No I haven’t had the pumps out and I’ve had the car for the past 5 years. If I dig into the tank I’ll replace the pumps and the filter.


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fullboogie

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There are a multitude of reasons why you can have low fuel pressure. Aside from the pump basket issues mentioned above, have you checked the fuel pressure sensor on the passenger side of the engine?
 

May93

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There are a multitude of reasons why you can have low fuel pressure. Aside from the pump basket issues mentioned above, have you checked the fuel pressure sensor on the passenger side of the engine?

I’ll definitely take a look at it as it’s a possibility. It seems to have regular fuel pressure until higher RPM’s. It seems sporadic which is what made me suspect the pumps.


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May93

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If you're having wild swings at both ends, I'd check the sensor first.

Looking at the data-log it seems to be more at the higher end. The car has 64,000 miles but its hard to believe a pump are bad. Unless I created a issue when the fuse to the secondary pump blew out. Is there a manual reset for each pump?
 

May93

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Fuel pumps my first guess.
I look at them as a wear item on E85 even storing with precautions.
-J
I was leaning towards the fuel pump failing myself. At 64,000 miles its good insurance if nothing else. Whats your thoughts on replacements? I do my own work so not a issue regarding labor. I was thinking stock replacements that are a direct fit. I see that DW300M ( DeatschWerks) has a direct replacement that's even compatible with E-85. I don't run the corn but i like the option.
 

May93

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I'd really recommend looking at the fuel pressure sensor before ordering pumps. It's quick and free.

Oh I definitely will. I thought I had a extra one off a used fuel rail but unfortunately I didn't. I did make it sure it was plugged in and all lines connected.
 

May93

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Well that's not really testing it...
I haven't been in the garage long enough to do anymore diagnostics. I placed the battery on the tender yesterday and while I had the hood open I poked around. I was looking for the obvious unplugged line or connector.
 

biminiLX

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I was leaning towards the fuel pump failing myself. At 64,000 miles its good insurance if nothing else. Whats your thoughts on replacements? I do my own work so not a issue regarding labor. I was thinking stock replacements that are a direct fit. I see that DW300M ( DeatschWerks) has a direct replacement that's even compatible with E-85. I don't run the corn but i like the option.
Ideally stock ‘13-14 pumps would be great (I think they’re just stock Coyote GT pumps), but I’m not sure if ‘07-12 guys can upgrade to ‘13-14 pumps/fuel hats.
That’s probably more work anyway as I really like DW and would trust they’re input. I’d also 100% choose an E85 compatible pump as you’ll eventually join the dark side and kick yourself for not doing it sooner :)
-J
 

RedVenom48

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Ideally stock ‘13-14 pumps would be great (I think they’re just stock Coyote GT pumps), but I’m not sure if ‘07-12 guys can upgrade to ‘13-14 pumps/fuel hats.
That’s probably more work anyway as I really like DW and would trust they’re input. I’d also 100% choose an E85 compatible pump as you’ll eventually join the dark side and kick yourself for not doing it sooner :)
-J
Thoughts on the DW300m? Think they can handle a 21V bap?
 

biminiLX

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I think DW would know straight away :)
I doubt it’d have a problem with a 21V BAP but they make a killer 400 pump and 2 of those even without BAP hold huge power.
-J
 

RedVenom48

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I think DW would know straight away :)
I doubt it’d have a problem with a 21V BAP but they make a killer 400 pump and 2 of those even without BAP hold huge power.
-J
Just trying to figure a way to run more pump in my 11 hat with returnless opertation. If its new hat time, it may as well be return system time. $$$$ Someday, Ill find a hobby that isnt this expensive haha
 

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