Rail pressure drop

[Bamaterminator]

I have looked but can't really find the answer. What is a normal drop in fuel rail pressure on an 04 with a 2.8 pulley. Or should there not be a drop at all. Example. Wot pull as soon as I hit the throttle I see a lean spike for a hundredth of a second then as it starts to come down I see the rail pressure drop to around 25. But this is for just a hundredth of a second then both plane out, the pressure goes up and AFR goes back to 11.5. thanks in advance

 

[01yellercobra]

The rail pressure shouldn't drop at all. Did it just start doing this?

 

[Bamaterminator]

I'm not sure as I have only recently started to really log it. It had a super chip from PO. I switched to sct, wasn't happy so I got a mongoose cable and BE. I've been working on it slowly for about 6 months. It has no drivability issues. I noticed a lean spike at tip-in, that's what lead me to this fuel pressure drop

 

[01yellercobra]

I'm thinking you might have a pump starting to go out. Maybe it can't take the initial hit, but then gets up to speed. Or one pump is just making it by for now.

What's the voltage doing when all this is happening?

 

[Bamaterminator]

The voltage table has a normal climb on the chart. It don't match the drop in pressure. I'm going to change the fuel filter in the morning and see if that helps. If not I think you may be right one of the pumps is on the way out. Thanks for the response

 

[03cobra#2]

It could just be that tip in needs to be adjusted. If it's a hundredth of a second can you feel it when driving? It this on every tip in or just going wot?

 

[Bamaterminator]

Can't feel it. I believe it's only wot, I'll check to confirm

 

[Bamaterminator]

Changed the filter. It did seem to help a little. It had a wix, I went back to a Ford. Loaded a screenshot of the log this morning.

 

[01yellercobra]

Honestly the tip in wouldn't concern me as much as the pressure dropping to 25psi and then ramping back up. It shouldn't ever drop that low. If at all. I would fix the pressure drop first. My guess is once you fix that the lean spot will go away.

I would add voltage to your log. When I asked about it earlier I wasn't refering to the table. You need to see what the alternator is doing under full load.

 

[Bamaterminator]

New kmj the min for the whole log is 12.8 and during the pressure drop it's 13.3. it's on there I just have it not showing. Too many lines at once.

 

[01yellercobra]

That's good then. I'd look into new pumps at this point and go from there.

 

[Bamaterminator]

While we're on the subject. What do you think about the Deatswerks dw300?

 

[01yellercobra]

I want to say I've heard good things about those. But I think that was mostly in the 3V community. I can't imagine them not working as well in our cars.

 

[Bamaterminator]

I guess there's only one way to know for sure. I would imagine it would come with a spreadsheet for the voltage table. Thanks again for the help

 

[01yellercobra]

In my experience pumps don't come with a data sheet. Each car is different. But a good tuner should be able to get you dialed in no problem.