[93mustang]

I've been losing 2 tenths et and 3 mph in the 1/4 mile at the drag strip recently.
I pulled a plug and it was lean.
I set the fuel pressure from 43 psi to 40 psi about a week ago.
Could 3 psi make that much of a difference? I didn't have my pressure gauge at the strip, but I put it back to 43 psi when I got back.
I changed the fuel filter 4-01-09.
Could the fuel filter be clogged already? Should I change it anyways just to be sure.
The fuel pump is 3-4 years old, 190 lph Holley. Could the pump be on it's way out? I fill the gas tank to half when I race which is 1-2 times a week.
I usually use a Motorcraft fuel filter. Are the other brands ok like Fram? I don't think I can get a Motorcraft around here for today.
Fuel direction arrow on the filter should be pointing at the drivers side rear tire , right?
Thanks for the help!
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1993 GT Mustang / Ford Racing GT-40 Crate Motor B-303 Cam / Tremec T-5Z / 4.30 Gears / Detroit Locker / Moser 31 Spline Axles/ Subframe Connectors / BMR Upper and Lower Control Arms / Lakewood Adjustable Drag Shocks/

Best ¼ Mile Time – 13.18 @ 104mph

[PLstang]

Do you not have a fuel gauge on your regulator?

Why did you decide to take pressure down to 40 from 43? Were you having an issue?

Sorry, I'm full of questions today!

If you are noticing a lean condition on the plug then I would say that it would be good to check the whole system over again. If you can't find anything wrong then I would look at the pressure.

When it comes to certain systems on the car it's never safe to make an assumption. If you have something like a lean plug then you need to check the whole fuel system. It's sometimes easy to say "well it's a result of this or that change". However, I have found that when making that assumption things tend to bite you in the rear!

You never know what the one change may have triggered in the rest of the system!

[RLG34750]

i'm with you on this Eric......

why would you drop the fuel pressure on a car that was running fine....

also if you are racing a fuel pressure gauge is a must

not to mention cheap for rail mounted one.......

Summit SUM-800199 - Summit® Chrome Plated Fuel Pressure Gauges

i also would check out the complete fuel system.....

For every action there shall be a reaction.....

[93mustang]

I use to run fuel pressure at 40 psi last year.
When I changed plugs this year, 2 plugs where a little lean so I increased my pressure to 43 psi. You're right , I should have just left it at 43 psi. As far as a fuel pressure gauge, the Holley doesn't have a port for one on it, should have bought a BBK which does have a port. I have read that it isn't good to mount a gauge on the shradder valve, that's why I haven't put one on there. I just have a Actron one that hooks to the shradder valve when i want to adjust or check it.
It's at 43 psi now. Do you think for the cost of a fuel filter I should just change it, or see what it does next time at 43 psi?
Thanks for the help!!

[PLstang]

If you have any concerns at all then at the least check the existing filter. Not sure what they cost but if it isn't that much then go ahead and make the swap.

I'd check the pumps also. Make sure the Holley's still up to snuff. they make a rebuild kit for the Holley Blue's and they aren't that much!

What type of regulator are you running?

[93mustang]

Originally Posted by PLstang

If you have any concerns at all then at the least check the existing filter. Not sure what they cost but if it isn't that much then go ahead and make the swap.

I'd check the pumps also. Make sure the Holley's still up to snuff. they make a rebuild kit for the Holley Blue's and they aren't that much!

What type of regulator are you running?

I'm running a Holley regulator.
How do I check the pump?
Thanks

[PLstang]

Originally Posted by 93mustang

I'm running a Holley regulator.
How do I check the pump?
Thanks

Unfortunately now your outside of my skill set. I got the first Holley pump on my car only a few days ago.

Maybe someone with more experience with their pumps can help!!

In regards to the regulator I'm not sure about all of them but mine has a bottom feed then two outlets (one on either side). You may have a plug in one of the outlets, just remove the plug and insert gauge.

[RLG34750]

i would just upgrade the pump to a walbro

a new fuel pump is cheaper than pistons....

based on the age of yours i would say you are about due......

[PLstang]

Originally Posted by RLG34750

i would just upgrade the pump to a walbro

a new fuel pump is cheaper than pistons....

based on the age of yours i would say you are about due......

you can't argue with that logic!!

[93mustang]

I had a new fuel filter and a new Holley 190lph pump put in today.
Unfortunately, I can still only get the fuel pressure to go as high as 44psi with the vacuum off. is that normal. I have a Holley adjustable fuel pressure regulator. Could the regulator be messed up. The regulator is suppose to be adjustable from 35 psi to 65psi. How much fuel pressure should I be able to get out of the 190lph pump with stock fuel rails?
Thanks for the help

[RLG34750]

based on the regulator it should pull in theory 65 psi with the vacuum on......

there is a possibility the regulator is bad.....

what is the fuel pressure at WOT....

[93mustang]

Originally Posted by RLG34750

based on the regulator it should pull in theory 65 psi with the vacuum on......

there is a possibility the regulator is bad.....

what is the fuel pressure at WOT....

How do I check fuel pressure at WOT?

Also I've be reading various articles on setting your fuel pressure and there's something mentioned about capping the vacuum line.
I thought you just unhooked the vacuum line , set the pressure and then reconnected the vacuum line and you where good to go?

Thanks again for all the help!

[93mustang]

Well as far as the fuel pressure gauge, I read this somewhere and tried it.
I released the pressure in the fuel line, backed the fuel pressure adjustment screw almost all the way out, and then turned it all the way in clockwise which would be max. pressure. Sure enough, I fired the car up and I now have full adjustment of 35psi-65psi. When I was turning the adjustment screw back in, I felt a very slight resistance at the point where I couldn't adjust any higher than 44 psi, like there was something caught or hung up in there. Once I got the screw past that point, it now adjusts freely from 35-65. Who knows? Maybe there was a small piece of debris in there or something was hung up.
I have it set a 43 psi and the car feels more responsive.
I'll find out how it is next trip to the track.

[RLG34750]

sorry didn't get back to you sooner.....

glad you got it figured.....

the increase fuel pressure will help.....

[93mustang]

Originally Posted by RLG34750

sorry didn't get back to you sooner.....

glad you got it figured.....



the increase fuel pressure will help.....

Thanks for the help!!!