Fuel Pressure Problem?

[mr2gq]

I got a 2.3 turbo swap and it pulls hard and then just kind of like it hits a wall. I put a adjustable fpr on it and set it for 35 psi idle. When I rev it it builds pressure but if I rev it and hold it at like 3-3500 rpm or so the pressure falls off to like 35 psi. Just wondering if this is normal. Trying to rule out problems. I checked and 're checked timing both cam and distributor.

 

[65ShelbyClone]

When setting the base fuel pressure, you're supposed to pull off the vacuum line, plug it, then set the pressure to 39-40psi to start with(which is the stock pressure). Put the vacuum line back on and the fuel pressure should drop in response to manifold vacuum. It will also ramp up the pressure on a 1:1 relation to boost.

I got a 2.3 turbo swap and it pulls hard and then just kind of like it hits a wall.

Could you elaborate?

 

[mr2gq]

Okay well what I was wanting to know is if you rev the motor the fuel pressure goes up, should the pressure stay that high as you hold the rev there? Meaning if I rev it to say 3k rpm and pressure goes to 45psi, if I hold the rev at 3k rpm should the pressure stay at 45psi as well or will it fall off some? Cause that's what's happening. And what I mean by pull hard and hits a wall is, when I take off the motor feels like it has all its power and once it gets to a certain rpm,probably 4k no tac right now, it just feels like it slows down tremendously. So I'm curious if it might be due to fuel pressure

 

[65ShelbyClone]

Is your pressure gauge mounted under the hood or in the cabin?

 

[mr2gq]

It's under the hood on a aeromotive adjustable fpr

 

[mr2gq]

Just so you know why I don't have gauges yet is cause I have a s197 dash swap lol

 

[65ShelbyClone]

Alright, so you've been revving it in neutral, which is what I initially thought.

When doing that, the fuel pressure should just about always be below whatever it was set to. The only time it should spike up to the base pressure is from a wide throttle snap.

 

[mr2gq]

Okay thanks I'm going to try and see if I can get a long gauge on it to see it while driving

 

[KhanTyranitar]

Sounds to me like you have a plugged filter, or a weak pump that can't keep up.

 

[mr2gq]

No fuel filter is new motorcraft. Put a long fuel pressure gauge on it. It showed only 42 psi at WOT and wouldn't go any further. Looked like it would actually 1 or 2 psi and come up. Hard to watch while driving and kicking it lol. But if I only half throttled it, it would go to like 55 psi or so. Im thinking fuel pump. It is one I got out the jnk yard for the swap. It came out a LSC mark 7. So it is the same as a turbo coupe, but... it is a junk yard fuel pump. What do yall think?

 

[KhanTyranitar]

Gets new Walbro 255 lph fuel pump. Don't waste your time with anything else.

 

[fess40]

+1 for the Walbro 255. Affordable insurance for future mods as well.