KLLRVET

I am checking my fuel pressure at the rail, and the gauge reads 100 psi!!

If I were to kink the line for the jet pump going to the other tank, would it be possible for the fuel pressure to shoot up to 100?

When I first started the car, it made about 65psi. I ran it for about 10 min checking for leaks, etc. After that I took it for a drive. About 3-4 miles in, the pressure started to creep up to 100. Now, after running for only a few moments it creeps up to 100!!

Any insight would be greatly appreciated

Tony

Milan

Did you adjust your regulator?

KLLRVET

im using the stock internal regulator

Unreal

Over running the stock reg?

Milan

Not gonna happen with that pump. Time to add a regulator and return line

KLLRVET

Others have used this pump as a drop in and have had no problems. ..

Milan

While others with a C5 will drop in a 255 and have problems with the stock regulator.

Add a return line and an adjustable FPR, your injectors will thank you

KLLRVET

Can you please show me an example or two where others had a problem? I'm not saying that creating a return style system wont work, but I am unsure if its the problem.

It was fine (65 psi) for about 15 min and then it shot up. I suspect that the jet pump system may be suspect. It is possible that I kinked that line or the return from the other side, and I wonder if it would make fuel pressure skyrocket.

C6 Curtis

Yeah you might want to check it out because mine never shot that high and I'm using a stock regulator. But I've seen it happen before with mitsu evos with changing the stock pump and over running the factory regulator. But they fix it with an aftermarket regulator.


-Curtis

narfdanarf

Most likely you have the bypass or one of the jet pump lines kinked. I know that in my car with the 450 and racetronix rewire I still couldn't get to 43lbs base pressure with a small hole in one of the jet pump lines so those lines will affect pump output a lot.

ProEFI

Tony that's may help you I had the same issue with my car, if your gauge is AEM then gauge is not reading at all.

KLLRVET

ProEFI I don't understand. I am using an external gauge attached to the Schrader valve on the oem rail.

ProEFI

what am trying to say I had the same issue and I fogger out that the sensor wasn't reading on my AEM gauge, I thud you running AEM so that suggest to check your gauge.

KLLRVET

I tried two different gauges, and had the same results. I pulled the tank again, and checked the crossover lines for any kind of kinks and found none.

I was trying for an economy fuel system upgrade, but it seems that simply wont be the case. As stated above, it seems clear the stock regulator cant handle the new pump.

I just don't understand why the pressure doesn't jump right up to 100. When I start it, it starts at 65, and over time (5 Min ) it creeps up to 100. It just doesn't make sense.

5 Liter Eater

You may want to bench test the assembly and/or take the regualator out of the bucket and inspect or replace it. I have two Walbro 255's Y'ed together in the stock bucket running all the time and I get 65# at idle and cruise and it drops to ~55# under WOT. The fact that its not shooting to 100 right away would indicate that it's not simply that the pump is putting out too much.

robert miller

KLLRVET

All the needed parts will be here today for the return side

UniTink72

I'm doing the return line too, mind posting your shopping list of parts?

rio95

I've been looking into 450 install stuff for a while now. Still not comfortable with pulling the trigger. Did u ever get this sorted out?

​​​​​​Im trying to figure out why some people claim the stock regulator won't keep up yet others disagree. Is it because most people do affect their fuel pressure and just don't know it? I suppose it could get baked into the tune, but I'm not cool with that.