New FP & FPR no rising FP?

[Omega]

I just installed a 255HP and the full throttle FPR. Everything seemed fine. I set the FP with the vacuum line off, but found it to hesitate and backfire when I free reved it. I took it for a spin and the damn fuel pressure doesn't rise with boost!

I have gone as far as connecting the FRP directly to the intake and that didn't help. Has anyone had issues with a FPR causing this? Tomorrow I will put the old 190 FP back in, but I really don't feel like messing with that again... I am leaning towards the FPR because I would think the FPR would cause this over the FP.

Suggestions?

 

[guitarXgeek]

You didn't forget to put the vacuum hose back on the FPR did you? That would sure cause it to not raise fuel pressure with boost, for sure !

 

[Omega]

I have gone as far as connecting the FRP directly to the intake and that didn't help. Suggestions?

Uh, yeah.

 

[sweet97]

First it's not the pump so leave it in there! Set the pressure with the line off. What pressure are you setting the base pressure to? I would suggest about 43 psi. Then when you replace the line the pressure should drop.
How do you know you are not getting an increase above the base setting with boost, fuel pressure gauge in the car?
I would call fullthrottle if you are sure it is not at least dropping when you replace the line. I use the same AFPR with no ploblems.
You mentioned sputtering when you set the base I believe. Does that go away when you replace the line or get worse?
My base is set at 45 psi. If yours drops when the line is put back on I would say it is working and also raising pressure under boost. Mark

 

[mattfastAWD]

I did the same thing on my car. I install a Full Throttle fuel pump and the pressure won't rise. I called Full Throttle and they said is was my gauge. I don't know haven't figured it out yet

 

[Omega]

I have had an electronic FP gauge in the car for ages now, I did set the pressure with the line off. It did drop when the hose was connected, but now it doesn't change.

It suddenly dawned on me what it could be. When I fired the car up for the first time, the port on the FPR for the FP gauge was leaking (my gauge is connected to the filter side). It isn't a tapered thread design.. NPT? I wonder if the plug it too far into the regulator causing something to bind up. If that is the case, I hope no damage has been done.

I'm going to pick up the proper plug and try it out tonight.

MattfastAWD, perhaps that is what fullthrottle meant by "it's your gauge".. that is has been screwed in too far and is binding the damn thing up.

I KNOW it's not my gauge, the sensor and any wiring was never touched during the install.

 

[Omega]

Right. I am still scratching my head about this. The port now has a FP gauge in there.. it wasn't the problem, and I now have one in the cabin and one on the reg.

I still think it's the FPR, but I have a concern about the FP. The plastic spacer on the output nipple was very loose when I put it in. The cap and gromet are there, but the spacer wasn't seated and did want to be either. I wonder if most of the fuel is just spewing out not going me the pressure i need... but....

The fuel pressure doesn't do jack until ~15 psi of boost, then it jumps to where it should be. As soon as I back off, it drops and stays there. Normal free rev has little to no impact either.

I got the back fire sorted, I had the pressure set too low

 

[99gst_racer]

I wonder if most of the fuel is just spewing out not going me the pressure i need... but....

You'd smell it if it was spewing out.

The fuel pressure doesn't do jack until ~15 psi of boost, then it jumps to where it should be. As soon as I back off, it drops and stays there.

Assuming the gauge is properly functioning and accurate, I would say that your regulator is defective. So, you had the same cabin-mounted fuel pressure gauge before you installed the regulator, right? And it was reading correctly (rising 1:1 with boost pressure), right? If yes to both, then it is a problem with the rugulator.

Normal free rev has little to no impact either.

That is normal. There is no load on the engine during a free rev; and most usually little to no built boost. Therefore, your fuel pressure will remain where it is at idle during a free rev.

 

[Omega]

The fuel spewing out comment refered to inside the tank. I am a little unsure if the outlet of the pump isn't seated well.

I know that there is some fluctuation with the FP between idle and reving. With the stock reg, when you rev it would see zero pressure and zero vacuum which was 42 on the gauge... similar to the line on the FPR being disconnected. At idle, it was at 38psi or something like that. Now it sits at 42psi (+- a few) all the time... boost or vacuum.

Full throttle thing it could be a weak pump. They say that since it is changing it's not the reg. They want me to use a compressor to simulate boost and see what happens.


Yes, the cabin gauge worked fine before, 1:1 rise and all that jazz. I now have a second one on the reg as well.

 

[dpbgst13]

I have the same problem on my 97 eclipse gst. I put in the new FPR along with a Walbro 255. When you rev the engine with no load my fuel pressure drops. I dont have a gauge in the car so i dont know what its doing under any boost or load. Does anyone know if thats normal or do i have the same problem.

 

[Omega]

Well, I found the problem.

I called Full Throttle to talk to them about it. He said that if I was able to adjust the fuel pressure, and the pressure drops when I put the vacuum line back on, it's not the regulator.
His guess was a weak pump or not enough voltage. I said the pump is brand new and the wiring is good.. and rewired.

He then said to dial an air compressor down to 10 PSI and apply it to the reg will the engine was running. If the fuel pressure goes up, it's definitely not the regulator.

Hmm. What could it be? I took the pump out and checked the o-ring, back in it went and still was having issues. I swapped the old 190lph in and viola! The car runs like a champ!

Contacted the vendor.. we'll see how they perform.

I like the FPR test though. It was a dead give away.

I'd look at the pump dpbgst13, same symptoms right?