Fuel Pressure

[Blizzard242]

I need help badly. I was unable to figure this one out my first try so now it's up in the air as to what exactly it is.

Ok, the story goes.. Well mother f'er I have 2 videos showing examples of what happens.

Well those aren't exactly ready yet thank you YouTube.
Basically, as far as my fuel system goes...
I've installed a walbro 255, 42.5 injectors, a new fuel filter, and the vacuum/boost line is still connected to the FPR. As far as I know or have been told keeping the vacuum line connected is fine. I'm only pushing 9 lbs of boost right now.

Driving after about 15-20 minutes my fuel pressure dies down to 0 and I have to stop. Sometimes it doesn't die down and fluctuates like crazy and eventually dies. I don't know wtf is going on with the damn thing. It's frustrating as all hell and the only way to replicate the problem is to drive and then I don't even know how far away from home I'll be. It seems to react to throttle pretty decently, being that.. it returns to normal after flooring it for a few seconds but about half a minute later the pressure wants to die again.

The only reason I made it home without stopping once today was because I had enough decent space to floor it whenever the pressure started dropping.

It seems to be associated with temperature. Seems to be.

I'll post up the videos whenever they're ready.

[Shodown]

Re: Fuel Pressure

Did you tune for the injectors?

Does the car actually die when this happens?

What kind of gauge do you have?

I'd also pull off the vacuum line from the FRR, it doenst need to be on there. I pulled mine and consistently run 53-55 psi.

[Blizzard242]

Re: Fuel Pressure

Did you tune for the injectors?

Does the car actually die when this happens?

What kind of gauge do you have?

I'd also pull off the vacuum line from the FRR, it doenst need to be on there. I pulled mine and consistently run 53-55 psi.

Yeah, if I don't get on the accelerator the car can die when it happens. But even if I dont jump on the gas it sometimes jumps right back to where it normally is.

I got my gauge from Shane. So... It's in the videos here..
http://www.youtube.com/watch?v=rqUrA-ICYZs
and
http://www.youtube.com/watch?v=y6b0fqJsj74
Those are pretty good examples of what's happening.

Oh and yes, the injectors are tuned. Someone is helping me very closely tune via email and as far as I've seen he's doing an amazing job over the internet.

And P.S. you'll need sound to hear when I'm revvin the engine in one of the videos.
I got stuck at a fairgrounds parking lot today letting it "cool down" for 10 minutes which didn't do **** this time. Luckily I was 2 minutes away from my brothers house.
On my way home I discovered that revving the engine enough would restore my fuel pressure for a short amount of time.
Which must have been funny to see on the way home.. trying to do 55 but I had to speed up to 70 just to keep my fuel pressure. This is a weird one. I'm gonna clamp off or do something to the fuel pressure line tomorrow to see what that does. As for now, it's bed time.

[Firebirdkid96]

Re: Fuel Pressure

did you put your sending unit RIGHT at the schrader valve?

[Blizzard242]

Re: Fuel Pressure

did you put your sending unit RIGHT at the schrader valve?

Yes...

As far as any other specific questions anyone might have.. I have a camera and the ability to upload so just specify where you might need to see anything and I'll be on it asap. For tonight though, i'm off to bed. I'm already gonna be dead for work tomorrow as it is.

[Shodown]

Re: Fuel Pressure

Sounds like your FPR, fuel pump or fuel filter are fvcked up.

[Firebirdkid96]

Re: Fuel Pressure

ditto on the above post

[Blizzard242]

Re: Fuel Pressure

lmao.. that's what I've determined too. I was hoping someone had anything more specific. I'm gonna be pissed if it's the fuel pump. I'll start small.. with the filter.

Oh oh, so if I take off the vacuum line from the FPR, do I need to plug the FPR or will that be ok to have it exposed to open atmosphere. Also.. What's that gonna do to my fuel pressure then? Will the FPR be taken out of the equation completely then?

[jrocstar]

Re: Fuel Pressure

what line did you use to connect the walbro. I used high pressure fuel injection hose by goodyear and had almost the same issue then when i pulled out the pumpo i saw the hose was basically blown out. I installed stainless braided line and no problems yet. that and also leave your frp hooked up it will be better for low vacuum driving especially for tuning. and might want to replace fuel filter. I am assuming that you did the correct install on the walbro with cutting out the plastic tank and what not to help fill the container.

[Blizzard242]

Re: Fuel Pressure

what line did you use to connect the walbro. I used high pressure fuel injection hose by goodyear and had almost the same issue then when i pulled out the pumpo i saw the hose was basically blown out. I installed stainless braided line and no problems yet. that and also leave your frp hooked up it will be better for low vacuum driving especially for tuning. and might want to replace fuel filter. I am assuming that you did the correct install on the walbro with cutting out the plastic tank and what not to help fill the container.

Yeah it did it the right way. hmmm.. lemme see if I can find a link to show you exactly what i bought and installed..

http://www.autoperformanceengineering.com/
Click on applications in the column on the left then
click on LT1 owners read this. That is what I bought.

I put a new fuel filter in when I installed everything including the pump. But I have a new one on hand to put in just in case I had a faulty filter.

[ssms5411]

Re: Fuel Pressure

Sounds like the hose to your fuel pump came loose or off and is just hanging there mine did that once and I saw my fuel pressure at 32psi and it would drop off to zero. I did the trap door method so I opened it up and the hose was off to the side and it was spraying enough to get the car started, put the hose back on and retighten the clamp. Problem solved. So I would check the fuel pump.

[Blizzard242]

Re: Fuel Pressure

Sounds like the hose to your fuel pump came loose or off and is just hanging there mine did that once and I saw my fuel pressure at 32psi and it would drop off to zero. I did the trap door method so I opened it up and the hose was off to the side and it was spraying enough to get the car started, put the hose back on and retighten the clamp. Problem solved. So I would check the fuel pump.

Sounds good, that'd be awesome since I did the trap door thing too with weather stripping and all that. I'll definitely check that out tomorrow cause I'm staying at my gf's house tonight and the car isn't here. I hope that's what it is because that's an easy fix.

Ok.. but theres the high pitch sound the pump makes when its running.. when the pressure is dropping off the whine sound fades away with the pressure.

[jrocstar]

Re: Fuel Pressure

that is due to the pump not needing to develop any pressure. The pressure really makes the pump alot louder. I am pretty convinced it is the line in the tank. and since you did the trap door it is easy to find that out.

[Blizzard242]

Re: Fuel Pressure

that is due to the pump not needing to develop any pressure. The pressure really makes the pump alot louder. I am pretty convinced it is the line in the tank. and since you did the trap door it is easy to find that out.

Ah I see now, that can make sense. Well we'll find out tomorrow. :D

[ssms5411]

Re: Fuel Pressure

Yep, it sounds like the hose came loose just retighten it until you see the rubber coming out of the slots in the clamp. Good thing you did the trap door method. On a side note,my dad worked for GM for over 40 years, 20 as a mechanic and 20+ as shop foreman and service manager(retired in june), I showed him the trap door method about 6 years ago he was amazed, had me make a copy for him so he could give it to his mechanics. He said GM should of done it from the factory. He said he would give the option to the customer if it was not under warranty, so they could save on labor. If the car had a warranty on it(like extended plans) they have to due it by the book time. Good luck to you and I hope it is the hose. Steve