Fuel Pressure dropping on Boost

[Arctic Thunder]

Fuel Pressure dropping on Boost-SOLVED

2009 Twisted Turbo on the M1000.

Running the high output fuel pump and the 1:1 raising rate fuel regulator.

Until today fuel pressure was working great, 40psi at idle, and 50 at 10lbs of boost.

Right out of the gate this morning, I had 40 at idle, and when I pin it and it starts to build boost, the fuel pressure climbs like it should, but then really falls off, down to 20-25 or so. So I back out of it not knowing what the heck is going on. Do it again and same thing. Pretty much just stayed out of the boost all day (and the weather sucked anyway). I did have a couple times where it seamed to hold a bit longer before dropping but for the most part same thing all day.

Any ideas?

Here are a few things I am thinking, tell me if I am on the right track.

1. fuel pump, not putting out enough, (but it will climb but drops)
2. Electrical power to pump, stator not putting out enough voltage to maintain pressure.
3. Cracked/chipped read, so my boost signal is messed up because I am getting back pressure through the throttle bodies. (I believe I have a chipped reed, I had to raise my idle last ride)
4. Something stuck in the fuel pressure regulator.

I am going to start out by putting 12v power to the pump, then put a pressure on the regulator one PSI at a time and see if it holds and raises. I might even pull the supply line to the fuel rail and put a valve on it so I can bleed fuel off into a container to check flow rate and pressure and again make sure it holds. If it drops or won't hold I will put a low PSI air supply and blow through the regulator in the same direction of normal fuel flow. Could have something stuck in it.

Pull the air box, throttle bodies and check reeds.

Need to check the output voltage from the coil.

Again any other ideas? It won't run this way that's for darn sure.

Thanks

Thunder

 

[Arctic Thunder]

Hooked up 12v power to the pump. Then increased the boost pressure to the regulator. Worked perfect. 1psi boost=1psi fuel pressure increase. And it holds (no flow, motor off)

Thunder

 

[Arctic Thunder]

Alright a new twist.

Last weekend my rboost.com boost controller came unscrewed. I screwed it back together, set it to the timing marks I had marked. Sled ran pretty good pulled about 10lbs of boost.

So tonight I pulled the rboost controller off when going after the reeds and unscrewed it again just for the hell of it. And guess what it is supposed to have a spring and a ball in it. So... When it was unscrewed and totally disconnected from the charge tube I was getting ALOT of boost. because I wasn't getting the waste gate actuator to open. So when I screwed it together I then couldn't get it to build boost because I basiclly had an open line from the charge tube to the waste gate controller. But on this setup I can't get below 8-9 lbs of boost no matter what. So here is my thought now.

Without the boost controller, the sled would build boost, and the charge pressure would increase my fuel pressure. So when I pinned it it would spool up, build boost, then dump the boost because of the faulty boost controller. At that point the sled was spooled up and pulling, any chance I could have a major swing in charge pressures maybe even to the point of a vacuum, the vacuum would then pull the pressure regulator down rather than increasing the fuel pressure?

Long story, and I am typing it out just because I am thinking through it.

Any thoughts.

Thunder

 

[m8magicandmystery]

seems like you have been put in the doghouse...all alone...no one to visit and help,

so I just dropped by to visit, i can't help ya though..

later gator , im on my way to a thread that I can contribute to with my lessor IQ..

 

[Arctic Thunder]

seems like you have been put in the doghouse...all alone...no one to visit and help,

so I just dropped by to visit, i can't help ya though..

later gator , im on my way to a thread that I can contribute to with my lessor IQ..

Not a lot of help on a Saturday night. Maybe more later. I probably put to much crap in the first threads. I am pulling reeds tomorrow. And will check the coil for good power.

Thanks for the bump.

Thunder

 

[stcatman]

I would be suprised if your reeds are all that bad, changed mine last year becuse i was in there , mine were chipped a little but not enough to matter much,

 

[Arctic Thunder]

Stcatman your right, they look good.

Just pulled my reeds, IMO they are in really good condition. I don't plan to change them. So this isn't an issue.

Thunder

 

[Snopro_69]

Need to invest in a 25 dollar bore scope cam from Hong Kong off eBay buddy!!! Ten mins to check reeds. Nothing to tear apart!!

 

[mmsports]

Help?

OK first you said it would drop some times but not all right?

That means a bench test would maybe show same results right.

Their is only one thing that I can think of and that is a leaky regulator. Does it hold fuel pressure with sled off? if not is probably time for new one.

Hooked up 12v power to the pump. Then increased the boost pressure to the regulator. Worked perfect. 1psi boost=1psi fuel pressure increase. And it holds (no flow, motor off)

Thunder

 

[matt159]

• I had same problem yesterday... 15 to 20 psi fuel pressure and haven't sorted it out yet. I swapped ccu on my 2008 & still 20 psi. I pinched off the return line after the external regulator & still 20psi. not sure when I will work on mine this week but I am anxious to see what u find. I put a new stator in mine 400 miles ago trying to figure out a tss issue. .. so hope it's not the stator... running Wahlberg hivol pump with bd booster board.

 

[Arctic Thunder]

Need to invest in a 25 dollar bore scope cam from Hong Kong off eBay buddy!!! Ten mins to check reeds. Nothing to tear apart!!

Funny you say that, I was looking at those just the other day. But with a scope you would see the major missing reed, or maybe a chipped corner, but you won't see the little defect like mine has. Granted I am not worried about the little chips like I have so maybe a scope would see the ones that cause problems.

I found a bunch of USB scopes for under $15.

Thunder

 

[Arctic Thunder]

OK first you said it would drop some times but not all right?

That means a bench test would maybe show same results right.

Their is only one thing that I can think of and that is a leaky regulator. Does it hold fuel pressure with sled off? if not is probably time for new one.

I think Ill order a new regulator as step to fixing it.

When I shut the sled off it will drop 1-2 psi in two minutes, then it will slowly drop to about 20psi over night, then after that if finally drops off to zero.

But when I said sometimes it would drop other times it wouldn't.

It appeared that it would work like it should if I pin the throttle and hold it. It would build boost and the PSI would increase and the Fuel psi held. But if I blip the throttle and get back into it it would try to build fuel pressure again but then fall 20psi kind of bouncing all over swinging 15-20 psi up and down. Still makes me think not having a boost controller (working) between the charge tube and the actuator is screwing with charge pressures thus messing with the regulator.

Hell I don't know.

At this time it's new reeds, new fuel pressure regulator, test the coil.

Thunder

 

[m8magicandmystery]

pay the extra few bucks and get a scope with color and the picture taking and movie feature that takes a card...( 9 mil head )

when your not using it on your sled you can make a buck or two doing a colon exam on your neighbor

 

[Arctic Thunder]

pay the extra few bucks and get a scope with color and the picture taking and movie feature that takes a card...( 9 mil head )

when your not using it on your sled you can make a buck or two doing a colon exam on your neighbor

I figured that was coming. Every time someone wants to borrow the boroscope from work the first thing we tell them is make sure it's clean when you bring it back. lol

 

[INDEEP]

Good luck and let us know. Could the fuel pick up's in the tank cause this issue?

 

[m8magicandmystery]

I.

It appeared that it would work like it should if I pin the throttle and hold it. It would build boost and the PSI would increase and the Fuel psi held. But if I blip the throttle and get back into it it would try to build fuel pressure again but then fall 20psi kind of bouncing all over swinging 15-20 psi up and down.

Thunder

how does the sled "feel" like its running during all this..??..normal...??

 

[Arctic Thunder]

how does the sled "feel" like its running during all this..??..normal...??

When the pressure is up and matching the boost it feels great, when the psi drops the AF goes lean, and it doesn't like it at all. So I get out of it really quick.

Thunder

 

[m8magicandmystery]

Still makes me think not having a boost controller (working) between the charge tube and the actuator is screwing with charge pressures thus messing with the regulator.

and is this still a possibility to be your issue or not..????

 

[m8magicandmystery]

have you given any thought to fuel lines delaminating and randomly collapsing an inner shell..??

 

[Arctic Thunder]

have you given any thought to fuel lines delaminating and randomly collapsing an inner shell..??

The fuel lines upto the rail are under pressure. So I wouldn't think it would collapse. On the pickup side maybe.

I will check the fuel pickups and make sure they are good.

Thunder