I have an 02 that's bone stock , I put an edge cst insight monitor on it beause the truck felt sluggish and I wanted to see what may hae been going on, well I put up the FRP and the desired FRP at idle in park they are pretty close together and sometimes right on now when I'm on the throttle driving my desired FRP says I should be up towards the 20,000psi range and its only producing a max of 10,000 psi most of the time less than that ... has anyone else had this problem...also my balance rates are within tolerance
LB7: fuel rail pressure problems
- Thread starter BryanLB7
- Start date
it throws the codes P1093 and P1094 For fuel pressure low under no load and fuel pressure low under load
the filter that's on it has maybe 1k miles on it if that and I feel like it did it the same on the previous filter but I didn't know exact numbers since I just got the monitor to check the problem
Not to hijack, but on a buddy's 03 he is experiencing same issue but his wont start. Started off being sluggish and got progressively worse until one day no start. I told him to change fuel filter for starters then go from there. He did the Nicktane adapter and cat filter and still no start. He then changed FPR and still, no start. I went over to his house with my CTS and checked codes, only had one for intake heater. Checked fuel rail pressure and it was under 250PSI. I told him to pull glow plugs and then crank to see if maybe an injector or two were stuck open draining fuel rails. Nothing. Cranked over with no sign of fuel spraying out glow plug holes. He bought a new CP3 and installed it. Told me last night he has more fuel rail pressure than he did but still not starting. I'm not sure on what the rail pressure is right now, he didn't say, but can injector dump or return enough fuel to get rail pressure so low that it won't start? I'm thinking it would have to be more than one injector dumping to get rail pressure below 250? I'm curious as to what your guys' thoughts are on this. I guess it only leaves the injectors that can be causing the issue.
Need to do the bottle test. How many miles on injectors? I've had stuck relief valves leaking by, injectors with near perfect balance rates but super high return rates, or cp3's with high return rates...
Mine had the trouble of not starting at all with injectors shot on the return side. It wasn't allowing them to build the proper pressure for it to start. Had to start it with gum cutter sprayed down the intake every day. See if that works on his. But take the advice, do a bottle test on the fuel return line back by firewall on drivers side. Crank over for 15 seconds, and measure how much fuel it returned into bottle. Good luck!!
Did the bottle test. On the return line it put roughly 2 ounces in bottle. Told him to isolate the CP3 and do it again. The CP3 returned a little more than the line. I have a few pics he sent me but nothing with a definitive measurement. I would say roughly 60ml from CP3 and maybe 50ml from injectors and relief valve. I told him to replace the relief valve or block it off and do the test again before replacing injectors. I understand that the CP3 will return more fuel while cranking only because desired FRP is 6k, but I can't find a measurement on injectors while cranking. I would think it would be little to none because with only a 6k desired FRP it would take most of that fuel to start. I will know more when he gets relief valve plugged and then redoes the test. Appreciate the feedback. I'll update when I know more.
20 ml on bottle test if i remember right. Sounds like return side of injectors is the culprit. Will it run if gum cutter is shot into the intake? Might need that lil shot of nose candy to help it start.
Didn't try that yet. I went by him after work to look at relief valve but he already had it back in. He shimmed relief valve with some washers he had. Said he ordered race plug but won't be here until Monday. Here's the issue, when this first wouldn't start it had 250PSI fuel rail pressure, replaced regulator- no change. Replaced CP3- got up to 500PSI. Shimmed relief valve- it's up to 700PSI. I know that is minimal change but don't you think shimming valve should have done nothing? After discussing this problem a little further I'm set on the issue being injectors. Which one or ones? Who cares right? It's a LB7 with 120k on stock sticks, that right there should be the biggest red flag of them all. Am I wrong for thinking this? It's hard to test, I'm thinking about buying an injector return testing kit but I told him that if he has to pull rocker covers and pull return lines to test, may as well pull the injectors and replace. So in a week or two, he will have new injectors, CP3, filter and a race plug. If this thing don't start I advised him to set it on fire and "do the jingle". I'll update when I have something to share. When I left today I told him to pull the relief valve and leave it out so I can see it. I'd like to see for myself if anything looks wrong. Mine is an LLY so mine is different than his and I'd like to know I'm not pushing him toward injectors for nothing.
I don't care how many miles u have on the fuel filter I think that's your problem I've seen them stop up with one fill up. I've seen this happen many times.
I'll try shooting it on Friday. At least if she starts we can do some testing while it's running. I'd just hate to see it leave him stranded somewhere.
As far as filter, it's new. Truck hasn't run since its been installed and he's got good fuel to CP3.
Thanks for sticking with me on this Millerman. Hopefully we'll get it running Friday.
As far as filter, it's new. Truck hasn't run since its been installed and he's got good fuel to CP3.
Thanks for sticking with me on this Millerman. Hopefully we'll get it running Friday.
It started spraying it and continued to run and saw a 4500PSI FRP and close to 8kPSI by just tapping throttle. Shut off and wouldn't start back up. Back to 700PSI.
I looked at FPRV and to me it doesn't look good. It has a deep groove in it. I have a pic but it sucks and I'm having issues with my photobucket.
Race plug will be here Monday, he couldn't let it run real long due to not having coolant in it. I will know more on Monday if this fixed his issue. I still think there has to be an injector issue. I think even if this fixes his issue its just prolonging the inevitable.
I looked at FPRV and to me it doesn't look good. It has a deep groove in it. I have a pic but it sucks and I'm having issues with my photobucket.
Race plug will be here Monday, he couldn't let it run real long due to not having coolant in it. I will know more on Monday if this fixed his issue. I still think there has to be an injector issue. I think even if this fixes his issue its just prolonging the inevitable.
If race plug don't fix it, and it still starts with a shot of gum cutter, then yes I would guess bad injectors. Possibly on the return side. If it don't start after installing race plug.
Race plug took forever to get. For some reason he said he couldn't find a stock replacement relief valve. Anyway, installed it and same thing. 700PSI rail pressure while cranking. 4K PSI after it starts with some juice. Stays running but won't start on its own. Tear down has begun. Removing injectors this weekend.
Question: when we pull these things, should the cups be replaced as well, or should I see how they look? Also I seen a few say they replace injection lines during injector replacement. I will make sure the return lines get replaced, and I'm thinking that's what the few are referring to. Why would the injection jumper lines need replacement? Maybe if they didn't seal or got bent somehow, but other than that I can't see why.
Again, thanks for all the info. And I've completely hijacked this, sorry about that.
Question: when we pull these things, should the cups be replaced as well, or should I see how they look? Also I seen a few say they replace injection lines during injector replacement. I will make sure the return lines get replaced, and I'm thinking that's what the few are referring to. Why would the injection jumper lines need replacement? Maybe if they didn't seal or got bent somehow, but other than that I can't see why.
Again, thanks for all the info. And I've completely hijacked this, sorry about that.
I resealed my cups. Only had one come out with an injector. But it's one of those things, your there, so why not avoid a future problem. You cant tell if the mating surface was disturbed on the cup while trying to remove the injectors. For the injector hard lines, I soaked mine in a bucket of gas over night. Then took some small wire brushes and cleaned up the ends that go on the injector, and the rail. They clean up nice that way. Then take a air nozzle and blow dry clean. Hope this helps. :thumb: