:confused: :confused: What do I need? I have an 04.5 lly With 4 into 5" exhaust and a edge atitude 3/5. With the edge plugged in, Every once in awhile it studders and buck and puts a little black smoke out. It also throughs a 1093 code.
I dont have alot of money so that is kinda why im askin a Lift pump and where is the cheapest I can find or should I just shim my FPRV?
Thanks for the help.....:confused: :confused:

I would just shim the FPRV. Lift pumps will not cure the 1093s alone and they are far more expensive than the shim kit. Do you intend to take your trucks performance much further? Do you intend to shim the FPRV yourself?

I would agree on how much more power do you want to make? I eliminated the P1093 on my 04 LLY with a lift pump (stock relief valve). I was running just a Hot Juice, and without lift pumps I would get the P1093 all the time in the upper levels. Once the lift pumps were installed I could not get my truck to set the P1093, and believe me I tried! :D If you plan on going for more power, you may need to do both the valve and a lift pump.

Does it do it on a fresh fuel filter? Does it matter on tank level? (will it do it on a full tank or does it ussualy do it on a 1/2 or less)

This is my post (my dad is smoker). These mods are all I want to do. It seems to usually do it 1/2 tank under and yes it does do it on a fresh filter.
Thanks
Jon

Take a 1 qt. container like a used milk container and tie it up under the hood over by the brake master. Locate the driverside fuel rail and follow it to the back end of the rail. About 1" from the end of the rail you will find a small black hose connected onto the rail. Remove the hose from the rail and plug the hose with a bolt and clamp. Route a new hose from the fitting on the rail over and into the container you tied up makeing sure the hose stays down inside the container. Go out and make the truck do the P1093 problem then pull over and open the hood and check the bottle for fuel. If there is no fuel in the bottle your safety fuel regulator is fine and your problem is most likely a fuel supply issue. If there is fuel in the bottle you have a regulator problem and I would take it to the dealer and get it fixed. Other may tell you to shim it but I would rather get the safety regulator fix properly as it should be under warrenty. Do not leave the test setup on forever once the test is done hook it back up to the stock setup.

I would do both lift and shim. My carter lift pump cured my 1093's but I went and spent the $9 on the shim anyway. Some of the more commercial units would work best (Kennedy, TTS, FASS, etc) but if money is an issue, a Holley or Carter could cure it around the $75 range.

The relief valve gets beat up due to lack of lift supply and "pressure cycling" Add lift supply and you will be better off.

To shim the FPRV doesn't help anything when you have not enough fuel avaiable to increase or keep the pressure. Take first a lift pump to bring enough fuel in the pump. When you go with higher power and have enough fuel avaiable then shim the FRPV or go with a dual CP3.

To shim the FPRV doesn't help anything when you have not enough fuel avaiable to increase or keep the pressure. Take first a lift pump to bring enough fuel in the pump. When you go with higher power and have enough fuel avaiable then shim the FRPV or go with a dual CP3.

:exactly:

Then this restriction/starvation can cause "pressure cycling" that can beat up the relief valve thus making the shim mod necessary eventually.

I am willing to bet if its more dependent on tank level you have a supply(need for lift pump) issue. Could be a combo of both though.....

I never played a LLY though......

The tank hight is kind a matter, but not rally eveluant. The CP3 sits in the V of the engine and higher as the tank. CP3 has a vaccum of 0.7 bar (10 psi) negative is equal as 7 meter or 21 feet of water. Now it doesn't matter wheter the tank is full or half empty (or half full) :D

In the real world I have noticed that if the tank is a bit more empty it drops rail easier without a lift. I think it has more to do with the pick up and bucket not getting fuel dumped over the top not the head develeoped from a full or empty tank but I honestly have no idea. And I also couldnt explain how using a lift pump to help suck outa the bucket would make a difference if it wasnt getting fuel over the top of it. I have no idea. All I know is I ran a Xtreme without a liftpump set up(Steve told me not to but I didnt listen to guys smarter than me back then and I still havent changed ):h ) and logged rail. I noticed a difference not only in what a scanner told me but also SOTP and smoke becasue I could get it to lay over HARD with a low tank level.

This was with my 03 LB7.....i duno if my experience is correct or applys....

As tank levels drop the system has to work harder to get the fuel to the engine so you can and will measure a difference when running a high Hp program with no lift pump. The lift pump does not solve pressure cycling of the system unless the system is getting air into it. The software controls the pump actions to keep pressures where they belong until it can no longer do so. The biggest issue with the LLY is caused by programming for higher Hp and not keep everything working together. The Safety Relief Valve has nothing to do with the problem but yet is the result from not fixing the problem properly. There have been some bad safety Reilef Valves and those should be replaced but do not try and cover up a poor performance tune by shimming the relief valve.

Thanks for clearing that up. I guess my understanding is incorrect. I thought that the pump is struggling, running behind and then the load is removed causing a surge that exceeded the relief psi. I then theorized that this surge/pressure cycling eventually damaged the valve.


Lift pumps cure 90%+ of the 1093's that I have encountered.


But what do I know?

Buy a lift pump, and if it does not cure it, just send it back for a refund.

;)

Seriously, there is alot of good reading on this subject, and it's one of the "hot" LLY topics.

Basically, you have two possible problems:

True fuel starvation, this will cause a P1093, and I call them Type 1. Dirty fuel filter, pinhole air leak, bad filter mount, etc. These are caused because not enough fuel makes it to the injection pump (CP3) so when the computer asks for more pressure, the pump cannot hit the target pressure, and the sensor reports low fuel pressure, and BINGO!! Check Engine Light and 2000rpm limiter.

There is also another type. In our fuel systems on the back end of the driver's side fuel rail is a Pressure Relief Valve. It's a simple needle, seat, spring device. When the pressure gets too high (25,000PSI?) it pushes the needle off the seat, all the fuel pressure bleeds off, and it sets a low fuel pressure error. I call this a type 2.

A lift pump will help stop type 1 P1093's by always having a good supply of fuel into the CP3.

But about Type 2's? There are two causes for this. One is just a weak PRV. There is a GM Tech Service Bulletin on this, and it's a warranty fix. These will occur with stock tuning. The "Bottle Test" will determine if this is the cause.

But more commonly, you will see this with "big tunes". We will program over twice the normal fuel flow with high powered tunes. When you lift the throttle suddenly (or engine shuts off fuel suddenly), the CP3 is going full tilt and takes a brief time to shut down. This is enough time to pop the PRV, drain the rail then get the code.

Whether a lift pump will fix a Type2 P1093 will always be a matter of debate. The guys who will scream loudest are normally the guys who sell lift pumps. I do know adding a lift pump has not fixed our LLY trucks. It was our first mod attempt to stop them. Many others have seen "reductions" in P1093's but not stop them entirely.

If you want to hedge your bets, replace the factory PRV with the 2006 LBZ PRV which should have a higher release pressure. Or shim yours. Shimming costs about a dollar + labor, and will accomplish the same thing.

You will not get Type 2 P1093's if you shim it. It goes away for good. You can still get Type 1's.

P1093 are set for several reasons. The test looks for total fuel flow, maximum current flow, maximum PWM and rail pressure feed back. If anyone of these items are out of the desired specification you will get the code. So if the modified code does not correctly set the parameters for the new conditions you will get a code, this is also the reason when you lift on the throttle the controls do not respond properly and the safety valve opens. Once that happens its all over so you either fix the modified code or raise the safety valve release point so when it does not correct properly it will not open.

The original poster has a simple Edge box and likely stock transmission and sets the 1093. This is something that I see most every day. A single pump is questionable and seldom cures it, but well over 90% of the time the twins do and all is well. Thanks for the education on tuning anyhow. I'll look into that...

:exactly: I agree to McRat, Diesel Tech, and Kennedy, PERFECT EXPLANATION!!!

what is the holley or carter lift pump part number? Is it just a electric pump? Will it have instructions to my truck? also I will try the hose in the bucket to check the fprv and determine from there but im not wanting to get to carried away with hp. I will most likly not get past level 3. If anything both of these should be good enough for me right?

I do not recommend the Holley or Carter for daily drivers. While they are effective, they have too high a failure rate for my taste. I've hosed one of each.

If you wanna go "cheap" IMO, the cheapest reliable unit is the Edelbrock 1792 which is made by Essex Ind. These are aerospace quality units.

Both the Kennedy and TTS systems are good choices too, and have low failure rates, are quieter, flowthru, and easier to install.

But I always recommend shimming regardless. I run lift pumps on all three trucks, but it is not to stop P1093's, they are to improve 1/4mi ET
s.

I think both lift pumps and shimming are good ideas, just I don't think a lift pump by itself is a guarantee to stop tuner induced P1093's as it did not work for us.

Lift pump didn't help me on my 1093's. New filters, etc., but I still would randomly get one usually at the worst possible time(oncoming traffic towing), didn't happen a lot.

Shimming fixed my 1093 for ever.

Is Shimming just a solution for LLY's. Does the LBZ Need shimming if it sets a 1093? From skimming the info here it sounds like we are talking LLY's .:)

I do not believe there is enough history with the LBZ at this time to truely know that answer, but so far there has been little to no problems with stock LBZ units. So if problems start coming up as people start to raise the power I think that will most likely change.

Good point dtech more power more problem:D .

Is Shimming just a solution for LLY's. Does the LBZ Need shimming if it sets a 1093? From skimming the info here it sounds like we are talking LLY's .:)

LBZ's don't P1093. Depending on your setup, I will sometimes recommend them. Full race: Shim 'er up. Just to run a 12 on a single tune? Nope. But there are certain setups you will always have to.

LBZ's don't P1093. Depending on your setup, I will sometimes recommend them. Full race: Shim 'er up. Just to run a 12 on a single tune? Nope. But there are certain setups you will always have to.
Cool then!, THANKS! Man there are a lot of knowlegable people here!!!

If you think the LBZ's don't 1093 you have another thing coming...

:confused: :confused: What do I need? I have an 04.5 lly With 4 into 5" exhaust and a edge atitude 3/5. With the edge plugged in, Every once in awhile it studders and buck and puts a little black smoke out. It also throughs a 1093 code.
I dont have alot of money so that is kinda why im askin a Lift pump and where is the cheapest I can find or should I just shim my FPRV?
Thanks for the help.....:confused: :confused:

888-360-EDGE ext 173 Ask Cody how he fixed his LLY 1093's

If you think the LBZ's don't 1093 you have another thing coming...

No shim, 12.92. Bottle test OK. Yes, we own/drive one daily with over 500hp.

The LLY could not run past 375rwhp reliably without a shim. LBZ's are not as much of an issue.

Neither of our LBZ test mules are having a problem. Only one has a lift pump.

Specifically, if you are running higher the 26,000PSI deliberately, shim it. Not required at 500+ rwhp though.

I don't know much.............but shimming mine cut out the 1093's !! Now why I was getting them with just a 65 hp tune may be the real question (lack of fuel or whatever).......but I shimmed mine and haven't got another 1093 !! My fuel milage went up........which may be wierd.......but it did right after I shimmed it !! May be a coincedence or maybe it helped......I don't know !!

If you think the LBZ's don't 1093 you have another thing coming...

I should rephrase= P0087 same meaning different number...

That code on a LBZ(I think its 87....it was in the 80's somewere) dosnt stick you at 2k and a reduced power.......or so I remember anyway

That code on a LBZ(I think its 87....it was in the 80's somewere) dosnt stick you at 2k and a reduced power.......or so I remember anyway
Didn't do anything to me other than turn on the check engine light.

What it does or doesn't do is irrelevant. It is an indication of a deficiency that is cured by putting psi on the supply. Shimming is treating the symptom...

P1093's on an LLY are a safety hazard and limit your race performance.

Underpressure on LBZ's are neither.

What it does or doesn't do is irrelevant. It is an indication of a deficiency that is cured by putting psi on the supply. Shimming is treating the symptom...

I dont disagree with it showing a problem. But just as I understand what happens on a LLY when you set a 1093 it dosnt react the same. The thing falls on its face while you have your boot in it and the rail is drained and sets a CEL but as soon as you lift it acts normal(other than now having a CEL)

Just by seeing what it does though and it just seems to be set off a low actual rail pressue.....I would say its probably more likely to be cured by a lift pump(as I believe its a supply issue)......but my point was it dosnt act like a 1093. Never got it while lifting or the like. Just got em while at WOT and the rail droped bellow 20k(just going off memory. I know I have ran 21-22k and it been OK.....maybe its also a function of time too?

It acts like my LB7 with big programing and no pump(except my LB7 never threw a CEL even when it fell on its face)

P1093's on an LLY are a safety hazard and limit your race performance.

Underpressure on LBZ's are neither.
Mine didn't always set the code, but it did lay down in the upper RPM range. There seemed to be a pretty significant decrease in performance from it. Since adding the lift pumps it doesn't seem to do that anymore.

My LLY never set a CEL when in P1093 limp mode, but if I checked the codes with a TechII, the P1093 was there. My LBZ has not set either the P0087 or the P1093.... yet. I need to get my pumps installed, as I dont want to see them in the future! :D

There are several things the P1093 can do depending on which part of the test it fails, so your results will vary just as is being stated by others. The question becomes whether you want to solve the problem or hide the problem. Lift pumps can and do help as does the fuel pickup but they are not the cure all for bad programming. At that point you either fix the programming or block the Safety Valve off, your choice. I do not feel shimming is right when you have no idea what your getting when your doing it. If the Safety Valve is bad it should be replaced just like any other defective part. If the programming is causing it then it should be reworked to cure the problem.

There are literally hundreds of "shimmed" trucks running around for the last two years. Nearly all the shops now offer shim kits. So far nobody we are aware of have seen problems associated with it.

I am not trying to reduce sales of lift pumps, nor do I sell them. I run lift pumps on all three trucks. But I have tuned alot of LiLLY's and helped many more. When I suggest certain things, it is based on alot of experience in this area with alot of trucks.

Fixing the problem has nothing to do with reducing lift pump sales or anything else. If the truck does not do it stock it should not do it after a performance item is added, if it does there is a problem. The choice is up to the consumer to find and resolve the problem or cover it up.

There are several things the P1093 can do depending on which part of the test it fails, so your results will vary just as is being stated by others. The question becomes whether you want to solve the problem or hide the problem. Lift pumps can and do help as does the fuel pickup but they are not the cure all for bad programming. At that point you either fix the programming or block the Safety Valve off, your choice. I do not feel shimming is right when you have no idea what your getting when your doing it. If the Safety Valve is bad it should be replaced just like any other defective part. If the programming is causing it then it should be reworked to cure the problem.

Diesel Tech, I see you have programmers on your website, and the power numbers are stated for LB7 engines. Does your programmer for the LLY offer a higher horsepower program (125hp +) that does not need a lift pump or modified valve?

does anybody have detail pics of the hose I need to take off to do the bottle test? and also is the fprv go in the end of the fuel rail (can you see it without removing anything)? Just wanting to make sure I do the right thing when I do it.
Thanks
Jon

chatcr250

We have not released the high Hp LLY product but rest assured it's already been tested and does not use a Safety Valve modification. We do recommend the use of a lift pump and pickup for any high Hp application LB7,LLY LBZ or LMM. We were the orginator of the billet pickup and lift pumps for high Hp. Back when we said they were needed and showed the HP gains everyone else said they were not, now everyone knows better.

GO FAST 1

Look for the fuel rail on the driverside of the engine and follow it towards the firewall. Just before it ends you will find a small black hose that goes up out of the rail then connects to the return fuel line. The hose looks like the letter "U" upside down. You remove the end of the hose that goes to the rail then plug the hose. Useing a new hose route from the rail to a catch bottle you make up yourself. We use a 1/2 Gallon plastic milk container with a few slits cut into the lid. Then tie the container out of the way. We tie it off over on the brake master area with the top faceing upwards. Go for a test drive and make the vehicle set the P1093 then pull over and check for fuel in the bottle. IF fuel is present in the bottle the valve is leaking. If you have a programmer remove it and test again. If you still have fuel getting into the bottle the valve is bad and needs to be replaced. If it does not P1093 then you've found your problem and have to decide what to do.

I do not believe there is enough history with the LBZ at this time to truely know that answer, but so far there has been little to no problems with stock LBZ units. So if problems start coming up as people start to raise the power I think that will most likely change.
Mine did good till I installed an MP-8. I installed a race valve from TS (said it did the same as the shim kit) and get a 1093 when I try to pass with it turned around halfway up - also falls flat on it's face and Iam limited to 2000 rpm till I pull over and fix it. Checked for leaks where i installed the valve and had none . Is it safe to say I need pumps or do I have something else going on?

Mine did good till I installed an MP-8. I installed a race valve from TS (said it did the same as the shim kit) and get a 1093 when I try to pass with it turned around halfway up - also falls flat on it's face and Iam limited to 2000 rpm till I pull over and fix it. Checked for leaks where i installed the valve and had none . Is it safe to say I need pumps or do I have something else going on?

There are a few "booby traps" in the LBZ computer software that can do this that are not even related to the fuel pressure. You need to see what codes are stored. In particular, you should look for MAF codes and P0299, both will limit performance. Sometimes these codes are invisible, and do not set Check Engine Light.

But there is also a good point about rail pressure. One time I always recommend shimming is when you run rail pressure "foolers". Anything that directly modifies the signal coming from the Rail Pressure Sensor should be shimmed.

Thanks diesel tech. I will try it and let you know.

Mine did good till I installed an MP-8. I installed a race valve from TS (said it did the same as the shim kit) and get a 1093 when I try to pass with it turned around halfway up - also falls flat on it's face and Iam limited to 2000 rpm till I pull over and fix it. Checked for leaks where i installed the valve and had none . Is it safe to say I need pumps or do I have something else going on?

If you did the bottle test and had no fuel in the bottle then my guess would be your asking for more rail pressure than the system will allow. A lift pump system will help but may not cure your problem. When the unit is above halfway up does it set any other codes besides the P1093?

There is no P1093 in LBZ's. P0193, etc.

I haven't set any other codes besides the "low fuel pressure during power enrichment" when I try this. At least none I can read with a downloader.
Steve; If the pump wouldn't solve the problem what else is needed? I shouldn't have any fuel coming through the return with the race valve and not just the shim kit should I ?

code for fuel rail and also fuel filter is p0087 on lbz

Not sure about the race valve as I've not looked at one but do the test just to make sure. Running lift pumps will only help but I do not like to sell something that the customer doesn't know all the facts about up front so they can make an informed decision. A simple thing like a bad connection can also cause a problem that you could be chaseing.

what are some dealers for lift pumps (looking for cost)? Do they make single pumps? I did the jug with my fprv with no edge and so far nothing. I will try with the edge tomarrow. If there is nothing then I will need lift pumps right?

TTS (Diesel Tech) sells a single and a dual lift pump kit, which is what I am running on my truck (dual pumps that is). I paid just a little over $500 for the pumps shipped to my door and they came with everything I needed to install them (except the tools). I asked a few questions before I ordered them and Steve was very informative about the product. He also answered a couple of questions I had after I had them in. Very good product support in my opinion.

There are a couple of other options as well. Kennedy sells a single or dual setup which you can get with a secondary filter head, Super Diesel sells a single pump kit that comes with a secondary filter, you can get the MITUSA belt driven pump (I'm not sure who sells it) or you can put together your own kit with an external electric pump of your coice (Holley, Carter and Edelbrock are the most popular). Just make sure you do some research before you buy to make sure you know exactly what you get with each system. In my opinion the TTS system is the most complete and cleanest install for a good price. I am extremely happy with what I got. I feel it was money well spent.

how long can you keep the bottle trick on? My studder only happens every once and awhile so I want to drive it with the bottle for awhile to see if it does it.
Thanks

It's up to you on the bottle test time. I would check it everytime I took it out for a drive just to make sure. Depending on the bottle size and many other things would be how safe it is, but if the valve does not leak there will be nothing in the bottle.

If the FPRV valve does pop, you will see it by just driving about 1 mile, hitting the throttle WOT, then chopping it. It can fill a 1 liter bottle pretty quick.

DO NOT drive extended periods. This might be very hazardous.

Is it going to help the test to turn the fuel box more to full on for the test or at half like it was ? I don't get any increased performance or smoke from this thing so something is going on. Is a 20 oz drink bottle large enough for 1 run or not ?

lol better use a 2 liter or even a 3 liter

try what ever level you are running in and having issues........go do a WOT pass through a few gears and lift qucik from WOT. check the bottle. Then try different power levels(higher) and even stock to see what happens

Well I just tryed level 5/5 and no fuel in the bottle and just a little black smoke. will tts pumps make it smoke a little more? and will you get more power by the seat of your pants? What did they cost with tax(allsaid and done)?

The pumps will supply fuel to the CP3 and help it output more fuel but if you programmer is not requesting any more it will not increase it. By the same token if the rail pressure is droping it will help stop it and you will get more fuel. Prices are on the web site but you would need to add shipping from CA to where ever your at. If your east of the mississippi you might check with Huckstorf Diesel as they are a stocking dealer.

http://www.ttspowersystems.com/GM_Diesel_Fuel.html

lol better use a 2 liter or even a 3 liter
Just wondered how I was gonna get a two liter bottle stood up in such a small space :)
I'll try it tomorrow and see how I come out. Thanks all. Chris

Tried to run the test but I had trouble getting the return hose off the fuel rail and it began raining before I could get it rigged up. Ran the thing and with the downloader on 69hp and I couldn't get it to set the code. Uploaded the 136hp tune and it didn't set it unless I punched it from about 45+ (in 5th or 6th gear) From a stand-still it didn't set one; only like when I would try a passing move.
Supposed to rain a few days here so I guess my test will be delayed. Anyone happen to know the inside dia. of that hose so I can get some?

Talked with my friend last night that has nearly the identical setup I do as far as programmer,exhaust and a TS MP-8. Only difference is he has the shim kit instead of the race valve. He's had the MP-8 on his last two trucks (this 2006 and his 2004.5) and has always had this same problem.
Says he just gave up using it unless he pulled a sled and not turned up much then. Neither of his had lift pumps.