I had a really scary incident yesterday caused by a 1093 code.

I was passing on a two lane highway when a 1093 popped. There was a small car in front of a semi coming directly at me, and I couldn't go past 65 mph due to the 2000 rpm limit. By this time cars were stacking up in the right lane, so when I tried to dive back into that lane, it caused mass confusion.

I pissed a lot of people off and put myself, my passenger, and all the other drivers in danger!

Is the shim mod considered safe? I've been reluctant to try it until something else comes out since my truck is really good about not throwing 1093s. Yesterday made me realize that 1093s aren't just a nuisance, they're dangerous!

I have about 5,000 miles on shimmed valve so far with no problems. If you are running a high hp stack you will also need a lift pump to completely get rid of 1093's. In my opinion it is far more dangerous (and frustrating) to leave it alone then it is to mod it.

The first thing you need to do is see why your throwing a p1093. There is more than one thing that will set the code and a shimmed regulator will only fix one sometimes and is just as dangerous as nott doing anything. If you have no idea of what you have shimmed the regulator too you run the risk of causeing fuel leaks and engine fires. Just adding a shim doesn't cut it. Look to Tim(midwest) who did all the research and see what he has to say about it. In short you need to test the regulator first then shim the proper amount for your regulator. If you do not have the equipment your playing with fire.

Also there is a 3rd generation fuel filter out that seems to help a little. Dealer only, I'm sure. One of my 05's threw the code and the dealer ordered a new rail assembly. In the mean time he put the new filter on and it hasn't 1093'd since. I will still have them change the rail when it comes in.

Thanks Diesel Tech. I'm not hell-bent on just going fast, I want to solve the 1093 problem correctly--to me it's not about getting a quick fix just so I can drag race.

I have no doubt you're working on a solution, but what do you suggest in the mean time? Leave it as is and just don't pass people? lol...

First thing I would do if you haven't done it is to add a good set of lift pumps. The most common reason for setting a p1093 is lack of fuel and since your going to race the truck you should have them anyways. Do not go for a single pump as it is not enough for what your doing.

The most common source of P1093 is a dirty fuel filter.

There are 2 kinds of P1093's:

1) True fuel supply issues, dirty filter, air leak in lines, bad lift pump (if so equipped).

2) "Overpressure" 1093's - These are caused by sudden rail pressure drop from popping the Pressure Relief Valve in the back of the driver's side fuel rail. Some stock trucks will see this, but more commonly tunes over 90HP tend to cause it. The "Shim Mod" only fixes these kinds. To date, we have seen no problems with this mod. But use it at your own risk. It certainly works very well.

How do you tell which kind you are? Two ways:

Tech II (less reliable) - Look at commanded vs. actual rail pressure. If you see a high spike (over 24000psi), then large drop, it might be #2.

Bottle method - Put a longer hose on the fuel return line comming from the back of the driver's side rail into a bottle. Block the other end where it used to plug in. Drive around and see if there is fuel coming out. If so, you certainly have #2 P1093's.

PS - You're right. It is VERY dangerous to throw a P1093 in traffic. Been there done that.

PS - You're right. It is VERY dangerous to throw a P1093 in traffic. Been there done that.
:eek: :eek: :eek: :badidea:

My 05 would throw the code stock and with the edge on lvl2, changed the fuel tank out for my 66 gal super tank and have not set one since running lvl 4 and 5. I have not set one for over 8k miles, and I did change the filter at a little over 8k. Truck now has 11.5k. FWIW

McRat

Your wrong there are three different conditions for setting a P1093 and as I said they are all from a lack of fuel as sensed by the ECM. That said, anything that will stop fuel flow can cause a P1093. The lift pumps solve most issues. I have yet to see anyone set a P1093 while racing or under hard acceleration it always just after when you let off. If your off and on throttle it will cause it as well with non stock tunes and there is a reason for it. If trying the bottle leak test pay attention when the leak is occurring not just that it is leaking. It is best to only do a bottle leak test on a dyno and not on the street!

McRat

Your wrong there are three different conditions for setting a P1093 and as I said they are all from a lack of fuel as sensed by the ECM. That said, anything that will stop fuel flow can cause a P1093. The lift pumps solve most issues. I have yet to see anyone set a P1093 while racing or under hard acceleration it always just after when you let off. If your off and on throttle it will cause it as well with non stock tunes and there is a reason for it. If trying the bottle leak test pay attention when the leak is occurring not just that it is leaking. It is best to only do a bottle leak test on a dyno and not on the street!

:rolleyes: Please. It's getting deep.

I already knew that 1093s are usually if not always set upon lifting the throttle, and I think that is what happened in this case now that I analyze the situation.

I pulled out to pass and mashed the throttle, then backed out of it because I realized I didn't need that much throttle! :)

I think a lift-pump should be my next mod--it's probably tied with exhaust right now.

Does the outlook for the new LBZs look any better, or they going to be plagued by 1093s as well?

The newest pressure regulators I have recieved are slightly different.The well pocket for the spring is not bored as deep and the 3 holed washer on top of the relief needle is .020 thicker. All this translates into more seat pressure. The springs seem to be alot more consistant @.750 (consistant@.750) than in the past, but still the overall measured assembled height is very inconsistant.

I have tested so many I lost track, but there still seems to be a temperature issue with the spring seat pressure.I can change these valves in 4-5 minutes and have disassembled them smoking hot and have recorded a few spring pressures droping as much as 10%.Not all act this extreme way mind you, but this issue along with poor fuel API and fuel viscosity on hot engines aggravates this condition.I've been working on a valve mod that seems to reset quite quickly if it pops but the original seat pressure still has to be shimed to not pop all the time.It's better and doesn't seem to set the 1093's as much but it should not pop all the time.
Lift pumps are a must with big HP files.Just verify if the valve is poping on decel too.
Someday I will get all this info compiled in a nice little spread sheet but time doesn't permit.SorryI know a few have asked, but maybe soon. Tim