P1093 code keeps coming up

captnduramax

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Dec 16, 2006
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DTC P1093 Fuel Rail Pressure Low During Power Enrichment

Last week after I loaded up my 5th wheel I changed tunes from a mileage tune to my stocker tune. Made it out of the drriveway and engine lost all power and I couldnt go faster than about 23 mph. Changed tunes to 1 Simon send ahile back (I have used before) and towed about 200 miles at about 5mpg(yeahh). For some reason I can not get this code to go away now and stay away. 3 diff tunes with the same result. Changed fuel filter today and it lasted for about 4 miles and dash lit up. Any Ideas? I am currently running my McRat tune and have yet been able to limp tranny (stock tranny) like I did before. any help would be appreciated.

Anything else is needed?


Capt
 

sweetdiesel

That's better
Aug 6, 2006
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Ok so you changed fuel filter and still no good
Does your fuel rail got a shim or a race valve in it?

Is it possible you got a bad tank of fuel? is the tank low on fuel?

Are the fuel lines leaking by chance?

Pm sent
 

captnduramax

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Dec 16, 2006
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Ok so you changed fuel filter and still no good
Does your fuel rail got a shim or a race valve in it?

Is it possible you got a bad tank of fuel? is the tank low on fuel?

Are the fuel lines leaking by chance?

Pm sent
has shim. just filled up 3 or 4 days ago, when i filled up still had 8 gal no leak but i will have to dble check that

think it might need a lift pump? maybe tired lol ...I dont know

thanks

Capt
 

othrgrl

Diesel Addiction Owner
Mar 10, 2008
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Once you throw a 1093 it gets easier and easier to do it it seems. I went straight to the PPE race valve and just put on a AirDog 150gph lift pump but am waiting to get my front end with elocker back so I can drive it.
 

McRat

Diesel Hotrodder
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Aug 1, 2006
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Good advice. No need to shim the PRV if it's not leaking.

The P1093 is the oldest of the LLY performance problems, and we know shimming/race-valve fixes 99% of trucks with this problem.

My racing tunes won't "limp", but that does not stop the valve from dumping rail pressure.

We first saw this at ~370rwhp, and it has also affected stock tuning trucks, so everyone is a potential victim with an LLY.
 

othrgrl

Diesel Addiction Owner
Mar 10, 2008
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You can also change the 1093 to not cause a limp mode through EFI Live, you will still be able to pull the code when it happens but it won't cut fuelling. Race valve and lift pump should have you fixed though - and ready for more when you are.
 

dmaxtruck

Perfect Sleeper
Jan 22, 2008
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I had the 1093 as soon as I got my injectors, I threw a shim kit on and that solved it except for at very high speed WOTs. Threw the FASS 150 on it and haven't had it since.
 

captnduramax

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I had the 1093 as soon as I got my injectors, I threw a shim kit on and that solved it except for at very high speed WOTs. Threw the FASS 150 on it and haven't had it since.
I think a lift pump is next to keep it consistant. I am hope there is no leak in the system, should know tomorrow if there is. (getting all the bushings in the front end replaced and he is pressure testing it for me).

thanks everyone for the input:hug:

Capt
 

othrgrl

Diesel Addiction Owner
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Do a search for the bottle test - it is the best way to pressure test it. If you are talking about pressure testing the fuel rails I kinda doubt that whoever is pressure testing it has anything that will put anywhere close to 23,000 psi in it. The PPE race valve is cheap and a quick fix. If you are talking about the rest of the system (tank to pump) leaking than it makes more sense but if you don't smell raw diesel or see any drips while it's running you are probably fine.
 

captnduramax

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Dec 16, 2006
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Do a search for the bottle test - it is the best way to pressure test it. If you are talking about pressure testing the fuel rails I kinda doubt that whoever is pressure testing it has anything that will put anywhere close to 23,000 psi in it. The PPE race valve is cheap and a quick fix. If you are talking about the rest of the system (tank to pump) leaking than it makes more sense but if you don't smell raw diesel or see any drips while it's running you are probably fine.
I have the race valve in... no drips at idle (that i have seen but will double check) not sure how he is testing it but will find out tomorrrow. Thanks for all the help...everyone. lift pump maybe next week and go from there.


Capt
 

egduramax

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Jan 5, 2016
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I’m curious what you did to resolve. I am getting P1093 when accelerating or hill climbing. I changed out my stock FPRV with one from Motor Sport Diesel. No change. I also put in a new Wix fuel filter. No change. I need advice on what to do next to diagnose. Thanks in advance. Craig
 

TheBac

Why do I keep doing this?
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Apr 19, 2008
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13 year old thread....if you get a response from the thread starter it would be a miracle. Most of the guys who responded arent even here any more.

A 1093 always seemed to be the toughest code to resolve on these trucks when it showed up.
 

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
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I’m curious what you did to resolve. I am getting P1093 when accelerating or hill climbing. I changed out my stock FPRV with one from Motor Sport Diesel. No change. I also put in a new Wix fuel filter. No change. I need advice on what to do next to diagnose. Thanks in advance. Craig
Like Tom said, you'll never see the OP come back and post an answer by now.

Will your pump build full pressure at idle? Check the supply lines for a collapsed one, look into testing return rates from the pump / injectors, utilize the factory test port for inlet restriction (up by the alternator), and maybe pull your new valve out to verify a burr wasn't created on the sealing surface
 

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