Got a check engine light last week. It cleared but came back yesterday after my wife drove the truck. I just borrowed a OBD II scanner and this is the only code that came back. A search on this forum show this as "Fuel Rail Pressure Low During Power Enrichment".

The parameters listed on the scanner:
Code: P1093
End speed 2064rpm
ECT 196 degF
Veh Speed 68mph
Eng Load 100%
MAP 53.3inHg

The only info I could find on this forum says this would be caused by fuel pump and/or fuel injector problems. Is this a correct statement?

Also, I have a pre-OEM secondary fuel filter located on the frame underneath the bed. Could the dealer point to this in any way and say this is causing my problem?

Just want to be sure before I drive down to the dealer on Monday

Thanks,

P1093 sets when max fuel pressure is needed but the fuel system is unable to get it. Could be leaking into the return side of the injectors, could be a dirty fuel filter not allowing full flow, could be the pump. It could also be caused by your add on filter system if it's not allowing full flow. A decent tech should be able to pinpoint the problem. A lazy tech might just blame your filter because it's there.

Well I just changed both filters two weeks ago so that is definitely not the problem. I am running a CAT filter and Perma-Cool base on the secondary fuel filter. This is hard piped with 1/2 inch stainless tubing which is identical to the factory tubing I cut into. I also have two 1/2 inch brass ball valves on either side to assist in filter change.

Could this setup be restricting fuel sufficiently to cause this?

Should I remove this filter and return to stock before visiting dealer?

Others on this forum are running this same setup. That is where I got my idea from.

Have any of you seen this problem?

I've never seen a problem with an add on filter and haven't heard of anyone here that had a problem with one. It's up to you if you want to take it off. It's most likely the very common injector issue. You never know and you can't predict what another person will say or not say about add on equipment.

You know I just had another thought. This problem only showed after the filter change. The previous filters consisted of a single pass filter (OEM) unlike the new double layer OEM that is now on the truck. In addition, the secondary filter was the cheapy Perma-cool filter that came with the kit. I cut it open after removing it, and was stunned by how little filter media was actually inside.

I guess what I am getting at is both of the new filters are a substantial increase in media. Could the increase in media be causing a pressure drop great enough to cause this?

The short answer is yes, the new filters could be causing it. The long answer is there are others running the same thing you are with no problems.

Thanks for the replies to my endless questions.

I think some investigative work needs to be done. I am going to temporarily bypass my secondary fuel filter and see what happens.

I will let everyone know how it turns out.

The short answer is probably no. You can eliminate the double filter very easily by checking the inlet side vacuum. I think OC_Dmax probably has the data on the new OEM and the Cat data is on this site somewhere also. I am sure Nick has it. Is the Cat the primary or secondary? Have you had a no start since changing? Later! Frank

see if you can get a kent moore vac gauge to plug into the test port at idle. that will tell you what direction to go in..

Just to update this thread.

After reading the conflicting opinions last night, I decided to research this problem a little more on this forum. It appears that a lot of owners get a "no start" problem that appears after the addition of a secondary fuel filter. I have not had this problem or any other symptoms whatsoever. The only indication of anything wrong was a "check engine" light. A check of the trouble codes showed only one code thrown: "P1093 - Fuel Rail Pressure Low During Power Enrichment".


Since I didn't have the means to install a vacuum gauge on the fuel rail, I decided to just bypass the secondary filter. I had the parts readily available to do this and only spent an hour and half doing so. I have reset the code and plan on taking her for a drive up a couple steep hills in the area.

Question- If this same DTC reappears is it safe to say that the problem probably exists in the fuel delivery system i.e. fuel injectors.

If it doesn't return, is adding a lift pump the only way to solve this problem?

Just to update this thread.

After reading the conflicting opinions last night, I decided to research this problem a little more on this forum. It appears that a lot of owners get a "no start" problem that appears after the addition of a secondary fuel filter. I have not had this problem or any other symptoms whatsoever. The only indication of anything wrong was a "check engine" light. A check of the trouble codes showed only one code thrown: "P1093 - Fuel Rail Pressure Low During Power Enrichment".


Since I didn't have the means to install a vacuum gauge on the fuel rail, I decided to just bypass the secondary filter. I had the parts readily available to do this and only spent an hour and half doing so. I have reset the code and plan on taking her for a drive up a couple steep hills in the area.

Question- If this same DTC reappears is it safe to say that the problem probably exists in the fuel delivery system i.e. fuel injectors.

If it doesn't return, is adding a lift pump the only way to solve this problem?
I don't see any conflicting opinions. I think everybody agrees that it is possible your filter is causing the problem but not likely. A simple test with a Tech2 will determine that. You're only choice to make is whether you disable the filter before you take it to the dealer or not. You are most likely having injector problems like 1/2 the people on this board have already had.

To get the code to return make a full throttle run on the freeway for about an 1/8mile.

I want to thank everyone for the replies. I can't imagine trying to decipher this stuff on my own. The wealth of knowledge and expertise from the people that moderate and participate here really makes solving these puzzles much easier.My lack of understanding on some of this stuff has led to my misunderstanding of some of the replies.
That being said, I did bypass the filter yesterday and took the truck for a short ride. We have rolling hills here on the coast of Cali so I was went WOT on uphill runs. During these acceleration runs of about a 1/2 mile I hit 80-90 mph and almost redline on the tach. I did not get a "Service engine soon" light. I made three such runs and everything seems fine. I guess at this point we will just continue to drive the truck and monitor the situation.
The general consensus prior to this was that the filters were probably not the cause of a P1093 DTC but was more likely related to fuel injector problems. The possibility of fuel injector troubles has always been a source of concern for me and was my main focus when this all started. The lack of other symptoms, in regard to the fuel injectors, has me a little puzzled.
If the code does not reappear over the next couple of weeks I will put the secondary fuel filter back in the loop and then see if the problem returns. This may be a slow approach to solving this but the extra time I can use to research the fuel system, so I will have a better understanding for the future.
I will keep you posted.

Well it's official. I just left my truck at the dealers for replacement of all 8 injectors. I bypassed the secondary fuel filter two weeks prior and while driving this past weekend the P1093 code returned. It happened while climbing a hill at WOT. I verified the code with a borrowed scanner on Monday and called dealer on Tuesday. The Tech II showed a fuel pressure demand of approximately 23,000 psi and my truck was only providing 19,000. The tech said that he had seen much worse but it was still grounds for changing the fuel injectors. He indicated that whenever they get a P1093 code these days that they just change all of them. I sure am glad of that :D

Suppose to get truck back by Friday.

I sure want to thank everyone here for thier input. You guys were right from the beginning.