http://www.dsmtuners.com/forums/151528384-post14.html quick search pulled up this. it may be a bad connection, or the lines need replaced.

I run with that code daily because I bypassed that solenoid altogether. My vacuum line goes directly from the nipple on the intake plenum to the fpr. I just clear it. Actually, I noticed the fuel responded better to the boost without that solenoid... It isn't anything major to worry about, but if the CEL bothers you, it is likely a corroded electrical connection or a bad vacuum line.

Alright I checked the hoses and everything is still in great shape, ill have to get ahold of my mechanic this week and have him try to fix it ### the light bothers me

Did you have any luck with clearing the P1105 code? I'm having the same issue with my eclipse, I even replaced the fuel pressure solenoid with another used one and I keep getting the code, sometimes it won't come back for a few minutes, but usually it comes back on the 2nd start...

I can clear mine, and while driving have it come back. It is just bothersome, not really indicative of any major problem, and I have not seen any problems from it. I use a basic cheapo Actron OBD2 scanner as my Check Engine Light, and disabled the one in the dash. If you have gauges for vacuum/boost, oil/fuel pressure, coolant temp, volts, a wideband, and EGT probe, you don't really need a CEL if you know what the values should be on those gauges. Really, it wasn't all that much to add in those gauges either, except for the wideband and EGT (they are pricey). I don't think I spent more than $100 for the other gauges total. No need for a CEL after that...

But as for the real question at hand, no. I never have rid myself of the p1105 and it's buddies. I quit trying to fix it, and I ignore them. Without ECULink or a stand alone, it will never go away on my car. As for you folks with emissions stuff and state inspections, I honestly don't know what to tell you. My car is not subject to inspection. I am running outlaw style, with no emissions, no cat, and short pipes... New Mexico may be isolated, but that is one thing we don't have to worry about.

My best guess would be look at the wires. They are getting older, corroded, and brittle. You can get breaks in these wires now and not see it because the sheathing is still just fine. If you have access to a decent multimeter, do a continuity test with the harness unplugged from the ECU. That is what I'd do if I actually wanted to bother clearing it.

I've also replaced mine with a used working one and the code doesnt go away. There has to be a way to fix the problem.

I had same code just after getting my GSX, went to dealership, bought a new solenoid and no problems since...cost about $30 maybe a bit more...

la-panocha said:

I had same code just after getting my GSX, went to dealership, bought a new solenoid and no problems since...cost about $30 maybe a bit more...

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My dealership quoted 60 dollars. I wish the vendors carried more extensive listings of oem eclipse parts

I bought a used one from another member here on the site, the problem didn't go away. Maybe I'll buy a new one from the dealership, anyone know that part number? I'll call them tabs ask the price

If you call the dealership, the mitsu parts department will know exactly what your talking about. Auto parts stores dont seem to have any kind of listing for it.

I've been living with this CEL ever since ive owned my car. I've tried everything to get rid of it with no luck. IT SUCKS.

tay97gst said:

I've been living with this CEL ever since ive owned my car. I've tried everything to get rid of it with no luck. IT SUCKS.

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did you replace the FPS with a new one from the dealership or a used one?

Ive also bypassed my FPS and plug my FPR directly to intake nipple. Just left FPS plugged in and havent had and CEL due to that code. Car runs just as good as before and as another member was stating its purely for emissions and if your lucky enough like me you can just remove all your emissions with no smog nazis in my area.

GsxAZman said:

Ive also bypassed my FPS and plug my FPR directly to intake nipple. Just left FPS plugged in and havent had and CEL due to that code. Car runs just as good as before and as another member was stating its purely for emissions and if your lucky enough like me you can just remove all your emissions with no smog nazis in my area.

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I HATE YOU! you live in car heaven!

all the smog nazis are here in california... I cant register my car until I figure this out

DSMnOOb00 said:

I HATE YOU! you live in car heaven!

all the smog nazis are here in california... I cant register my car until I figure this out

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That sucks big time. Ive heard horror stories of back to stock sales due to the smog nazis. But im actually not that lucky since 115 degree summers tend to be brutal on my dsm's so the money I save on not having to keep up on emissions I spend on keeping these cars alive!

I ran the CEL on my '97 Eclipse today and got the P1105 code for the FPS. I was directed to change the fuel filter, check the vacuum lines, or replace the solenoid itself. I think mine may have something to do with not having an O2 sensor but I can tell that the car is burning the fuel too rich. When the exhaust was done I don't think they put the O2 back on (I've only had the car for a month). Any help?

DrakeRogers said:

I ran the CEL on my '97 Eclipse today and got the P1105 code for the FPS. I was directed to change the fuel filter, check the vacuum lines, or replace the solenoid itself. I think mine may have something to do with not having an O2 sensor but I can tell that the car is burning the fuel too rich. When the exhaust was done I don't think they put the O2 back on (I've only had the car for a month). Any help?

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Check and see if the o2 sensor is there.

When I got thats same code, I ended up replacing both the fps & the rear o2 sensor at once, try that first its an easy job, the hardest part is taking out your from seat to unplug the rear o2 sensor

DrakeRogers said:

I ran the CEL on my '97 Eclipse today and got the P1105 code for the FPS. I was directed to change the fuel filter, check the vacuum lines, or replace the solenoid itself. I think mine may have something to do with not having an O2 sensor but I can tell that the car is burning the fuel too rich. When the exhaust was done I don't think they put the O2 back on (I've only had the car for a month). Any help?

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Here's your help... If you already know the O2 is.gone, then you have already identified a MAJOR problem, and you need to go to a muffler shop, have them weld an O2 bung in, and put the O2 sensor back into the downpipe. Simple as that. Until you have a working O2, there is no point in asking about anything else. That is an absolutely critical piece of equipment to the proper functioning of any fuel injected vehicle.

DSMnOOb00 said:

When I got thats same code, I ended up replacing both the fps & the rear o2 sensor at once, try that first its an easy job, the hardest part is taking out your from seat to unplug the rear o2 sensor

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^^^^ What he said. Get to it.... And have fun.

(only joking in a rougher manner because the learning curve is steep, and you've barely begun to climb)

FYI the rear o2 sensor is just emissions BS, not really a critical part unlike the front o2 sensor. You should replace it anyways or you'll keep getting a Check engine light..

GST-1997 said:

So my CEL light came on, on my way home from the grocery store friday. I got it tested at advanced auto parts and the code it got was P1105 which the guy told me was the Fuel Pressure Up Solenoid. My car still runs as good as it did before the light came on. What exactly does this do? I read it dumps your to much when you dont need it or something, or maybe that person didnt no what they were talking about. Where do I purchase a new one ( im guessing from mitsubishi)? and where is this located I tried finding pics but had no luck.

Would that have something to do with when I shut it off near the back end I hear like a vibrating noise, and I cant think of what it reminds me of. or does everyones make that noise when It gets shut off. Just wondering because my 99 N/A doesnt do it when I turn it off.

And also being in ohio it is cold here, and is taking it a second to start. So do you think its just my fuel pressure regulator?

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Hey guys. So I had this issue myself. Previous owner sold me car with blown tranny I never bothered checking anything else. Anyways long story .. I been looking for the part the actually fps .. it's the same thing as the egr vsv switch solenoid. I went to the junk yard today and pulled one off of a Mitsubishi mirage .. I was really just hopping it would work. And it did. $13 bucks put on no more engine code. The part number is diffrent .. here's the link. I just pulled it off at a junk yard worked perfect. Don't forget to reset ecu or unplug battery . 91-97 Mitsubishi EGR VSV Solenoid Vacuum Switch Valve K5T49681 K5T47172

Forgot to mention the part looks just a little diffrent. And I have a 1999 gst. But plugs right in.. good luck

I am digging up this this thread because I had the same issue recently on a 1997 GST Spyder. I hope my findings can help someone else.

Facts:
1. My original Mitsu solenoid looked brand new and the factory wiring is strong.
2. Vacuum lines are solid and connectors tight.
3. CEL would trip P1105 after 300 miles or 2 miles. No situational pattern detected.
4. I took the solenoid out of the vacuum system (I don’t have emissions requirements) and left it wired.
5. In desperation, I even completely removed the solenoid.

Since it is difficult to find a new Mitsu replacement solenoid, I bought a Dorman 911-850 Vacuum Switching Valve for Chrysler/Dodge/Mitsubishi (Amazon $25). Even though it isn’t a direct wiring fit, I made my own conversion connector and haven't had a CEL since. With the custom connector (it takes 2 micro pins for the solenoid side), I was able to relocate the solenoid to a better out-of-the-way location.

Hi folks,

To follow the last post:

I too, used the Dorman solenoid (found in the above post) and just cable-tied it in place of the original. It appears to be working, has kept the CEL light off for 2 months so far, and allowed me to pass state emissions.

Thanks to all for sharing their knowledge and experience.

Cheers