Fuel Pressure problem, need help

[Mopar1973Man]

I've got 2 Dodge's (1996 & 2002) both have good dashes no cracks... Am I just lucky or what I don't know but I've pull the dash in both truck and the plastics are good and strong and no signs of cracking...

[dripley]

if i pulled mine it would fit in one the smaller if it fits it ships boxes from the post office.

--- Update to the previous post...

I've got 2 Dodge's (1996 & 2002) both have good dashes no cracks... Am I just lucky or what I don't know but I've pull the dash in both truck and the plastics are good and strong and no signs of cracking...

mine always sits in the sun year round. very seldom sees the shade. how about your 2. yours too RJ does it seemuch shade?

[RJC2]

Well here we go again. I have noticed recently that the pressure is dropping slowly. It has gone from 17.5 psi about a week and a half ago, to 16.5 a week ago, to 15 few days ago (while on a 90 mile trip to the hospital), now it is down to about 13.5 psi. this evening (at idle). Just revving it up a bit it would drop to 11.5 psi. (not under load) I haven't been able to look at it to see what the problem is as I have been pretty much bed ridden for a week due to a back injury. It's is hell watching your fuel pressure drop while driving to the hospital! I can't get in my wife's puddle jumper when I hurt like this so old blue had better not quit on me now.Until I get well enough to check it out I thought I might ask and see if anyone would have any idea of what is going on so I know what way to look once I am back on my feet.Thanks guys for all the help. This forum has been a God send for me. I can't turn the wrenches right now, but my fingers still work.

[dripley]

Bob, i sure hate to here this. my first thought is the filters, but i believe you did those not very long ago when you first had the problem. you still might want to check the prescreen and see if something is in there. Might be a sign you picked up some dirty fuel somewher. i'd check the needle valve and see if maybe it has vibarated closed. i think mine has opened a little, seems pressure up a little quicker now. do you still have anywhere to hook a test gauge up. the gauge might be messed up from the isolator going bad

[CUMMINSDIESELPWR]

i had fuel pressure start dropping on my 01'. turns out the injector tube fuel leak and the return banjo bolt on the back of the head needed orings and banjo washers to fix my pressure problem. no fuel leaks and pressure is back where it should be. hopefully you dont have an injector oring bad dumping fuel into your oil. if you are quickly making oil i would look there if you dont have signs of leaks when you parknot sure this is relevant to your issue

[RJC2]

There are no apparent fuel leaks that I can see from beside the truck looking under. My wife said she can't see anything wet under it when she got down and looked, that is as good as I can do right now as far as checking it until I can walk better again. Dave, the Air Dog 100 doesn't have the pre screen. In the last "go round" I tore it apart and it wasn't there, so I called Pureflow and they said they quit putting them in.As far as the needle valve. It appears to be working right. Upon start it takes about five seconds for the needle to rise to full pressure, and when I shut if off it does about the same. No apparent fuel leaks inside the cab. In order to leak that kind of pressure off it would be spraying a good bit and I am sure I wouldn't miss that.The idea of the gauge being bad is probably a good start. As soon as I am able, I will put my pressure test gauge back on it and see what it reads. I need to plumb a test port in there somewhere as I have to unhook my gauge line under the hood in order to test it, then I have to bleed the air out of the line again. I get to screw around with that "Pain In The ___" line hook up at the back of the gauge again. Those little crush ferrels are a pain to get to seal right. I need to put that gauge on hinges, I have looked at it so many times.

[dripley]

Bob, if you had a leak causing the pressure drop you would know it. you would be loosing enogh fuel to see it somewhere and smell it also. i still have to lean toward the gauge or a retriction in the line or filters. i was suprised that they dont put the screen in anymore, it seemed to be a decent feature. try that test and see what happens. good luck

[RJC2]

Well, I managed to limp out to the truck today to go to McDonalds, I am having caffiene withdrawal not having that sweet tea for a few days, (I am sure someone out there knows what I mean). I start it up and Guess what, 16.5-17 psi @ idle and 13.5 wide open throttle. I can't believe it, 12 hours ago it was at least 3.5 psi lower at idle. I am going to wait until the pressure drops again and then hook up the test gauge to see if the gauge is reading right. This is a worry that I am getting tired of.Hey Dave, Do you think her whores are moaning again? For those who didn't read the other post where we talked about this, that's what my wife calls it when she is hormonal.

[JAG1]

I'm not sure about a lot of things now-a-days but, you might have just a simple problem with a clogged tank vent.Try running the truck with the fuel cap off and see what it does. On my 92 CTD I drilled an1/8th hole in between the little spokes of the center of the fuel cap. Don't drill thru the top just the plastic under the cap.On my 2002 I added a tank vent with a screened inlet.Maybe this will help..... Mike

[RJC2]

Jag1, The other day when I left for the hospital I fueled up and headed directly onto the interstate for nearly 100 miles. The fuel pressure was good before filling up, then after filling (to the filler neck) and driving for a while it started dropping to the lower levels.Thinking about this problem on the drive home, I stopped on a exit ramp and took the fuel cap off and looked at the fuel pressure gauge. It was still reading 14.5 at idle with the cap off. I put the cap back on and resumed my trip and the pressure stayed at the same levels as before taking the cap off. I assumed it couldn't be the cap as I thought the fuel pressure gauge would have returned to normal after taking the cap off. Where is the tank vent located?Still think it could be her hormones. Is there a dipstick for that?

[JAG1]

It is on top of the fuel module cap. Called an anti roll over valve, they have been known to fail or clog on a few I've heard of. Only my first gen ctd did this and ran fine but lost power over time while running. no fuel pressure gauge on that truckIf your lift pump is down on the frame you can disconnect the fuel line and put a few pounds of air back into the tank. I think doing this with the cap off helps push out any clogs that might be in the line/ drawstraw, but with the cap on it can also clean out the tank vent.I have also heard of a few guys finding their fuel module screens clogged, draining down the fuel and sucking some air.I removed my screens with a razor blade and added a filter before the lift pump. I did not want to drop the tank, clean the screens only to have them varnish up again later.I did these mods because I think the fuel system needs all the free flow it can get. The way they designed it ...... I also did the Vulcan big lines and draw straw. That made a huge difference in pressure and showed how restrictive the design is.

[RJC2]

I have the draw straw 5 installed with the Air Dog 100 and the big line kit from the original fuel canister filter. This has only been on for about 3 or 4 tanks of fuel now. I am down below half a tank now and the pressure seems to be getting better again. (This doesn't explain last nights lousy pressure though) If I am able to walk well enough tomorrow I will fill it up and see what happens. If it drops I am going to take the cap off and drive it that way to check it. I wonder if one could ake an old cap from a wreck and modify it with a tube to hook an air line to and be able to pressurize the tank to clear the valve?Thanks for the help.

[dripley]

Howdy Bob. Hormonol might be an understatement. Jag has a point on possibly a clogged vent, but i am like you and feel your pressure would have gone up operating without the cap. Did the presssure ever come back up after removing it? Putting some air into the fuel line sounds like a good idea to see if there is anyhting in that part of the system. There might even be something in the line to the fp gauge. I think checking with the test would be th easiest thing to do first. Though with out a port for it i could be speaking out of turn.

[RJC2]

Yes, when I am able I will put a test port in the line to the gauge so I don't have to bleed the system everytime I need to check it. I had hoped that I wouldn't ever need one, but that isn't the case. This morning it had 13.5 psi at idle. There wouldn't have been a vacuum situation in the tank when starting it in the morning. It was 47 degrees, not too cold.And to answer your question Dave, No, it made no difference when I took the cap off. The pressure still stayed the same.

[JAG1]

I'm interested in finding out what's causing this. Right now I can only suggest making a test wire to run the pump directly off the battery. hook up the ground and hot to the pump, turn the key on, engine off and hook wires directly to the battery and watch what the F/P gauge does.

[RJC2]

That is a very good idea. I think I will keep it simple at first and check to pressure with the test gauge to see if my gauge is the problem. After that I will try the wire switch.I just took the truck for a short drive. When I started it, 13.5 psi. 20 minutes later started it again to come home, 15.5 psi. I need to break out the old crystal ball I used to use when I first married my wife (to be able to read her mind like every good husband should) and figure this thing out. I am better at mind reading these days and don't need it so much.