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Unread 04-16-2013, 08:21 PM   #1
atldude
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High fuel pressure

So recently i struggled to set my proper idle (http://www.jeepforum.com/forum/f12/c...erent-1508918/)

Just when i thought i was done seems like the problem continued with the idle coming down pretty slow to the 700 rpm. It doesn't take a minute but i can tell its abnormal since it will hit about 1100 and strt slowly creeping down to 700. About 4-5 seconds maybe.

I read some stuff that made me think maybe just maybe the dang thing is running lean or rich and sometimes the o2 sensor might have gone bad.

Went to get an o2 sensor today and accidentally forgot to plug it in before i ran the engine - problem went away immediately! Of course when i plugged it back in, tere it was again lol

So got a fuel pressure testing kit and checked out how things go with idle and engine at operating temp.

Idle - 54psi
Idle with vac off fuel pressure reg - 54psi
Revving up to about 4k - 52psi
Off - 40psi and holding for a while so no leaks

One thing i noticed is that the very front exhaust manifold bolt is broken inside te head lol

My question is would the bolt be the culprit of this since in essence might cause the o2 sensor to read out lean mix or should i be looking at the fuel pressure reg?

It neve ends does it lol

Thanks in advance guys!

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Unread 04-16-2013, 08:50 PM   #2
atldude
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Also tried takong the o2 sensor off and measured the pressure an same thing 54psi
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Unread 04-16-2013, 09:10 PM   #3
atldude
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Just looked at the return line and has no visual kinks that i can see seems like the rubber hose toward the end of the line on top of the tank just about is about rotted but other than that i don't see much wrong with it i almost wanna say its the dang regulator. What do u guys think?
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Unread 04-16-2013, 09:39 PM   #4
atldude
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Ok last development. Ran an alternative line from the return port to a container and psi went down to 32psi i think although not visually identifiable, there is a blockage on the return line somewhere. I guess that means i don't have to get a new fpr lol
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Unread 04-16-2013, 10:32 PM   #5
atldude
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Found it! Rubber hose all the way at the top of the tank of course lol dan it gonna have to drop the tank

Is there a valve or something at that part of te return line? I did pop the fuel cap off while testing..
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Unread 04-17-2013, 07:21 AM   #6
pete1991YJ
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Ahh you got the return line pinched... its pretty common. I was gonna say maybe your regulators shot, but try freeing up that return line first, yeah the head bolt ain't helping anything but the return line is the worse prob so do that first.

You *might* be able to just take out the front bolts on the tank skid and not have to drop it out all the way, its how I do it. That gives you just enough room to get you hand up in there to move things around.
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Unread 04-17-2013, 08:35 AM   #7
atldude
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Quote:
Originally Posted by pete1991YJ
Ahh you got the return line pinched... its pretty common. I was gonna say maybe your regulators shot, but try freeing up that return line first, yeah the head bolt ain't helping anything but the return line is the worse prob so do that first.

You *might* be able to just take out the front bolts on the tank skid and not have to drop it out all the way, its how I do it. That gives you just enough room to get you hand up in there to move things around.
Oh that is a great idea Pete. Actually wanna take a look in the tank and take the fuel pump out too just this one time. Gonna see if that filter pouch needs replacing. Would dropping the front only allow me to do that or is that enough just to get to the hoses?

Other than that the weird thing is i don't see any visual kinks or the line being pinched. I have a 3in body lift from the PO which, although i want to remove some time this year, is helping me quite a bit seeing over the tank's top. I think the line might have collapsed on itself or something...

Anyway both lines are in pretty rough shape i think will replace all hoses there and we'll see how the idle goes after that
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Unread 04-17-2013, 09:15 AM   #8
TSEJEEPERS
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Quote:
Originally Posted by atldude View Post
Oh that is a great idea Pete. Actually wanna take a look in the tank and take the fuel pump out too just this one time. Gonna see if that filter pouch needs replacing. Would dropping the front only allow me to do that or is that enough just to get to the hoses?

Other than that the weird thing is i don't see any visual kinks or the line being pinched. I have a 3in body lift from the PO which, although i want to remove some time this year, is helping me quite a bit seeing over the tank's top. I think the line might have collapsed on itself or something...

Anyway both lines are in pretty rough shape i think will replace all hoses there and we'll see how the idle goes after that
No that will not give you enough room to get the pump out.
Also check where the lines go through the crossmember. It is pretty comman for the lines to get pinched there.
The high fuel pressure could have messed up your regulator too.
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Unread 04-17-2013, 09:17 AM   #9
pete1991YJ
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Quote:
Originally Posted by atldude View Post
Oh that is a great idea Pete. Actually wanna take a look in the tank and take the fuel pump out too just this one time. Gonna see if that filter pouch needs replacing. Would dropping the front only allow me to do that or is that enough just to get to the hoses?

Other than that the weird thing is i don't see any visual kinks or the line being pinched. I have a 3in body lift from the PO which, although i want to remove some time this year, is helping me quite a bit seeing over the tank's top. I think the line might have collapsed on itself or something...

Anyway both lines are in pretty rough shape i think will replace all hoses there and we'll see how the idle goes after that
Nah you have to drop it all the way to pull the pump. With a 3 inch body lift the line should not be pinched. There is a dent molded on top of the tank for the lines to run thru.

On the end of the return line, inside the tank, is a little pipe that goes almost all the way to the bottom of the tank. If anything wedgies between the end of that pipe and the bottom of the tank, that could choke it off. Might wanna pull the assembly and see if its all clear in there. And replace lines like you said. I like to test everything by blowing thru it with my mouth before and after it all goes back together. Just to guarantee that the lines are all clear.

Cheap gas tases like BBQ sauce after you get used to it.

If the fuel pressure is still too high after doing all that, then I'm gonna say its the regulator.
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Unread 04-17-2013, 09:38 AM   #10
atldude
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Lol i am sure i will get to taste plenty of bbq today

Cool, so tank definitely coming off. I will see that pipe in the tank. I saw the fitting yesterday just couldn't reach it to get the line unhooked. I will check it out definitely thanks for bringing it up. I will most def check on it.

I tested the reg yesterday with alternative hose spitting into a gas can, pressure went to 32 immediately. I think that's reasonable psi right? I guess the real teat would be hooking everything up and then trying...
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Unread 04-17-2013, 10:46 AM   #11
pete1991YJ
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Quote:
Originally Posted by atldude View Post
Lol i am sure i will get to taste plenty of bbq today

Cool, so tank definitely coming off. I will see that pipe in the tank. I saw the fitting yesterday just couldn't reach it to get the line unhooked. I will check it out definitely thanks for bringing it up. I will most def check on it.

I tested the reg yesterday with alternative hose spitting into a gas can, pressure went to 32 immediately. I think that's reasonable psi right? I guess the real teat would be hooking everything up and then trying...
You tested the reg already and it worked? OK then, I guess that takes care of that question.
You definitely got something weird with your lines then. The pipe in the tank is only like 1/4 inch off the bottom of the tank, so if the tank got mashed or any junk got in there, it could block it off. It goes vertically from the top of the sender unit to the bottom of the tank. Might wanna pull the sender and stick a light in there, look around. The sender hole is big enough. For sure the rubber lines, the return line is definitely blocked somewhere.
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Unread 04-17-2013, 12:53 PM   #12
atldude
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Something's definitely weird. Dropped the tank pulled the lines - they are fine!

Looked at the fuel pump, blocked on the return of course.

Now whats strange is that i didn't see anything in there thr could have blocked it. I tried to put it back and see what the deal is. The pump drops all the way with space about 1/16in up top where it bolts to the tank. I had to press it down to get the bolts going.

Another thing is the rubber piece on the bottom of the return line - it's cracked good bit like u can see onthe pic below.

I have not dipped in there to feel the blastic piece at the bottom of the tank but it seems ok. The only thing i can think of is the tank has somehow deformed maybe ie collapsed and the vertican height in the middle is now less ????

Anyway will need to dip in and see how that plastic piece is doing...

Know how far up the rubber end piece is supposed to go on the steel return line? I see a groove that leaves 1/8 in till the pipe. Wonder if it needs to go further up though...

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Unread 04-17-2013, 01:12 PM   #13
TSEJEEPERS
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I think that rubber peice is just there to keep the metal line from rubbing a hole in the tank.
Did you check the lines at the crossmember?
The one the lines go through before the tank.
If that line is sitting on the bottom of the tank it could be blocking it.
You could just drill a hole up higher than the end of the tube.
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Unread 04-17-2013, 01:15 PM   #14
atldude
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Yes all lines are good. Mouth tested and compared to a little hose i had laying around they are perfectly good.

Its that dang thing in the tank. And i can't tell if the tank is crooked or if something else is whack.
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Unread 04-17-2013, 01:17 PM   #15
atldude
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Quote:
Originally Posted by TSEJEEPERS
I think that rubber peice is just there to keep the metal line from rubbing a hole in the tank.
Did you check the lines at the crossmember?
The one the lines go through before the tank.
If that line is sitting on the bottom of the tank it could be blocking it.
You could just drill a hole up higher than the end of the tube.
Can you explain that last part.. Sorry i don't think i understood.
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