|03-11-2011 04:00 PM|
|03-11-2011 03:48 PM|
My neighbor has a fuel pressure gauge that I'm going to use to check my fuel rail pressure this evening. If I do find out that my fuel rail pressure is leaking down quickly, is there any way to determine whether or not it is the drain back valve leaking or an injector leaking? I'd hate to drop my fuel tank to replace that and then just find out that I have to spend money on a set of injectors...or vice versa! Any help would be appreciated.
Thanks so much,
|05-01-2009 10:30 AM|
Just in case anyone else is having the same problem...
Problem solved. I picked up a set of used injectors on EBAY for $60. They had been tested and cleaned. Installed them in the Jeep....runs like a champ. Starts instantly every time, idles better, runs smoother, and I'm pretty sure it will help on MPG.
|04-24-2009 10:43 AM|
I know this is an OLD post but I'm having the same problem and wanted to see if the OP had ever fixed his problem.
I'm having exactly the same problems. I thought it was the fuel pump allowing it to bleed the pressure off of the line. I had the fuel pump replaced under my extended warranty ($100 deductible is all it cost me is only reason I had someone else change it). Picked it up and its doing the same thing. I hooked a fuel pressure tester to the fuel rail today. With the Jeep not running but key in the ON position, the fuel pump pressures the fuel rail up to 50 PSI. but almost immeadietly the pressure starts bleeding off and within a minute or so it is down to 30 PSI, and still going.
What makes me think mine is an injector is the fact that I can turn the key off, then turn it back on and the start the jeeps but it takes a while to start. Once it starts the fuel smell is overwhelming (especially if its in the garage). So I think I have an injector thats leaking. I believe that the fuel pump pressures the rail fine, the injector leaks into the cylinder and loads it with fuel. I think thats causing it to be "flooded" and takes longer to start and causes the strong gas smell.
Any comments ideas or suggestions would be greatly appreciated. I havent been on in a while. This is the wifes Jeep, so bacially I work on it when she's not happy. lol
Thanks in advance for any help.
|08-09-2006 02:50 PM|
Okay, so I finally got the fuel pressure checked. My dad's friend, who is a mechanic, stopped by with a gauge and we checked it. The pressure is between 49 and 50 psi with the engine at idle. But as soon as you shut it off, the pressure drops below 30 psi within a minute. He said it's the check valve in the fuel pump.
My question is does anyone know if there's a website where I can look at TSB's for Wranglers?? I stumbled across one for Cherokees and found TSB #1400201 "Longer than normal engine crank time prior to engine start" for the 1999-2001 models. It recommends replacing the sealing ring before a fuel module assembly replacement is attempted. I'm wondering if 1999 Wranglers had the same fuel module sealing ring problems.
Also, does anyone know what causes the check valve or maybe the sealing ring to go bad? Would only driving it once a week or every two weeks for a couple of months cause the problem? I don't want to fix the problem only to have it happen again because I'm doing something to cause it.
Thanks for all the helpful input.
|08-05-2006 11:30 PM|
The valve is not servicable and you will have to replace the entire fuel pump in order to correct it. Check the fuel pressure and see if that is the source of the long start time.
As for the electrical connector, I doubt you are having a problem there because if it is a failing electrical connector the problem you will have will be intermittent (working and not working). It appears that the fuel pump is working and your jeep is not stalling out while it is running.
|08-05-2006 07:31 PM|
I took the back wheel off on the driver's side and found the electrical connection for the fuel pump. It looked okay but I couldn't see it well enough to figure out how to get it disconnected. Stupid question, but is there a trick to it? I thought I had the little lock tab pushed but it wouldn't come undone and I didn't want to break anything. Maybe I'll be able to see it better if I have to drop the tank.
Also, it turns over fine, as fast as it ever has. The battery is about a year old and fully charged. I also checked the alternator input at the battery and that's good. And it's a 1999 with 68K on it, not 99K.
I'm wondering if this checkvalve or seal dried out. I drive the Jeep every day in the winter when I'm commuting 30 miles one way across rural MN & WI but this spring it sat a lot (probably a couple weeks at a time) while I drove my Taurus which gets better gas mileage. Right after that is when I started having problems. It wasn't very obvious at first. I thought I just let go of the key too soon. I had read that slow starts on Jeeps were common. Not a big problem at that point because it only did it if it sat overnight or longer. But now it does it whenever it sits more than an hour. It cranks for 3-5 seconds, then I let off it and try again. It usually starts on the second try.
So where is this anti-drainback checkvalve? I know the pressure regulator sits on top of the fuel pump assembly. So is the checkvalve in the fuel pump, the pressure regulator, or in between the two? There are also two o-rings where the pressure regulator connects to the fuel pump. Could these have dried out?
|08-05-2006 10:58 AM|
|Jerry Bransford||My money's on the anti-drainback checkvalve that is part of the fuel pump & regulator assembly. When that valve starts leaking, it allows the fuel to drain out of the fuel injectors and fuel rail which is required for fast starts. The long start cycle is how long it's taking the fuel to get back up to the injectors when it should never have left.|
|08-04-2006 08:04 PM|
Well it might be fine, but it might not be upto spec's, thus not getting the proper turn speed it needs to start the 1st time. With 99k miles that is something that I would check and rule out along with the battery. The other item i would check is the fuel pump connection located near the top of gas tank, this group of wire's has a way of pulling out and causing issues.
|08-04-2006 05:50 PM|
Ok, it sounds like the fuel pump or a leaky fuel injector. Inside the fuel pump there is a valve that holds the fuel and keeps the fuel from draining back. Over time this valve wears out and allows the fuel to drain back after you shut it down. This will account for the longer start time.
You will need to do a leak down test and here are the steps;
1. You will need to connect a fuel pressure gauge to the fuel rail (you will need a fuel pressure gauge to will go at least 60PSI.
2. Start up motor and the pressure to be up to 44-49 PSI within 2-3 seconds.
3. Let engine get to temp and pressure should never fall below 30PSI for five minutes (even under high RPM).
4. Shut down engine and pressure should hold above 30PSI for at least five minutes, if not you will have either a leak in the fuel injector or the fuel pump check valve.
|08-04-2006 04:53 PM|
|bluvikng||He said it was cranking fine, just not starting. Sometimes the basic things are over looked. When is the last time you cleaned out your throttle body? If it has been awhile, get some Barryman's carburator cleaner, and give the throttle body a good cleaning, wouldn't hurt to do the links as well. Do this while running the engine. Gas builds up residue over a period of time, and makes things very sluggish, and sticky.|
|08-04-2006 04:46 PM|
|4Jeepn||does is turn over "fast" or seem sluggish? If so then you may just need a new starter, also how is the battery?|
|08-04-2006 03:33 PM|
Thanks for the reply. At least I can pretty much rule out the CPS now.
As for hard starting, it does it hot or cold. Anytime it's off for more than 45 minutes. Even after I drive it 30 miles home from work, if it sits outside for a while and I go to put it in the garage, it cranks for several seconds before it starts. That's why I was thinking that maybe the fuel was running back into the tank and it had to re-prime the line when I try to start it.
I'm going to check the plugs and stuff this weekend. I should have thought of that before but I spend most of my time on the highway so I figured the plugs weren't too likely to be bad. Can't hurt to check anyway.
|08-03-2006 07:36 PM|
It might not be any of the above. CPS will either work or not work and there isn't too much in between. As for the fuel pressure that is a possible source and it may be a failing valve inside the fuel pump and if this is the case, you wll need a fuel pressure checker to trouble shoot it.
As for the hard starting, does it happen when it is hot or cold? If it only happens when it's cold, you may have fouled spark plugs. I would check the easy things first like plugs, condition of spark plug wires and cap and rotor.
|08-03-2006 04:21 PM|
CPS or fuel system--help
I have a 99 Sahara 4.0 w/5sp. manual transmission. Lately it's been starting hard. It cranks fine but takes a while to start. Sometimes I let it crank a few seconds, let off, try again and then it starts. Sometimes it takes 3 times. It always starts eventually (at least so far) and it runs fine once it starts.
I've been reading posts about CPS problems, great site by the way. I tried testing the resistence like the Haynes manual says but it says test terminals A & B (engine up to temp). My terminals aren't marked and there are three but if I put the probes on the center one and one of the outside terminals the resistance stays at 1. Then I take the probe off and touch the outside terminal again and it will flash a resistance reading between 125 and 200 and then go back to 1--different each time. Not sure if I'm testing it wrong or if my meter is bad. I took the CPS off because for some reason I thought I read that it was optical and might need to be cleaned. Mine's magnet and clean so I just reinstalled it--no better, no worse.
So now I'm not sure it's the CPS because my Jeep has never died on me once it's running like other posts have said and it does start eventually.
I've also been reading posts on the fuel system. I really need to get a fuel pressure gauge to do a proper check but so far the only thing I've done is take the cover of the Schraeder valve and press it with my finger after the Jeep has sat for a while--it just drips out. If it's only sat for 5 minutes or less, it sprays out. Also, I can hear the fuel pump hum when I turn the key to on. Could it be the fuel pressure regulator or the o-rings on it?? It runs fine once it's started so tell me it's not the fuel pump $$$.
The check engine light doesn't come on and I did the OBDII thing to get the codes. It just goes through 111111-999999, the guages move, and the check engine light comes on once toward the end of the sequence just like all the other lights on the dash but then it just goes back to showing the mileage.
If anyone can help me narrow the diagnosis it would be greatly appreciated. I was hoping for the simpler CPS problem but the symptoms are similar but not really the same as others have described. I don't want to replace parts without being fairly certain that they are bad.