Installed BMW inline check valve and now...

On start-up I keep blowing rubber lines off that I didn't even touch! I've now blown off the hard rubberish lines at the fuel injector rail and connection between the hard lines between the tank and the one going up to the rail. No problems with the rubber lines I installed with the check valve. Along with this, it will also not start sometimes. On one occaision I began to remove one of the lines after the check valve to see if I anything was getting passed the valve and the line came blowing off. After I put the line back on, it started right up.

This tells me (in my mind anyway) that the fuel pump is working and that the check valve is working and that I have pressure. I have heard that if the pressure is off up or down just a little it can throw things off. What I don't understand is what has caused the increase in pressure that is blowing off the lines upon start-up.

Kinda typed this in a hurry but hopefully I got enough info up to atleast get some ideas going. I'm gonna get sick of driving my Mom's caravan real fast. Thanks a ton in advance guys!

Why did you decide to do this mod again...???

Fue pressure regulator plugged in and functioning? those quick couplings should be replaced every time it is disconnected and are you using high pressure fuel injection clamps?

jeepman121 said:

Why did you decide to do this mod again...???

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Because the check valve in the whole pump/sending unit thing was bad and this part was much cheaper and didn't need the tank dropped to be put in.

I never disconnected any couplings. The rubber parts blew off. Yes, when I replaced them, I used the lines and clamps specifically for fuel injection.

Fuel Pressure Regulators... School me on these. Where are they? Is it possible I disconnected it along the way? That would make a lot of sense as to why the pressure is out of whack...

Did you put the check valve on the return line accidentally?

Wildmatt said:

Did you put the check valve on the return line accidentally?

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Correct me if I'm wrong but I don't think there is a return line...

Now that I have all the lines double clamped at each end, they seem to have stopped blowing off. I still am getting occaisional no-starts when it is warm. Happened today and started right up about an hour and a half later. I'm stumped.

What is the vehicle in question? If you didn't pull the unit that was failing, and have added a dissimilar part to fix it, and it works worse than before, it sounds like you haven't fixed anything, and have only magnified your problems.

What's the background story on all of this?

xjh3 said:

Correct me if I'm wrong but I don't think there is a return line...

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Ummmm, hate to say it but...(Here goes)................YOUR WRONG!

Sorry, should have said this already. 97, 4.0, 160k.

I was having very long cranking cold starts, but it would always start. I did some research on here and found that check valves were a common problem on 97 and up Jeeps. Through that research I found people had success installing this inline check valve rather than dropping the tank and installing a new original one. I installed it and have since had the said problems with what seems to me to be too much fuel pressure.

Ummmm, hate to say it but...(Here goes)................YOUR WRONG!

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Where is it? I can only find one line that goes from the tank to the rail. I don't see any lines anywhere else. I thought I read that on the 97-up Jeeps there is no return line.

Are the sensors and whatnot in good working order? Plugs and all that good? Can you rule out anything else that might cause hard starts when cold? My Jeep was getting a little cranky last year, and a simple tuneup kit had it starting instantly.

I hadn't heard about the check valve dying until I searched your old posts. Did you verify that you lose fuel pressure when it sits, and that the check valve is the problem? Given that you're still having issues, albeit different ones, I tend to suspect the check valve isn't the original problem. I wouldn't think another valve would raise the pressures either- maybe you've got other pump/regulator issues?

XXX said:

Ummmm, hate to say it but...(Here goes)................YOUR WRONG!

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Care to tell us where the return line is on a 97? My Jeep seems to be missing this line.

xjh3 said:

Where is it? I can only find one line that goes from the tank to the rail. I don't see any lines anywhere else. I thought I read that on the 97-up Jeeps there is no return line.

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Sorry to be so anal but........It's not on the rail, it's integrated in the pump assembly. OBD-II changed this to keep the fuel cooler. Fuel doesn't make it's journey to the rail, get heated and returned to the tank, it only circ's at the tank, thus remaining cooler with less vapors. It's all about the vapors!

xjh3 said:

Sorry, should have said this already. 97, 4.0, 160k.

I was having very long cranking cold starts, but it would always start. I did some research on here and found that check valves were a common problem on 97 and up Jeeps. Through that research I found people had success installing this inline check valve rather than dropping the tank and installing a new original one. I installed it and have since had the said problems with what seems to me to be too much fuel pressure.

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If you go back and read my response from 2 weeks ago about this very subject, you will see that I suggested that you turn on the key for a few seconds to let the pump prime up, and that will help narrow it down to the check valve. Did you try this? You will also note that I said then that you should not put it in because it may cause problems similar to the one you are having. Hate to say it, but I told you so.

88 Wagonman said:

If you go back and read my response from 2 weeks ago about this very subject, you will see that I suggested that you turn on the key for a few seconds to let the pump prime up, and that will help narrow it down to the check valve. Did you try this? You will also note that I said then that you should not put it in because it may cause problems similar to the one you are having. Hate to say it, but I told you so.

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I did try the priming method, and found that it started right up. In fact, since installing it my cold starts take no longer than two cranks. I did not buy the check valve off eBay, I bought the one that I had found other people had success with in this same situation. But yes, I suppose you did tell me so.

I've found that the no-start only happens somewhere between about 5-30 minutes after shutting it off hot. I'm ready to just remove it, but I don't understand how it can be adding any pressure to the system. I would think it would either not work and I'd have the same problem or it would maintain the pressure in the system. Is it actually possible that the fuel pressure regulator has been bad all along, and because the bad check valve would never let much pressure accumulate that I never noticed it?

97 will not have a return line to the tank.

Did you put the check valve in correctly? Not in backwards?

Not sure why it would cause such a build in pressure when all it is supposed to do is make sure fuel doesn't drain back into the tank via the main fuel line when the fuel pump is off.

Blaine B. said:

97 will not have a return line to the tank.

Did you put the check valve in correctly? Not in backwards?

Not sure why it would cause such a build in pressure when all it is supposed to do is make sure fuel doesn't drain back into the tank via the main fuel line when the fuel pump is off.

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Yes, there was an arrow on the valve clearly indicating the direction of flow.

I'm seeing the writing on the wall that this cheap fix isn't going to cut it. I've had trouble finding information through the search feature. Where is the check valve in the sending unit? Will the whole unit back there need to be replaced? I don't know how much things cost because I had trouble finding a price on anything but a fuel pump, but it being 11 years old with 160k I wouldn't mind replacing everything back there while the tank is out if it isn't going to cost me an arm and a leg.