Blowin fuel lines off???

Last friday I couldn't get my 96xj started then I noticed fuel running down my driveway. I got underneath and saw that the plastic line that makes the bend up the firewall had blown off. I cut that out and replaced it with a piece of fuel line and fuel line clamps. Then the next day it had blown off so I tightend the clamps.

This morning I tried to start it to go to work and nothing. More fuel running down my driveway. This time it was the plastic line that connects to the fuel rail. So I cut that off and replaced with rubber line and clamps. When I left work tonight no start again, more fuel running down the parking lot. The one clamp had blown off. I put it back on and retightened the clamp to drive home. Just a min. ago I went out to see if it would start because I have to be at work early tomorrow morning. I blew the line off again at the other clamp. I put it back on and didn't try restarting hoping it will start for me in the morning.

What is causing the lines to blow off like this? A pressure spike on startup? Any help would be great. I am getting tired of smelling like gasoline all day.

Is it possible you're just not doing something right? I hate to laugh man, but damn that's some bad luck right there! lol

Clog somewhere?

keep0njeepin0n said:

Is it possible you're just not doing something right? I hate to laugh man, but damn that's some bad luck right there! lol

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It's always possible I am doing something wrong. I kinda doubt I am doing something that wrong though. I was a helicopter mechanic in the Army for 6 years so I do have some mechanical ability.

Blaine B. said:

Clog somewhere?

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I forgot to throw in that I have a BMW check valve inline back at the fuel filter. I installed it to solve a mysterious hot start problem, which it didn't fix. I put the valve in several weeks ago though so I am not sure why it would cause the current problem now. As far as a clog it runs fine once I but the line back on and start it. It is just when I try to restart it. That makes me believe there is excess pressure being stored in the line. Then when I fire up the pump it spikes and blows the lines. I may try to remove the check valve unless anyone has any other ideas.

What is your fuel pressure? Check with key-on-engine-off and engine running. Excessive fuel pressure will cause your problems.

bottleworks said:

What is your fuel pressure? Check with key-on-engine-off and engine running. Excessive fuel pressure will cause your problems.

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I actually just discovered tonight that the line blew off while the engine was turned off. Tuesday morning I drove it down to my parents and parked it. Went away until tonight for business. When I got back to my parent's I popped the hood to check everything out before I fired it up to drive home. The fuel line was blown off at the fuel rail.

I am thinking maybe the heat from the exhaust manifold is causing the fuel in the line there to vaporize, and the vapor pressure is blowing the line??? I drove home and popped the hood right away to see if maybe it cools down before it vaporizes and hopefully the fuel line will stay on.

Does this sound like an idea? Is there a solution to this? Could the check valve be causing the pressure to stay in the line instead of bleeding back into the tank?

Do you have a fuel pressure regulator on your 96?

When I look at Rockauto.com I see that they sell one for a 96 Cherokee Sport...

ColoradoRaptor said:

Take the check valve off, double clamp all hoses you replaced and cross your fingers.......:eeks1:

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Well it seems to be heat vaporizing the fuel. I let it cool down with the hood open and the line didn't blow off, even when I restarted it. I am still going to remove the check valve. I am also going to take the insulation off the underside of my hood and keep any eye out for some hood vents. Any other suggestions?

How the heck is that blowing the lines off?

Alot of people have heat soak.

Some have done the BMW check valve...

I don't see a connection.

Blaine B. said:

How the heck is that blowing the lines off?

Alot of people have heat soak.

Some have done the BMW check valve...

I don't see a connection.

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Me either but that is all I could think of at the moment.

Blaine B. said:

How the heck is that blowing the lines off?

Alot of people have heat soak.

Some have done the BMW check valve...

I don't see a connection.

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Thats what I am trying to figure out here. It is blowing off though. I have the nasty looking driveway to prove it.

Obviously the problem is excessive pressure in the line!! The problem started after the check valve was installed. How long after, several weeks? Heat appears to be causing the excessive pressure and the check valve is doing it's job. Remove the check valve double clamp all fittings and see what the outcome is.

ColoradoRaptor said:

Obviously the problem is excessive pressure in the line!! The problem started after the check valve was installed. How long after, several weeks? Heat appears to be causing the excessive pressure and the check valve is doing it's job. Remove the check valve double clamp all fittings and see what the outcome is.

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It did start several weeks after the check valve was installed. I am going to remove it tomorrow morning since it didn't seem to solve my hot start problem anyway. I am starting to think my hot start problem could be a vapor problem all along and the check valve just make it that much worse.

DevWinXJ said:

It did start several weeks after the check valve was installed. I am going to remove it tomorrow morning since it didn't seem to solve my hot start problem anyway. I am starting to think my hot start problem could be a vapor problem all along and the check valve just make it that much worse.

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That is exactly what I am thinkin!!! Hope that solves your blown line problem!!

Not sure for 1996, but if your year uses the fuel supply line, fuel pressure regulator on the injector rail, and excess fuel return to tank line, then I would look at the regulator and return lines. If these are working properly, then you would not get a seriously over-pressure spike even if the fuel pump was pushing too much. The BMW check valve isn't likely to be the problem, since it worked fine with that valve for a while before the problem showed up.....and the valve is between the pump and the blown connection, not past the connection acting as a blockage.

DevWinXJ said:

Thats what I am trying to figure out here. It is blowing off though. I have the nasty looking driveway to prove it.

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Can I come and vacuum up your gasolene?:flame:

Blaine B. said:

Can I come and vacuum up your gasolene?:flame:

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It is all dried up at this point. Trust me I thought about how much money ran down my driveway.

4xBob said:

Not sure for 1996, but if your year uses the fuel supply line, fuel pressure regulator on the injector rail, and excess fuel return to tank line, then I would look at the regulator and return lines. If these are working properly, then you would not get a seriously over-pressure spike even if the fuel pump was pushing too much. The BMW check valve isn't likely to be the problem, since it worked fine with that valve for a while before the problem showed up.....and the valve is between the pump and the blown connection, not past the connection acting as a blockage.

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No, my 96 doesn't have a return system. It is just straight into the fuel rain and that is it. The check valve is between the fuel filter and the motor. I think the check valve is working properly. My only though as to why it may cause the line to blow is because it is trapping the vapor in a small area. Basically when the vapor expands it doesn't have anywhere to expand so it blows the line. If it could expand into the fuel filter and into the pump/beginning of the tank they may act as a buffer. Don't know if that makes any sense?