Ironically, while driving to AAM to replace a leaking valve cover (drivers side) the car stumbles and at first I thought the dreaded limp mode since it would'nt go beyond 2k..The smell of gas suddenly made me realize it was most likely the previously reported Vortech fuel lines and fittings that come with the kit and which is used to connect the FMU and the Aux fuel pump to the OEM fuel system. Fortunately I was able to pull off into a parking lot shut it off and push it away from the large amount of fuel that was spilling out and wait for a tow truck.

In the shop and sure enough the Aux fuel pump outlet line had come loose. The shop replaced the clamp fitting with a better fitting. I think it would be good advice for all Vortech owners to have the lines and fittings checked out during oil changes just to verify they are solid and reliable...

 

yep, its not fun to be boosting and then the car dies going down the interstate, then the smell of fuel, check and replace those fittings kids.

 

No boosting when the line went..

 

Any way to upgrade to AN fittings on that system?

 

Good advice on the check; adding that to the list with blowing out the nozzle on the oil feed every oil change

 

Yes, it can be done. I looked into it a while back after my lines came apart but, decided to hold off. It would probably be cheaper just to upgrade the fuel system and replace the aux pump, FMU, etc. with either the CJM or AAM kit.

 

mine did the same thing, luckily i was on the way back to my house and was less than a mile away. got the car jacked up and put on new fittings. all is well now.

 

glad I'm going with the CJM fuel return system. It's bombproof

 

Check your FMU. I originally reported this issue last summer. The lines coming loose is usually a symptom of the real issue.

The FMU design is not the greatest and the internals can stick when fuel deposits build up on its metal parts. I had the exact problem you describe. We rebuild the FMU, used the exact same fuel fittings & clamps as originally installed and I haven't had a problem since.

If you don't run a good injector cleaner on a regular basis, you should. This will help cut down on the fuel deposit build up. I run a Techron based injector cleaner every time I change my oil.

 

The fuel line fittings that come with the kit are crimp-on. I installed all the fuel lines with screw clamps. Hopefully, that'll prevent lines from separating.

 

Same happened to me, good job I was only going slow at the time. Replaced all the hose with better stuff, not Aeroquip stuff though.
Very very dangerous design.

 

Not sure I understand how the FMU can cause the fittings to come loose.. The FMU allows the fuel to enter the Aux fuel pump when the boost pressure reaches a certain # and the Aux fuel pump gets energized by the S.S. box raising the fuel pressure delivered to the injectors.. The FMU function is either allow fuel to the Aux pump or bypass it..A sticky FMU would seem to have the effect of restricting fuel flow but it's not obvious how it would cause the fuel line fittings to fail??

 

A stuck FMU creates a situation where the fuel pressure rises unabated (the SS readings are saying more fuel, but the stuck FMU gives the extra fuel nowhere to go). The hose blows off because the clamp is not designed to hold under the raised pressure conditions. A better clamp may prevent the hose from coming loose, but if the FMU is still sticking you are not correcting the real problem and are probably incurring other fuel delivery issues that are not readily apparent.

I'd advise anyone who has experienced this issue to take their Vortech FMU off and have it rebuilt just to be safe.

 

What does this involve in terms of disconnection etc Thnx

Pretty scary stuff in your later post, you could actually mask a serious problem for longer by making the fitment better

 

I don't think it's that hard to get the FMU off if you can get the car in the air on jackstands or something. It's pretty accessible.

The first thing you should probably note is **which** fuel lines are coming loose. This should give you a better indicator of if it is just a clamp problem or possibly something more. In my case, it was the lines closer to the FMU. Initially, we fixed one as others are describing in this thread only to have a different one nearby pop off.

 

I appreciate the response but I guess I see the problem different than you are describing.. I see the problem as strictly a poor design of the fittings that attach the fuel lines to there barb fittings..The FMU is simply an "on-off" fuel supply to the Aux fuel pump. when its "on" fuel is delivered to the Aux fuel pump. The fuel pump increases the flow and pressure to the injectors which are controlled by and trying to meet the specific fuel settings in the S.S. Map B. The systems fuel lines and fittings should be designed to not separate at the max fuel pressure the system can produce which I believe is in the 100-110 psi range..At least that what my fuel gauge reads at full boost..No FMU failure can make the fuel system read a greater fuel pressure than that..

I agree a sticky FMU would cause a fuel delivery problem but that is another failure mode not coupled to the hoses popping off..Hoses popping off is a very poor to marginal design of the fittings..

 

My experience proves different. After we rebuilt the FMU (cleaned internal, new seals, etc), my system went back together with **the exact same clamps** used originally. My problem with fuel lines popping occurred about 6000 miles after the SC install. Since the FMU rebuild, I've added another 20K+ miles and have had no further issues with the system, running the clamps/fittings that came with the kit.

Not saying better fittings/clamps would not be an improvement, but there are potentially other issues folks should be checking as part of a regular maintanence routine on the Vortech. Just like the car has a maintanence schedule provided by Nissan, you should be checking key components of the Vortech kit at regular intervals.

 

To further elaborate on this point you will need to have seen the inside of the FMU. The "on-off" function you describe is performed by a float type mechanism which has metal on metal contacts that can stick when fuel deposits build up on the surface. IIRC, the FMU is activated by vacuum pressure. The Auxilary Fuel pump gets its instructions from the SS box which are determined by a variety of inputs.

Your description applies if everything is working as it should, but a different set of circumstances applies here. You could have the FMU sticking close when the Aux Fuel pump is active (which could result in too little fuel). You could also have it stick open when the pump is not active (resulting in excess fuel in the auxillary fuel pump loop)

As for your fuel pressure gauge, that is completely dependent on where your gauge sensor is located. Unless you are taking a reading off the specific line that is coming loose, you cannot conclude it is not a pressure issue there as pressure between the tank and FMU, FMU and Aux Pump, and Aux Pump and injectors could all be different dependent on what is working or not working on the system.

The high fuel pressure situation is why you will see many tuners recommend changing to a return line fuel system to regulate fuel pressure better than the stock system does.

 

I totally agree with your advice on periodic servicing intervals and that I recommended earlier. The hoses can pop off due to either (1) seeing a higher fuel pressure than they were intended for or (2) they are marginal for the intended fuel pressure they were intended for or (3) they were not installed properly. In any event a sticking FMU would not cause the system fuel pressure to go above what the system is designed for..

IIRC the previously documented hose popping failures were not related to the FMU.. Again, in the interest of trying to understand our system and the exact mechanism(s) of a problem(s) we may be experiencing it is in all our interests to try to focus on possible causes and rule out non contributors..Good discussions and appreciate the advice on servicing..

 

But that was my whole point. That WAS my issue and I haven't had a problem since rebuilding the FMU. I have replaced none of the parts you suggested replacing.

Was never trying to discount the areas you are saying to check, but the FMU can obviously be a factor because it was the problem point on my car. I posted a thread about this last summer and know at least one other person who had a similar issue at that time who rebuilt their FMU and no longer had a problem after that.