Aeromotive FPR Spring

[red_gsx]

I have an Aeromotive 13105 FPR and have been having problems adjusting the fuel pressure (vacuum line on or off nothing changes). Looking around I noticed a post suggested to another user that they could have used the wrong spring. I had a shop put in my fpr, I gave them the box and they did the rest. Attached is a copy of the spring I have left over. Anyone know if this is the one that is supposed to be inside the fpr or not? Thanks ahead of time.

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[zippyshoe]

It appears that the Aeromotive model 13105 fpr only includes one spring. On the other hand, the model 13301 does come with two springs - a lower pressure spring is installed from the factory and a second higher pressure spring is shipped with the product. With the model 13301, you have to replace the factory-installed spring with the higher pressure spring when installed into our vehicles. Are you seeing any pressure at all at your fuel pressure gauge?

 

[romeen]

Clearly since there is a spring left over the kit did come with two springs. I have the "soft" spring from my Aeromotive fpr here and it looks very similar size wise to the one in the picture but I don't know how reliable that is for determining which spring you have there. I can completely compress it using my thumb and index finger and hold it like that for a couple seconds if that helps at all.

If I remember correctly the top part of the fpr housing which contains the spring is sealed from the lower compartment which contains the passages for fuel flow. Therefore you should be able to swap springs without removing the fpr or even having to relieve fuel system pressure. Just remove the 4 allen head bolts which hold the upper and lower halfs of the unit together. You may want to remove the adjusting screw first just to be positive that there is no spring pressure that can suddenly pop the top half off and down into the engine bay. Then you can compare springs to make sure the right one was installed.

Since I am not 100% positive about not having to relieve the fuel system pressure for this you may want to do it anyway just to be safe. Just unplug the electrical harness from the fuel pump beneath the back seat then run the motor until it shuts down. (Sorry if you already know this........not trying to insult, just don't want to assume ).

 

[red_gsx]

Thanks for the quick replies.
zippyshoe- Good call, I just found my fpr box and it is the 13301 and not 05. Since the shop did the install I don't know if they bother to switch the springs or not. As far as fuel pressure goes, I am seeing pressure on my gauge but its about 8 pounds over what it should be, sorry brain farting on the exact number.
romeen- Its alright about the info, you can never be too sure what someone knows and its always good to hear someone verify what you already know. I can see how the fpr comes apart, I just don't want to swap spring if it is the right one in there already.

All in all is the "soft" spring the lower pressure spring because I can push this one completely shut just like romeen. I'm going to give the guys at importevolution (where I bought the fpr) a call tomorrow and see what they say. I'll post results and hopefully it helps someone else down the line. Thanks to the both of you for the quick reply once again.

 

[romeen]

So your fp is actually too high and you can't lower it? Make sure there isn't a kink in the return line. And yes, the spring that I can compress with my fingers is definitely the softer spring from my kit (13301).

 

[red_gsx]

Yeah the fuel pressure is sitting happy at 42 and not budging. As far as return line this might sounds a little stupid but is it the line below the fpr? Also how far back should I trace it because if I remember correctly the next time I see fuel lines is by the back underneath the car. Also I don't know if this help to diagnose or not but I've read that in order to adjust the fpr I would need to take the vacuum line off and then the car will start to feel like its going to die. Well mine runs just fine with no change when the line is off.

 

[romeen]

Yes, the return line is the one coming straight out of the bottom of the fpr. From what I remember there is only about a foot of rubber hose to worry about before it connects to the hard pipe which runs to the back of the car.

So the 42 psi is with the vacuum hose connected, correct? When you disconnect it to set your base fuel pressure make sure you cap the end of the hose with your finger or something, otherwise you will have a vacuum leak which is what can cause the motor to feel as if it is struggling to stay running. This would affect the accuracy of the bfp.

Have you checked to confirm that you are getting vacuum through that hose? It sounds as if there may not be any vacuum through it.