AFPR fueling issue

[GRace]

I have an aeromotive afpr. For some reason, I've been losing fuel pressure above 10 psi of boost. I'm leaning out. I've replaced the fuel filter and ran a straight fuel line from the pump to the fuel line in the tank to rule out an o-ring leak with the same results. My pump is rewired.

I guess my question is, how do I tell if I have the low pressure or high pressure spring in my afpr? Would I be able to even hold a base fuel pressure of 43.5 psi with the low pressure spring? I can crank the base fuel pressure up to 65 psi, I didn't go up any higher because I'm having problems below that fuel pressure...

 

[99gst_racer]

1) What part number regulator do you have?
2) How do you know you're losing fuel pressure?
3) Have you checked the diaphram for a tear?

 

[miguelmcv]

Most of the time, when afpr goes bad, it gets richer instead of lean.
I just replaced the diaphram in my afpr and I was running rich.

 

[GRace]

1) What part number regulator do you have?
2) How do you know you're losing fuel pressure?
3) Have you checked the diaphram for a tear?

I think the regulator is the Aeromotive 13301. At least mine looks exactly like it. I bought it used...

By losing pressure, I mean pressure increase by boost. Afrs are fine until around 10 psi boost and they slowly increase the higher boost goes. I have a competent tuner so it's not in the tune.

I have not checked the diaphram for a tear. I always though that fuel would leak out of the vacuum line if it was torn. I can look into it.

 

[josh1095]

they are supposed to rise 1psi per 1psi of boost correct? sorry to jack ## thread bro but its kind of pertinent question to ask. thats the idea of a 1:1 afpr?

 

[GRace]

I understand they rise 1 psi per boost psi...

I checked my diaphragm and I didn't see any tears. I'm losing fuel pressure down to 0 psi right when I turn the car off, I thought that was a symptom of a torn diaphragm? Maybe it can be torn where it isn't obvious?

I also may have an Aeromotive 13105 afpr instead. My bracked looks like the one in those pics online. There aren's any numbers anywhere on mine.

Another theory I just came up with, would a boost leak at the afpr cause it to lean out higher up in the boost levels? I didn't find any leaks on the afpr last time I tested it but who knows if one popped up. That's the only thing I can think of. Unless my 6 month old walbro 255 hp isn't cutting it anymore.

 

[josh1095]

thats a good theory. if everything is flowing right, pump is working, afpr is working, then it would stand to reason thats the only thing left. if the vac line on the fpr isnt seeing full boost it isnt going to give you the appropriate amount of fuel. but then again thats an awfully short and simple hose. youd probably just blow it off before it developed a small leak, ya know.

 

[99gst_racer]

Post a pic and we'll identify which regulator is it.

Also, you guys should set up a gauge to monitor fuel pressure while boosting. Without doing that, we can't really be sure you have a fuel pressure issue.

 

[GRace]

Post a pic and we'll identify which regulator is it.

Also, you guys should set up a gauge to monitor fuel pressure while boosting. Without doing that, we can't really be sure you have a fuel pressure issue.

Here's a pic of the afpr. I think the problem is now fixed. I took the afpr apart last night and the diaphragm wasn't torn. I put it back together, resealed the screw and now it is running pretty rich at wot. I just boost tested and it isn't leaking so I think it may be running like it should. I would still like to know which model of afpr I have if anybody can help me out. It says aeromotive on the back side of the black part so I don't think it is a knock off.

 

[99gst_racer]

That is the 13105.

 

[GRace]

That is the 13105.

Awesome, thanks. I'm glad it wasn't the cheaper model!