1G CANT ADJUST FUEL PRESSURE

[dalawoi]

Okay guys, want to try and get some opinions on what might be wrong,

90 TSI

Rewired Walbro 450
-6an feed line
fuel lab filter w/ brand new e85 filter
-6an line to rail
stock fuel rail
FIC 1450's freshly cleaned
fuel lab AFPR
stock return line

seems like out of nowhere i noticed my A/F has been running way leaner then normal, eventually getting to the point where i couldnt go past 3k rpm without going 18:1 A/F, started trying to diagnosis the issue, checked AFPR and noticed i was down to about 25psi which it was set at 43. Tried adjusting and it wouldnt adjust, swapped to an Aeromotive AFPR and still the same thing no adjustment, decided to check fuel filter turns out mine was toast, replaced with a new Fuel Lab e85 filter, fuel pressure jumped up to about 38psi but still cant adjust it, so i took out my FIC 1450s and sent them off for cleaning due to the looks of my fuel filter. Got them back and still the same issue, cant adjust my fuel pressure and car is running lean. Took it to my tuning guy to see if he could adjust the fuel tables and make it work with 38psi and no matter how much fuel he added everything stayed the same.. Anyone have any ideas what my issue could be? Car used to run perfect on the same set-up seemed to have just slowly gotten worse and worse to where i'm at now..

is it possible my return line is to small? maybe feed line has a clog?

Thanks for the help.

 

[1990TSIAWDTALON]

Hate to say it but there is not a lot left except the pump or a clog in a line. Turn the pump on without the motor running and see if there is any change. If not I would inspect the pump and its sock to see if there is garbage on it restricting the pump since your filter was bad.

 

[sidewaystsi]

Check the pump itself for a malfunction with its pressure relief valve.

 

[gofer]

All this time swapping, did you use the same mechanical gauge on the AFPR?

 

[dalawoi]

All this time swapping, did you use the same mechanical gauge on the AFPR?

no different gauge

Check the pump itself for a malfunction with its pressure relief valve.

how does one do this with a walbro 450?

for reference my fuel pump has maybe 2k miles on it, was wired correctly, all soldered connections.

 

[gofer]

Good you tested it with a different gauge, those cheap things are known to fail too.

Check voltage at the pump, you said you rewired it and soldered the connections. Maybe it's not a case of a bad rewire just a bad solder joint or connection somewhere so the pump's not getting the 12v+ it needs to maintain fuel pressure properly.

 

[dalawoi]

Good you tested it with a different gauge, those cheap things are known to fail too.

Check voltage at the pump, you said you rewired it and soldered the connections. Maybe it's not a case of a bad rewire just a bad solder joint or connection somewhere so the pump's not getting the 12v+ it needs to maintain fuel pressure properly.

okay i'll go ahead and test voltage tonight

 

[sidewaystsi]

no different gauge


how does one do this with a walbro 450?

for reference my fuel pump has maybe 2k miles on it, was wired correctly, all soldered connections.

http://www.driven2modify.com/showth...2588054cd2de6bdf00f28f75b&p=305115#post305115

Its more of a "mod". I had to also do this with my 450 because of poor fuel pressure.

 

[Nate355RS]

Your AFPR could be bad. If you have Link, turn the fuel pump on with the car NOT running. Squeeze and hold the return line just below the AFPR. If the fuel pressure jumps and holds the fuel pump is probably good and the AFPR is messing up. If it doesn't the problem is back on the pump side of things.

 

[tmoney20g]

How about that spot where the pump meets up with the pump hanger tube, the o-ring/tube thing that can be loose/failed. Excess pressure will find the path of least resistance, and if that's it, then your pressure is just bleeding off right from the top of the pump into the tank.

 

[dalawoi]

finally got around to working on figuring out the issue, check voltage was getting over 13v at all times, squeezed fuel return line after AFPR and noticed no change in pressure, pulled the pump to find the little 3" of hose that goes between sending unit and fuel pump busted open and had a huge hole in it, changed it and all issues were resolved. Thanks again for the help everyone.