risen
05-08-2008, 01:03 AM
Has anyone else here had a factory FPR start to not hold pressure for them when boosting over 15 psi during long pulls? I ask because my car just recently (yesterday) started going lean in boost.
Previous it would run a solid 11.5-11.1 afr from 2k to 6k. Now all of the sudden, if I go WOT with it in 2nd or 3rd, the afr's drop to 11 or so, but they climb back up so that by 3k it's almost 13, and I'm lifting off the throttle.
I did notice one time that they had gone over 14.7, which was what first caught my eye, so it seems like the longer I'm on it, the worse it gets. Luckily, my idle vaccum is still @ 20inHG, and it runs the same so I haven't damaged anything yet.
I do have a walbro waiting in the wings if the pump seems like the more likely culprit. But I wanted to do my rail, aftermarket fpr, feed/return fuel line upgrade at the same time so I'm holding off. I've got spare fpr's laying around, so I was curious to know if anyone had a fpr cause this sort of issue as it's cheap and an easy swap. I'm going to double check the vaccum hoses tomorrow to see if there are any leaks, but everything has been zip-tied down and inspected previously.
EDIT:
I found the problem, the vacuum line going from the 4-way splitter, to the fpr was loose enough that i could pull it out by hand. Under vacuum the permatex from the previous owner was likely sealing well enough to hold. But under boost, it was probably being forced out and allowing pressure to bypass enough to drop the fuel press. I've epoxied the 4 lines back into the splitter with a piece of coat hanger thru the line so I can make sure the passages are clean once things dry up a little. I guess I should get a vacuum block from TU/FWD.
Previous it would run a solid 11.5-11.1 afr from 2k to 6k. Now all of the sudden, if I go WOT with it in 2nd or 3rd, the afr's drop to 11 or so, but they climb back up so that by 3k it's almost 13, and I'm lifting off the throttle.
I did notice one time that they had gone over 14.7, which was what first caught my eye, so it seems like the longer I'm on it, the worse it gets. Luckily, my idle vaccum is still @ 20inHG, and it runs the same so I haven't damaged anything yet.
I do have a walbro waiting in the wings if the pump seems like the more likely culprit. But I wanted to do my rail, aftermarket fpr, feed/return fuel line upgrade at the same time so I'm holding off. I've got spare fpr's laying around, so I was curious to know if anyone had a fpr cause this sort of issue as it's cheap and an easy swap. I'm going to double check the vaccum hoses tomorrow to see if there are any leaks, but everything has been zip-tied down and inspected previously.
EDIT:
I found the problem, the vacuum line going from the 4-way splitter, to the fpr was loose enough that i could pull it out by hand. Under vacuum the permatex from the previous owner was likely sealing well enough to hold. But under boost, it was probably being forced out and allowing pressure to bypass enough to drop the fuel press. I've epoxied the 4 lines back into the splitter with a piece of coat hanger thru the line so I can make sure the passages are clean once things dry up a little. I guess I should get a vacuum block from TU/FWD.