Walbro 450 Problems with stock FPR
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Evolving Member
Joined: Mar 2009
Posts: 173
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From: Lag All Day, Boost All Night
Walbro 450 Problems with stock FPR
Hey guys, I thought I'd post this up so that you guys don't have to go through the same problems I did.
I recently upgraded from a 255 to a 450 to run E85. The car was on the stock FPR still. I had the car tuned and it ran great for about a week. All of the sudden one day as soon as I would hit boost the car would lean way out. like 15.5:1 or leaner.
I found the problem to be the small rubber grommet that seals the outlet of the pump to the sending unit. I figured it was just old (the car is an 01, and it's had the pump swapped for 2 different 255's in its life and the 450 now). I figured that the grommet was the original and had just gone bad. It had split down the side and wasn't giving enough pressure/flow to the injectors.
I replaced the grommet and everything was fine. But the same problem happened again about 2 weeks later. I figured the grommet was ok, so i checked the FPR First. The FPR was fine so I pulled the pump again. Same problem.
I then started to think about it and Decided the FPR was the issue. my thought was that the flow of the 450 is probably double what the stock pump was. The FPR couldn't return enough fuel fast enough and the pressure was getting too high for the grommet to hold and it was bursting.
I got the Fuelab kit from MAP and everything has been fine since. I knew that the FPR was the problem because the car was sitting lean at idle under regular fuel pressure. The stock FPR couldn't hang. I needed the car retuned obviously, but that's a minor inconvenience.
I recently upgraded from a 255 to a 450 to run E85. The car was on the stock FPR still. I had the car tuned and it ran great for about a week. All of the sudden one day as soon as I would hit boost the car would lean way out. like 15.5:1 or leaner.
I found the problem to be the small rubber grommet that seals the outlet of the pump to the sending unit. I figured it was just old (the car is an 01, and it's had the pump swapped for 2 different 255's in its life and the 450 now). I figured that the grommet was the original and had just gone bad. It had split down the side and wasn't giving enough pressure/flow to the injectors.
I replaced the grommet and everything was fine. But the same problem happened again about 2 weeks later. I figured the grommet was ok, so i checked the FPR First. The FPR was fine so I pulled the pump again. Same problem.
I then started to think about it and Decided the FPR was the issue. my thought was that the flow of the 450 is probably double what the stock pump was. The FPR couldn't return enough fuel fast enough and the pressure was getting too high for the grommet to hold and it was bursting.
I got the Fuelab kit from MAP and everything has been fine since. I knew that the FPR was the problem because the car was sitting lean at idle under regular fuel pressure. The stock FPR couldn't hang. I needed the car retuned obviously, but that's a minor inconvenience.
thanks for sharing your experience im sure this will help someone and myself since I was thinking of dropping in a 450 and call it a day. you are obviously still on stock feed and return lines? your fuel lab kit hoses right to the factory return hose from the engine bay? would you happen to know how much power a walbro 450 + 2200cc can feed?
Thread Starter
Evolving Member
Joined: Mar 2009
Posts: 173
Likes: 0
From: Lag All Day, Boost All Night
thanks for sharing your experience im sure this will help someone and myself since I was thinking of dropping in a 450 and call it a day. you are obviously still on stock feed and return lines? your fuel lab kit hoses right to the factory return hose from the engine bay? would you happen to know how much power a walbro 450 + 2200cc can feed?
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Joined: Apr 2013
Posts: 29
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From: San Diego, CA
Hey guys, I thought I'd post this up so that you guys don't have to go through the same problems I did.
I recently upgraded from a 255 to a 450 to run E85. The car was on the stock FPR still. I had the car tuned and it ran great for about a week. All of the sudden one day as soon as I would hit boost the car would lean way out. like 15.5:1 or leaner.
I found the problem to be the small rubber grommet that seals the outlet of the pump to the sending unit. I figured it was just old (the car is an 01, and it's had the pump swapped for 2 different 255's in its life and the 450 now). I figured that the grommet was the original and had just gone bad. It had split down the side and wasn't giving enough pressure/flow to the injectors.
I replaced the grommet and everything was fine. But the same problem happened again about 2 weeks later. I figured the grommet was ok, so i checked the FPR First. The FPR was fine so I pulled the pump again. Same problem.
I then started to think about it and Decided the FPR was the issue. my thought was that the flow of the 450 is probably double what the stock pump was. The FPR couldn't return enough fuel fast enough and the pressure was getting too high for the grommet to hold and it was bursting.
I got the Fuelab kit from MAP and everything has been fine since. I knew that the FPR was the problem because the car was sitting lean at idle under regular fuel pressure. The stock FPR couldn't hang. I needed the car retuned obviously, but that's a minor inconvenience.
I recently upgraded from a 255 to a 450 to run E85. The car was on the stock FPR still. I had the car tuned and it ran great for about a week. All of the sudden one day as soon as I would hit boost the car would lean way out. like 15.5:1 or leaner.
I found the problem to be the small rubber grommet that seals the outlet of the pump to the sending unit. I figured it was just old (the car is an 01, and it's had the pump swapped for 2 different 255's in its life and the 450 now). I figured that the grommet was the original and had just gone bad. It had split down the side and wasn't giving enough pressure/flow to the injectors.
I replaced the grommet and everything was fine. But the same problem happened again about 2 weeks later. I figured the grommet was ok, so i checked the FPR First. The FPR was fine so I pulled the pump again. Same problem.
I then started to think about it and Decided the FPR was the issue. my thought was that the flow of the 450 is probably double what the stock pump was. The FPR couldn't return enough fuel fast enough and the pressure was getting too high for the grommet to hold and it was bursting.
I got the Fuelab kit from MAP and everything has been fine since. I knew that the FPR was the problem because the car was sitting lean at idle under regular fuel pressure. The stock FPR couldn't hang. I needed the car retuned obviously, but that's a minor inconvenience.
I think I'm having an issue as well. My idle afr is fine, drivability is fine too. But when I get on it the car is a bit too lean. Sometimes hits 13 or a little over. And also recently has started to cut out when I go WOT. Wally 450 with 2150cc.
There are a few people who are on stock FPR with a 450. Most have upgraded their feed lines. I know MrFred runs a -6AN feed line. And I think Tom as TSCompUSA has the stock FPR.
Do any of you guys know what your fuel pressure is?
Do any of you guys know what your fuel pressure is?
I'm running stock feed and return lines, with the stock FPR. The only fuel system mod I have is that I drilled the siphon to 9/64", and my pump is rewired but still has dual voltage capability same as stock.
I don't know what my fuel pressure is, but I do know that at my power level I'm at 80% IDC with the FIC 1650 Hi-Z. Aaron told me it is due to the flow constraints of the stock lines and what not. So when I build the motor, the car will be getting 6an feed and return lines, and a radium fuel rail with AFPR and radium's new boost referenced pulse damper.
I don't know what my fuel pressure is, but I do know that at my power level I'm at 80% IDC with the FIC 1650 Hi-Z. Aaron told me it is due to the flow constraints of the stock lines and what not. So when I build the motor, the car will be getting 6an feed and return lines, and a radium fuel rail with AFPR and radium's new boost referenced pulse damper.
Trending Topics
-8 AN Feed
-6 AN Return
Aftermarket rail and regulator
Return siphon drilled to 9/64" (3.5 mm)
This simple formula guarantees no issues with fueling or pressure, and will support as much power as any sane person wants to throw at it. Teflon lines are best for E85 and/or corrosive race fuels. Do it once, do it right, and never have to worry about it again.
I've never understood the logic behind throwing loads of money and effort at the engine/turbo setup, while being left with a puny factory fuel system that creates pressure issues at low speeds and friction losses everywhere else.
-6 AN Return
Aftermarket rail and regulator
Return siphon drilled to 9/64" (3.5 mm)
This simple formula guarantees no issues with fueling or pressure, and will support as much power as any sane person wants to throw at it. Teflon lines are best for E85 and/or corrosive race fuels. Do it once, do it right, and never have to worry about it again.
I've never understood the logic behind throwing loads of money and effort at the engine/turbo setup, while being left with a puny factory fuel system that creates pressure issues at low speeds and friction losses everywhere else.
-8 AN Feed
-6 AN Return
Aftermarket rail and regulator
Return siphon drilled to 9/64" (3.5 mm)
This simple formula guarantees no issues with fueling or pressure, and will support as much power as any sane person wants to throw at it. Teflon lines are best for E85 and/or corrosive race fuels. Do it once, do it right, and never have to worry about it again.
I've never understood the logic behind throwing loads of money and effort at the engine/turbo setup, while being left with a puny factory fuel system that creates pressure issues at low speeds and friction losses everywhere else.
-6 AN Return
Aftermarket rail and regulator
Return siphon drilled to 9/64" (3.5 mm)
This simple formula guarantees no issues with fueling or pressure, and will support as much power as any sane person wants to throw at it. Teflon lines are best for E85 and/or corrosive race fuels. Do it once, do it right, and never have to worry about it again.
I've never understood the logic behind throwing loads of money and effort at the engine/turbo setup, while being left with a puny factory fuel system that creates pressure issues at low speeds and friction losses everywhere else.
-8 AN Feed
-6 AN Return
Aftermarket rail and regulator
Return siphon drilled to 9/64" (3.5 mm)
This simple formula guarantees no issues with fueling or pressure, and will support as much power as any sane person wants to throw at it. Teflon lines are best for E85 and/or corrosive race fuels. Do it once, do it right, and never have to worry about it again.
I've never understood the logic behind throwing loads of money and effort at the engine/turbo setup, while being left with a puny factory fuel system that creates pressure issues at low speeds and friction losses everywhere else.
-6 AN Return
Aftermarket rail and regulator
Return siphon drilled to 9/64" (3.5 mm)
This simple formula guarantees no issues with fueling or pressure, and will support as much power as any sane person wants to throw at it. Teflon lines are best for E85 and/or corrosive race fuels. Do it once, do it right, and never have to worry about it again.
I've never understood the logic behind throwing loads of money and effort at the engine/turbo setup, while being left with a puny factory fuel system that creates pressure issues at low speeds and friction losses everywhere else.
I think what Ted B posted can be achieved with a -6 feed line and a 450 when not using a super-huge turbo. I will be using FIC 1650's with a 6 feed line and OEM return line. Like I said previously, that is MrFred's set-up, and it works really well. THat also includes a hardwired pump. No need to mess with base fuel pressure.
If someone has technical questions on that set up, I'll ping him because he can give all the technical details on it.
If someone has technical questions on that set up, I'll ping him because he can give all the technical details on it.
I had a 450 on stock lines/fpr for over a year with no issues. Only thing I did was drill the siphon out. On 2150's the car made 630/500ish at 32 psi on an hta86. I imagine base fuel pressure was probably a little higher than it should have been but the car idled and drive just fine.