Bad walbro fuel pump?
Yes its quite possible. Fuel pump going bad wont supply enough fuel therefore it will run lean and if its running lean enough the motor will struggle to stay running which means low vacuum
This has recently started happening to me. I don't mean to hijack this thread, but can anyone help me out? I just replaced my fuel pump with a brand new walbro, however, occasionally on start up, my boost gauge would read 0 vacuum for about 30 seconds and my afrs would read super lean 17.9 - 18.0 + . Then after that the vacuum would shoot to -18 to -20 as its supposed to be and the afr's would read normal, around 14.7- 15.1 . Its like for the first couple seconds the fuel pump is jammed or just isn't on, then all of the sudden it kicks in and everything is back to normal. It only does this on start up and i have no issues with it while driving around after that. Can anyone offer me an explanation for this? Could it be that I received a bad walbro and need to replace it again?
I am not saying that you have a bad Wally, but it might be. I have had two bad ones in a row myself. That is my first Wally went bad, and then the new replacement was bad as soon as I installed it. It can happen.
A more direct indicator of your fuel pump's health is to monitor fuel pressure with a fuel pressure gauge. AFR's and manifold vacuum are indirect indicators. Another important factor is electrical voltage at the pump.
A more direct indicator of your fuel pump's health is to monitor fuel pressure with a fuel pressure gauge. AFR's and manifold vacuum are indirect indicators. Another important factor is electrical voltage at the pump.
I see. Monitoring fuel pressure does sound a lot smarter. I'm currently tapped for boost at the fuel pressure regulator, what happens with that thing to cause the boost gauge to read 0 vacuum?
Thanks for your help sparky, these walbros are nice, but sketchy at times.
Thanks for your help sparky, these walbros are nice, but sketchy at times.
Since you are tapping into the FPR line for your vacuum/boost source, let me ask you this: Did you secure the hose connections right up tight where you tapped into the FPR hose with zip ties, and etc.? I mean there is no source for possible leaks there, right?
Last edited by sparky; Sep 22, 2011 at 08:05 PM.
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Correct! Its all air tight, ill go ahead and change the boost line tonight to see if there might be a hole in it. What else could it be ?
Just make sure that they are in fact air tight. Double check all the connections. My policy is that if you can spin a zip tied hose with your fingers...then it ain't quite tight enough. So, then I'll replace that particular zip tie with an ugly 1/4" hose clamp.
pal215. Your boost/vacuum problems and the lean AFR's may not necessarily be related causally. They may not be fuel delivery issues at all. At least you should consider other alternatives.
Specifically the lean AFR's on start up may be due to the condition of your wideband O2 sensor. When these sensors start to go they'll frequently produce erratic and/or lean readings. Even when they are in good condition they need to reach operating temp before they produce accurate readings. Just another thing to look at.
Specifically the lean AFR's on start up may be due to the condition of your wideband O2 sensor. When these sensors start to go they'll frequently produce erratic and/or lean readings. Even when they are in good condition they need to reach operating temp before they produce accurate readings. Just another thing to look at.
Last edited by sparky; Sep 22, 2011 at 10:43 PM.
Check out your fuel filter too if you haven't already. You might have gotten some bottom-of-the-tank dirty gas and the filter's clogged. It's not super likely, but it only takes 5-10min to check.
pal215. Your boost/vacuum problems and the lean AFR's may not necessarily be related causally. They may not be fuel delivery issues at all. At least you should consider other alternatives.
Specifically the lean AFR's on start up may be due to the condition of your wideband O2 sensor. When these sensors start to go they'll frequently produce erratic and/or lean readings. Even when they are in good condition they need to reach operating temp before they produce accurate readings. Just another thing to look at.
Specifically the lean AFR's on start up may be due to the condition of your wideband O2 sensor. When these sensors start to go they'll frequently produce erratic and/or lean readings. Even when they are in good condition they need to reach operating temp before they produce accurate readings. Just another thing to look at.
. Its all very strange. Tonight the issue disappeared, perhaps due to a cold start ?
Just took the car for a ride and really got on it. Fuel pump revealed no signs of weakness. One thing I did today right before this issue came up was fill up on 91 instead of the normal e85 that I always use since I'm dual map tuned and decided to try it for a while. I doubt that this could have effected the fuel pump in any negative manner but I just wanted to put it out there.
You know, my boost gauge sticks at 0PSI on warm starts sometimes as well. I don't have a wideband to see my AFR and my car doesn't idle badly or anything when it's happening. I thought it was my boost gauge being a little janky, but maybe I'm experiencing the same thing you are?