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Discussion Starter #1
Hello,
I installed a kenne bell supercharger on my Bronco this weekend. I was able to drive it a little bit but it seemed like it was not running quite right. I also installed a 255lph Walbro fuel pump at the same time. Today I tried to run it and it barely even idled. I bought a fuel pressure gauge and it measured only 10psi at the rails with the Walbro. I reinstalled the old pump and it did not read anything. I clamped the return line shut and no change in the pressure. What do you recommend I do next? I am thinking fuel filter, but even a clogged one wouldn't block off all flow would it? If I hear the pump prime fine it means it is getting the right amount of current, correct? I have a '96 so I dont think I can do the trick to make it run all the time. Please give suggestions if you have them. Thanks.
 

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Satyr of the Midwest
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It's either a clogged filter or something's not hooked up right. Are you using an FMU or what, to control fuel pressure?
 

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So you spent lord knows how much on a KB, but didn't spend the $10 on a new filter and $2 on a new sock?

Make sure your filter is clean, i'd drop the tank and make sure the in tank sock was clean, and make sure the whole system is run in a minimum of 3/8 line.

At idle you're not asking for a lot of fuel, so the idling i'd go with a bad filter or a bad reading, but if you weren't having issues before a bad filter shouldn't "just show up", it would have presented earlier. Make sure your gauge is good first.
 

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Most 5/16" stock fuel lines are good for around 400 hp. When exceeding these demands one should definitely upgrade to 3/8" diameter fuel lines.

Additionally, the stock fuel filter can be restrictive, especially when contaminated. I am using a Canton Racing Products CM EFI High Flow Fuel Filter (PN 25-910).




I am just curious: What are your engine specs and HP estimate? What size injectors are you using? Are you still using stock fuel lines, FPR and fuel rail? Have you tuned your PCM for the new Kenne Bell?
 

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Can you still hear the fuel pump cycling when you key on without starting the motor? If you haven't changed the fuel filter while you owned the truck, just change it. They are cheap... Could be the FPR too.
 

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Discussion Starter #6
It's either a clogged filter or something's not hooked up right. Are you using an FMU or what, to control fuel pressure?
I am not using anything to control the fuel pressure. I figured I would let the computer take care of the fuel as I am only running 6lbs of boost on a stock 302. I figured the fuel demands would not be that much more than a slightly build 351; which a lot of people here are running on the stock system.
So you spent lord knows how much on a KB, but didn't spend the $10 on a new filter and $2 on a new sock?

Make sure your filter is clean, i'd drop the tank and make sure the in tank sock was clean, and make sure the whole system is run in a minimum of 3/8 line.

At idle you're not asking for a lot of fuel, so the idling i'd go with a bad filter or a bad reading, but if you weren't having issues before a bad filter shouldn't "just show up", it would have presented earlier. Make sure your gauge is good first.
Most 5/16" stock fuel lines are good for around 400 hp. When exceeding these demands one should definitely upgrade to 3/8" diameter fuel lines.

Additionally, the stock fuel filter can be restrictive, especially when contaminated. I am using a Canton Racing Products CM EFI High Flow Fuel Filter (PN 25-910).
I am just curious: What are your engine specs and HP estimate? What size injectors are you using? Are you still using stock fuel lines, FPR and fuel rail? Have you tuned your PCM for the new Kenne Bell?
My plans are to replace the fuel filter next. I figured I would limit the amount of variables in the install and replace the filter once I have it running, but it looks like I will have to do that now. The more I think about it the fuel delivery has seemed to got progressively worse since I installed the KB, I was able to drive it the first day, now it won’t even idle. Maybe the higher fuel pressure from the pump cause something to lodge in the filter? I installed the new sock with the new pump, the lines are still stock but with 6lbs boost I didn’t think I would need to replace them. Maybe if the computer throws a lean condition code during normal driving, but until then I will stick with the stock size. I am running the 19lb injectors, they should be good up to 300hp, and I don’t think I will get there. I have not tuned the PCM; I wanted to see if it would run fine until I invest in a Troyer tune/Moates system.
Can you still hear the fuel pump cycling when you key on without starting the motor? If you haven't changed the fuel filter while you owned the truck, just change it. They are cheap... Could be the FPR too.
Yes, the fuel pump still cycles with key on engine off. I am going to change the filter tonight, just ran out of time last night and I wanted to get some ideas if the filter is not the cause. I tried to test the FPR with the ‘pinch’ test, but it wouldn’t even build pressure that way so there is something wrong other than that.
Thank you for all your replies. I will change the filter tonight and let you know how it goes.
 

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Discussion Starter #7
Well I got it all sorted out tonight. Put in a new fuel pump; no change, however when I poured out the last of the fuel it was pretty dirty so it looks like a worthwhile change. I figured out when I upgraded to the Walbro pump, the top part of the fuel sender got messed up somehow; the fuel sprayed back into the tank rather than through the tube to the engine. To remedy this I used the procedure at the following link:
http://fullsizebronco.com/forum/showthread.php?t=109519&highlight=fuel+pump+walbro
Fuel pressure reads around 35 psi now so I think I am good. Also no codes. Thank you for your help and suggestions.
 
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