I've been having problems. At WOT, the car is running so lean that it stutters and backfires and is slow as %$#@. Needless to say, I don't get on it anymore. Normal driving seems to be fine. The car has a Kirban AFPR. I adjusted it so many times, I made it to both extremes with no difference felt. So I ran to Advance today and bought a Fuel Pressure Tester. It hooks up to the shrader valve in the fuel rail. At idle, the pressure reads about 42 or 43 psi. When I adjust the AFPR, the needle does not move at all. No dice. Am I doing something wrong here? I have a feeling there's a tiny leak somewhere that's not letting the system hold pressure. When you turn the key into the On position and let the fuel pump kick on, I can see the needle jump up and then gradually drop. Let me know if you have any ideas. Thanks!
Your FPR must have a problem... You could rip every vac line off the engine and it still should adjust from 30-60 PSI or more...
A gradual drop is normal. Anything more than a 5 psi drop off in under one minute following shutting the ignition is cause for concern about a leaky injector.....
You are adjusting the AFPR correctly, right? I.E. loosening the hold-down bolt and adjusting the rod with an allen key while the vacuum line is disconnected?
More often than not the leak down occurs from the check valve in the FP or maybe the regulator... Yes a injector could cause the prob but isn't usually the case...
A friend did have a injector blow the bottom out in his F-150, and literally filled the crankcase with gas in about 6-8 miles of driving... Parked it in his garage to check it out, and the next day the gas/oil mixture was running out the door into the driveway...
In this case it doesn't sound like either though as he holds good pressure.....just won't adjust. Sounds as if the diaphram is stuck.
Is the vacuum line to the regulator dry upon removing it?
FWIW I've never actually seen one of the check valves go bad.
I believe the vacuum line was dry, I'll check again. It's not just a 5psi drop either, it drops to zero fairly quickly.
Common in original high mileage pumps for them to leak off in a few minutes, even seen a couple that dropped back to zero almost instantly...
I've actually looked at mine after sitting for about an hour and it still holds some pressure....
Pinch off your return line while the car is running -- not for too long a time though; a few seconds should suffice......You should see a considerable pressure increase.
What fuel pressure do TC's run stock?
All Ford EFI/SEFI engines are supposed to have 30-32psi with vac. and 39psi without vac...
Boosted engines have one additional LB FP for each LB of boost... OR 39psi + boost...
So with the vacuum line OFF the regulator, and the boost at 17 lbs, I want 56psi?
On a side note, I was looking at other regulators. A lot of them do not have vacuum ports. Is this necessary?
no. you set it at 39 with the line off(plugged), engine at idle.
the line is there to reference the boost and increase the FP to match, so if you could see your FP while driving, it would read 56 at 17psi of boost.
why do you have an adjustable regulator installed if you dont know what the stock pressure should be, or how it works? what did you set the FP to when you installed the regulator? how do you know the car is lean at WOT?
The regulator was installed when I bought the car. Aside from running terribly, at WOT my Air/Fuel gauge reads "LEAN" therefore, I assume it's running LEAN. At that point I began adjusting the AFPR to try to get it out of the LEAN band. When I couldn't feel, hear, or see a difference at either extreme, I bought a fuel pressure tester which proved to me that for some reason there is no effect when I adjust the regulator.
wide band or narrow?
have you made any recent mods or is this condition "out of the blue"?
It's a narrow band, which I know isn't too accurate, but before it would get one notch into RICH at WOT. This condition arose 2-3 weeks after I installed a 65mm TB. I reinstalled the old one to see if this was the problem only to find no effect. The 65 is back on.
Time for an update. I installed a new Kirban AFPR today. I was excited to find out this one actually adjusted the fuel pressure lol.. And then I was utterly let down when I fould out that I could not adjust the fuel pressure over 38psi. I haven't looked at the pump yet -- I'm assuming the problem is here. Is it possible that a hose is cracked or something? I guess the only way to find out for sure is to drop the tank (something I'm not looking forward to). Anything I should know about dropping the tank? I helped my brother on his Cougar but that was probably 5 years ago. Also, I was wondering where everyone got their Walbro pumps? Just looking for a reliable source. Thanks in advance for your replies!
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Tom posted a direct website no too long ago....Mine came in a holley box. Walbro makes Holley pumps. Have you tried pinching the return line?
If you pinch it like you would a garden hose to stop flow, you should see a spike in pressure.....
**EDIT** Here's the link: http://www.autoperformanceengineering.com/
Still haven't gotten around to pinching the return line -- if the pressure doesn't spike, what problem would that point to?
Also, the link posted has 255lph kits and "High Pressure" 255lph kits. Which one is best for my application? Thanks a lot!
Pulled the pump the other day. No real setbacks other than rusty bolts! I pulled out the old pump which had a big WALBRO stamp on it... and it rattled. Something was definitely loose inside. So I installed by BBK 255lph pump which had a big WALBRO stamp on it and voila! Back into the boost! Hey, I like my car again. Feels like the first time...
...Feels like the very first time.