? for the guys with AFPR experience... ***SOLVED***

Topic: ? for the guys with AFPR experience... ***SOLVED*** (Read 2189 times) previous topic - next topic

? for the guys with AFPR experience... SOLVED

July 16, 2008, 01:55:39 AM

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!

? for the guys with AFPR experience... SOLVED

Reply #1 – July 16, 2008, 06:48:40 AM

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...

? for the guys with AFPR experience... SOLVED

Reply #2 – July 16, 2008, 07:41:36 AM

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?

? for the guys with AFPR experience... SOLVED

Reply #3 – July 16, 2008, 08:03:41 AM

Quote from: V8Demon;227615

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.....

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...

? for the guys with AFPR experience... SOLVED

Reply #4 – July 16, 2008, 08:12:37 AM

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.

? for the guys with AFPR experience... SOLVED

Reply #5 – July 16, 2008, 04:35:38 PM

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.

? for the guys with AFPR experience... SOLVED

Reply #6 – July 16, 2008, 06:04:54 PM

Quote from: V8Demon;227624

FWIW I've never actually seen one of the check valves go bad.

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...

? for the guys with AFPR experience... SOLVED

Reply #7 – July 16, 2008, 06:11:13 PM

Quote

it drops to zero fairly quickly.

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.

? for the guys with AFPR experience... SOLVED

Reply #8 – July 18, 2008, 05:36:55 PM

What fuel pressure do TC's run stock?

? for the guys with AFPR experience... SOLVED

Reply #9 – July 18, 2008, 08:01:49 PM

Quote from: tc²;228046

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...

? for the guys with AFPR experience... SOLVED

Reply #10 – July 19, 2008, 03:32:28 PM

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?

? for the guys with AFPR experience... SOLVED

Reply #11 – July 19, 2008, 03:42:10 PM

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?

? for the guys with AFPR experience... SOLVED

Reply #12 – July 20, 2008, 02:03:52 AM

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.

? for the guys with AFPR experience... SOLVED

Reply #13 – July 20, 2008, 07:24:16 AM

Quote from: tc²;228199

at WOT my Air/Fuel gauge reads "LEAN" therefore, I assume it's running LEAN.

wide band or narrow?

have you made any recent mods or is this condition "out of the blue"?

? for the guys with AFPR experience... SOLVED

Reply #14 – July 20, 2008, 02:08:21 PM

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.