TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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When I replaced my stock leaky injectors on my 305 TPI, I used Design III 22lbs. I didn't see any increase in fuel economy (though I no longer get a rich O2 sensor code), so I bought the holley unit to lower my fuel pressure. My original FPR was supplying 36 psi at idle.
The install was a bitch, the screws and bores were all stripped out and I couldn't get a tight seal on the cover. Needless to say, when I started it up, fuel started pissing out between the cover and the rail base. Also, the torx screws were all messed up, so I ended up having to smash off the heads of them in order to remove the FPR assembly. It was a total hack job, won't make such a mistake again. Anyway, one of the diaphragm holes was ripped to the outer edge of the diaphragm.
I got the base re threaded and replaced the screws. I installed it and didn't think the rip would make any difference because that area is sandwiched between the cap and and base.
Now I have a small amount of fuel being sucked in the vacuum line! Apparently this little rip is somehow causing this problem (though I still can't visualize how). It doesn't matter what PSI I run it at.
So now I'm left with the reasonable option of just throwing the stock unit back on, because the diaphragm is still completely intact. What a waste of 100 bucks and again, no ability to control pressure. However, I was wondering if it was possible to create a bastard child from the two, using the diaphragm/spring assembly from the stock and the adjustable cap from the holley?
Any thoughts on this situation? Need a solution, currently trying to sell the car!
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the reason the torx were "screwed up" was they are security torx, with a post in the middle. the set of them that contains the one you need is about $9 at autozone.
i'm not 100% sure this will work, but what you might also be able to do is use a dremel to grind the post holding the spring assembly to the stock diaphragm so that you can free the diaphragm to use it with the holly spring and housing.
__________________ The only difference between genius and stupidity is that genius has its limits - Albert Einstein
That's a good idea. It's strange because it isn't a constant flow of fuel...like today for example. I didn't suck in any fuel in 10 min of idling. It's a strange problem and even when it does start pulling a bit of fuel in, it's pretty minimal. Plus, I'm sick of pulling that plenum off.
However, I was wondering if it was possible to create a bastard child from the two, using the diaphragm/spring assembly from the stock and the adjustable cap from the holley?
I'd be surprised if there was any way to mix and match parts from the stock and Holley FPRs. Replacement Holley diaphragms are available although they are not listed as a replacement part. Call the Holley tech line and they will send you a new diaphragm for about $13.
FYI: If you need to clean up the threaded holes where the regulator mounts, try a 3.5 mm x 0.6 pitch tap.
Those diaphragms suck. They leak around the edge of the metal piece mounted in the middle of the diaphragm. Toss the Holley and get a new stock diaphragm for the stock housing.
With 22 lb. injectors the engine will always run rich unless you change the fuel injector constant in the PROM.
When I replaced my stock leaky injectors on my 305 TPI, I used Design III 22lbs. I didn't see any increase in fuel economy (though I no longer get a rich O2 sensor code), so I bought the holley unit to lower my fuel pressure. My original FPR was supplying 36 psi at idle.
Why did you put 22's in yout 305?
Lowering pressure will only makes thing worse because injectors have a min operating pressure.Below that the fuel just dribbles out meaning it does not atomise correctly and engine will run bad and use more fuel.Also most regs will only go so low; you can take the adjuster out altogether and they will still maintain a certain pressure because of the pressure supplied by the pump.
If installing larger than stock injectors ; as stated above only way is to adjust the tune in computer and run correct fuel pressure (43lb ?), not lower fuel pressure to try and correct
Most people run a AFPR so they can raise fuel pressure.
