Chevy86 IROC-Z

Hi guys. This may be a silly question but, is it ok to drill out the tiny pinhole where the vacuum line connects? Would it make a difference as in good response or is it a bad idea to make the tiny hole bigger?

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y84pauloflondon

1)you would most likely damage the fuel pressure regulator!
2)I don't think it would make any diff cause the vacuum line is still the same size as the hole on the regulator! Bigger hole would need a bigger vacuum line.
IMO.

vetteoz

If you want to do a useful mod ; drill a hole in the cover and braze a nut on there so you can fit a bolt to make pressure adjustable

http://www.thirdgen.org/techboard/tp...djustable.html (DIY TPI AFPR (adjustable fuel pressure regulator))

Chevy86 IROC-Z

let me explain. I have a issue with my camaro. It turns on just fine but once I open the throttle, i begins to sputter and starts to backfire softly. Sounds like it is starving for air or gas. TPS set to spec, Idle air control valve good, timing set at 0, 2, 4, 6, 8, in both directions and the same thing happens. A life time mechanic told me that he has seen similar problems on other chevys and that through experiance, he suggested that my fuel pressure regulator is either stuck or leaking. I noticed that the hole for the vac line is tiny. So if I were to drill out the hole a little bigger, would it make a difference? I could just remove the housing and replace the diaphram cant I? I really dont want to spend more money on a new fuel pressure assembly. If it's "bad", do I need to buy the whole assembly or just the diaphram? Is there a way to test this part before I buy a new one?

madmax

Well first, drilling a hole will make absolutely no difference. Second, there is no reason to replace the thing because some old school mechanic THINKS that is what is wrong. Why not check things?

If you take off the vacuum line and you dont smell a lot of gas or its not dripping in gas, its not leaking.

If you get a fuel pressure gauge and hook that up to the fuel rail (there is a fitting right where the FPR is) it should read about 43PSI with the vacuum line disconnected from the FPR. If thats what it reads, its fine.

If the car backfires or sputters when you step on the gas pedal, its either a timing issue or issue with the data being sent to the computer. I'd first check the timing mark, get the #1 piston at TDC and see if the balancer mark is at zero or not. When mine slipped on my 86 about 10 years ago, it was off around 20 degrees... so going back and forth about 8 wont be enough if its way off. Make sure your TPS is set between 0.35-0.5V. Do you have access to a scan tool? And clear out that code 33, disconnect the battery for 15 seconds and drive the car again and see if it resets. If it does, you have an issue you need to fix first.

BTW disconnecting the MAF affects more than just fuel mileage, with it disconnected the engine has essentially no sense of load so driving on a flat road or driving uphill is something the computer cannot account for in the short term and it will really run awful. The default tables are read strictly based on RPM and while an engine is running there is a lot more to how much air is in there than just the RPM of the engine.

Chevy86 IROC-Z

madmax, I agree with you on the MAF sensor. My timing cover reads 0-2-4-6-8. With the EST disconnected, Ive set the timing at different settings and I get the same result as in back firing when I try to open the throttle. I remember that I had disconnected the vac. line at the FPR about 2 months ago and I did get a hint of gas, not to strong though. Ive always had a code 33 and Ive never had any problems at all with the trouble code of 33. I never replaced the MAF due to financial reasons. I have a trouble code of 42 which is a bad ignition control module. Ive replaced that (7 pin ignition control module) but I still get that code. So Im going to buy a new pick up coil and capacitor. Everything else inside the dizzy is new. Can these two things (pick up coil, capacitor) give me trouble or a false trouble code that is not related to the Ignition Control Module? Also due to the fact that my car wont respond to any throttle, It move, it crawls. As for the trouble with the throttle response, I dont know if its fuel related, or electronically related.

madmax

Well, start from square one.

Have you ever cleared the codes from the ECM? This is as simple as disconnecting the battery for a bit, a minute is more than enough. The 42 will be set when disconnecting the tan/black wire to set the timing so that may be why its there. Code 33 is generally not a MAF fault, its usually something else that triggers it like an incorrect TPS setting, IAC/throttle plate adjustment, or modified motor. So clear the codes, start and maybe drive the car, and see if they come back.

Chevy86 IROC-Z

yup, ive disconnected the + side, and still i get the trouble code. Ill tell you what. Im going to replace my fuel pump because my uncle siphoned my gas when I wasnt around. So when I went back, I tried turning on the Camaro over, and over, and over agian. then I noticed a dry winding coming from the tank. The whole time that I was trying to get the car started, my uncle played the stupid part and never said a word. So the damb 2 month old pump burned out on me. So now I got to geta replacement. Its covered under warantee but when I called to conferm at Autozone, they couldnt find the part under my 3 phone numbers. So Im out of luck. See, the guy (Autozone sales associate) who sold me the pump has a IROC too. So im thinking that he might of put the purchase under his phone number. Im gonna have a talk with the manager tommorrow. Anyway, Ill get back at you with the results when I finally get the new pump in. Thanks for giving me advice bro. Ill check in with you later. Peace.