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35psi after 5 minutes, 20psi after 15 minutes and 0psi after 25 minutes.
My sniffer isn't as good as it used to be, I smelled a little maybe but that could be the errant gas spilled while connecting the the tester. I figured Id see if it would hold a vacuum but it wouldn't, am I correct to think it should hold vacuum?
I have never heard of any pressure regulator that didn't hold vacuum. I've also never heard of a pressure regulator problem causing a starting problem, that didn't also cause a significant drivability problem at all times.
So is the starting problem on cold starts ? or hot restarts, or at all times ???
What was the issue that caused you to replace the injectors in the first place ???
A 1992 LT1 is programmed at 23.8. Therefore, if fuel pressure without vacuum applied is 42 a 24 lb injector rated at 3 bar (43.5 psi) should be used. The praise on this board for FIC cracks me up. Individuals need to understand their vehicles and not depend on a salesman for proper replacement.
The OP should also investigate his fuel pressure loss. A properly operating system should not lose more than 10 or 15 lbs in an hour.
Last edited by MrWillys; May 12, 2016 at 04:15 PM.
I have never heard of any pressure regulator that didn't hold vacuum. I've also never heard of a pressure regulator problem causing a starting problem, that didn't also cause a significant drivability problem at all times.
So is the starting problem on cold starts ? or hot restarts, or at all times ???
What was the issue that caused you to replace the injectors in the first place ???
Not sure if the pressure problem happens when hot if that is your question but the starting problem happens hot or cold. My decision to replace the injectors was because it has a slight misfire and set aside money for new ones, I know, sounds like I'm just throwing money at it but that's really not the case here. I drive this car long distances at times and want zero problems with it. next trip may be almost 1300 miles so any new parts are an added bonus for dependability for me the way I see it.(within reason of course)
The pressure regulator concerns me, especially since you say it should hold vacuum. Probably pick up a new one today.
I also think I should probably just go ahead and replace the fuel pump. What are your thoughts?
A 1992 LT1 is programmed at 23.8. Therefore, if fuel pressure without vacuum applied is 42 a 24 lb injector rated at 3 bar (43.5 psi) should be used. The praise on this board for FIC cracks me up. Individuals need to understand their vehicles and not depend on a salesman for proper replacement.
The OP should also investigate his fuel pressure loss. A properly operating system should not lose more than 10 or 15 lbs in an hour.
No software here to troubleshoot, maybe in the future. I don't know the formulas and details so I have to rely on what I know and learn from others. Are you saying I need 24lb injectors? After reading on here it sounds like the regulator is supposed to hold a vacuum and mine wont so I will replace that. Maybe that is why my fuel pressure drops so quick? Like I mentioned before. No problems at all before with starts or pressure before the injector change so if the problem has nothing to do with them it is a coincidence and will need to look into it further.
No software here to troubleshoot, maybe in the future. I don't know the formulas and details so I have to rely on what I know and learn from others. Are you saying I need 24lb injectors? After reading on here it sounds like the regulator is supposed to hold a vacuum and mine wont so I will replace that. Maybe that is why my fuel pressure drops so quick? Like I mentioned before. No problems at all before with starts or pressure before the injector change so if the problem has nothing to do with them it is a coincidence and will need to look into it further.
Your regulator doesn't hold vacuum. If your losing pressure you either have a bad pump or leaking injector(s). Your car needs 24 lb injectors. Can you tell what the number on the injector is? The regulator has a spring in it. When the engine has high vacuum it lower the fuel pressure and when you got wide open throttle and vacuum drops the pressure rises.
The new pumps will not hold as good as the factory. Make sure you get the right hose to replace the pulsater and a new sock and fuel filter. Get the tool to release the hoses in the engine and take the filter out the top it will save some cussing. If the tank is full disconnect the hose before tyring the filter will save a bath. I would do the o2s while under there. Orielys rent the socket set use the short one.
I have never pulled a vacuum on the FPR to see if it will hold and you have two differant answers so take your pump with you to the store and see let us know.
Last edited by antfarmer2; May 8, 2016 at 10:33 AM.
OK, just watched a video that had the engine running and they pulled the vacuum line off the regulator and took a few minutes for it to leak. I will try it to eliminate that.
I now wonder if the injectors are pushed completely into the intake and causing the fast leak down. They have two sets of o-rings on that end and the second set may not be where they need to be. There are no visible leaks near the injectors so I figured they were seated properly. I will call Jon Monday at FIC to see why they feel I need 22lb injectors and not the 24s.
The injectors I received are LT1 Bosch 3. The label on the bag reads 22LB@43.5PSI LT1 MATCHED.
If and when I replace(most likely will) I will make sure to get the filter, sock, hose and pulsater. I think I have fuel disconnect tools in my toolbox.
I replaced the O2s last year, drivers side was a pain til I figured if I compressed the converter shield it would allow for me to get the socket on much easier.
My 94 is all stock and will hold pressure all nite. I had a harder time with my pass side o2. You can not get the pulsater they use hose that can be submerged in fuel only need a small piece but it is something like $20 a foot.
The injectors I received are LT1 Bosch 3. The label on the bag reads 22LB@43.5PSI LT1 MATCHED.
If and when I replace(most likely will) I will make sure to get the filter, sock, hose and pulsater. I think I have fuel disconnect tools in my toolbox.
Are the injectors yellow? The regulator can go bad but just pull the vacuum hose and turn the key forward and pressure the system and watch and smell for leaks. Mine is original from 1985 and is just fine.
Let this be a lesson to those who rave about FIC. Those are either 0280-155-700 or 0280-155-710. The 700 flows 20 and the 710 flows 21. Call them and get the right injector. You need a 0280-155-715 or equal.
Let this be a lesson to those who rave about FIC. Those are either 0280-155-700 or 0280-155-710. The 700 flows 20 and the 710 flows 21. Call them and get the right injector. You need a 0280-155-715 or equal.
Just wondering, will I have to tune the car? I really would rather avoid any tuning at this point.
Thanks! I was hoping not since no one has ever mentioned tuning theirs after going to 24s. I just figured that is why FIC sent me the 22s, as to not need a tune. Will call tomorrow and hopefully get things squared away.
I went ahead and disconnected the vacuum line at the regulator then turned the key on. sat for a few minutes and no leaks. I then started and let idle for almost 10 minutes, no leaks. I will consider the regulator good.
Then started the engine with everything hooked up and started, at idle it had about 36psi. Then disconnected the regulator vacuum line and it jumped to about 45psi.
Here is a photo of the injectors top o-ring. Does it look properly seated? I know the point is moot since these are 22lb injectors but just wondering.
I went ahead and disconnected the vacuum line at the regulator then turned the key on. sat for a few minutes and no leaks. I then started and let idle for almost 10 minutes, no leaks. I will consider the regulator good.
Then started the engine with everything hooked up and started, at idle it had about 36psi. Then disconnected the regulator vacuum line and it jumped to about 45psi.
