Dave WM

For fun Tomorrow I will check the PSI on my setup with just the rail and no FPR to see if I get the same 5 psi.

5 psi does not sound restricted, I presume you had a very solid steam of fuel being pumped. Now one step at a time hook up the FPR ONLY to where you attached the line from the gauge to the fuel rail (taking the rail out of the equation completely) hook up the return line from the top of the FPR to the bucket, block off the other side of the FPR. Testing JUST the FPR now to see where is hold pressure with no vacuum.

I am posting up a video.

the test you did by blowing into the return line only pressurized the tank since nothing was coming out. you need to hook up as I described, with the return line to a bucket, and then check pressure with the pump on engine off. in operation the pump is taking out and putting back into the tank (slightly less going back) so a vacuum happens in the tank. the gas cap has a one way valve that allows outside air to replace the gas as its consumed.

I don't know if you hooked it up the way I described, it takes about 3" total hose to bypass the FPR and then block off one of the rail ends. That stream of fuel looked pretty weak if it was from the bypassed line.

as you can see the fuel will flow along one side of the rail and return to the tank with no restrictions, should have very low recorded fuel pressure. Two pieces of hose one for bypass one with a bolt in it to plug is all you need.

see pic

the FPR seems to be reacting to the vacuum (it drops) you may have a weak vacuum for a lot of reasons, #1 is a poor running engine (under ideal settings of the A/F ratio at idle you will get about 17-18"). I think the bigger issue is as ZH noted there has to be a explanation for the high no vac readings. its got to be: gauge not right FPR bad restriction somewhere higher that it should be assuming 1 and 2 are not the issue (and the only way to know for sure is more testing and checking of calibration), that leaves 3 If 3 checks out (no significant restriction with FPR out of loop), then you will have to reconsider 1 or 2. That's it bottom line. What ever you do its important to stick with one issue at a time, Fuel pressure now, the AFM adjustment later (if needed). So I would focus on item 3 connect one side of the T to the return line, plug the other side of the T and see if you can blow thru the fuel rail, if so hook up the fuel pump and get another reading, fuel pressure MUST be lower by a lot if there are no internal hard line restrictions. For some reason I thought we were at about 40psi with no vac at some point and chalked that up to a calibration issue, but 44 no vac is just way to high and needs to be addressed.

you can prob just connect one side of the T to the return line with a short lenght of hose, then plug the other side of the T with a hose with a bolt in it. as long as you can flow back thru the return line, you should be able to test.

what ever you can righ up should work, again the presssure should be low, but yes that diagram is correct. If CO is right it would be classic, too rich mess with the AFM... as if it just suddenly got way out of spec.

Test your setup by just seeing if you can blow thru the feed line and have flow out the return before engaging the pump to be safe. again with no restriction it should flow pretty easy.

well its a possiblity, its pluged since I can't think of any other reason for the high pressure. you need to feed fuel from the pump thru the rail with the FPR out of the equation. You will have to rig up some way to bypass the FPR, so the fuel goes from the injector rail then directly into the return line where the FPR sits. Remove the FPR and rig up some pluming. Just make sure you do have a return path, you dont want to dead head the pump, they can make a LOT of pressure if there is no means of return, enough to burst hoses and spray fuel everywhere. with no FPR restricting the return flow the pressure should be very low.

with the consistant 44psi with no vacuum you have to figure out why that is. I would seem the vacuum is doing something. so either the gauge is wrong or the return hard line is plugged up. Not sure what the the adj of afm to white line means, did you manually close it (lean out)? if so yes the mixture is way rich and manually clsoing will improve the A/F ratio for better running more eff better vacuum etc... but its not the fix or at least the thing to go to yet. Peeps aways want to monkey around with the AFM. That should be the last thing to mess with, there really is nothing to go out of spec, only issue could be worn traces. but that would not indicate any reason to adjust the tension.

he is talking about the rail itself, being steel it could rust internally. If you have vacuum and the FPR is still not responding and the return line was disconnected and directed into a bucket and you still have high pressure, then about the only thing left is rust in the rail. The only way to know about that would be to bypass the see if the return leg has any pressure build up. You will need to rig up a test line to see if fuel passes easily thru that metal hard line. Essentially replace the FPR with a T connector and run the pump, pressure should be quite low since there is no restriction

ditto

there are so many odd readings its hard to answer your question. Logically a large vacuum leak (un metered air) would result in a lean run. BUT 1st things 1st have to get the FPR working like it should. The reason so many odd ball things are being suggested is the illogical behavior seen so far in the test results. Like no change in FPR with vacuum seemingly present. When things like this go on, I find you have to deal with the immediate problem (fuel pressure too high). CO missed the blocked fuel tank line conversation, so at this point its one test at a time, that one item is checked off. Next up apply a vacuum to the FPR manually to make sure it works. If it does, check for vacuum at the intake nipple for the FPR, There has to be a reason. I try to not speculate (like the brake booster) but it hard with such a frustrating presentation of results. I hope it not something goofy like a gauge issue.

when you are ready.... test yours if its defective you can try this

I can assure you the water temp switch is bad, everyone I have tested (several) were bad. However other than a slightly rough idle when cold it would not account for this magnitude of problem. I made one out of some old parts and a new heat activated switch some time ago for my car. Beware of buying one, you need to make sure its correct, N.C. or N.O. I don't recall but the ones they sell are for fans which I think tend to be NO until operating temps are reached. IIRC you need a NC until operating temps are reached.

The problem is the leak has to be massive to account for the FPR not working. I mean HUGE, and you would hear it anywhere but the EGR. I use a rubber tube held to my hear and poke around suspected places for vacuum leaks. The smoke test is the best way to find difficult cases. This assume the NEW FPR is working correctly, that is if you apply a vacuum it should reduce pressure. a brake bleeder like in my video works well but in a pinch you can just get a length of hose attach it to the vacuum port on the FSR and suck on it. you should be able to get at least a decent enough vacuum to see the effect.

Clearly you need to test the vacuum the finger test is easy and quick, the gauge will be better.

that all looks correct. Disconnect the line from vacuum line from the EGR for now, but remember it could still be stuck open, or a piece of carbon jamming it open resulting in an air leak. The FSM test is to idle the engine and then stick your finger under the EGR diaphragm and lift it up, which should open the valve and cause the engine to stumble. But since yours is not running right its not a good test. The only way to know for sure is to unbolt the EGR (try not to break the bolts, lots of PB blaster and patience) and examine it. Its a pretty simple device you will know if its stuck open.

FYI I just ran another test on the same kind of rail that you have (the two piece rail) and same results as my video, 30 psi at 17" 38 with no vacuum. I was going to try to use the ZX rail in my test run but it was just such a pita getting it installed, I found the old rail a bit easier. Plus I used some really nice injector spacers off a maxima they work much better than the fiddly earlier stuff I have.

I don't think he has a vacuum leak in the conventional sense. It something wrong with the FPR failing to regulate. The most likely suspect is a problem with the vacuum source. I find it odd that there is NO change in pressure with the engine running. Compound that with what appears to be a over RICH condition point away from normal un metered air issues.

Maybe you should take a pic of some of the vacuum hookups, specifically the FPR and the EGR.