Nissan Sentra Cold Start problem.

Hi, I could use some assistance, I have a 95 Nissan Sentra GLE giving me a headache here lately. It has not been wanting to crank in the mornings, but afterwards she is fine. To get to the beginning the car sat for 2 years then I put a used motor in it. And had to change the fuel pump then, I did not clean out the tank then. Well been driving it a cpl years now and after the problem I noticed when changing the fuel filter that rust poured out the back, changed the filter. Then I took off the fuel rail to check for leaky injectors, they weren't leaking, however there was the same rusty grime(muddy looking) inside the screens on the injectors, then checked fuel tank, it was full of rust, and in the plastic holder for the fuel pump and covering the strainer, I went ahead and replaced all 4 injectors even though they weren't leaking, incase there was build up in them, and took the tank off cleaned it out with iron out, got it cleaned and completely dried, blew out all the lines, and put everything back together. There are no trouble codes, I checked the coolant temp sensor and the intake air temp sensor both are within the specs from the haynes manual. I hooked up a pressure gauge, sometimes it would as soon as I turn off the key with the car running it would drop to zero. Well, I tried and clamped the return line, it held pressure, so I bought a regulator. Same problem again, so just went ahead and replaced the fuel pump. But it still has the same problem, and it will crank fine if I use starter fluid, or if I keep trying over and over again without starter fluid. Everything is new, fuel pump, regulator, injectors, filter, strainer, and the only code I get is the MAF but that is b/c when I take it off to crank it with starter fluid, and after clearing the code only comes back when I take it off to use starter fluid. Looking for any ideas that maybe I should take a look at that I might be overlooking. Any help would be appreciated. Sorry this is a long post. P.S. New spark plugs, rotor button and distributor cap, checked spark it is good when trying to crank it in the morning, distributor isn't loose. Checked compression it is good.

How much pressure are you getting on the gauge?
Have you checked the voltage at the fuel pump while cranking?
Have you checked the fuel pump relay?

Hey, thanks for the reply, after I replaced the regulator and pump I couldn't recreate the prob with pressure dropping checking it with the gauge, I didn't want to write a novel so I left some things out, voltage is good at the pump, and the pressure is good now. I went over everything in the Haynes Manual for cold start problems. Saw after looking through either the forums here or some other forum that the IAC valve can also create this problem(if they would have only listed this in the darn manual) , and someone wrote to try tapping it with a ratchet extension while trying to crank it when it has the problem, I did that and it fired right up after tapping on the IAC valve. I was headed to work so haven't had time to take it off yet and clean it yet. Thanks for your reply.

I'm back, that wasn't it, it was just a coincidence that it wanted to crank that morning along with tapping on the IAC valve, been having the same problem ever since then again, it is the same problem from the start, after hooking up the pressure gauge, letting the car run, and immediately turning the car off it (sometimes) drops down to zero. Which is why it is so hard for me to know exactly what it is b/c it isn't doing it all of the time. The first time I noticed it held pressure after clamping the return line, which is why I got the regulator, and that didn't fix the prob is why I got a new fuel pump. Well, I still have the problem, I have about 38 PSI with the car running, which is within the specs, I also did check just fuel pump it is within specs too. They are both new. I was checking again today with gauge, it is doing the same thing, every so often the pressure drops immediately to nothing after turning the car off, and I have no way of knowing if I try to clamp off a line and try again if it holds if it is b/c I clamped off a line or this is one of the times it actually wants to hold pressure.

I'm wanting to think I bought a bad regulator b/c that is what I got first and still have the problem after getting a new fuel pump too. I just don't want to take another guess like I've been doing.

I checked over and under the whole car for leaks in fuel lines and didn't find any.

I'm back, I tested the car again this morning, will be testing again here in a few. Once again hard to crank, left gauge on the car over night this time. Started out zero before doing anything. The pressure didn't drop to zero however any during this test. This time I did notice something different though. After getting the car running, the needle jumped back & forth between 33 & 35 PSI very rapid with the car running. And with the vacuum hose detached it was jumping between 40 & 44 PSI. Were with in specs however. The oddest thing is that when I turned the car off and checked it for about 10 seconds, it held at 30 PSI. I was thinking this is definitely going to fail the hold pressure test since 30 is the lowest it can be, however going back to check 5 minutes later it was at 35 PSI. I think the test went like this now b/c I have so much air in the lines, which is expanding but I'm not sure. I will check it again and come back with the results. I need it to do like it has been and drop pressure below the spec values so I can check and see where it is bleeding.

I checked again, same thing, only difference this time the needle didn't move back & forth as rapid, and it stayed around 34 PSI for running test, 43 for running with the vacuum hose not attached. After shutoff once again dropped to 30, after 5 minutes it was up to 35. I'm going to check again but I will wait until it as at normal operating temperature before turning the key off.

I tested again, it started leaking down again, I clamped off the feed line after the gauge, and it held pressure good, then clamped off the feed line before the gauge, it started leaking down, then I pulled the fuel rail up and was checking for leaking injectors, was none, so apparently I got a bad fuel pressure regulator, unfortunately no parts store feels it is necessary to carry this item in stock, just like the last one I just got I had to order, just waiting on tomorrow to get here now. Advance(the only store that can have it tomorrow and not middle of next week) will have one in the morning so I'll have to go back to autozone get money back for the last one I got which I paid $75.99 for. Advance had it for $118.99 and said couldn't price match b/c there brand is BWD and the one I got from autozone is GP sorenson and cheaper brand they say. Called orielly auto parts and they had the BWD brand for $71.99, so now Advance had to match that price.

Just wanted to come back and let everyone know it was the regulator, the mistake was in my first post, after getting the new one the first time and it didn't fix the problem I automatically assumed that I was wrong the first time and bought a fuel pump instead of doing all the proper tests again. Anyways she starts fine now just wanted to share that info, just b/c it's new doesn't mean it's good.

you should also check the battery. the battery could be getting old and not have as many cca's (cold-cranking amps) you could try that too.