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Discussion Starter #1
2000 I30t ~120k miles
Car was occasionally (starting to happen more frequently) stumbling a bit when at idle, never while driving, so concerned it was getting worse I brought it to my mechanic and told him I was thinking it was becoming a bit gas starved and perhaps the fuel pump was failing.

So, he replaced the fuel pump and I brought it home and the next morning I started having ‘hard crank’ starting problems. I told him I wouldn’t know if the original problem was resolved (as it was intermittent) however the new problem was completely separate. He then tried putting in a crank sensor and a temperature sensor and neither changed the behavior. He recommended I take it to a dealer as he was clueless (btw, it was not throwing any ECU codes).

The mechanic also told me he checked the pressure at the pump (which seems weird) and told me the pressure was in the 24 range when he had key-on-engine-off (KOEO). This is way to low and may explain the problem. He even said he tried another aftermarket pump.

I took it home and decided to check the plugs, which I SOO wish I did before bringing it to him as one of the plugs electrode was severely worn out compared to the others. I think this was causing the rough idle problem. Since I have replace all the plugs I don’t see the stumbling idling problems at all now. I do question what caused that one plug to wear so unevenly, perhaps a slowly failing coil-pack. I will keep an eye on the plug wear.

I put back in the OEM fuel pump myself (he put in an after market) and still the same problem (hard starting). It’s worse when it’s cold, when it’s warm it still struggles but fires up quicker. Once it’s running it runs like a champ!

So, took the car to the dealer, they told me it was the fuel pressure regulator (FPR). They replaced it and guess what, that didn’t solve the problem! They told me they were seeing the pressure bleed back so they believed it was the FPR . I moaned and groaned about replacing a part and they agreed to only charge me the parts costs, which I view as something I probably would have replace to rule out the starting issues. They next wanted to start replacing the fuel pump and the fuel pump housing. Worse case scenario would have been $650 in parts. I decided to take it home and have another go at it.

Sorry to be long-winded but I wanted to make sure you had all the details. So a few questions:

1) The pump sits inside an assembly and it looks like that assembly itself if some type of filter. Perhaps this got clogged and that explains the bad fuel pressure. My next step is to replace this assembly.

2) I noticed one of the 6 bolts that hold the pump lid down (compresses the lid on the O-ring) was stripped. Could this be a gas tank ‘pressure issue’? If pressure was leaking out of the tank would that effect cold starting? Note, when I open my gas cap I don’t hear a pressure release, however my brother has a 2000 maxima and he doesn’t either. OH, I did replace the gas cap just in case.
3) I tried the approach of repeatedly ‘priming’ the engine by turning the key /wo starting the engine. Wait a few seconds, do it again, etc. This seemed to help however today it didn’t seem to make a difference, go figure.


I am losing my mind, any thoughts, and ideas of what I should try next? Should I start replacing the assembly?

Thank you !!!
 

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NF Mod/Nissan Master Tech
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If there was a leak at the fuel sender "O" seal, it would not affect the fuel pump. It could cause a fuel odor issue and will cause a check engine light to set for the evaporative emmissions system (small or large leak code). A rethreader might be able to restore the threads and I woudl recommend a new bolt. Personally, I would do a proper fuel pressure test and fuel pressure leakdown test. Fuel pressure is measured at the rail, using a fuel pressure test adapter between the fuel rail and damper (part of fuel pressure test kit, Kent-Moore #J-44321, or equivalent). If the fuel pressure and leakdown test pass, then I wouldn't do anything with the fuel pump.
 

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Discussion Starter #3
smj999smj,, thanks for the reply.

The dealer told me they did a pressure test and they were seeing leak-back to the tank, therefore the replaced the FPS, however, when i picked it up and asked them where they tested the pressure he showed me the hose and it was after the FPS going back to the tank. So they may have seen leak back and assumed it was the FPS which has been replaced. So I can rule that out

They never checked the supply to the injectors.

I still am struggling as to how this can't be fuel pump related seeing it all started when the pump was replaced.

Could a clogged 'fuel filter' (not the strainer but the fuel filter assembly the pump sits inside of become clogged and prohibit proper flow of gas upon startup? I was thinking of replacing this as its only $40 after-market part and with 120k miles it wouldn't hurt to replace it. It looked very 'charcoal' in held up to a light.

With Ignition ON, engine OFF PSI should be at 43 and 34 PSI when running. Sounds like it needs more PSI when running then when it gets primed (ignition on engine off). When it's running it's fine, runs like a champ.

I'd have to do some modifications to add a T for a fuel pump pressure before the injectors. BTW, the original mechanic that replaced the fuel pump said he checked the pressure at the pump and he was only getting 204 or so PSI, ignition on engine off. What do you make of that?

Thanks again...
 

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NF Mod/Nissan Master Tech
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I can't really make anything of it because I wasn't there when he tested it. Fuel pressure is actually tested at the end of the fuel rail, before the regulator. Fuel pressure is lower when the engine is running because vacuum is being applied to the fuel presure regulator, which drops the pressure by venting some of it to the fuel return line, which goes back to the tank. A clogged or restrictive fuel filter would result in low fuel pressure readings when the vehicle is running.
 

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Discussion Starter #5
smj...circling back on this issue, thanks for your feedback:

I got a fuel filter thinking that perhaps it was clogged and causing some of the initial starting issue. Replaced the fuel filter and put back the OEM pump (the one that was probably never bad). During the process I broke the wire off the diod that is stationary (not the float, that moves up and down). So I wasn't sure what wire went to what side so I guessed and sodared (sp) it back on. Put the unit back in the tank and bingo car started up right away. Next morning same thing fired up right away, so I was excited. I am guess it may have been a clogged fuel filter (not the strainer) or perhaps the rubber grummet that connect the fuel pump the assembly wasn't seated right.

One catch was it would start no problem but was running very very rough. So I was like, WTF, and called it a night. The next day it fired up and was running fine (not rough) however there was an engine light on. So, that night I figured I'd take it for a drive hoping it would cycle off the engine light so I could get my inspection sticker.

So, was driving it on the highway, all good, got off, drove around then stopped and the car was idling for 5 mins, started then driving away and the car starts stumbling badly....giving it gas but wasn't going any faster. I pulled over and it wouldn't' start, had it towed home. So, I believe this is a new issue so I will post a seperate thread on that issue. Uggggg why did I ever buy this car, I had a 97 maximum with 280k on it and never had much of an issue at all!
 

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I am having the same hard starting problem with my 00 i30. Dealer replaced the ecm and plugs. Helped for a day, then right back to the same problem. All this with no codes. Have since replaced fuel pump, both crank sensors, cam sensor, mas, 02 sensor and ignition switch. Runs great once started. Oh, also replaced starter after so many cranks it gave up. Any ideas where I should go next?
 
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