Thread: Fuel injector install went wrong, what’s next?

Hey all,

I posted the quick version of my injector issue in the new member thread, but I’ll be more descriptive and give some clearer information here. I have a fair idea that I’ve got some major work (for my skill set) and/or money spending ahead of me if I’m going to get it running again, so feel free to school me on what might have gone wrong.

So, car’s a stock 91 SE-R, super well cared for and is a commuter. There’s never been a major problem with it besides fifth gear pop out (fixed by previous owner in the mid-90s) and two fuel pump replacements, stock one was faulty and replaced in the 90s, I did the other last year at 150,000 miles. It’s been great and reliable. Driving to work a couple months ago I felt a huge loss of power and throttle response which took me a few days to figure out was the fuel injector for cyl #1, which was a relief because I thought it was something worse initially. I towed it to my father in law’s house, who helps me with nearly all of my maintenance because he has a backyard shop and has done most of this before, we took an injector out of my parts car NX2000 and installed it. Worked great. The car ran like it should again with absolutely zero issues.

Later that month I ordered four brand new injectors from Courtesy Parts Nissan after matching the the part number and figuring I’d just do all of them since I had the money and wanted the peace of mind that my stock ones might crap out at any moment. Didn’t want to break down on the way to work again or anything like that.

So, we installed them just like we did the other one. They fit like they should, we double checked all of the o-rings, made sure multiple times things were how they should be and went to start the car. This is where it gets bad.

All we heard when I started it was a “clunk” from the engine bay, nothing else. So I tried again (which I regret) and heard the same thing again. I realized then that It sounded like it was internal in the actual engine now, so after contemplating it, I stopped trying to start it and we checked the cylinders and saw that the first one was FULL of fuel. It had locked with fuel for the first time and something was definitely wrong internally. I’m pretty sure I made it worse by trying to start it again after the first time, which really sucks.

Haven’t driven the car since due to funds being less available because of work crap and some vet bills, so I’m kind of saving a little at a time to go toward some work, parts or whatever I’ll need to do to hopefully get it running again. After doing a little bit of reading, it sounds like my timing chain could be a big part of the issue, but this is where my knowledge of what to do starts to fade. I didn’t do anything different during the install than I did the first time, which is why I’m confused, but obviously something didn’t work.

I’m pretty bummed out about it but would really love the car to be back on the road again, but I don’t really know how that can happen yet. Please feel free to ask any questions or tell me if I did something wrong, or what kind of work or $$$ I’m looking at. This car was too great to be toast! Thanks everyone, sorry for the long thread!

It seems two me that one of two things happened.

1) You have an o-ring seal issue. Maybe you re-used old o-rings? Don't do this, they age quickly and will fail if removed or re-installed.
Fuel has leaked past an o-ring into the cylinder.

or

2) You somehow got faulty new injectors, but that seems much less likely than the o-ring issue mentioned above.



Either way, you're not likely to damage the engine with the starter, even if a cylinder is filled with fuel. You should be fine there.

Get the fuel out of the cylinders, and check the engine operation, by removing the spark plugs and cranking the engine until you've cleared the cylinders of fuel. Make sure the fuel pump is disabled for this. Pull the fuse, or whatever. I think disconnecting the CAS works too.

An oil change is likely in your future as well to get rid of that oil which likely has a lot of raw fuel in it now.

I don't think things are as bad as you think they are.


This next time when you do the fuel injectors, make sure to use brand new o-rings, Vaseline or other decent petroleum-based lubricant for the o-rings, and assemble the injectors into the rail with the rail off of the intake, with the injectors in open air. This way you can test the injectors by cranking the car, and check for any leaks afterward. Just have rags ready to catch the fuel spray.

Hey Ben, thanks for taking the time to answer. I really appreciate it.

We can definitely eliminate the second option because that’s what I thought it was at first. I brought them in to the injector shop near me and told the guy what happened and showed him the injectors. Then he tested one and told me “they’re great”. He specifically said he’d be more concerned if they were used or from a junkyard etc., but their condition and testing proves it just wasn’t the case. Which was relieving because I spent the extra money on new ones for peace of mind, hilarious as that sounds now.

A bad o-ring sounds way more likely of the scenarios. That bites that it was likely such a simple overlook, but I’m pretty sure I can do all of the things you mentioned in the next steps. My biggest worries after it happened was either making something worse by further testing and problem solving or that it wouldn’t be worth trying at all. So it’s welcome, positive-seeming news at the very least.

Thanks again, Ben. Feel free to ask any more questions or whatever you can think of.

Just clear the cylinders, reseal the injectors properly, do an oil change after the car runs properly, and report back.

I wish to write a side note, here goes

I installed an aftermarket fuel pump and went back to stock Nissan 150k+ miles fuel pump. Aftermarket fuel pump didn't deliver steady pressure. Car went to open loop. Now I don't want to advise against your fuel pump replacement since mine might be a one time bad luck thing or it isn't, not sure here, but stock Nissan fuel pump are like the best moving part on the b13. Just keep it in your mind and if possible change back to old pump to see if problem changes. I don't expect it to go away because my after market fuel pump gave normal driving 100% (besides the open loop) but redline, not so. Fpr and related like Fpr vacuum hose, injectors, wiring etc. unchanged.

But to be more answering your question, a chain has to be really really bad to give issue but yes intake and exhaust cam aren't timed perfectly on to each other. I just can't tell how bad that can get nor never saw noticable issues. Should redline well with stretched chain. Chain might hit valve cover, nothing to worry but in a perfect setup you don't want to hear that. Won't hurt either.

I recommend checking mass connections and state of idle (AICV, can clog) if EGR, make sure it works and replace vacuum hose on fpr if old. Just a new one there. This just for making your issue you have there smaller and better readable, don't expect miracles. But if what I mentioned is in a bad shape, you will profit from it when you solved your issue. Just listen to Ben, he knows his stuff really and really well, is a pro in explaining things without loopholing what he wrote just there. If you go on the internet, be aware of loopholes. I suspect stretched chain story is a loophole that might be true on a different engine but for a Sr20 I only am willing to believe so if Ben confirms this. One last thing, just good advice, replace all vacuum. Use stock hose (no bents), Won't go everywhere but you can trick this (can photograph if you wish so).

Make sure ignition is like this. On the ignition, this is good but it isn't very good. But it is stock.


And b13 is no rocket science it can and will be solved in a reasonable way without throwing a lot of coins at it. Hope to read your progress.

Hey, thanks for adding some thoughts Richard. Like my injectors, I spent the extra money getting the OEM or closest to OEM fuel pump I could find just so I wouldn’t have to think too much about it in the near future. It was a Bosch (the one I pulled was too, which was put in due to an old TSB in the 90s I’m pretty sure?) and I did the o-ring at the same time. I’d be really surprised if that was adding to the trouble, but given my faults I can’t rule it out completely.

As for my chain: I could be very wrong on this, but I was wondering if I could have messed up my chain due to the multiple cranks I did without realizing what was going on. The “clunk” I heard was internal in the engine, but I had mistaken it for the starter — hence my attempt at multiple starts. I think o-ring issue would explain why only the first cylinder locked with fuel (correct me if I’m wrong) because I definitely overlooked that when we initially took a look at them. That’s definitely on me. I’d love to rule that out though, because one of the reasons I loved these models of Sentras was that it had a chain that I wouldn’t have to worry about too often since I was keeping my car stock. I never had chain/tensioner issues, for the record. So I’d imagine it was pretty well taken care of.

Thanks for all the other info, too. Vacuum hoses were on the to-do list before this all happened. So if this gets figured out hopefully it’ll be done before too long!

I've experienced this same thing, but I went further than you before I realized what was going on.

I actually tried to push start it, which bent a rod.

Your situation doesn't sound dire to me at all, and I think you'll be back up and running before long.

The two things that will prevent your engine from turning over right now are:

1) Hydrolock - so much fuel in the cylinder that as the piston tries to compress the air/fuel mixture, it hits the incompressible liquid fuel and just stops.
-Address this by removing a spark plug and getting the liquid fuel out (I'd suggestion suctioning as much as you can.)

2) Excess friction between piston and cyl walls - fuel will "wash" oil off of the cyl walls. If you are able to get a tiny bit of oil on top of the piston and slowly turn the crank by hand, you can help this along before you try cranking it with the starter to get oil pressure. (This might be wholly unnecessary, but I would still do it.)


In my case, the ebay injectors I got had the wrong size pintle cap, so the cap popped off under pressure, allowing pressurized fuel past the o-ring and into the cylinder unchecked.



I resolved this by purchasing some new pintle caps and o-rings to get the right fit. Specifically, I bought these and these I got plenty extra so I wouldn't run out if installation went poorly, and I'm glad I did.

white = correct, red = incorrect ebay pintle cap as they arrived from my ebay purchase

Anyway, If your issue isn't that, it may just be a pinched o-ring that is allowing fuel in. This is very common and is why vasoline is often recommended.

Thanks for chiming in, vorin. I’m trying to keep positive but also harbor some wariness that I might have really screwed something up, but all the the reinforcement I’ve received in this thread is nice — so thanks for that. However, I guess something along the lines of a bent rod was also kind of weighing on me. I didn’t attempt to push start it, but I definitely turned the key enough to worry me. If it is damaged in that way I’m sure I’ll have to seek other fixes, but I’ll focus on what I can do for now.

Since you shared the pics, here’s the comparison of new vs. stock/old injector (from L to R), just in case I screwed that part up too. I cross referenced part numbers quite a bit so I was pretty confident I made the right buy. You can see the difference in the cap (which gave me pause at first) and no o-ring. Like I said earlier though, I know they at least function as they should. So assuming they’re the right ones I’m definitely leaning heavily into the o-ring mishap.

Interesting to see the fuel inlet on the new injector is in a lower position. That will have nothing to do with your issue, but it makes me wonder if Nissan has redesigned the part.

Anyway, I still don't think you've bent any valves or rods with just the starter motor. You should be fine once you sort out the leaky injectors and clear the cylinder(s).

Ben has it right.

Also don't sweat that old style pintle cap, the ones I pulled out had that kind too(likely since it rolled off the assembly line.)

The main thing is to pressure test the rail with injectors before putting it in the intake manifold and make sure that you aren't trying to compress liquid.

Secondary is lubrication.