E30 Build Thread

Originally Posted by FenderBender

Hrm, so my stock M50 injectors might work enough to know if that's the issue?


Also, how and can I clean these?

you can clean them in part by soaking them in a bowl of Injector cleaner, to clean them internally... the easy method is to get them running and just run cleaner in the fuel... I've yet to meet a person who's been brave/dumb enough to crack an injector open and attempt to clean it internally.

I think I'll try the injector cleaning tomorrow, would be sweet if that's the problem!

Originally Posted by Kdoherty

you can clean them in part by soaking them in a bowl of Injector cleaner, to clean them internally... the easy method is to get them running and just run cleaner in the fuel... I've yet to meet a person who's been brave/dumb enough to crack an injector open and attempt to clean it internally.

Yes you have


That was an injector out of a diesel Merc though

Originally Posted by cj.surr

Yes you have


That was an injector out of a diesel Merc though

thats a little different but still... too many little things inside to lose or break or fubaru but we already knew your were kind of nuts CJ

You could do this....

I soaked them in cleaner overnight. While I was waiting I tried my M50 injectors, didn't run.

Put these back in, does the same thing as before pretty much. I am getting it to backfire every once and a while. I think I read to check out the fuel pump relay?

Also, when it was running I had it revved up, then pinched the cold start injector line, still died. Then as usual it went back to not starting.

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really?? wow...woulda thought that it would have at least tried to run better with the m50 units rather than with clogged up injectors.

the m50 cylinders are 0.416 liters each, while the m10 is 0.45 l each. not really that much of a difference...which is why i figured they'd work.


of course the m50's are about 17lb hr rating, while the m10 are probably about 13-ish. still not enough to flood it out, i would think. the pressure rating is lower on the m10, as well, which would decrease the 17lb hr rating a little as well.

hmmmph. i guess see what happens when you throw the old injectors back.



df

I did, on my phone hard to explain. When I wrote "put these back in" I meant the cleaned M10 injectors.

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ah, gotcha. misread that...


was there a lot of crud in the injectors?? how about the rail??




df

Nah not really. Rail seems clean as well.

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I'm thinking one of my first guesses was correct, FPR.


I was fiddling around with it tonight, put a new fuel pump relay in, no change and I can hear the in line pump running all the time with the key on.



Then my buddy comes over and pinches my return line while I start it, boom, stays running as long as I want it. As soon as I remove the vice gripes, it slowly dies.

i thought that you took a fuel pressure reading, though...




df

I did, not while the car was running though and didn't pinch the line.

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Originally Posted by FenderBender

I'm thinking one of my first guesses was correct, FPR.


I was fiddling around with it tonight, put a new fuel pump relay in, no change and I can hear the in line pump running all the time with the key on.



Then my buddy comes over and pinches my return line while I start it, boom, stays running as long as I want it. As soon as I remove the vice gripes, it slowly dies.

Bingo! Nice dude.

Hopefully will have a new one tomorrow then first test drive!

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Persistence pays off! Nice work.

Hrm, not the problem. Must be fuel pressure, I'm going to get a T connection tomorrow and test pressure with it running if I can.



You can see in the video below, it seems to run pretty well with the vice grips on. However, I had to jump the relay to get the fuel pump under the car to run, is it only supposed to run while the car is running? Confused here because I'm pretty sure it was running all the time with the key on last night. And you can see that when I remove the vice grips, the car dies. This is with the new FPR.


Another tidbit, with the fuel pump jumped, I can hear fuel going right back the return line, normal?

Originally Posted by FenderBender

Hrm, not the problem. Must be fuel pressure, I'm going to get a T connection tomorrow and test pressure with it running if I can.



You can see in the video below, it seems to run pretty well with the vice grips on. However, I had to jump the relay to get the fuel pump under the car to run, is it only supposed to run while the car is running? Confused here because I'm pretty sure it was running all the time with the key on last night. And you can see that when I remove the vice grips, the car dies. This is with the new FPR.


Another tidbit, with the fuel pump jumped, I can hear fuel going right back the return line, normal?

video isn't there? if pinching the return made it run... and unpinching it makes it stall... and you can tell there's fuel pissing back down the return. i think there's something amiss with the FPR and or the fuel rail. The fuel should only bypass the rail and back down the return when there's an overrun like high rpms then going to no load IE stopping from a high speed. what it sounds like here is there is nothing checking the fuel from being pumped out of the rail and back down the return line. pinching the line seems to cause the fuel to "back up" and feed the engine efficiently, when you open the line there's not enough fuel to meet the demands of the engine remaining in the rail. so in some weird way it seems like a pressure regulator and whatever system controls the fuel rail bypass.

Brand new FPR though, any way to check it?

Here is the other video.

is there an off chance that there's a vacuum line hooked backwards? the fuel shouldn't immediately return. you should pressure test the fuel rail if at all possible. I doubt a new FPR is at fault. but whatever's metering fuel leaving the rail is surely causing some shenanigans. I wish I knew more about the M10 or whichever 4 banger they came with so I could be more useful.
Standard practice on modern fuel injection though, relay fires the pump, pump pushes x amount of fuel per hour FPR regulates how much fuel makes it to the fuel rail. fuel rail should pressurize to between 40-50psi, a fuel return valve will open when that pressure is exceeded usually when the engine was in a high load situation and no longer has the need for a high volume of fuel... enabled by the increased vacuum at high engine speed to the FPR. So, if anything's wrong here it's the check valve going to the return side of the fuel system.

Vacuum doesn't matter because when I jumped the relay, and unhooked the fuel line from the FPR, the fuel just FLOWED right out without the car running.


Normal?


And if it matters, the vacuum line is run from the FPR to the intake manifold on this thing.

Originally Posted by FenderBender

Vacuum doesn't matter because when I jumped the relay, and unhooked the fuel line from the FPR, the fuel just FLOWED right out without the car running.


Normal?


And if it matters, the vacuum line is run from the FPR to the intake manifold on this thing.

well the vac to the FPR just controls the internal diaphragm which in turn controls the flow of fuel, so unhooking it will just let the fuel pump, pump at it's will. im not sure that fuel getting there is the problem, i think it's keeping the fuel there. something is letting the fuel pressure inside of the rail go away. think of blowing up a balloon. if there's a hole in the other end you can blow for hours and it's never going to pressurize. you need two ends that seal to create pressure. So you're getting plenty of fuel going to it, but you're having too much fuel leave it too quickly.

The only thing letting the fuel out is the regulator, with the pump running, it pushes fuel of of the regulator just like it's coming right from the pump.