X64v

Yeah, I checked to make sure they were clear. Both separate feed systems were fine. I don't know if this is taking its toll on the new pump or what, but now it's not passing the flow test even after it's had time to sit. I checked it after running some new pressure lines, only 30gal/hr (should flow 60). I let it all sit for a few minutes and checked again, only 45gal/hr. Edit: I just remembered I have a known-good stock 280zx pump that should still flow enough for my motor (I know Prox was running a stock 280z pump at something like 17psi with his 440cc injectors). I'm going to swap that in and see if it makes a difference.

I'm running 15x8s all around, stock suspension style, no fender mods (except beating the lip in on the rear fenders. Running 225/50/15s

Tried running errands with the gas cap off, it didn't help. Also, I parked the car (still running, pump still loud), unbolted the pump, and lowered it to the same level as the bottom of the tank. No help either. I shook the pump as hard as I could and tapped the feed line, but the sound remained constant.

Nothing in the engine bay has moved, and the lines out back actually got moved farther away from the exhaust than they were. I ran yet another test. I put a pressure gauge right at the outlet of the pump to compare with the pressure gauge on the fuel rail. They both read the same under all conditions, when the pump is dead quiet and when the pump is howling. This means there's no blockage in the fuel system or anything like that that's causing the pump to have to work hard to push fuel. I retested voltage when it was loud - 13v. I filled the tank up again to be sure it wasn't having to suck too hard up-hill - no help. I felt the pump again while it was loud - not hot. The only thing that changed from when I dropped the car off at the body shop to when I picked it up was that I had taken the tank home and welded in a sump, that's all (the process can be seen in my build thread). When I drove it home from the body shop it was doing this, and it was still hooked up the exact same way it had been before, with the stock 240z pick-up and the lowest vent line for a return. Absolutely any more suggestions are welcome, I'm totally stumped.

I've run some more tests, still haven't figured it out. I can bring the car in when the pump is screaming, disconnect the return line from the regulator and route it into a 5 gallon race jug, run the car, and the pump is super quiet, and flows 60gal/hr (timed with marks on jug and stop watch). This lead me to believe there was a blockage farther back in the return line, but I couldn't find anything, and if I disconnect the AN return line from the tank and run it into the jug, I get the same thing, quiet pump and 60gal/hr fuel flow. I tried a spare stock FPR that I had and it made no difference at all. I can run the pump manually without the engine on, and it will pump well and stay quiet for a half hour (longest I've tried it), but it gets loud after 3 minutes of driving. If I just start it up and let it idle, it will idle all day without the pump getting loud. But if it gets loud while I'm driving, it stays loud at idle, or even when the engine is off (if I manually turn on the pump). I've used two totally separate feed routs from the the tank to the pump, as well as two totally separate return routes from the hard line to the tank. Absolutely any suggestions are appreciated, I'm supposed to drive this car to San Diego tomorrow morning, but won't be able to without solving this. Edit: I just ran another test. Let the car idle for about 15 minutes, pump was quiet, all was fine. Jumped in and drove around the block (no more than 1/4 mile) and by the time I got back the pump was screaming again. The only thing that changed was that I drove around the block. Edit #2: I ran this same test again, same results. When I parked it and the pump was screaming at idle, I felt it to see if it was hot. It wasn't even warm to the touch, it was ambient temperature all over.

Yes. Use one of the vent lines as your return, not the stock return port. The stock feed is fine as far as flow capacity goes.

Use the 1/4" emissions vapor line on the left side of the engine bay. It's plenty big enough. I've been running the stock 5/16" feed and the emissions line for a return for years now, mostly with my walbro 255lph pump, and never had any issues. It's been discussed at length in a thread in the L6 forum I believe. Edit: I just searched and found the thread, you were the one that started that thread.

Seasons of the Z [in the southwest]: - (Spring) Enjoy - (Summer) Enjoy/Sweat - (Fall) Enjoy - (Winter) Enjoy

Well between having to write essays (on spring break no less ) and chasing down a nasty fuel system problem, I haven't gotten much done at all. New master cylinder installed: At the same time, I switched to Earl's speed bleeders all around. Now, my brakes are super mushy, worse than before. I bled the master and got lots of air out, but it's still bad. I suspect the rear bleeders aren't sealing properly, letting air in. The fuel plumbing at the other end of those pretty braided lines: I ran the return line over the top of the tank instead of around the side, and flared the emissions vapor line for a -4 AN tube nut. I had to cut the last section of the hard line out of the car to do this, so it's connected via that blue Earl's -4 push lock hose. Fuel pump pigtail: Now I'm pressed for time to fix my fueling issue, install my new stereo and harness, plumb my boost gauge, and get the car cleaned up, all tomorrow because I'm leaving for San Diego in this car Tuesday morning.

Alright, it's not the pump. I put in a brand new one today, everything was fine for about 15 minutes, then it started getting louder and louder and then I ran into the same problems as with the other pump (super loud, not enough fuel flow to barely go 45mph). It's definitely not a blockage before the pump, it's done this with two totally separate pick-up systems, and the fuel flowing from the tank is perfectly clear. It's not a wiring issue, I've got 13v there at all times. It can sometimes get so bad that I can't even accelerate past idle in 1st gear; when that happens, if I shut it down for 2-3 minutes, I can resume driving and have enough fuel flow for 45-50mph. When it does almost die at idle or near idle, the pump sounds like its working super-hard, but the pressure at the fuel rail drops to near nothing. The only thing I can think of is a blockage between the pump and the rail, but what? And why would it reset after a 3 minute shut down? EDIT: I removed the rail feed line and pointed it into an open bucket. When I turn the pump on, a huge steady stream of fuel comes flowing out like a garden hose, and the pump is super quiet. This means there is a clear, normal path for the fuel to travel from the tank, to the pump, to the rail, no obstructions. Also, I checked the rail by disconnecting the regulator and blowing through it, it was perfectly clear. I'm 100% completely out of ideas.

I really enjoy my 3" open system. Very aggressive without being so loud as to bother the neighbors or drown out in-car music/conversation.

I finally got it back from the shop Wednesday. I'll post up more detailed pics later, but here's a quick shot of the finished work. It's not perfect, but considering how bad it was, I'm definitely happy with it. I'll have quite a few updates over the next few days as I make a ton of changes and get all the parts I've got installed.

It's supposed to be like that. The page darkens and the picture pops up, with control buttons below it. Nice feature IMO.

Good call on the pump screen, I'd forgotten about that. I checked today, it seemed clear, though it was hard to see much through the inlet threads. I sprayed it out with carb cleaner, then with a bit of WD-40. Same thing happened when I hooked everything back up, it primed, ran fine for 30-40 seconds, then got loud again. I filled up the tank (it was at about 5 gallons) to see if not having to suck uphill would help, but it made absolutely no difference. I checked the voltage at the pump with a DMM, it's got a solid 12.9v at idle. Cygnus - FWIW, I've never run a fuel damper.

I've had my Walbro fuel pump (same one as everyone else uses) for a good 20k miles with no problems whatsoever, nice quiet operation. My car has been in the body shop for the past month with the gas tank out, and when I picked it back up today, the pump is much, much louder, and I'm getting some pretty bad fuel starvation (will sometimes rev okay to 4000rpm, sometimes it practically dies in the intersection). Replaced my fuel filter, redid my fuel lines (I had SS braided lines to put in anyways), no change. Fuel coming from the tank is perfectly clear, tank itself is clean. It's wired on its own relay with good connections (the pump wasn't touched at the body shop AFAIK). When I redid the feed lines it definitely primed well, and sounded completely normal, but after about 45 seconds it went right back to screaming. I'm guessing it's about to die completely, but does anyone know of something I can check/do before I just buy a new one?

Border Patrol. My cousin is doing that since he's back from Iraq and out of the Army. He really enjoys it.

Thanks, excellent write up. Bookmarked for when I do mine.

I ended up grabbing a set of 3000gt coil packs off eBay for super cheap, and buying 3x BIP373s from DIY to run them. What dwell times did you find for these? I've seen 4ms thrown around but haven't seen any proof of that number.

Q: What did the mathematician find when (s)he went camping? A: Natural Logs.

Sounds great in the video Jeff! Judging by how quickly it revs, he's probably using a paper plate. Maybe a Frisbee.

AHAHAHA once I realized what song those lyrics are written to I just about died.

MS will run pretty much anything. Even if in the most extreme case you can't get a steady vacuum signal, MS will do Alpha-N.

Didn't have to change it, mine's still in good shape.

I used Earls Super Stock rubber hose (also called Push Lock). Flexible enough and available in sizes large enough to fit.

Most of us are nerds at heart (or just nerds). Show your nerdy side by telling us your favorite Math/Science/Engineering jokes. I'll start, of course. An architect, a civil engineer, and a mathematician go to a farm. The farmer asks the three their ideas regarding how best to keep his cattle inside a fenced area. The architect thinks for a second, then draws up a circular pen, to get the most amount of area per length of fence, and give the farm a more 'industrial modern' look. The civil engineer looks around, draws up the land (a stream running directly adjacent to the barn), then draws a two-sided fence, with the barn and stream making the other two sides, so that the cattle could drink but would not leave the area. The mathematician quickly draws a very small round fence and in the center writes 'outside'. ------ Officer: Son, do you know how fast you were going? Engineer: Sure do, .2 kilowatts per pound.