Captain Obvious

Bummer. Shag carpet!! That's nasty! The good news is that you've identified the problem, right! I think there's some internal baffling and some kind of filter inside the tank. I've (thankfully) not had to mess with that myself, but I think I remember some threads about it. And some pics.

Haha!! I was wondering if someone was going to catch that one, as it was admittedly a little obscure! Gold stars and a new 5 1/4 floppy for you!!

So... What would you little maniacs like to do first?

The mfgr's recommended retaining method is the staking. I wouldn't be surprised if that dictated other dimensions like the ID of the bore where the bearing cap get's pressed into: Too bad the removal process is destructive to the yoke. If you could reuse the yoke, you could probably just replace the cup bearings: That said... How to retain the similar, but slightly wider replacement? I wouldn't weld it. Not only is the yoke cast (which is trouble to weld), but you'd mess with the hardness of the cap. And I don't think epoxying the back of the cap would do much. If there's enough force to move the cap, I don't think epoxy has enough strength to hold it back. Set screw(s) might work. Maybe grind a shallow groove in the cap first so the setscrew has a ledge on which to retain. Loctite the setscrew in place? The ostrich approach might work as well. How much force did it take to get the caps seated in place? Only other independent thought I have is some Loctite sleeve retainer compound. I've used that stuff for bearing and sleeve retention (duh), and it really holds. If you do it right, things aren't coming apart without heat. I don't know if the gap you have is too small though. I'm not sure what the minimum gap is. Maybe file a few shallow grooves through the ID bore so the Loctite has a larger gap in some places?

Here's to hoping it really was that simple!

Sorry if just created a run on those gauges. Keep your eyes out and I bet you can snag one. I didn't look into it, but I bet I don't even want to know what they go for new from an authorized distributor!! And here, I made this for you:

JR, Sorry to hear about your friend. Agreed. Don't buy cheap metal ramps! :mad: And SteveJ & Mike, That was awesome.

Lucky dog! In my next life I'm gonna have a lift. That, and all the whatnots I can stuff into my toolbox. Here's my nyet-skid ramps: Used a very thin coat of that polyurethane based water curing glue. Elmers and Gorilla snot both make the stuff. Best thing I've found for this kind of application. Don't use too much or it foams and expands. Very thin coat.

I'd be happy to send mine on loan if you cover shipping. It's a big brass chunk so it's not the lightest device in the world, but I bet it could make it round trip for less than $20. I might be able to take the reed switch housing off the back, and if so, it might even fit into the smallest flat rate priority box which is cheaper. Shoot me a PM if you want.

There's been a lot of discussion recently about gas caps and pressure/vacuum. Take a look at these two threads: http://www.classiczcars.com/forums/body-paint-s30/53136-hands-down-best-gas-cap-our-cars.html http://www.classiczcars.com/forums/misc-s30/53139-gas-tank-vacuum.html

Haha! I'm with you on that. I sometimes buy stuff when the situation is convenient and then pack it away in a box... "Good, got the part, Now I'll get to installing it when I get a chance." And then open the box a year later and it's like a birthday present because I didn't even remember I had it! Squirrels! On edit - Took some pics of my festoon (does that sound clownishly dirty?). If you look closely, you can see what I had to do to the bulb clips to get the larger festoon to fit. I used a carbide burr on a dremel. Don't get tiny brass slivers stuck in your fingers (or eyes): And even though you can't tell much because there's nothing else to compare it to, here's the obligatory "ON" pic:

Forgot about this part... No. It will read true under all conditions and that's part of the beauty of it. The trick is that if you've got vacuum problems, your fuel pressure regulator will be adjusting the pressure WRT to the same leaky system. In other words, even if you've got a vacuum leak, your fuel pressure should be OK because the regulator is referenced to the same leaky source. And this kind of gauge, being also referenced to the same leaky source should show proper fuel pressure even if there is a vacuum leak.

The gauge is from Orange Research and I got it off ebay for $40. So it's not disposable and lives in the toolbox as a diagnostic aid. It's a little too valuable and bulky to be a permanent installation. I got Orange Research 1203-PGS series. I pulled the vacuum off the intake manifold off the carbon canister purge source which is the nipple near the cold start injector. I don't see any reason why you couldn't use that gauge as a standard vacuum gauge by hooking up the LO side and leaving the HI side open to atmosphere. Here's how that gauge works... Inside there is a floating piston and cup seal that is spring loaded to one direction. The pressure ports are connected to a cavity on either side of that piston and push/pull it to one side or the other depending on the magnitudes of the pressures. The spring pushes toward the HI side, so pressure on the HI side compresses the spring and pushes the piston towards the LO side. Vacuum on the LO side will also compress the spring and pull the piston towards the LO side. One of the neatest parts to the whole thing is that there is no mechanical connection between the piston and the needle movement... It's MAGNETICALLY COUPLED!! There are no springs to wear out, no gears to strip, nothing like that. The only link between the wetware and the needle is the magnet. Here's a sketch of the guts design: They also make a diaphragm version for gaseous applications where there is a diaphragm between HI and LO instead or a cup seal. The diaphragm does a better job of sealing between the two sides, but for liquids you don't need that. So it's true real time differential. Don't have to do the math in your head at real time. It does it for you. No springs, no gears, no linkages. Cup seal between HI and LO sides. (I'm not positive what seal composition I got, but it's either Buna-N or Teflon, either of which is suitable.) It's also got a reed switch built into it that you can adjust to close at a desired pressure if you want to set off an indication or something. Red warning lamp if the differential gets too high or too low. Of course, I'm not connecting to that feature, but it's there.

I've been meaning to post this thing, and this thread is a great segway... I bought a differential pressure reading meter. It's got two ports on it for the high and low pressure connections and it provides a true real time differential reading. There are a couple different designs for differential pressure meters, but I really liked on this one. Here's the pressure reading with the engine running and just the high side connected. The vacuum side is open to atmosphere and it reads like any other single input pressure gauge that you would hook up to the fuel rail. The reading is lower because the vacuum is higher. Also you can't see it (because it's a still pic), but if you rev the engine, the reading is all over the place accounting for changes in manifold vacuum: Then you hook up the vacuum side, and it's like magic... Rock steady under all engine conditions. Goose the throttle. Hold the RPM's high and then snap the throttle closed? No change. My FPR is doing exactly what it's supposed to be doing, and the pressure drop across my injectors is rock steady where it's supposed to be even in the face of rapidly changing manifold vacuum. It's awesome!:

I bought from superbright as well. My first try was one of these in cool white. Fit easy, but it was harsh and could stand to be brighter: Second (and final) try was one of these in warm white. Didn't fit that easy though. I had to grind a little off the connector clip fingers in the lamp housing to get it to fit between the fingers, but it's a once and done job, I've very happy with the outcome. Brighter and not harsh:

I didn't see it, but a friend mentioned this the other day. Is this show a real thing yet, or was that just a pilot?

Nice! I glued non-slip rubber mat to the bottom of mine so I don't chase them around the garage with the car. I'll take a pic if I get a chance. Now that the ZX has been replaced with the Z, the wood "ramps" don't get much use.

Rossiz, I share your theories on the silicone fill and will be interested in any ensuing discussion. I've not done any investigation, but what you described above is exactly what I would expect as well. And Zed Head, Thanks much for finding that. I searched and searched and couldn't find it. I searched so much that for the rest of today I had myself convince that I really DIDN'T post it, but only THOUGHT about posting that info. Thanks for helping me back (closer) to sanity. Now that I know it's really there, I'll dig a little into why I couldn't find it. That'll help me in the future. And I've got the end all of fuel pressure gauges for all you Neanderthals to drool over. Give me a little bit to upload some pics and I promise you'll be jealous.

I used to drive my 300ZX up on a pair of 2x12 slabs just so I could get enough room under it to then use a floor jack. The extra inch-n-a-half lift was just enough room to get my floor jack under the center front onto the jack point. The first bunch of pumps were still very short because the handle hit the lower lip of the facia. That was a pain in the butt.

I experienced the exact same failure of a pressure gauge. I could have sworn I posted about it a while ago, but (even with the advanced search**) I honestly I can't find it. So if I didn't talk about that, I'm sorry because I could have saved you the trouble. My experience went like this... I was hunting for hot restart issues and I installed a cheap pressure gauge just like you did between the filter and the fuel rail. I tracked the cause of my hot restart to a bad check valve at the pump, but after fixing that I figured I would just leave the gauge installed as a diagnostic tool just to keep an eye on things. Over the next few weeks my fuel pressure seemed to be gradually dropping. But the interesting thing is there seemed to be no change in the way the engine was performing. Tracked the issue to a failed gauge with eaten up brass gears inside just like you had. The pressure shocks of the constant hammering from the injectors opening and closing ate up the brass and started skipping teeth. I put a new gauge in the system and verified that it was a measurement problem only and my fuel pressure was fine, and then I took the gauge off the system so I didn't ruin another gauge. **Mike, if you see this, I'm not sure the advanced search works as intended... What I was thinking would be an "AND" search on keywords seems to be an "OR" search instead? Send me a PM if you want to discuss? Maybe it's just me, but I couldn't get it to do what I wanted.

Glad to help. Of course, I can condense all of my above ramblings above into the following... "My 77 behaves the exact same way yours does, and after reviewing the system and the documentation, I believe that's the way it's designed to perform. If you find that the tank has a VACUUM, you have an issue, but a little pressure is normal." The difficult part for me is that my non-Z daily driver never develops any tank pressure. Whenever I get gas, there's no "woosh". No nothing ever. I dug into it a little and it seems that it's about 50/50 with that car. Half the drivers get a woosh and half (like me) don't. I've not been able to figure out who's is normal. My 50 or their 50. It's OBD2 and I'm not throwing any EVAP codes, and that car isn't intended to be the project, so I just drive it.

I pulled my pump out a while ago for refurb and I didn't have any trouble getting it to prime when I was done. I know there's a statement in some of the manuals that warns against running the car completely out of fuel because it may be hard to get pumping again, but I didn't have any issue. I pulled the starter solenoid wire and the pump primed itself and got fuel up to the rail in a few seconds. Gravity did all the work. So you did make sure your fuel filter isn't plugged completely with crud, didn't you? Sorry, I have to ask... If the one in the engine compartment checks out OK, there's also a small screen filter on the inlet to the pump itself. Pain to check, but that could be an issue as well.

The good news is that I think that's exactly the way it's supposed to work for pressure. My read on the way it works like this... The fuel filler cap is supposed to be a positive check valve in that it allows air to flow into the tank, but won't let anything out. So why doesn't it build up pressure uncontrolled when you park the car in the hot sun and heat up the fuel and vapor in the tank? Because there is also a device that is part of the EVAP carbon canister system that they call the "check valve", and it's in line with the vapor line that runs from the liquid/vapor separator overflow tank in the rear wheel well up to the carbon canister in the engine compartment. Note that this "check valve" is not to be confused with the check valve on the output of the fuel pump. This one does vapor while the one on the pump does liquid. Here's a layout of the items involved in the EVAP system. The check valve is #8: It's not a simple normal "check valve" that allows flow in one direction, but blocks it in the reverse. Instead it allows unrestricted flow in one direction and restricted flow in the other. Here's the test procedure. Note that I had to go to the 78 manual to find this. Earlier manuals showed the check valve in the system, but didn't include test procedures: It's unrestricted flow if the tank runs a vacuum, but it's restricted flow if the tank pressure is positive. So I wasn't there when they design the system, but what I believe happens is that the pressure inside the tank will build up some until you reach the cracking pressure of the check valve and then the valve will "burp" into the carbon canister. Then the pressure will build up again until there is another "burp". This will continue as long as necessary until the pressure stabilizes right below the cracking pressure, and that's the residual pressure that's in your tank when you take the cap off to put gas in.

I'm with ya! I've lost count of the number of times now that I've studied the heck out of something and taken lots of pics... Only to find out later that I just reinvented the wheel and Blue already has the same analysis on his site from years ago!

Mike beat me to it... I wanted to ask if you're sure it's vacuum and not pressure. It would make perfect sense for there to be some pressure in the tank. As a matter of fact, it's all related to the vapor recovery system that includes the carbon canister in the engine compartment and it's designed to operate such that there could be some pressure in the tank. Either neutral, or positive pressure in the tank. But there shouldn't be a vacuum.