chaseincats

I smell gas in the rear of the car on the inside - coming from the vapor tank area. I pressure tested the tank then all hoses and none of them had a leak after I replaced them - but I still will periodically get a fuel smell in the cabin anyway. Hooking up the carbon canister (the hose was open since I got the car) was my idea to fix the issue because I thought vacuum was pulled through the canister to pull fuel vapors out of the vapor tank but I now know that isn't how it works 😞.

Got it - ok that makes more sense, sorry. I originally had the hose just open in the engine bay but never smelled any vapors coming from it - only from the rear of the car in the cabin. Could my check valve between the vapor tank and carbon canister be bad? I can blow hard into the line in the engine bay and sometimes smell gas inside the cabin even after changing the hoses (but it got considerably more difficult after changing them).

Sorry if I'm not explaining this properly. The purge line is connected where the vacuum actuator line used to connect (the t-fitting by the throttle body) - for the idle vacuum leak reason. The purge hose is larger than the hose used for the old vacuum actuator line (which isn't in use now and replaced by the purge hose) so I have a larger t-fitting and had to heat the smaller hose ends to fit on the t-fitting. Does that make sense? I can make a video if that would help?

This might be a stupid idea but I’m going to ask it anyway haha. Could I connect the ported vacuum line on the throttle body to the vapor tank hard line to have the fumes sucked out as I drive?

Gotcha, that makes sense. I ended up hooking the carbon canister back up assuming (wrongly it seems) that the vacuum would suck the fuel vapors out of the tank instead of having them continue to leak into the cabin (despite changing the hoses). What I ended up doing was pulling the cap off the vacuum valve and plugging the large purge hose directly into the top nipple (since the valve doesn't hold vacuum), and connecting the purge hose to the T-connector allowing vapors to be sucked in through the throttlebody inlet. I don't understand why it wasn't done that way to begin with since it's still going into the intake manifold through the throttlebody as you press the pedal... That said, it sounds like the canister doesn't really pull vacuum from the vapor tank so that idea won't fix the issue. It's odd because I only smell fuel in the cabin sporadically - I'd have thought if there was a hose leak, I'd smell it all the time. Have you encountered this?

Right, but I’m not hearing any thing being pulled from the tank-side hose of the canister when off idle when I put the hose up to my ear

So I ended up hooking my carbon canister back up but noticed the amount of vacuum going into the canister from the engine is not the same level of vacuum going from the canister to the tank. I pulled the vacuum line off that goes into the canister and pressed the throttle body accelerator arm and put my ear to that hose and it was considerably louder than when I put my ear to the hose that comes out of the canister (the one that heads to the vapor tank). Is my canister plugged or is that how this is supposed to work to not pull full vacuum to the vapor tank?

Do you recall which parts you recommended?

In my experience bulb that sticks out of the back of the housing is too long to close the stock dust cover, no?

https://www.dapperlighting.com/products/datsun-s30-extended-headlamp-bucket

So at the end of the day, here's what I did: - pressure tested all of the hoses/vapor tank (by taking them all off and blowing in one end while plugging the others with hands/fingers - replaced all of the original style clamps to gates belt clamps - replaced the short hose that makes a u-turn on the filler neck (no idea why this exists) - cut the ends of all the hoses off so they have a new tighter fit on the vapor tank - cut about 6 inches off the main large hose that comes out of the gas tank and bought some new hose, then joined the two with a plastic joiner (a straight piece that you cram both hoses on. Reason being that the hose held air when straight, but when curved (needed to plug in to vapor tank) there were small cracks One thing I noticed was when you blow into the metal rail in the engine bay, it becomes noticeably more difficult to do so after doing all the above. Hope that helps -chase

Wow, did you give it a shot?

Got mine today and while you can pop it on so that it fits tightly to the valve cover, screwing it fully down isn’t possible…

Just bought it, thanks for the reminder

Yeah, the hose clamps. I changed the original clamps to a more modern style gates/belt clamp because you can get more clampage out of them

Update: I took the entire vapor system apart and pressure tested each hose and the vapor tank by blowing into one inlet and capping the others with my hands; didn't taste great. The result was finding all of the hoses and the tank hold air perfectly. I put everything back together and when blowing from the front could still smell gas in the back. I threw caution to the wind and cranked the belt clamps down to within an inch of their life and problem solved - no fumes. Crank those clamps down boys and girls - case closed

This is perfect, thanks @Zed Head!

unfortunately it looks like there wasn't a tuneup chapter in the manual at all for an ZX year according to the table of contents. how are people going through a tuneup on these cars?

Hey gang, I will be working on a friend's 1981 280zx over the weekend but after looking at a few FSMs for 208zxs (on nicoclub & xenonzcar) they don't seem to have the ET Engine Tuneup chapter that comes in my 1978 FSM. I know they're both L28 engines but are the tolerances, valve lash values, etc identical? Is there a different manual specifically that has the tuneup specs for the ZX cars or should I use the 1978 manual's ET chapter?

Have you tried the tapered lugs like I tried? They fixed my shake.

I don't think PSI especially that minor change would affect much outside of making flat spots on your tires more noticeable (do you have any?). The FSM I believe says your car should be sitting at 28 psi.

Whoa! You’d adapt it by just capping off the other diaphragm right?

yikes what a nightmare

Just out of curiosity, how do you end up getting the hood up with a broken cable?

The line should be fine since I could blow through it when it tested everything. Also in the past I was able to blow through it and have gas fumes be ejected into the cabin so that portion should be good (unless it is only somewhat blocked). The exhaust problem was finally fixed with a shop vac and a friend holding a halloween fog machine near the back. Wherever smoke came in, was handled. A huge culprit was the new taillight gaskets. Those should be glued/siliconed to the car, as-is bolting them on does next to nothing. I called and sassed thezstore a tidbit for that not being on their site haha