Zed Head

When you came back with AFM testing I assumed that you had fixed the fuel pressure drop problem. I'm guessing now that you did not. The EFI must have proper fuel pressure to work correctly. There's no way around it. 26 psi is probably the lowest pressure number you should ever see on these engines. Don't get distracted by the new pump or the recently cleaned tank. Something is still wrong with your fuel system.

The popping is a typical sign of lean mixture and the fact that it's worse as it gets cold fits. The fuel pump contacts are only for the relay and will not cause problems since yours runs all the time. 60 ohms is about right for a relay, but in your case the relay is not being used so it doesn't really matter. 60 ohms is also about right for the AAR citcuit. That is the resistance of the heater wire inthe AAR. looks good. What you need to measure is Pin 8 to Pin 6 (180 ohms) and Pin 9 to Pin 8 (100 ohms). Measure at the ECU connector if you can. IF you're using the 1980 EFI Handbook, they would be tests #1-3A 1975-78, and test #1 3C 1975-78 Those are the circuits that control the fuel mixture. I have a theory that as long as the ratio of those two is 1.8 the AFM will work correctly, but if you're way off, typically the engine will run lean, causing popping and backfiring.

The fuel pump provides the pressure and the fuel pressure regulator (FPR) controls it, by bleeding off excess. You want to measure between the filter and rail so that you read the pressure that is in the rail at the injectors. Since the FPR is in the middle of the rail the only place to connect the gauge is between the filter and the rail. The pressure is not directly dependent on load but the FPR does adjust pressure based on intake manifold pressure. That's what the vacuum hose to the FPR is for. When you first measure the pressure, pull the hose off of the FPR. The engine will run rich but the reading you get will be the baseline reading. It should be about 36-38 psi. Reconnect the hose to the FPR and go for a drive. The fuel pressure should vary between ~28 psi on the low end (it could go a little lower or a little higher but it should definitely be lower than 36-38 psi). When you hit the throttle the pressure will increase as intake manifold pressure increases (vacuum level drops). When your problem happens you will probably see the pressure drop down to the low 20s or less, if the fuel pump or fuel intake is the problem. Fuel starvation.

Define the current state of the idle. "Not right" doesn't give any clues about what's happening. Have you confirmed that there are no leaks in to the intake system? All air must pass through the AFM. Any leaks at all will affect the way the engine runs. Even leaving the dip stick out will have an effect.

Looks like a gear puller helps, #146 - Subaru WRX STi R180 Side Axles - Page 8 - Vendor's Forum - HybridZ

It's reddat. Well-known. He is karma for people who don't use internet search tools. Funny that the ad only shows a picture of a drawing, not an actual part. I'm pretty sure that he just buys parts from MSA, BlackDragon and the local parts stores and resells them. He may not even buy them until someone buys on eBay. Check out this $125 O'Reilly pump for $174.99. Used. http://www.ebay.com/itm/Datsun-280z-280zx-Fuel-Pump-NICE-/321254685937 http://www.oreillyauto.com/site/c/detail/DLP0/FD0035/02535.oap?year=1976&make=Nissan&model=280Z&vi=1209226&ck=Search_fuel+pump_C0401_1209226_2513&redirectkeyword=fuel+pump&pt=C0401&ppt=C0025

IF you can keep the engine running while you see low pressure, one way to check the FPR and pump and/or the fuel tank is to squeeze the return line. If pressure increases the problem is the FPR. It's not doing it's job. If pressure does not increase then there's a problem with supply, either the tank or the pump. If you determine it's supply, you'll still have a dilemma since the problem only happens when things are warm. But you can let your fuel pump run for hours with no issues as long as your battery holds up so you could follow-up by trying to recreate the problem with the engine not running, in the garage. Just keep narrowing things down until you have one possibility.

These things seem to be typical of either a bad fuel pump (over-heating) or crud in the gas tank (clogging the inlet then floating away when stopped). If you go with a gauge kit and run the hose out of the hood you'll be able to watch pressure while you drive. If you put the gauge in the engine bay you'll have to jump out and open the hood and hope the engine stays running. Something to consider.

Can't tell if you guys are driving 240K's or 240Z's but the 60 amp alternators from some of the late North American market 240Z's, 260z's and 75-77 280Z's used a 60 amp alternator with the external voltage regulator. Should be a straight bolt-in.

The air has to come through the AFM. If you run a filtered external source you'll run way lean when the valve is open. The valve should be placed where the AAR was. You could probably plumb in a later model AAR that might have a little more engineering in to it to make it more robust. But the basic design has lasted many years.

I live in the Portland area and I removed my my cold start soon after getting my car. I don't notice any problems starting my engine. On the other hand, when I had a fuel pressure regulator that leaked fuel pressure I did notice extended cranking times. The "crank and crank and crank" description sounds like it might be more than just a fuel pressure problem though. Could be a combination of fuel pressure weakness and a weak pump. Leaving a gauge on will provide a lot of information. Check the pressure before trying to start and watch it while cranking - where did it start and how long did it take to build. The engine might also just need a tune-up. Weak spark can cause extended cranking, trying to light up cold fuel. But with these engines, knowing fuel pressure is never a waste of time so it might as well be done first. With fuel injection, proper fuel pressure is critical.

Do you have a gauge yet? Do you have any plumbing experience? If you are not handy with threaded fittings and making them leak-proof you should probably buy or borrow a fuel pressure measuring kit. It will come with a plastic T-shaped fitting and a short piece of hose that are inserted between the filter and the fuel rail. The old fuel hose will be difficult to remove and may need to be cut off. Gas will spill. If you need to cut the old hose off you can just cut it and insert the gauge then replace the hose with new when you're done. Quicker. If you know how to work with fitting you can buy a gauge and fittings and fabricate your own gauge system. Depending on the price of brass fittings at your location it might be cheaper to just buy a gauge kit at a parts store. The hose is 5/16" internal diameter.

Kind of depends on what the $20k is going to buy.

My understanding is that the condenser was originally added to damp excessive arcing across the points to make them last longer. Then some electrical wizard discovered that they also made for a stronger spark through some sort of electrical oscillations,allowing the coil to charge faster. Read up on Kettering ignition systems, it's pretty interesting stuff. So when your condenser went bad, you got a weak spark that also wore your points out faster. Probably why a set of points usually comes with a condenser (capacitor) included.

These guys are right, and to be clear I was just offering things to look at and another perspective. Considering how well emulsified the oil-water blend is it's possible that the OP or someone drove the car for quite a while with a small coolant leak. And when the engine is running the crankcase is under vacuum while the coolant system is under pressure so a small passage from coolant to oil in the HG might pass that much coolant. Who knows. As you're taking things apart don't clean things up. Leave the grime and old gasket material in place so that you can see signs of damage.

The distributor is not an issue but make sure that you get the oil pump shaft installed correctly. That's where the problems with distributor adjustment happen. The procedure is well-described in the Engine Mechanical chapter. Interested to see what you find, take pictures. You might have to remove the engine to replace all of the core plugs, I've never done it.

I searched around on hybridz.org where a lot of engine work tends to happen and found the thread below. There's a core plug (aka "freeze" plug) behind the timing chain cover that might be the source of your problem. You'll find out when you remove the cover. If it is, check to see if the PO just dinked around with the plug and messed it up or if it's rusted out. If it's rust you'll need to check all of the other core plugs. Clear some space in the garage. Problem: Oil POURING out of the coolant inlet on the block - Nissan L6 Forum - HybridZ Found the thread with this in the Google box - site:hybridz.org coolant leak timing chain cover Here's another, same core plug - http://forums.hybridz.org/topic/82490-coolant-in-the-crankcase/

If he has enough current to drive a relay that might effective. Tap the line between the fuse box and the switch and insert a relay. Milliamps to drive the relay, full power to the lights. Assuming the grounding circuit is okay, which a new headlight switch won't fix anyway.

That's a lot of stuff in the crankcase. I'm no expert but it seems like a lot of fluid for just a head gasket problem. If you really have no other signs of head gasket damage, the timing cover might be worth examining closely. The oil leak might be a sign that the cover is loose or the gasket isn't sealing. I don't know well enough how it seals so can't say how likely it is that you could have a connection between cooling and lubrication systems. Consider whether or not your head needs work, like a valve job. Maybe the head is worth removing anyway. You have a dilemma.

Carrying on with the theme that you will try to fix it alone if nobody offers to help, you should probably drain the oil/water blend and replace it with oil, then spin the engine without starting to push the oil/water blend out of the various places it's ended up. The stuff on the cam indicates that you've blended the water into the oil and spread it through the engine. It might not be that harmful to let it sit in there but it needs to come out anyway and might prevent some rust where you don't want it. The quantity of water in the bottom of the pan will be a clue about how bad things are. I blew a head gasket or cracked a head (never took it apart) on a Ford Escort and quarts of water came out before the oil did. On the timing cover leak - it would be unusual but if your timing cover was damaged it might be possible to connect the oil and water passages. The oil pump and water pump both push their fluids from the cover to the block. I've heard of corrosion through the cover's water passages causing leaks.

Well then, I would open up the Engine Mechanical chapter of the Factory Service Manual and start there. The Nissan FSM's are very well written and will get you far. The first part of the chapter is about disassembly. The first thing you need to do is remove the manifolds, or at least disconnect them if you plan to pull everything out at one time. You'll probably break a few studs and bolts but once you get those off the head will be exposed. Then remove the valve cover gasket and start popping head bolts loose. Take the two short bolts holding the timing cover out. Insert the cam tensioner retainer. See if the head will come loose. It will probably be stuck. Worst case, you get halfway and need help. You might be surprised though and it comes right off. Removing stuff is relatively easy. Getting it re-installed right is more work.

It looks like you've decided that you have a blown head-gasket, or someone told you that you had one, due to the oil/water emulsion, and you're assuming that replacing the head-gasket will fix your problem. But there are several possible causes for coolant leaking in to the lubrication system. You could also (some would say probably) find that your head is warped. I took a head off of a good running engine, no HG problems, and it's warped .007". It might be cheaper just to replace the engine or the head if you're looking just to get the car running. If it's a hobby and you want to dig in to engine work, then that's a different scene. Just adding something to think about. You'll probably spend a lot more money and time than you plan to, even if the head-gasket is the cause of coolant in your lubrication system. Forgot to say that nobody has even mentioned the manifolds and problems associated with just removing and replacing those. Removing and replacing a head is a pretty big job and can nickel and dime you pretty hard.

I would try to break your problems down in to individual, manageable projects. The high idle may or may not be related to the engine acting like it's running out of gas. I don't think that the potentiometer or the BCDD will fix that problem, but that seems like the most important one. When you have several things happening at once it's easy to get distracted or decide to work on the one that seems easiest, but you might find that you're fixing something that doesn't need fixing. If you're not super-comfortable with how your engine works, changing several things at once is almost a guaranteed way to create new problems. Most of these posts are suggestions for things to consider, not calls to action. If you think you have a fuel problem, the most direct way to confirm it is to connect a gauge and drive the car. See where fuel pressure is when the problem happens.

You can also remove the small wire from the starter solenoid (it pulls off) and turn the key to Start to run the pump. That works on any of the 280Z's. The starter won't run, but the pump will run. Don't let the end of the wire touch anything since it will have power when the key is at Start. I would not mess with the BCDD yet. You'll just complicate things. There are many other possible causes of a high idle, like sticky throttle plates or sticky throttle linkage. Nissan actually issued a recall in 1977 to fix that type of problem.

One good clue would be the tachometer behavior. If the ignition module, or coil, or power to the ignition system, is going bad the tachometer needle will probably jump around or just go to zero. When mine was going bad the engine would still run but poorly and the tachometer needle was jumpy and read about 1.5 times actual engine RPM. You'll need to have a general feel for what RPM should be for your speed and gear. For example, mine showed that I should have been going about 80 mph, when I was only going 50. Mine also would fix it itself if I turned the engine off and restarted. They become more heat sensitive when they're failing and higher RPM generates more heat. If it's a fuel problem the tachometer will probably be fine when you're in gear because car speed will dictate engine speed. Assuming you have a stick shift.