racebird1

When all is the way it is supposed to be it will run very well without adding extra cooling fans or higher fuel pressure. If it is running rough at restart something is wrong. Make sure the fuel pressure is correct and the fpr is letting the excess fuel return back to the fuel tank( and there should be fuel returning). If the fuel is vaporizing then it is running too hot because when everything is normal this will not happen. You can try pulling out the fuel rail with the injectors and placing the rail into a large pan and crank the engine untill full pressure is reached. While doing this make absolutely sure that there is no source of ignition or you will start a fire. Check the spray pattern while you are at it and then make sure the injectors are holding pressure and not leaking down. Just because they were replaced does not mean that they may still have an issue. I also noted that you put grease or oil on the orings be careful what you use because some greases will attack the rubber.

Well the AC stopped working I pressure tested the system before evacuating and charging. I charged the system and after a few days I believe the freon is low. The clutch still engauges but no cool air now. I did not replace the cap after I charged the system because I knew I was going add more freon. The question is, will it leak from the low side valve if you don't put the cap back on? Is the cap there to seal the valve?

Even though it is working I am still curious about the pressure switch. The factory manual I have specifically states that the switch is to protect the system from abnormal buildup of high pressure. I can't test the switch to see if it is open or closed at low pressure now because I have freon in the system. According to the wiring it is in series with the Thermostst and the micro on / off switch and all three needs to be closed to send the curent to the relay which then sends power to the Compressor clutch. I know it shouldn't matter now that it is working but I just like knowing exactly how things work.

I got it working Just in time for the current heat wave. It turned out to be a bad relay. I still have a question about the low pressure. Is there a low pressure switch because the manual states that the pressure switch on the drier is to protect the system from high pressure. That switch only has two wires so I don't understand how it can see too high and too low of a pressure. There is no other pressure switch only the thermostat and a micro switch which is only a switch connected to the lever when you turn on the AC. I only have one 14 oz can in the system and the sight glass is full of bubles but the air is ice cold. It's probably the first time anybody was glad to see bubles in there sight glass but at least that means the compressor was working.

I have searched hear and can't find what I am looking for so hear is the question. I have pressure tested the ac system and it held 80 lbs pressure. I evacuated the system to -30" for 1 1/2 hours and put one 12 oz can of r-12 in system and the gauge is showing 80 psi and I can't seem to get the compressor clutch to come on. I have 12 volts to the pressure switch on the receiver / drier. Does this power come in from the micro switch and thermostat or does it go there after the pressure switch. I tried to jump out the PS pins at the connector but still did not come on. Does it need a certain minimum pressure in the system before it will come on and if so what tells it what the min pressure is. I know it still does not have the reccomended amount of r-12 in the system yet but I don't want to put the rest in if something else is wrong. Thanks AC is not my specialty.

I finally got back to the Z today and did some more checking. I found that the cold start injector is not injecting. I pulled it out and checked it when my son started the car and nothing. It put my injector tester lead to it gave it power and it works fine but not when I start the car. I will need to look into the thermo time switch. I tested the main injectors a litttle differantly, I pulled the fuel rail and and turned the key to on and fingered the AFM enough to get the pump on then powered up the injectors up one by one and they all sprayed great so I don't think the injectors were bad after all. I installed the new ones anyway. I advanced the timing to about 25 degrees cold and the vacuum went up to 18 inches but the engine races too much so I backed it down to 20 and I don't get any intake backfire. I also fingered the AFM all the way when it was running and it bogs down the engine from being too rich so I think that is working fine as well. I will install the pot switch this week and see if that will help.

As you may not know the fule pump signal runs through the air flow meter so it will only give you voltage while the engine is cranking or starting. The flap needs to be sucked open slightly to close the switch in order for the pump to run. This is a safety feature in case there was an accident that would stall the engine and with the key switch still on and if ther was a leak it would continue to pump gas. That is why they ran it through the afm. If you have your cover off of the afm and you open the flap a little with the key switch to on I would think the pump should run.

You may also have other issues that are contributing to your problem. Your air flow meter boot has tons of duct tape on it which tells me it must have large cracks in it. You will need to replace it you cannot have any leaks in the air and vacuum system. Those arn't too expensive you can find them on e-bay. Good Luck

I haven't had any spare time to get some of the changes to the car done yet this week so I can see if anything improves. My new E-bay injectors arrived today, that only took three days to get here so hats off for good service and the hoses are plenty long enough and I will even need to shorten them because they have about 3" of hose on them so naturally I was glad to see that. They look great and I hope they work as well as they look. My potentiometer my be here as well so soon as I get time I will try these changes and see how it goes.

Hey blue the calibration method took a ton of time to produce and I really appreciate the time you put into it. I will be using to the pot adjustment and I have one on order and should have it in a day or two. I have not decided where I am going to put it yet. Mybe temporarily under the hood then move it to the ECU area. I am going to order the new injectors so I can be sure that they are giving me the right amount of fuel. The two older afms don't have the serial number on them but both newer ones do. I am going to try one of the older ones since one of them was from the car and I have it calibrated to Blue's method. Since I am so close to it running pretty decent now these changes should get me where I need to be for awhile.

I have been going through all the afm tests on the four afm's I have. Two are older much heavier with the back flow valve which are probably from the 76 and two are much lighter and might be a newer version. I did the weight tests with the measured water and the two with the glue missing were way off and one of those was completely sprung. It took about 13 teeth to get it back from fully sprung. The one that was on the car was still glued but was comomg up a hair too tight which is towards a lean fuel mixture which is also part of my problem. I will attempt to go with a setting of just below normal to try for more fuel. I then did the reccomended cleaning of the contacts and such with testing before and after the cleaning and some of the tests it did make a difference from cleaning. Here is the thing, I tested the ohm readings as per instructions and they all passed after the cleaning but I noticed that if I did a more detailed test of the ohm test of the carbon trace the two newer ones came out almost exactly the same and the two older ones came out almost exactly the same but the new compared to the old are a little differant. I measured the resistor strips right on the board so I was getting an accurate reading. I have concluded that there is some difference between newer and older 76 version but I don't really know if it is enough to change anything? The other one with the glue still on the screw was just about right on with the weight test. The fully open weight test is a little tricky because of the friction of the string dragging and the angle really doesn't allow the flap to fully open it is just shy of open. I am going to get a new set of the injectors and see if I can set the afm and timing to get me through the summer.

I was looking at those injectors and I thought I saw somewhere in a post where they did not think they worked too well but maybe they had other issues. How are they working for you? I did not see any negative feedback. The AFM link was great just what I was looking for thanks

Do you use fuel hose rated for fuel injection from a local parts store or get special hose somewhere? I used some from a local store a while back and it didn't hold up all that well.

When I pulled the plugs I checked them all out and found that it is indeed running very lean. All the plugs have a white coating on the electrodes. I have ordered a 5k pot to try on the temp sensor but I also looked at the three extra AFM's and they all have a differant resistance of tension on the flap and I don't really know which one was on the car. I searched the site and can't find out how to tell if it is at spec or how to set it there. Does anybody know how to do this? I am sure they must set them by how much tension it takes to open the flap. I can turn the wheel but to what? I still think I need to pull the injectors again to make sure the screens are clean. A local injection company says they can rebuild them in two days for $20 each. It bothers me a little that all I get from them is a steady stream not any kind of spray. They al trigger fine with no sticking or leaking. The $20 each does not seem too bad.

I had my friend over with the scope and we put it in through the spark plug holes and checked out the condition of all the cylinders. All the cylinders have avery good cross hatch pattern on the walls and very little carbon on the pistons, now this isn't going to tell me what condition the rings are in but I would think that an engine with such a low compression would no longer have cylinders that look so good. I should probably take the valve cover off and make sure the valves arn't a little sticky. Never the less untill I can find a fix I have been looking for someone local to possibly rebuild my engine. I just don't have the time right now to do it myself. I will in the mean time try to find some simple instructions to vacuum time and put the potentiometer in to see if they can help get it through the summer. Anybody have simple quick instructions on the vacuum timing method. Do I simply turn the distributor untill I get the highest vacuum?