zwilson2148 Posted January 23, 2010 Share Posted January 23, 2010 Hey, I have a 1976 datsun with a problem i cannot figure out. the car just doesnt run right. the problem is when i step on the gas the car will rev when its just idoling but when i start to go it has no power what so ever and back fires. i changed out the mass air flow sensor and with the new one when i turn on the fuel pump the car floods out without hitting the gas but if i turn off the fuel pump i can rev the car very very slowly only when not moving though. i have changed just about everything i put a new fuel filter fuel pump(hooked up by toggle switch) manifold gasket new mass air flow sensor i have cleaned or replaced all the grounds and any bad wires i did all the vacuum lines i just cant figure it out. PLEASE HELP ME i got laid off from my job in november and i needed money for the bills so i had a chioce to sell my nice caddy or my crappy z and of course i sold the caddy and kept my junk because i love the z cars so much and i wont give up on it...... Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted January 23, 2010 Share Posted January 23, 2010 Have you replaced the cylinder head temp. sensor? Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 23, 2010 Author Share Posted January 23, 2010 NO i have not i am afraid of putting any more money into this car.... is this the sensor on the front of the engine? or where is this one located Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted January 23, 2010 Share Posted January 23, 2010 It's about $40, located on the head, towards the back, passenger side. Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 23, 2010 Author Share Posted January 23, 2010 OKay Thank you i will try and get the part tomorrow i will post to let you know how it goes Quote Link to comment Share on other sites More sharing options...
rossman Posted January 23, 2010 Share Posted January 23, 2010 Your car doesn't have a mass air flow sensor. It has an air flow meter (AFM). The AFM is a large box ahead of and in line with the throttle body. So what is it that you replaced? Have you read the fuel injection bible? The temperature sensor is on the front of the head in the thermostat housing. Clean the connector on the sensor and the harness side and the bullet connectors just upstream from the connector. SEARCH my friend and your questions will be answered. Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted January 23, 2010 Share Posted January 23, 2010 Your car doesn't have a mass air flow sensor. It has an air flow meter (AFM). The AFM is a large box ahead of and in line with the throttle body. So what is it that you replaced? Have you read the fuel injection bible? The temperature sensor is on the front of the head in the thermostat housing. Clean the connector on the sensor and the harness side and the bullet connectors just upstream from the connector. SEARCH my friend and your questions will be answered. Front, rear, same thing, been awhile since I looked at one. Sounds like your AFM might be out of whack as well. Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 23, 2010 Author Share Posted January 23, 2010 Mass air flow meter is what i replaces. NO i havent read the the fuel injection bible. Where are the bullet connectors? i have looked and someone told me on top of the manifold but i cant seem to track them down. i have cleaned those sensors and the ground connection and the car had no response to it Thank you so much for your post i will give it another look Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 23, 2010 Share Posted January 23, 2010 (edited) I have a 76 280Z with the original motor. I feel your pain. The 1976 engines used the water temperature sensor as an input to the ECU for fuel supply. They don't come with a CHT, it came in to use a few years later I believe. The water temperature sensor is on the front of the motor, in the thermostat housing, and will cause the engine to run rich if the connection is corroded or it is not working correctly. Mine also backfired and had poor power when I got it. It turned out to be the Air Flow Meter. That's what it's called, not Mass Air Flow sensor. With a bad Air Flow Meter (AFM) the car will idle well, but run terrible at part throttle, stumbling and backfiring, then run great when you floor it. If you have an ohm-meter you can check a few pins at the ECU connection and get a good idea if the AFM is OK or not. The AFM also has an air temperature sensor that the ECU references to add fuel. It can be checked at the ECU connection too. Edited January 23, 2010 by NewZed Red downer thumb keeps getting my posts Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 23, 2010 Author Share Posted January 23, 2010 Yes i bought a new air flow meter and it would idol fine but spit when even floored.. i put the old one back on now though and the car runs better but the old one is adjust my friend took off the box and did something to it but it wil rev fine(slower than usual) but all the problems when driving i will try to clean all the sensors better tomorrow i have tried before but they wer tuff to get off thank you so much noone around here knows crap about datsuns not even mechanics Quote Link to comment Share on other sites More sharing options...
Sparks280zt Posted January 23, 2010 Share Posted January 23, 2010 This thread and link might help: http://forums.hybridz.org/showthread.php?t=135748&highlight=bible Quote Link to comment Share on other sites More sharing options...
rossman Posted January 23, 2010 Share Posted January 23, 2010 Mass air flow meter is what i replaces. NO i havent read the the fuel injection bible. Where are the bullet connectors? i have looked and someone told me on top of the manifold but i cant seem to track them down. i have cleaned those sensors and the ground connection and the car had no response to it Thank you so much for your post i will give it another look To find the bullet connectors, just follow the wires coming out of the connector back towards the back of the engine. Read this: http://www.atlanticz.ca/zclub/techtips/EFI&fuel.htm and this (FI bible): http://www.atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 23, 2010 Share Posted January 23, 2010 (edited) Long as you're downloading, you should really get the manual. It is free at http://www.xenons30.com/reference.html . It describes how to check the AFM and all of the sensors. Plus it shows where the sensors are and what they look like. You can download the WinRar program to unzip it, there's a link to it on the page. Edited January 23, 2010 by NewZed Clarity Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 24, 2010 Author Share Posted January 24, 2010 okay yesterday i posted fuel problem. I think i found the problem. when i mess with the mass air flow meter i can get the car to run better. the problem is when i step on the gas the air flow meter weight goes to far and it floods out.. but when i rev it and push the meter slightly back i can rev the engine just fine it runs nearly perfect how can i fix this problem? THANK YOU ALL FOR ALL OF YOUR HELP Quote Link to comment Share on other sites More sharing options...
rossman Posted January 24, 2010 Share Posted January 24, 2010 If I'm understanding what you wrote correctly it sounds like the engine is running too rich. So, when you push the AIR FLOW METER flapper in the direction that closes it off, it runs better? That has the affect of leaning out the air-fuel mixture. You may not have found the problem - that may just be a band-aid if something else is causing it to run rich. Make absolutely sure your temperature sensor is working correctly and that all of its connectors are clean. Don't forget the bullet connector. If you haven't found that one then you haven't fixed the problem. By "clean" I mean that all the corrosion on the tips of both sides of the connectors are clean. I used a little bit of sand paper and a small file to get mine clean back in the day. Clean the prongs on one side and shove the sand paper inside the female part on the other. Once it is clean put a little dielectric grease in there to inhibit further corrosion. Quote Link to comment Share on other sites More sharing options...
rossman Posted January 24, 2010 Share Posted January 24, 2010 how can i fix this problem? Oh, and to answer your question. You can tighten the spring to make it run more lean. There are instructions how to do it in one of the links I sent. Basically you loosen the screw that holds tension on the spring, adjust the spring tighter then tighten down the screw. Again, this may be a band-aid fix if it is running rich because of a bad temperature sensor signal. Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 24, 2010 Author Share Posted January 24, 2010 ALright thank you very much.. i am going to head out there now and do exactly what you said with the connectors first then the air flow meter thanks again ill post to let you know if it works. Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 25, 2010 Author Share Posted January 25, 2010 Okay, so i changed out the temperature sensor and the car does really run to much different it sounds alot better at idol but i couldnt mess with it all that much because its pitch black outside and raining even though i did change it in the rain i just could see that well to countinually to fool around with it so first thing tomorrow morning i am going to go out and tighten the sensor because it was a little loose then i am going to recheck everything and ill post and let you guys know how it does if it doesnt do well i might just videotape everything so i can show exactly what its doing and maybe someone can help that way. Quote Link to comment Share on other sites More sharing options...
zwilson2148 Posted January 25, 2010 Author Share Posted January 25, 2010 ANother problem i do have i figure i minds well post is i get alot of water on the passenger side floor my weather stripping is bad but it comes from the front to and i am not sure how to fix it exactly yet i tried getting up under by the i think its a fan or heater core? i am not sure but its under the dash HAS ANYONE ELSE HAD THIS PROBLEM AND FIXED IT? Quote Link to comment Share on other sites More sharing options...
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