dark91zc Posted May 19, 2009 Share Posted May 19, 2009 i have a 1981 280zx that i just switched the engines on. the old engine kept breaking harmonic balancers. now the new engine only runs if the fuel line is pinched or the fuel pump relay is removed. i have replaced all fuel lines and vacuum lines on the intake manifold. i am at a stand still on what it can be. thanks for the help Quote Link to comment Share on other sites More sharing options...
evan1242 Posted May 19, 2009 Share Posted May 19, 2009 sound like you have a FPR that is not allowing gas to return the tank. it could also be a clogged return line. check to make sure that the vacuum line that goes from the intake manifold to the FPR is nice ans tight. Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 the car ran before just fine. and i am using the im and em off of my old engine. cause the engine that is in the car now did not run right in the donor car. so i decided to run all of my stuff off my old engine Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted May 19, 2009 Share Posted May 19, 2009 Sounds like we dont have enough info to even take a guess at what the possible cause could be... Exactly what was switched... be specific. Engine, Trans, harness(harness parts), etc... What condition was everything? How do the electrical connectors look on the inside? Sensors from new or old motor? Why did you switch motors because the balancer kept breaking? was the snout damaged? How did the old engine run before the swap? There is no such thing as to descriptive and no-one should be giving you crap for being too descriptive... So feel free to take some time in greater detail describing what has happened other than you pinched the line and it runs and the relay pulled it runs. That means very little to anyone that can help you over a forum. Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 ok i switched the engines because i kept breaking harmonic balancers. the keyway notch has a 45 degree smash in it. the last time i fixed it i used quick steel and let it sit for a week and it lasted 6 months. it ran like a champ. no issues what so ever. the new engine is out of my rusted out 82 280zx the issues with it was it ran like crap. i tried to fix it but it just bogged and the electrical on it was in so so shape. so i put it in my good shell. i used the dizzy and the intake manifold from the stock engine. all the electrical is the same. i did not change anything. the only major change i did do was replaced every fuel line on the intake manifold with newer fuel injection line. and replace all of the water and vacuum lines. i am running msd street fire wires. new g2 ngk plugs. i did not switch any sensors on the engine. some of the connectors were a little corroded. but i tried to clean with a paper clip and put die electric grease on it. i checked all of the fuel injectors one by one while the engine was running. all sounded good but i think i need to clean 1 and 3 alittle more. they work but are tempormental. all i run is 91 octane from 76. oil is 20w-50 vr1 valvoline and a k&n oil filter. oh i put a new water pump on it. and the dizzy that is on it is from the stock engine. i am lost. thanks for the help. sorry had a brain fart. so i dropped the engine in this morning and connected everything up. and went to turn it over and it just turned over. so my brother put some gas in the intake and it started and ran for a little bit ( like 45 seconds) but it was at 2g on tach and wot. so we played with it. checked spark checked to see if the fuel pump was working and everything was. so i am starting it and it starts to run but 50% throttle it was idling. so my little bro pinches the fuel line and boom it runs normal and is at 4-5g on the tach then bogs. (he is pinching and releasing the pinch really fast.) but while it is un pinched it looks like it is running super rich. it was smoking a bit out the exhaust. so he decided to remove the fuel pump relay and it idles perfect and i am like wtf how is that possible. so i try to rev it and it wants to die. so i barely start opening the throttle and it starts to rev at like 15% it is at 5-6k on tach so i am lost. i have played with honda and old muscle cars but never had a issue like this. my brother thinks it will bite me in the butt. but i dont know. i hope this helps some. thanks guys Quote Link to comment Share on other sites More sharing options...
evan1242 Posted May 19, 2009 Share Posted May 19, 2009 you are exactly right. it IS running to rich. if you reduce the amount of gas (by squeezing the line) going to the injectors and it runs better then it basically pin points your problem. you need to get a fuel pressure gauge on there, and see what kind of numbers you are getting. get a T fitting and put the gauge between the stock filter and the fuel rail. (you want to be around 32 psi at idle) my bet is that it is a faulty FPR, or a bad vacuum line to the FPR from the intake manifold. Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 if that was the case how could the frp go bad in a week plus it has a new vacuum line to it. Quote Link to comment Share on other sites More sharing options...
evan1242 Posted May 19, 2009 Share Posted May 19, 2009 mine went bad in one day. it has diaphragms inside it, and they are unpredictable. do you have a FSM yet? if not, you need one, they can be very very help full. if you do not think that it is the FPR, then go through the entire EFI section in the FSM, and test every sensor that there is, and you will eventually find your problem. things such as the CHTS, TPS, AFM. (you know what i mean) Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 fsm sorry lost on that one or i am just really tired. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted May 19, 2009 Share Posted May 19, 2009 Take your AFM apart and make sure it isn't stuck. Quote Link to comment Share on other sites More sharing options...
evan1242 Posted May 19, 2009 Share Posted May 19, 2009 the FSM is the factory service manual. i call it the book of answers. you can get a free download of it here >>>>> http://www.xenons130.com/reference.html (just select your make and model and then go from there. good luck!! P.S. don't mess with the AFM unless it is your last resort. just clean the connections on the outside of it, and make sure that the flap opens/closes smoothly Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 yup i am tired lol. i am just really confused cause the old engine ran fine with everything and the new engine is all crappy Quote Link to comment Share on other sites More sharing options...
evan1242 Posted May 19, 2009 Share Posted May 19, 2009 thats weird, have you checked compression yet? Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 only thing i have not done yet i am waiting for my buddy to bring a tester by. Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 ok i hope this helps some i made a video. http://videos.streetfire.net/video/my-280zx-issue_683051.htm hope this helps Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted May 19, 2009 Share Posted May 19, 2009 Easy way to check your Fuel isnt a tester... Pull the return line on the rail after the FPR on its way to the line on the car. Get a catch can and place the return line off the rail into the bucket. while running at idle the return line should dump about 2.5quarts in 30 seconds through that line into the catch can. IF you have less than 1quart you have a problem... Also after this test is complete repeat the test only this time watch the return line in the bucket... Give it a goose on the throttle... see how it interrupts the flow of fuel. If you notice the interrupt in flow your FPR is good... Typical failure of the FPR will result in fuel coming out of the vacuum fitting on the FPR when you remove the vacuum line. These tests will determine if you have a fuel delivery problem and you will not have to use the pressure tester. Pressure is not Volume and Volume runs your engine. Dont pull your AFM appart... At least specifically dont remove the electrical cover that hides the magic inside. Remove it from the car and check that the flapper door moves back and forth. There are some specs around on the internet and I think on "BLUE"s website. Blue is the handle for a guy over at zcar.com. Sorry, your going to have to look for the specs and how to test the AFM properly. Removing the cover is a bad idea in most cases unless you have a clean room to preserve the internal components. As far as the old motor goes. How did it not run right? Is it acting the same way as it was in the old car? Or is this in fact a new symptom for this engine? Which motor did the coolant temperature sensor come with that is now in your car? Have you cleaned that sensor and tested its resistance? If you cant find the specs( on Blues website again or the FSM) you can compare it to the other sensor you have as well. Not that, that is a great test of anything but it could help determine a difference between the two. This sensor is a thermistor and its value changes by temperature. So make sure the two sensors are about the same temp. And you should really fix the temperamental injector connectors. Compounding any problems will give you head ache and make it virtually impossible to diagnose. And thats just what leaving the connectors for the injectors or any sensors on the engine will do. Compound other problems... leaving you with "hidden" problems. Quote Link to comment Share on other sites More sharing options...
dark91zc Posted May 19, 2009 Author Share Posted May 19, 2009 i dont have any fuel coming out the fpr. and i am going to check the 2.5 quart test Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted May 20, 2009 Share Posted May 20, 2009 Dont pull your AFM appart... At least specifically dont remove the electrical cover that hides the magic inside. Remove it from the car and check that the flapper door moves back and forth. There are some specs around on the internet and I think on "BLUE"s website. Blue is the handle for a guy over at zcar.com. Sorry, your going to have to look for the specs and how to test the AFM properly. Removing the cover is a bad idea in most cases unless you have a clean room to preserve the internal components. I'm sorry, but that's total nonsense. It isn't magic; it just a rheostat and a few other minor things. They won't implode if you take the plastic cover off. It is specifically made to access and adjust. I'd recommend anyone using it to do pulls and adjust as necessary. Read the link. http://www.atlanticz.ca/zclub/techtips/afm/index.html Take the cover off, start the car and blip the throttle. It will tell you if it's moving through a range smoothly. Quote Link to comment Share on other sites More sharing options...
rayaapp2 Posted May 21, 2009 Share Posted May 21, 2009 (edited) I'm sorry, but that's total nonsense. It isn't magic; it just a rheostat and a few other minor things. They won't implode if you take the plastic cover off. It is specifically made to access and adjust. I'd recommend anyone using it to do pulls and adjust as necessary. Read the link. http://www.atlanticz.ca/zclub/techtips/afm/index.html Take the cover off, start the car and blip the throttle. It will tell you if it's moving through a range smoothly. For anyone that doesnt know exactly what is going on in there it might as well be magic. The fact that by pulling the cover off the unit will expose the carbon trace on the inside to anything that may be floating around. Being that the board is sensitive to even dust accelerating the wear on the unit it is best just not pull the cover in the first place unless you have the proper place and equipment to adjust the unit into spec. There are some "back yard" ways to adjust the unit of which I myself have dabbled with in the past, but again I HIGHLY suggest that you know what you are doing before you pull that cover off. It really is simple once you know what is going on but most people just adjust the spring "til it runs good" which isnt always right. I have spoke with Phillip (aka BLUE) about that link above before. It was posted a few years back. "NOTE: DOING THIS CORRECTLY OR INCORRECTLY CAN POSSIBLY CAUSE PROBLEMS. DO SO AT YOUR OWN RISK. I DO NOT TAKE RESPONSIBLITY FOR ANY RESULTANT PROBLEMS/DAMAGE/HARM." He puts that there to COVER HIS REAR! In this particular case Modifying the unit would most likely be a bad idea. IF the details reported here are accurate then the unit is most likely in good shape as it ran well before hand and the only change was the engine. Then you can deduce the problem lays somewhere else and not with the AFM. Modification of the AFM would only lead to covering up the current problem and again we can talk about compounded issues. BTW The cover was not designed to be removed and adjusted. THE ONLY intended adjustment was the air bypass screw built into SOME of the units. There are even some units in which the cover is counter-sunk to prevent tampering. The Unit is sealed to prevent contaminants in which can disturb the carbon trace and cause a bad signal back to the computer. It was cost effectiveness that Bosch designed into the plastic cover and sealant that prevented the need for a mated surface and cover to be machined and bolted down like other parts on some of the other AFMs. So rather than say all that in the first place it was easier to say what I said the first time through. "...dont remove the electrical cover that hides the magic inside,,, Removing the cover is a bad idea in most cases unless you have a clean room to preserve the internal components." I was not mis-leading or hiding information intentionally. I was hoping that those words would motivate some initiative to anyone reading to search more if they really needed to rather than provoke anyone. Such as search for that link that you did find... and there are many more on specific details about the unit. Edited May 21, 2009 by rayaapp2 Clarification Quote Link to comment Share on other sites More sharing options...
woldson Posted May 21, 2009 Share Posted May 21, 2009 Gonna have to disagree with you sir. I've had mine off for over a year. You do need to mark for original start point and make sure it dose not get away from you when the set screw is loosened. I personally kept having sputtering issues and left it off to get her tuned out correctly, never putting it back on. Now I'm at the point if I put it back on, (been running fantastic for 6mos?), Murphy will bite me. Anyhow, this 25yr plus device is problematic, and down right junk,,,,comparatively. Quote Link to comment Share on other sites More sharing options...
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