Hsoj Posted July 18, 2015 Share Posted July 18, 2015 Ok, Something isnt right. 1982 lifted wagon. So intermittent wipers stopped working last year and I havent gotten a new relay. Now move forward. My ride left me stranded 8-9 times, wondering whats wrong. Just as I'm about to call a truck, it starts. So fast forward past 2 fuel pumps and wires for them as I have a gauge that shows no fuel pressure, always inline. Past the full tune including a new coil. Past my fpcu being checked and resoldered and an ignition switch replaced. I could walk out in the morn and start it. and in 3 min, its dead. When it starts, the fpcu clicks, (relay works) fuel pump primes and fires like a champ. When it doesn't, there is nothing. No click, no pump priming. I've got 2 82-83 FPCUs and both seem to work....or dont. So, whats in front of the fpcu, but down wind of the ignition that could be causing this crazy failure intermittently? What am I missing? I put a switch in to give power to the pump if needed but since the fpcu runs the coil, disty and the pump in a feedback situation nothing works when it doesnt work. What am I missing? ( besides hair now...) Quote Link to comment Share on other sites More sharing options...
Dinky26 Posted July 18, 2015 Share Posted July 18, 2015 Can you get it started by jumping it? How old is your starter? Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 18, 2015 Author Share Posted July 18, 2015 (edited) Starter is fine, battery is fine, good grounds everywhere, Weber is fine, there is like... no power or ground to the fpcu or some signal getting through to power the coil and the fuel pump. Distibutor was rebuilt about 5 yrs ago. I'm thinking this might be an 82-83 only thing as the later models all have 4 pin fpcus instead of 6. So I've noticed when there is no fuel, there is also no spark. Edited July 18, 2015 by Hsoj Quote Link to comment Share on other sites More sharing options...
TomRhere Posted July 18, 2015 Share Posted July 18, 2015 Check the wire that feeds power to the fusible link box. Make sure that the connection is good at the box. The center link (Red), feeds power to the ignition switch thru the White wire in the harness. Check to see if you have power there when it acts up again. The Black wire from the ignition switch feeds fuses 12 thru 16 in the fuse box. The FPCU is fed from this wire before the fuse box. If you have power on the White wire, but not the Black wire with key in "Run", check the connector for the ignition switch. The body side of the connector for the White wire tends to lose it's connection. Age and heat from the amp draw are the culprits there. 1 Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 18, 2015 Share Posted July 18, 2015 The FPCU or revolution sensor doesnt run the coil or disty. It uses the tach signal to trigger an internal relay for the fuel pump and, on some cars, the choke element. So if you dont have spark you cant get fuel. Theres probably nothing wrong with that sensor. Toms post suggests a much more likely cause for your troubles (intermittent wiring issue). Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 18, 2015 Author Share Posted July 18, 2015 Ok, turned key this morn. It cycled the fp and started fine. The relay clicked like normal. then the pressure in the fuel line dropped and the car died. No click from fpcu after that and it didn't cycle. The fuse box reads normal the fusible links check the coil has power. Now it wont start again.. Later I'm going to test the ignition control unit, the primary and secondary electronic ignition system if I can find them from the haynes book just to not miss anything as it has the tests for the disty and on. I'm not sure where the icu is on this thing or the ignition relay if that has anything to do with anything. Is there an easy way to test the tach wires? Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 18, 2015 Share Posted July 18, 2015 I put a switch in to give power to the pump if needed If you are bypassing the FPCU correctly then you should be able to get fuel despite the failure. Are you sure you are having intermittent no spark? The ignition module is under the disty cap. It gets its power at the coil. IIRC tach signal wire is yellow from the coil to the tach and at the FPCU, not sure where it splits in the harness tho. Do you have a tach? I realize the safety factor and purpose of this system, but if the ignition module checks out and you know you have proper voltage to the FPCU (the controller is bad or wiring mystery) it might be time to just consider a permanent work around. You could simply wire up the pump to the run position of the ign switch. Or if your like me there would be a relay (-) triggered by an oil pressure switch, which could also be triggered by a seat belt timer relay, or such, that would be thermostatically controlled (for priming). I m just that wacky... Im also a huge fan of eliminating hard to find old parts and replacing them with stuff thats readily available. Quote Link to comment Share on other sites More sharing options...
TomRhere Posted July 19, 2015 Share Posted July 19, 2015 How much time between loss of fuel pressure and engine dying? If, the float bowl is full when fuel pressure drops, the engine should idle for a few minutes, until the bowl empties. If the engines dies relatively close to the time the pressure drops, you are loosing the signal from the module in the disty. Bad wiring, faulty module, yadda, yadda. I had an instance of the magnet under the "C" shaped piece in the disty shattering, causing loss of signal and engine dying. That one threw me for a bit, until I started tearing the disty apart. 491987401 for pre '84 491988711 for '84+ Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 19, 2015 Author Share Posted July 19, 2015 Thanks you guys. The switch does tell me I have an intermittent spark, because when it doesnt fire I can give it fuel....regardless of it working right. It takes a few minutes after pressure drop for the car to die... after it starts....when it starts. I can assume its from the bowl emptying. But then it wont start again even when I give it fuel by using the switch. Its funny because It would drive sometimes a few miles, then die or just die right away and not start again. One day I could make it about 5 miles between deaths. (of course I had the thing strapped with tools and the rack covered in ladders and I needed that thing to drive!) Tom, what are the part numbers at the bottom? Are they disty part numbers? I'm checking out the module this morn..I'll update soon. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 19, 2015 Share Posted July 19, 2015 I had an instance of the magnet under the "C" shaped piece in the disty shattering, causing loss of signal and engine dying. That one threw me for a bit, until I started tearing the disty apart. 491987401 for pre '84 491988711 for '84+ The part numbers are for the distributor magnet he mentioned. I kinda think such a failure would be due to the well known slop these distributors develop. That would have been a tough one to pin down. There is also several points for wire connections to weaken or corrode. The nuts on the posts of the coil could be loose. A ring terminal there could be failing at the crimp. Then theres also the connections on the module under the cap. Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 19, 2015 Author Share Posted July 19, 2015 (edited) I think I got somewhere..not out of the driveway yet though... disty seems fine, pick up coil is working. So as I was testing out the coil wires, tach wires ect. I pulled a black white wire off the coil that goes directly into the harness and the fp started to work. I've checked it for shorts all the way into the passenger bay but cant find out where it goes from there or if it changes color. I comes out of the green smj at the passenger door hinge area and looks to go to the dash area but I cant find the other end. It carries 12 independently of the coil. Also, if I pull the coil fuse, the fp starts and the fpcu clicks over. So I have 3 wires off the coil, positive side, one to the disty, one to the noise condenser, and one into the harness. Why would the fp run if I pull the power to the coil? Edited July 19, 2015 by Hsoj Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 19, 2015 Share Posted July 19, 2015 Disconnecting power to the coil, with ign in run, will cause the the FPCU to trigger momentarily. Its normal as the breach creates the pulse effect its looking for. You could keep it going by hooking and unhooking. Dont do it tho . The wire that is giving you grief is the power for the ignition system and ties in somewhere heading to that fuse you noticed had the same effect. What your noticing sounds normal, as long as the FPCU only turns the pump on for a second or 2. If it runs continuously with the fuse out Ide think the relay inside may be hanging up. Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 19, 2015 Author Share Posted July 19, 2015 Ok good to know. It does run continously. I'll check the relay. I rechecked the pickup coil in the disty and its not reading any ohms either now. I'm going to see if I have a spare or pull one from another car to try it out. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 19, 2015 Share Posted July 19, 2015 Are you refurring to the ign module? Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 19, 2015 Author Share Posted July 19, 2015 Yeah. So I replaced the battery in my good tester, went to my storage tested 2 good distys and one unknown and they all read the same 2.200 to 2.500. I thought it was .600 to .850 but whatever. I guess my other tester wouldnt read the proper ohms...I...dunno. Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 19, 2015 Author Share Posted July 19, 2015 (edited) Ok. I replaced the fpcu and still no prime. Though when I pulled the fuse after installing the newer one, it only cycled for a few seconds instead of running continuously. The magnet in the disty is fine too. I'm at a loss. Edited July 19, 2015 by Hsoj Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 19, 2015 Author Share Posted July 19, 2015 Does anyone know if an 82' 6 pin and an 83' 6 pin fpcu are really interchangeable? They look different on the inside and the relays are different. The wiring diagrams say the cars are wired the same but there are a lot of 82 only bits out there. The harnesses look the same and only have very minor color differences. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 19, 2015 Share Posted July 19, 2015 Bypass the FPCU for now. Solve your spark issue 1st. Im wondering if your meters are fine but the module is not. Remember you cant get fuel without tach pulses (spark). If your really getting fed up you could try running a wire right off the battery to the (+) of the coil. If that works then hook the up FPCU and try the same test with it installed. If all is solved your issue lies with the ign switch or the wiring. My opinion.... Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 20, 2015 Author Share Posted July 20, 2015 Ok. I put in a new/used disty pickup coil, she fires and starts but there is no fpcu relay click until it runs. The power to the coil is fine and has been. I've just about ran all the tests I can. I can prime it by switch which is fine with me as long as she runs. I'm wondering why both fpcus dont fire for initial pressurization now. I just put in a new ignition switch (non subaru though) too. I think I might try to yank a subaru one to try out...Are ea82 ignition switches the same? I know they look the same but I don't know if they interchange. I wonder if that is part of the problem with the intermittent fp startup, the ignition switch. ($140 at the dealer is why I went aftermarket.) Every, time, I think, I get somewhere, she runs, and, leaves me, stranded. (shatner comma) 251k on this girl. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 20, 2015 Share Posted July 20, 2015 Im not aware of a priming cycle for these cars. As Ive mentioned it needs a tach signal. If you drive the car regularly this wont be an issue even if it sits for days and the float chamber runs dry a couple extra seconds of cranking and pedal pumping is all that you will need. The switch you installed should be fine. Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 20, 2015 Author Share Posted July 20, 2015 That's the second to three you hear the pump prime before you hit the starter I assumed. I'm hoping it is at least going to be drivable...Its not a turn key car unfortunately but we'll see as time goes on. I gotta make my wiring more solid than the temp stuff i ran. I totally thank you for the help! With the feedback from the coil to run the f/p and the total failure all at once of this car, some clarification was truly needed. I'm hoping we're at the end of it. Thanks again! To summarize; fpcu, disty pickup coil, and starter switch failure combining into a month of fun leading a whole new ignition system and fuel system. Oodilally fun! Whoopie! Quote Link to comment Share on other sites More sharing options...
TomRhere Posted July 20, 2015 Share Posted July 20, 2015 Here's hoping that the problem is solved. Chasing electrical issues can be down right aggravating at times, especially if one doesn't have good wiring diagrams. I have never heard the fuel pump "prime" before starting on any of the 4 Factory Stock BRATs I've owned. My '82's pump is hot wired, not by me. I've read on here that some say they should, others say they don't. Quote Link to comment Share on other sites More sharing options...
ihscout54 Posted July 20, 2015 Share Posted July 20, 2015 I as well, have noticed others mentioning the priming cycle. Yet Ive never noticed any of my cars do it. Altho ive never kept the stock setup for long either. There are several different revolution sensors that Ive seen. 4 pin, a gray 6, and a black 6 pin. Perhapse one of them has an internal timer circuit. Sure hope its solved. Quote Link to comment Share on other sites More sharing options...
Hsoj Posted July 20, 2015 Author Share Posted July 20, 2015 I hope its solved too! If its not im pretty sure i can bypass the wiring or redo it if it comes down to that. I have a spare harness I can use as a reference if really needed. So, funny, my 87 brat and my 82 wagon prime like that and my 87 has an ej with the brat fpcu disconnected! Quote Link to comment Share on other sites More sharing options...
ferp420 Posted July 21, 2015 Share Posted July 21, 2015 ive had simmiler issues with a ea82 it was a missing ground i went round and round the car i couldent figure it out then my daily driver did it after a funky off road off camber play run and it pulled my negative cable off the body the trans side was still hooked up as where the other body grounds but they wouldent run with out the main ground running to both the body and trans i felt so stupid that it took me so long to figure it out its easy to over look Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.