letitsnow Posted September 7, 2009 Share Posted September 7, 2009 As the title states, The engine will start and run on 6 cylinders but numbers 1, 2, and 3 die after 5-10 seconds. Things I've tried: Check ignition timing Check cam timing Check valve lash Change spark plug wires around Change spark plugs around Change injector wires around Change injectors around Check compression(125-135 on the offending holes) Listen for hissing when pressurizing the cylinder with an air hose at TDC Play with dwell settings on the MS1 Swearing loudly at it The plugs and wires are new, the cap and rotor came with the dizzy and looked new, I'm going to replace the cap tomorrow. The engine is a '77 bottom end with a solid p90 head, 280zxt manifold and turbo, 280zxt injectors and fuel rail(had the injectors cleaned and flowed), MS1, open MSA downpipe, 280zxt optical dizzy, no turbo to TB pipe yet. If the cap doesn't fix it, I'm stumped. Datalog of it losing the 3 after startup, I put a flag roughly when each one died. You can see one coming back when the rpms increase and then drop back off. Throttle didn't move at all after it was started. 3 cyl.zip Quote Link to comment Share on other sites More sharing options...
eec564 Posted September 7, 2009 Share Posted September 7, 2009 How's the megasquirt wired? I bet it's injector channel 1 to cyl 1, 2 & 3, and channel 2 to cyl 4, 5 & 6. It certainly sounds like a problem with the injector driver or something else in the megasquirt. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 7, 2009 Author Share Posted September 7, 2009 That's how I've got it wired, I did switch them around to test. It didn't make a difference as to which ones fired. I also checked to see if the injectors are firing by listening with a large screwdriver. Quote Link to comment Share on other sites More sharing options...
eec564 Posted September 7, 2009 Share Posted September 7, 2009 What exactly did you switch around? Did you drive different injectors from different injector drivers? Did you simply swap injectors between cylinders? Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted September 7, 2009 Share Posted September 7, 2009 to me it sounds like you have your warm up enrichment going through both injector channels but you only have one injector channel reading off of ve table one Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 7, 2009 Author Share Posted September 7, 2009 I switched the drivers around and the injectors between cylinders. I looked at the datalog and noticed that DC2 was twice DC1, the I went out to the car and changed the injectors to simultaneous from alternating, this made the DC's the same but it didn't make it run any better. I can hear all of the injectors firing when I listen to them with the screwdriver method. Checked compression again, it's 135-140 across the board. This is the msq I'm using. running on 3 cyl.zip Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 8, 2009 Author Share Posted September 8, 2009 It was air in the fuel lines. I haven't figured out if I just didn't prime the fuel pump correctly or if there is an air leak in the tank. Quote Link to comment Share on other sites More sharing options...
eec564 Posted September 8, 2009 Share Posted September 8, 2009 That is kind of weird. Normally air goes through quick with an electric fuel pump. That was still weird to see different duty cycles on the different channels. Maybe take a quick run through review mode to see if you left anything on. Simultaneous vs alternating shouldn't really change that. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 8, 2009 Author Share Posted September 8, 2009 It's really weird, but if it still runs good tomorrow I'll be happy. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 13, 2009 Author Share Posted September 13, 2009 It appears that my fuel pump is bad now. There is no pressure at all in the fuel rail after running for a few minutes. Quote Link to comment Share on other sites More sharing options...
eec564 Posted September 13, 2009 Share Posted September 13, 2009 Check the filter, and you can do a free-flow test as well. Check the FSM, there should be a certain amount of fuel that should flow per minute if you unhook the line from the rail and put it in a bucket. Or do you have a pressure gauge on the rail and know for certain? Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 14, 2009 Author Share Posted September 14, 2009 No filter, I know, it's dumb, but I drained the tank and there was NO rust or other garbage. It's a walbro 255lph gsl392, it gets super loud if there is any pressure in the line. It also takes at least ~2 min to pump a gallon of gas free flow(it might not have even been a gallon), that works out to about 115lph. I should really time it, but I'm convinced it's bad. It flows a similar amount pumping from one gas can to another outside of the car entirely. Quote Link to comment Share on other sites More sharing options...
naviathan Posted September 14, 2009 Share Posted September 14, 2009 That's odd that it gets louder with pressure. Every inline gravity feed pump I've used gets quieter with pressure and screams when it's dry. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted September 14, 2009 Author Share Posted September 14, 2009 If I pinch the pressure side with my fingers, the pump howls. Quote Link to comment Share on other sites More sharing options...
Bart Hoedemaker Posted September 14, 2009 Share Posted September 14, 2009 Get a new fuelpump and filter. Quote Link to comment Share on other sites More sharing options...
eec564 Posted September 14, 2009 Share Posted September 14, 2009 Sounds like it could be bearings in the pump that are no longer bearings. The best pump/filter combination I've found is tank - strainer - filter - engine. Quote Link to comment Share on other sites More sharing options...
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