I have an issue with my 1995 3.8L SC. It will not run and after changing a few sets of plugs, it’s getting way too much fuel. It tries to start if I have the throttle wide open or unhook the fuel delivery line. I pulled the injector rail off and it is firing all 6 injectors at once. I have consulted several sources and they all say this engine should be sequential injection. My question that no one can answer is: what would make my injectors “batch fire”? Does the computer see something it doesn’t like? Cam synchronizer in the wrong place? I don’t know. If anyone could help me out here that would be great. Thank you guys!
1995 Thunderbird SC 3.8L- Batch Fire
- Thread starter tbird95sc
- Start date
Same car that you finally got running January of this year after rebuilt engine installed in July? I know you had Injectors in & out twice then. Maybe harness got pinched-shorting them to all energize at the same time? Did this issue come after changing spark plugs & if so, why were you changing them again? Unless you've moved Cam sensor since it ran last, I see no reason you would suspect that.
Dougs suggestion to check the harness for a short is a good idea , but it sounds like your ecu injector driver circuit is fried ...exterior sensors , cam and crank only tell the comp where the crank is at and when to fire the plug and inject fuel per cylinder, [ not batch fire ] ... easiest test would be swap in another comp if you can get one to do a quick test .
If you have attempted many times to get it running in this state it could have a load of raw fuel in your oil by now, I would be changing that first .
Dave.
Yes same car, and I never got it running. It loads up with fuel and floods too bad. That’s why I’ve went through 3 sets of spark plugs. I’ve tried switching computers. I bought a brand new on and had it programmed, same issue. It squirts all injectors at the same time with the rail off. I have good compression, air, and spark…this is the only I can think of why it won’t run. It tries to start if I hold it WOT or if I unhook the fuel supply to the rail. I will look around the harness and check that out. Thanks
Thanks Dave. I’ve tried a new computer already, I had it programmed and still same issue. I installed another ground strap from the head to the body, thinking it may help but it didn’t. Like I said to Doug, I have good compression, air, and spark—I’m thinking it’s flooding itself out. I just have to figure out why it’s squirting all 6 injectors at the same time. I am not a huge Ford guy, so I was unaware what “batch fire” was until I did some more research. Definitely a frustrating situation.
Ok in that case, pull the engine harness, get a proper schematic and do a continuity test and cross short test, so example , test wires - point A to point B with a beeper type volt meter , then do a short test from the same point A to each of the other wires in that harness ..it will take a while but it could regain some sanity lost chasing this problem . ... side note , in the 90s I build some test fixtures for the Fords keyless entry modules ... delivered them , got a call from the engineer shortly after stating my fixtures were blowing up there very expensive RF test equipment ... I of course panicked.. then went over to the plant and did the full test including cross test to prove no short outs.. no issues... turned out engineer gave me the wrong pin out to build the harnesses for the fixture that he signed off on .. ... crisis averted .. well mine anyway.
some things to keep in mind, with ignition on , each injector always has voltage on one wire and at the same time , they are grounded to fire them threw the injector circuit [ those ground wires I believe are black on the injector harness ?, you could pull each injector connector and do a quick test-light test on the ground side to battery power to see if they are grounded at some point ] , BUT make sure you **disconnect the cars power or the main harness completely from the comp and power source before you start messing around in there** .. best/safest way is to take the engine injector harness off for proper inspection first .. you may find it quickly at that point ... pinching wires is easy to do ... I am tired ,its late, so hopefully this makes sense.
PS, if possible I would only be using a known good comp out of a running car , not a re man , or re programed to test , its a slight chance but still a chance that new comp is no good .
Good luck
Dave.
Well you can see why I'm confused, on Jan 10th you posted that it started right up & ran well after replacing a damaged 175 amp maxi fuse? Now you are saying it never did? Seeing you've just fired the parts cannon at it with little or no diagnostics( you didn't buy a reader until 3/4 of the way through your process) I don't know what to suggest. Anybody trying to help you should read all your post's from July forward to get a better idea of all the components you have touched/replaced/disturbed. The biggest one being the car didn't run when you purchased it & never has. Rebuilding the motor didn't cause the issue.
Good luck
Doug
