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Engine Will Not Start - Injectors not Firing
Hi all. I'm looking for some help with a non starting problem.
Engine is 5.0 HO from early 90s Mustang. Only modification is alloy heads. This is a fuel injected motor with an A9L computer. Engine has been running fine but all of a sudden will not start. Engine cranks and there is plenty of spark. Plenty of fuel getting to the engine. Fuel filter is clean and the tank half full. Attached a Noid light and seems the injectors are not firing. Tried to read fault codes using test light. This light is constantly on with ignition off or on even before I trigger the test. I believe this indicates a problem. If anyone can come up with suggestions I would be greatful. Cheers Bob |
Crank angle sensor? If it has one.
Earth wire for injectors? Probably not earth wire because i think there would be more than one. |
I believe they are controlled through a ground connection. There is a constant 12V at each injector with ignition. Have measured this and is OK. Experts please correct me if wrong.
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I dont have experience with that particular set up, but i would be looking at the crank angle sensor or equivelent.
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spray aerostart down throtle body
if it starts then it sure is a fuel issue noid lights are not the perfect tool if u run aftermarket ecus some aftermarket ecus will not pulse a noid light get afew small leds and try them and see if they pulse or get a long screwdriver and place flat tip on injector and hanlde on your ear listen for clicks i know ive had issues with autronic ecus which sometimes wont pulse injectors its weird but ive only had these issues with aftermarket so try another way of testing to see if injectors pulse if u have spark then cranks sensor should be fine if error light is on when ign is off then its probably wired up wrong as u should not have ign to the globe when ign is off light should come on when ign is on then i guess flash if u put it in test mode i dont knwo bout a9l ecus so not sure on how to retrieve codes if its factory ecu then should not be to hard getting info for it |
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Thanks Sideshow. This is exactly what I did with a test light.
The test light stayed on constantly (not ign light). Installing the trigger jumper wire did not make any difference. I have tried aerostart. Tries to run for a very short time. I'll try the screwdriver trick but don't think they are firing. Thanks Bob |
some ecus have main earths for ecu
and other earths for injectors so might be bad earth check power to injecotrs when cranking u might have power with ign on then loose it once u goto crank very very common when people fit new motor to old car the crank or balast/coil bypass wire might work but not the main power find the red power wire to injecotrs and splice into it then run other end to pos battery then try starting it |
Thanks Sideshow, I'll give that a go
Cheers Bob |
Just read this Bob. I had the same problem and the same motor and EEC. I did what Sideshow suggested and it started, thus showing it was electrical. I checked the voltage at the TPS and it was just ok, and also the voltage at the injectors. All down. So then to the fuses and relays and connections and earth/s ... Last it was down to the EEC. In my case that was the problem. Got another one and hey presto!
I have lots of info on this motor and a Trouble Code reader (costs only $25 and is worth its weight in gold) and two spare A9L computers if you need one. |
Oh and Bob another common problem is the connector to the EEC. - clean all the points of the connector and ensure that none are pushed back or bent. Peter H was a great help in my case.
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Merv, Thanks for the advice. This is frustrating. Engine was running one minute and wont start the next day. Hadn't had a chance to try sideshows suggestion od powering direct from the battery into the red injector wire although I have 12V there at the moment. Gut feel is EEC.
Would like to borrow a spare A9L if I could to rule that out. Cheers Bob |
check the ground at the back of the cylinder head, check the computer ground it has a wierd black connector, and also the salt and pepper connectors had issues it connects the engine harness to the computer harness they are to large connectors at the back of the motor one is white and one is black. also go to fordfuelinjection.com there is alot of good info there.
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Thanks wrench87. I have checked these areas and they seem OK. That is a handy website. I have downloaded information from there in the past. Appreciate the input
Cheers Bob |
I know how you feel Bob. I had the same experience. Happy to lend you an EEC. I also found this below, as it applied to mine - I had a manual harness and an auto EEC (A9P). You are sure that you have a manual harness? The A9L is the manual EEC. It all centres on pin 30:
"Manual/Automatic EEC Code Wiring Differences There is a hardware difference between an auto processor & a manual processor. The difference is because of the way the NDS [neutral drive switch, manual trans] & the NSS [neutral safety switch, auto trans] are wired. They are both wired to the same pin#30 but the auto trans wiring grounds the pin to the starter solenoid & the manual grounds to signal return, during crank mode there is a voltage spike sent to pin-30 so the auto trans processor has a diode on pin 30 where as the manual processor doesn't, most of the time this won't cause a problem unless you get into a prolonged crank condition. I've been warning people about converting an auto to a manual and using the manual EEC with the auto wiring harness; those that want to convert their automatics to manuals, and swap the ECM, need to clip the wire going to pin 30 or else the ECM will fry." |
Merv, Pretty sure my harness is from a manual. Engine, gearbox, EEC (A9L) and harness all came together and connected.
Wouldn't mind having a spare EEC if you are interested in selling one. PM me if interested. Thanks Bob |
If the ECU has had a chip added to tune it, the chip may have went bad. If so, pull the chip out and it will go back to the factory tune.
Since it is not flashing the codes, I suspect ground, fuse, or bad ECU. |
Happy to Bob but call Peter H first and check with him.
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My spare A9P EEC is on the way Bob. For interest sake, check the 'board on your old EEC and see (with a magnifying glass) if one of the small wires at the base (see pic) is burned/blackened. They can often be repaired easily (blue wire).
http://www.clubcobra.com/photopost/d...EEC_repair.jpg |
Good to hear that the EEC arrived Bob and even better that all is working now.
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