Any ideas why this car still will crank, but not start?...thanks,...Renee
Any error codes (DTC) from the ECU module? Is there gas at the injectors? Fuel pump OK?
Hi, Might you know if there was a fuel problem, i.e. the ecu, or fuel pump...would it inhibit the car from firing?...it's cranking all day long...not interested in starting up.
thanks so much!
Step#1: verify that you are getting fuel. There's a fuel pump test connector floating on the firewall harness. This should show +12V if the pump is getting power.
Step#2: crank the engine for say 10 seconds. This should allow the pump to fill the injector rail. Ign off, take out the two M10 bolts that secure the fuel feed pipe to the injector rail, CAREFULLY crack the joint. There should be some residual gas pressure. If there's not, you are not getting fuel. Could be that the pump is not working (you should be able to hear a whirring sound from the as tank), or the fuel filter is blocked.
Step #3: verify that the engine is getting spark. A timing strobe is best. Hook it up on lead#1 and see if you get spark on cranking. If there's no spark, the ECU is not driving the coil for some reason.
Step#4: is the ECU putting out an error code. The Check Engine Light (CEL) should turn on when the IGN is switched on, then after about 5 seconds turn off. You can check codes on a 91 with an analog voltmeter across the check connector diagonal corner pins. A long pulse == 10, short pulse = 1, so eg L L S S S == code 23. A steady short pulse L L L L L L L L L L is normal operation. If the output is +12v, then the ECU is NOT working.
NOTE THIS DOES NOT MEAN THAT THE ECU is fried. A wiring error/fault or a misconnected engine harness can also cause the ECU to shut down, which means of course the engine won't fire.
If the ECU check is showing +12v, try this: Disconnect the harness connections to the air cleaner, the throttle body, the crank sensor and the engine coolant temp sensor (This is the two pin MIDDLE sensor on the thermostat housing: the upper two pin is the A/C temp switch). See if the ECU starts showning any error codes. Reconnect sensors one at a time to see what is shutting the ECU down.
Check the engine coolant temp sensor: one pin (black or green-black wire) should be grounded, the other should be either +5v or +12v. This sensor is critical: if its disconnected or the wires are broken due to engine heat (common problem), the engine can be very hard to start.
Good luck.
Stewart DIBBS
Check fuel pressure, hot/cold and see if the plugs are firing. TG
Even easier...pull the fuel pressure regulator return line and see if gas pours out.
After you have cranked it a bit, remove one or two spark plugs. If they are wet, and smell of gas, then you are probably getting the fuel you need.
Have you checked for ECU error codes?
Could this be a timing issue??
are there any ignition sensors that would prevent the coil from firing
- if they're bad... other than the camshaft position sensor and ignition power transistor, and obviously the coil packs, and ecm?....if all these are working, and its not a wiring harness problem, are there any other sensors that could cause the coils not to fire...theyre getting gas to the injectors....and also the timing has been checked. Many, many exasperated thanks!.
Maybe I missed the post, I did go back and reread them, but,,,, do you have any error codes coming from the ECU, what is the output of the ECU error port? Have you tried step 4 in Stewarts post? Is the ECU new from the OEM, or just new to you (in other words, is it used) how do you know it's working (see step 4 in Stewarts post). Do you have, and know how to use, a Digital or analogue meter.
No...short of a bad wire, I can't think of one. You may want to re-verify the cam/crank angle sensor is at TDC. 180 degrees off may be a problem with a 4 cyl. But be sure you are getting spark first....hell pull a wire and hold it to a good ground and really be sure. Just wear gloves or dance the
20KV dance like I have done many times (doesn't really hurt..much). Next is compression. If you don't have enough compression, the cylinder wont fire at all. In fact, raw fuel hitting the cylinder walls will lower the compression even more. Also double check the injector circuit. Fuel in the rail doesn't mean the injectors are firing.MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.