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I just started the truck up by starting it with the pedal to the floor. Once it started up, I reved it a little and slowly let of the accelerator. It ran on its own but rough for awhile. The longer it ran the better it seemed to run. I shut it off and tried to restart it. It wouldn’t start without me holding the gas pedal to the floor. I restarted it holding the gas pedal to the floor and once it would idle I got out and checked the injectors to see if one looked like it was spraying more than the other. They look the same to me. Than I started spraying starter fluid around the upper intake looking for leaks but it apparently found none. I shut it down and the third and fourth times I was able to start it without holding the pedal to the floor.
I got some data here that hopefully you can make heads and tails out of. I google how to test the map sensor, coolant temperature sensor and throttle position sensors. This is the results.
Map sensor is showing…
4.78 Volts with 0PSi vacuum applied
3.89 Volts with 5 PSI vacuum
2.78 Volts with 12PSi vacuum
2.08 Volts with 15 PSI vacuum
1.15 Volts with 20 PSI vacuum.Sensor maintained the 1.15 psi for over 2 minutes and the voltage went up to 1.17 towards the middle of two minutes, however the voltage never dropped until I released the pressure.
Coolant temperature sensor showed…
approximately 2.5 ohms at room temperature and went down to 0.21 ohms in 190 degree boiling water. It started to go back up slowly once it was removed from the hot water.
Throttle position sensor shows…
0.51 volts on the signal wire, a good ground and the power wire shows 5.07 volts. The signal wire goes from 0.51 volts at an idle to 4.56 volts at wide open throttle.
Oil pressure sensor tan middle wire shows a good ground. Grey wire show 8.75 volts and the red wire shows 12.37 volts. If I jump the two end wires together the fuel pump runs constantly however, this time is wont start. I had this same issue about a week ago where the truck was flooding out and not starting. Once I jumpered the two wires on the oil pressure sensor, the truck started up on its own. I think it was a coincidence though.
Truck was showing three DTC’s however the light was not on the last time I drove the truck. I think all three are from me disconecting sensors and cranking the engine over trying to start it. It shoued DTC 15 open circuit in coolant temp sensor, 22 something about the throttle position sensor and 54 which is fuel pump circuit low voltage.
BTW, I found out the truck will start if I keep the gas pedal to the floor when cranking, however the engine just dies as soon as I let off the pedal.
I got some data here that hopefully you can make heads and tails out of. I google how to test the map sensor, coolant temperature sensor and throttle position sensors. This is the results.
Map sensor is showing…
4.78 Volts with 0PSi vacuum applied
3.89 Volts with 5 PSI vacuum
2.78 Volts with 12PSi vacuum
2.08 Volts with 15 PSI vacuum
1.15 Volts with 20 PSI vacuum.Sensor maintained the 1.15 psi for over 2 minutes and the voltage went up to 1.17 towards the middle of two minutes, however the voltage never dropped until I released the pressure.
Coolant temperature sensor showed…
approximately 2.5 ohms at room temperature and went down to 0.21 ohms in 190 degree boiling water. It started to go back up slowly once it was removed from the hot water.
Throttle position sensor shows…
0.51 volts on the signal wire, a good ground and the power wire shows 5.07 volts. The signal wire goes from 0.51 volts at an idle to 4.56 volts at wide open throttle.
Oil pressure sensor tan middle wire shows a good ground. Grey wire show 8.75 volts and the red wire shows 12.37 volts. If I jump the two end wires together the fuel pump runs constantly however, this time is wont start. I had this same issue about a week ago where the truck was flooding out and not starting. Once I jumpered the two wires on the oil pressure sensor, the truck started up on its own. I think it was a coincidence though.
Truck was showing three DTC’s however the light was not on the last time I drove the truck. I think all three are from me disconecting sensors and cranking the engine over trying to start it. It shoued DTC 15 open circuit in coolant temp sensor, 22 something about the throttle position sensor and 54 which is fuel pump circuit low voltage.
BTW, I found out the truck will start if I keep the gas pedal to the floor when cranking, however the engine just dies as soon as I let off the pedal.
I know I just replaced the coolant pressure sensor on top of the intake but lots of stuff points to that. Is there a way to test this? I read if the sensor is bad it could make the ECM think the engine temp is -26 degrees and flood the engine with fuel to try and get it to start. Also what about the throttle position sensor? Is there a way to test that?
I know I just replaced the coolant pressure sensor on top of the intake but lots of stuff points to that. Is there a way to test this? I read if the sensor is bad it could make the ECM think the engine temp is -26 degrees and flood the engine with fuel to try and get it to start. Also what about the throttle position sensor? Is there a way to test that?
I just had a feeling I would be back here again. Almost one full week since it started working again and its back to no starting. Same issue. Flooding itself out. I did replace the oil pressure sensor and fuel pump relay last time so they are new. I tried unplugging the oil pressure sensor pigtail and jumpering the wires to get the fuel pump to constantly run like we did last time and this time is made no difference. The car didn’t magically start working after I did this like last time. I unplugged one of the injectors and once again the truck tries to start, however this time I wasn’t able to get it to run.
So here we go again. How disheartening is this although I can’t say I didn’t expect it to pop up again.
I just had a feeling I would be back here again. Almost one full week since it started working again and its back to no starting. Same issue. Flooding itself out. I did replace the oil pressure sensor and fuel pump relay last time so they are new. I tried unplugging the oil pressure sensor pigtail and jumpering the wires to get the fuel pump to constantly run like we did last time and this time is made no difference. The car didn’t magically start working after I did this like last time. I unplugged one of the injectors and once again the truck tries to start, however this time I wasn’t able to get it to run.
So here we go again. How disheartening is this although I can’t say I didn’t expect it to pop up again.
I have found another thread on a different website where the guy describes exactly what mine is doing with building 12-13 psi of pressure and releasing it as soon as the pump stops. He updated the thread where a couple people said TBI have a built in pressure release. Does this sound correct to you? Here is the link. http://coloradok5.com/forums/showthread.php?t=163275
I have found another thread on a different website where the guy describes exactly what mine is doing with building 12-13 psi of pressure and releasing it as soon as the pump stops. He updated the thread where a couple people said TBI have a built in pressure release. Does this sound correct to you? Here is the link. http://coloradok5.com/forums/showthread.php?t=163275
I clamped off the fuel return line and the pressure tester maintains pressure even when the pump stops running. So what could this mean? I guess the check valve isn’t bad. I took the truck for a test drive and it did good. I just hate when problems fix themselves because I don’t know if the problem really is fixed or not. Hate to have it die on me again. I did replace the oil pressure sensor. The engine does die when I unplug the fuel pump relay when its running. From what I understand of that flow chart, the engine is supposed to keep running if you unplug the fuel pump relay as the oil pressure sensor takes over. Not sure if this will be an issue or not. Drove the truck to work this morning and its running normally.
I clamped off the fuel return line and the pressure tester maintains pressure even when the pump stops running. So what could this mean? I guess the check valve isn’t bad. I took the truck for a test drive and it did good. I just hate when problems fix themselves because I don’t know if the problem really is fixed or not. Hate to have it die on me again. I did replace the oil pressure sensor. The engine does die when I unplug the fuel pump relay when its running. From what I understand of that flow chart, the engine is supposed to keep running if you unplug the fuel pump relay as the oil pressure sensor takes over. Not sure if this will be an issue or not. Drove the truck to work this morning and its running normally.
Well I replaced the oil pressure sensor. It didn’t seem to change anything, although the car is still starting on its own. Gonna test drive it tonight. No idea what to think
Well I replaced the oil pressure sensor. It didn’t seem to change anything, although the car is still starting on its own. Gonna test drive it tonight. No idea what to think
ever since I did the thing jumping the two leads of the oil pressure switch together the truck has been starting almost normally with only a small amount of hesitation. This sure is strange