Help With Electrical
- Thread starter Foxfirst846
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That is perfectly normal.
The fuel pump runs when the PIP sensor in the distributor sends a pulse to the computer; no pulse and the fuel pump does not run.
That prevents the engine from being flooded when you turn the ignition to run but don't crank the engine. The pulse signals the computer to turn the fuel pump relay on for 2-3 seconds.
Once the RPM increases past a certain point, the pulses become a constant on signal that is sent to the fuel pump relay.
What seems to be the problem? Cranks but no start, runs rough, just fiddling with stuff to see how it works?
Tell us what the symptoms are and we can point you in the right direction.
Unlike the goverment we really are here to help, but we do require an audit of any modifications done.
Tell us what the symptoms are and we can point you in the right direction.
Unlike the goverment we really are here to help, but we do require an audit of any modifications done.
Hey thanks for all the help!! The car will start and run fine when it first starts. But then after it warms up I have to press gas pedal to get it to start. I've gone through the crank no start checklist.. I've replaced the ECT sensor.. Checked the codes only getting egr valve and O2 sensor code. Just trying to figure out why it takes holding gas pedal to floor to start when warm. Not a serious problem I can do that and it's fine. But I know it's not supposed to be that way and if it's an easy fix I'll do that. Plus I bought a used MSD distributor that supposedly was in great condition. But it didn't make the fiel pump prime like that.... Does that mean that distributor I bought needs pickup coil replacement?
Hey thanks for all the help!! The car will start and run fine when it first starts. But then after it warms up I have to press gas pedal to get it to start. I've gone through the crank no start checklist.. I've replaced the ECT sensor.. Checked the codes only getting egr valve and O2 sensor code. Just trying to figure out why it takes holding gas pedal to floor to start when warm. Not a serious problem I can do that and it's fine. But I know it's not supposed to be that way and if it's an easy fix I'll do that. Plus I bought a used MSD distributor that supposedly was in great condition. But it didn't make the fiel pump prime like that.... Does that mean that distributor I bought needs pickup coil replacement?
Check all you vacuum lines and grounds, go through the surging idle checklist, you ran both koeo and koer codes?
Yeah I ran both and posted them on here somewhere. But I'm still navigating this forums.. Checked all vacuum lines and grounds under hood. Even had a buddy with a tester come make sure everything was grounded. I'll try to find surfing idle checklist. Or if it's on here tell me where I can find it as a sticky. Thanks guys!!
Yes, at least while it is cold and at low speed...
E.) No start when hot - Press the throttle to the floor & try starting it, if you get this far. If it starts, replace the ECT.
Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
[color= blue]Revised 6-Apr-2017 to add diagrams and resistance check for ECT wiring.[/color]
Possible bad ECT sensor, or wiring. Possible missing signal ground – black/wire broken or bad connection. With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 1 ohm. Check the same black /white wire on the TPS and MAP sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.
The computer Engine Coolant Temperature sensor has absolutely nothing to do with the temperature gauge. They are different animals. The ECT sensor is normally located it the passenger side front of the engine in the water feed tubes for the heater. It has two wires that connect by a weathertight plastic connector.
The water temperature sender for the temp gauge is located in the driver's side lower intake manifold. It has a single wire that connects by a push on connector on the temp sender.
If you have replaced the ECT sensor and are still having ECT like problem symptoms, check the ECT wiring .
See the graphic for the 10 pin connector circuit layout.
Check the resistance of the green wire on the ECT connector to the green wire on pin 7 of the computer connector. You should see less that 1 Ω (ohm)
Use Pin 46 on the computer for ground for both ECT & ACT tests to get most accurate readings.
Pin 7 on the computer - ECT signal in. At 176 degrees F it should be .80 volts
Pin 25 on the computer - ACT signal in. At 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.
50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v
Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
Last edited:
Ok thanks for the info! I have already replaced the ECT so it must be in wiring.. However, this is WAY above my skill level. Unless you can explain how to do this in leymans terms... First how do you measure these things from the computer and engine with them being completely different area of the car... Thanks for all your help guys. Until I figure it out I'll just keep putting pedal to floor to start it!! Lol
Yes, at least while it is cold and at low speed...
E.) No start when hot - Press the throttle to the floor & try starting it, if you get this far. If it starts, replace the ECT.
Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
Revised 6-Apr-2017 to add diagrams and resistance check for ECT wiring.
Possible bad ECT sensor, or wiring. Possible missing signal ground – black/wire broken or bad connection. With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 1 ohm. Check the same black /white wire on the TPS and MAP sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.
The computer Engine Coolant Temperature sensor has absolutely nothing to do with the temperature gauge. They are different animals. The ECT sensor is normally located it the passenger side front of the engine in the water feed tubes for the heater. It has two wires that connect by a weathertight plastic connector.
The water temperature sender for the temp gauge is located in the driver's side lower intake manifold. It has a single wire that connects by a push on connector on the temp sender.
If you have replaced the ECT sensor and are still having ECT like problem symptoms, check the ECT wiring .
See the graphic for the 10 pin connector circuit layout.
Check the resistance of the green wire on the ECT connector to the green wire on pin 7 of the computer connector. You should see less that 1 Ω (ohm)
Use Pin 46 on the computer for ground for both ECT & ACT tests to get most accurate readings.
Pin 7 on the computer - ECT signal in. At 176 degrees F it should be .80 volts
Pin 25 on the computer - ACT signal in. At 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.
50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v
Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
A marginal sensor will sometimes cause problems, but is not enough out of range to trip a code. That's why the code 21 and 51 test paths have the sensor readout data included in them.
Do the test and measurements and see what you get...
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