GP system tests

[fsSnowboard]

This is frustrating. Every time I post a question it’s because I'm having trouble starting my truck. Anyways, I thought some of my glow plugs were dead, but I did the test light test on them and all of them lit up. So, I continued with the tests found in my Haynes Diesel Engine Repair Manual on page 3-42 and 3-43.

For people who don't have the book I will write the steps so that everyone knows what’s going on.

Wiring Harness Check
1. With the engine and ignition off, disconnect the wire from GPs.
2. Remove cover.
3. Using an ohmmeter or continuity tester, check for continuity between each glow plug lead and the test terminal.
4. Reconnect GP wires.
Results
0 ohms in each lead. (A photo of the setting I had for the ohm meter http://flickr.com/photos/fssnowboard/194838670/ the switch is pointed to 20k)

Control Unit Ground Test
1. With the engine and ignition off, connect an ohmmeter to the ground wire terminal eyelet and to the ground terminal on a battery.
2. if the resistance is more than one ohm, clean or repair the ground connection.
3. If the resistance is more than one ohm, perform the supply voltage test.
Results: I got 0 ohms with same dial position as test above.

Supply Voltage test
1. With engine and ignition off, connect voltmeter to the control unit power terminal.
2. If there is less than ten volts, repair the wiring or recharge batteries.
3. If there is more than 10 volts, go to ignition switch test.
Results: about 12.3 v

Ignition Switch Voltage Test
1. Connect the voltmeter to the ignition terminal on the control unit and to ground.
2. turn the ignition switch to on, all accessories off.
3. If there is less than eight volts, check the fusible link, recharge the battery or repair wiring.
4. if there is more than eight volts, go to control unit function test.

Control Unit Function Test.
1. with engine and ignition off, connect a test light to the test terminal on the control unit.
2. have an assistant turn on the ignition switch. compare the amount of time the test light stays on to the test light chart. Note: WTS light may not come on if the engine temp is at or near normal Operating temp. Total test light on time is measured from the beginning of the on cycle to the end of the last on-off cycle.
3. if the test light is incorrect, disconnect the ground from batteries and replace the control unit.
4. if test light time is correct, control unit is OK.
Results: first test, 21 sec, counting in my head. second test was 17 using stop watch. 3rd test was also 17. Now, it is 85 outside, so the unit has to be at leas 70 degrees.

Control Unit Temp WTS lamp on time Test light total time
35 F 5-12 15-35
70 F 3-5 7-15
105 F 1-3 3-5

There is a note saying control unit temp is no ambient temp but temp of the control unit.

So, i think i have a bad controller? The WTS light stays on about 10-12 seconds.

Another note, earlier with everything hooked up, i only heard the clicking of the GP controller only once, and kinda heard a whining/wheesing sound at the same time.

So, would my broke GP controler make my rig hard to start?

One thought i had was, could my fuel filter be letting air in. I changed it last summer, but since then its been a little harder to start. should i just tighten the heck out of the filter?

Thanks for the help guys.

 

[EvergreenRanch]

hey there, sorry to hear you got frustrations with starting your truck. whats the smoke like on start up? blue/black/white? quantity? duration? whats the mileage on your injector pump and injectors? just fyi i havent heard of anyone having air intrusion problems at the fuel filter.....much more likely (if it is air intrusion) to be at the injector return lines, or before the filter. might not be a bad idea to check your fuel pump, use some injector cleaner in the fuel, and make sure you dont have a fuel supply issue. my WTS light stays on prolly 9, 10 seconds first thing in the morning and starts up fine.

 

[fsSnowboard]

I haven’t started it in a while, but its usually white. i get a decent amount of white smoke on startup. I also have to keep the peddle in it to for a second or two because if i don't it will stall. i think its some air in the lines. However, this winter i did replace my IP, injectors and all return lines. I don't see any leaks on any of the return lines.

 

[fsSnowboard]

Ok, so i got my truck started and my last comment was based ont he last time i started it. This time, the WTS lit for about 10 seconds (normal). I needed to crank it a bit but it got started. Almost no smoke that I noticed and i didn't feel like that it was starving for fuel and would die. When i cranked it would almost fire, then keep going around, and almost fire and eventually fired. What causes that? I went to fill up my tanks. When i restarted there the WTS light came on for about 3-4 seconds. however, i drove my truck on the highway about 5 miles and its 91 F now. so the truck should have been fully warm and i shouldn't have needed my plugs. Correct?

Man, I thanked God that it started. its kinda had me worried because I'm moving in a few weeks to South Carolina. So i've been praying that my truck will work. Anyways.

Thanks.

 

[EvergreenRanch]

well the white smoke is saying you GP's arent working very well, that you have some serious timing issues, or that theres some air. ambient temp has very little to do with glow plug timing, so its not surprising if you had a few seconds on the GP's...... sounds like you need to put in a manual GP button and be done with it!

 

[sle2115]

My 87 6.9 with the same solid state system ALWAYS cycles the glow plugs and will crank a couple of revolutions if I don't wait on it. If I let it go out, the first cylinder up fires it, way less than a revolution. Now, mine cycles about the same, 10-12 seconds cold (80-100 degree F outside) and about 4-6 seconds when the motor is over 160 degrees F. When it is cold, like 30 or below, my glow plugs cycle for a real long time, 30 seconds is not unusual and it gets longer as the mercury drops.

Do you know what kind of plugs are in there? I have a Ford Manual scanned for the 87 system, which is the same as yours, if you want a copy, drop me an email at [email protected] but I don't know how it differs from your procedures and right at this point, I don't have time to compare. You are welcome to a copy however if you want it.

Scott

 

[fsSnowboard]

i think its running good, but i'll have somebody check for smoke tomorow when i start up. I have motorcraft GPs in there.