Clarification regarding ohm testing GP's

[RL1]

Hey guys, I have a 96 PSD with 128k on the clock. I purchased the truck 2yrs ago with 108k on it. I noticed hard stars from the beginning, it progressively got worse over time. I checked the GPR last year and it was sending voltage through when I turned the key on. I didnt test it with a MM just a light so I dont know how much. I tested it today and it's dead, that explains why it has gotten worse.

Anytime it gets below 75 degrees or so it takes forever to get the truck running. Blows white smoke like a s.o.b. so I knew fuel wasnt an issue. When it starts and I drive it enough to get up to running temp it will start all day long as long as the temperature outside is 40 and higher, and always starts immediately when I plug it in. I just signed up here today to do some research and learned a bit. I decided buy Motorcraft GP's. I'm sure a few if not all the GP's are shot so as long as i'm in there I'm replacing them all.

As far as the ohm testing goes, I found articles stating anywhere from 0.6 - 2.0 indicates a good plug. I think the article I found was regarding a diffrent year PSD because the plug description sounded diffrent. I have 2 plugs with 5 wires each on both covers. I set the MM to 2m and i'm getting readings out of all 4 plug bunches of 0.4 on the outermost wires in the plugs, nothing from the remaining wires in between the plugs. I also hooked the test light up to 12v and hit those outermost wires in the plugs and it lit up with all of them.

Now, if what I read was correct, and i'm doing everything correctly my 0.4 reading indicates all 8 GP's are bad Correct?

[SteveKran]

How accurate of a multimeter are you using?

What brand? How much did it cost?

[RL1]

Originally Posted by SteveKran

How accurate of a multimeter are you using?

What brand? How much did it cost?

As far as I know its pretty decent, bought it about 4yrs ago. Its was the top of the line craftsman at the time.....cost? Don't remember

[SteveKran]

I've compared one of craftsman's cheaper multimeters to my expensive fluke 89 and the craftsman is fairly accurate.

As far as you readings on your multimeter, are you saying that you are getting .4 megaohms? If you are, that's probably way to high. Check out this thread, NCHornet is a pretty knowledgeable person on this subject. Troubleshooting GPR & GP's

[Rantheman]

At each terminal into the valve cover you will want to check the out wires those are your glowplugs take a test light unplug the harness from the valve cover go from positive battery and hit the terminal in the valve cover it should activate the glowplug your test light should light up then on the harness side you just disconnected put your test light on ground and prob the terminal and have a friend your you switch the igntion on to see if your getting power to the glow plugs. Lastly your glowplugs should read from .1 to .6 Ohms you can do this with everything pluged in and one lead on the negative battery the other lead on the wire for that glowplug. hope this helps

[RL1]

SteveKran I've compared one of craftsman's cheaper multimeters to my expensive fluke 89 and the craftsman is fairly accurate.

As far as you readings on your multimeter, are you saying that you are getting .4 megaohms? If you are, that's probably way to high. Check out this thread, NCHornet is a pretty knowledgeable person on this subject. http://www.powerstroke.org/forum/gen...g-gpr-gps.html

That is the article I found and was referring to when I did the testing yesterday - though it doesn't indicate to have the ignition forward when testing the GP's (sorry, it's obvious I'm totally new to this particular field, rarely used a multi meeter for anything but checking voltage) and your right, my initial post of 0.4 was totally incorrect with the meeter set @ 2m (milli) I get .004 and I get 0.04 when set to 20k with ignition forward - off I get .000 and 0.00 respectively.

Originally Posted by Rantheman

At each terminal into the valve cover you will want to check the out wires those are your glowplugs take a test light unplug the harness from the valve cover go from positive battery and hit the terminal in the valve cover it should activate the glowplug your test light should light up then on the harness side you just disconnected put your test light on ground and prob the terminal and have a friend your you switch the igntion on to see if your getting power to the glow plugs. Lastly your glowplugs should read from .1 to .6 Ohms you can do this with everything pluged in and one lead on the negative battery the other lead on the wire for that glowplug. hope this helps

With the test light hooked to positive then hitting the outer most 2 prongs in the receiving plug on the valve cover the light goes on (same thing with the male plug, makes sense) with the test light grounded bumping the ignition forward to activate the GPR I get nothing - I knew it was dead, I jumped the GPR with a screwdriver while the test light was contacting a prong and it lit up right away.

I appreciate your patience wi

[CHUCK]

Replacing GPs isent bad, the worst part is removing the right side vlv cover.

[RL1]

Originally Posted by Rantheman

Lastly your glowplugs should read from .1 to .6 Ohms

Also, the other article byNCHornet states 0.6 and 2 ohms, there is almost no resistance if it reads .1

Also, just to be sure my meeter is working correctly i'm going to the electronics store to buy a .5 ohm resistor to compare my meeter reading in relation to the resistor.

[RL1]

OK, I finally figured this out, I thought M stood for milli, so I assumed that was the lowest setting and it's actually the second highest next to 20M - M = Megaohms mm = milli - regardless both are wrong. So I set it totally left to 200 and tested my 1ohm resistor and it's reading 1.1 - 1.2.

I retested the GP's and i'm getting anywhere from 0.5 - 0.8 at best through all 8. I tested a brand new one out of the package and i'm seeing 2.1 - 2.2

So, i'm going to throw in a new GPR and see if it gets better, i'm not expecting anything great. i assume I should just replace all the GP's since they have such low readings compared to a brand new one

[Southpaw]

GEt the Stancor GPR for about $45 This is how it stacks up to the stock one.