7.3 won't start when cold

[fire1972]

I have a 1999 Ford Power Stroke. Won't start when the temp gets below 50 degrees I have checked the glow plugs and the glow plug relay and they both work. I pluged in it will start fine. I also have replaced the cam sensor and the IPR valve.

[trrun]

what method did you use to check glow plugs and relay? Later Tim

[fire1972]

I checked the relay with a voltage meter to see the voltage drop when turn the key on and the voltage never got below 10 volts. I tested the voltage coming from the regulator to the valve cover gasket wiring harness. Tested the glow plug resistance and with a light tester to the positive battery terminal.

[Clay Henry]

I don't know anythin about testing them but it really does sound like it would be glow plug related....

[trrun]

The relay should have eventually stopped showing voltage depending on how cold the engine was, up to 2 minutes I think? Try this clip the positive lead to the output terminal with yellow and brown wires connected, and the negative lead to a good ground point. Turn the key to on. If your GPR is good, it should click, and you’ll see 11 volts or so on your meter. You should do this a couple of times to make sure it consistently makes the connection. If you don’t get voltage with this test. Remove the two small wires from the smaller two of the four GPR terminals. If your voltmeter now reads voltage on the output terminal, your GPR is ok, and the problem could be in your PCM. Hope this helps

Later Tim

[No-Neck-Shrek]

I've been having the same problem as well, the other day I stop at one of the best shops in town and the tech told me "even though the test show the glowplugs to be OK (test light & resistance), changing the glowplugs has fixed a few of the truck they've had in their shop, even his own truck". He went on to say "the smoke indicates fuel & if the block heater helps it almost has to be the glowplugs".

[cblackb]

I agree, you still have a problem..make 100% sure that your batteries load-test fine too. There's been a lot of head-scratching over glow-plugs only to find bad batteries. Also make sure your ground cables on the block-side are good and clean. I found super-bad corrosion on my 2000 under the ground cables and also on the wires hooked to the glow plug relay (on the bottom side of the wire). Just cause you see voltage present doesn't mean sufficient current is able to pass through the system to effectively turn on the glow plugs. I'd check all your connections.

[Dude00]

I would Try just replacing the relay first before digging into the Glow plugs. Had the same problem, Bought a glow plug relay and installed it myself took me 5 min and now my truck starts great in cold weather

[djsdiesel]

To properly test the glow plug relay. Hook the positive clip of the volt meter to one of the big terminals on the relay, and the negative clip to the other big terminal on the relay. With key off it should read battery voltage, when you turn the key on and the relay activates it should drop below .02 volts. Doing this measures the voltage drop across the relay. If it is above .02 volts replace the relay. When checking the glow plugs use Ohm meter. Connect the negative side to the battery ground. then probe the glow plugs they should all read about the same ohms. less than 7.

[No-Neck-Shrek]

I have tested every glowplug and the relay, & I have 2 new batteries. Actually thinking about it I haven't checked to make sure that I have voltage at the hanress that plugs on to the v/c connector. I'll test that and let you know.