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Discussion Starter #1
I can't find this exact issue when searching. I have a 1995 f350 cclb. My truck starts hard when cold like really hard unless I have it plugged in even in 40 degree weather. I figured it was uvch I did them both not to long ago but had a couple bad plugs so thought I'd check the glow plugs they all tested good but I needed to change the plugs coming from the wire harness on the motor side. The back passenger was melted on the glow plug end so changed the 2 glow plugs near the firewall on the passenger side just because. Changed both wire harness plugs and the ucvh on that side again. Truck still doesn't run right once it is warm it runs like a champ. No smoke starts everytime. Where do I need to start looking now.
 

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Is the glow plug relay good? It's best to replace all glow plugs at once. If pins are burnt then the UVCH and Valve cover gaskets should be replaced.

Check voltage across the glow plug relay. Also, make sure your battery terminals are perfectly clean and tight. A weak starter will cause issues too.
 

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How many miles on the truck? Here are some tests to perform:

For checking the injector/glowplug wiring: From each valvecover gasket connection's outermost pins (2 per connector) to ground you should get 0.1 to 2 ohms (indicates good plug and wiring). From each valvecover gasket connection's center pin to each immediately adjacent pin, you should get around 3 ohms (indicates good injector solenoid and wiring). You should not get any continuity from any of the outer pins to the 3 inner pins (indicates no shorts between injector and glowplug wiring). You should also get 0 to 1 ohms from each of the external harness connectors outer pins back to the Glowplug Relay's large terminal on the GP side (indicates good wiring from external connections back to the relay).

To check the glowplug relay (GPR), measure the voltage drop across the GPR's large terminals. While the GPR is active (up to 1.5 to 2 minutes after the key is turned to Wait-to-Start) put your meter leads on the large terminals (one lead on one large terminal and the other lead on the other large terminal). This measures how much voltage is being "lost" across the relay. A reading of 0.3V or more indicates a bad relay. Also, check the relay’s control wires (smaller wires) disconnected from the relay for battery voltage at the Red/Light Green striped wire and ground at the Purple/Orange striped wire (check both when the key is turned to Wait-to-Start).

Cheers!
 

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Discussion Starter #4
327xxx miles on the truck. I check the glow plugs even the ones I took out they were all .2 including the 2 new ones that's why I only changed 2. I did the gasket, wires, and pigtails on the side that had the melted plug.

I have checked the relay key off 12.3 volts key on wait to start 10.2v on both posts. I was told that voltage drop is normal. Maybe the relay is bad though if that is too much drop?

I don't have my shop book for this truck anymore and most of the local diesel shops ha e moved on to the newer motors since here in PA the obs trucks are about rotted out. I have a good concept of how diesels work but there are always little things especially like electrical that I hate just poking and hoping at because I end up over looking something that I think is good but isn't.

Sorry for the monologue. Thanks for the help.
 

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At 327k, if your truck still has original injectors, they could have worn poppet valves which can cause hard cold starts. A bunch of my 94's injectors were worn out of spec causing hard cold starts. Good batteries, clean and tight connections (at ALL ends), and a good starter also make a big difference in cold starts. Cheers!
 

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Jump the large posts on the glow plug relay (battery cable clamp works well for this) for at least 30 seconds prior to starting
 

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For the GPR test I prefer to put the meter leads directly on the large posts (one lead on one post, the other lead on the other post) and measure the drop "across" the relay when it's active. Cheers!
 
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