Hard Cold Starts

[dboo]

I have a 97 F250 which as just started have hard cold morning starts I checked the Glow Plug Relay and it was good,installed new Wix Fuel filter and it still takes two wait GP delay times to start and then blows white smoke and really shakes before getting warmed up, I took it to the Ford dealer and they said my GPR was bad and i told them I had just tested it and it was good, now they want to test the truck in cold condition, any suggestions on what be going on.

Thanks dboo

[madpogue]

The WTS light has nothing to do with the glow plug run time. If you want to run the glow plugs for longer, just leave the key in RUN an extra 10-20 seconds.

But it does sound like your glow plugs are weak. Measure the resistance of the glow plugs at the UVCH connections; each one should be 0.8 - 1.2 ohms. (I have read in some places that a resistance up to 2.0 ohms is acceptable.) Also look at the wiring to the valve covers and the connectors; look for burning/melting or other damage.

When you get it started, remove the oil filler cap and give the crankcase a sniff. Does it smell like melting plastic? That indicates melting/melted wire insulation under the valve covers.

How exactly did you test the GPR?

[dboo]

I just measures 12 volts to GPR with the key just like the Ford Service man was doing today.

[madpogue]

Which terminal(s)?

[dboo]

The one powers the GPR only hot with the key on

[madpogue]

Sounds like an issue downstream. With the key in RUN, the voltage at both big terminals should actually be below 12V, closer to 11 or 11.2. The resistance of the glow plugs will bring the voltage down. If the voltage is still closer to battery voltage with the key off, that suggests the glow plugs aren't really drawing anything. This is where checking the GP wiring and measuring the resistance comes in.

[dboo]

Thanks, for the advice will recheck the voltage again.

[dboo]

Ok I re-tested the GP relay and I have 11.66 volts, what next?

[madpogue]

Again, which terminals? You need to measure voltage at both big terminals with the key in RUN.

[dboo]

Yes, I checked the one left hot terminal which I had 11.6 volts then I turned the key on and checked the right hot side on the GPR that powers the Glow Plugs and I had 11.6 volts. What Next? could some of my glow plugs not be working? I thought about just changeing all of then since they are not that expensive just some labor to do it.