No start - glow plug relay?

[drericg]

Everything has run perfectly, but one day won't start (2000 F350). Starter turns, engine turns, but won't kick over at all, not even a little. Acts like no fuel, so replaced fuel filter. Reservoir is full and pressurized.

Daily temp is over 90F here, but was told glow plugs are still in question. Checking glow plug relay: there are two relays next to each other and look very similar, only one is shorter than the other (shorter is towards rear of engine, taller towards front). Which is glow plug relay?

Shorter relay appears to work as expected for glow plug: Battery voltage on one large post, energizes other large post when ignition is turned to On, releases after a minute or two. One small side post is energized with key on, other is not.

Taller relay has Battery voltage on one large post, but other large post does not get voltage when key is On. Both smaller posts have voltage when when key is On. My guess is bad relay, but what does it go to?

Any ideas?

[drericg]

Glow plug relay functions as expected - activates, with no voltage drop. Glow plugs each checked OK by test light. Other relay turns out to be to intake heater - I believe unrelated to starting problem and likely functional.

Found HPOP reservoir 2 inches low, so filled to top and charged batteries. No change. Still starter turns, engine turns, but no hint of catching.

What else should I check?

[black99stroker]

is the wait to start light coming on?

[drericg]

Yes - wait to start light comes on for several seconds as usual. (Glow plug relay activates for a minute or so, as well.)

[TODDC]

Crank Position Sensor maybe? There is a trick I learned on here. When engiine is turning over. Does the Tach needle bounce? If not? Than dead CPS. There is a recall Ford is doing on them too i seen. The newer ones are grey in color. Older ones are black. We replaced the shop truck one when we first bought it. Ran fine and never had problems. Now Ford did the recall so we put a new one in just for safety.

[drericg]

I'll double check it - I don't think it was moving at all. Thanks - I'll follow up.

[drericg]

Finally replaced CPS and it started right up. Thanks!

Interesting note: I found my 'recall' letter about the CPS. I called the dealer and they wouldn't do anything unless I towed it in - wouldn't get me a part, either. Cheaper to buy from the parts store and do it myself than for 'free' at the dealer...