below 25 wont start help

[dairieman36]

i have a 1994 F250 that will not start when it is below 25* glow plugs are motorcraft and they are all fairly new. it just cranks but wont start tach. says @ 500 rpm which should be plenty. need advice on what else could make it not start? also glow plug relay and controler are new this year. when i cycle the glow plugs the wait light is on only 5 to 8 seconds after light goes off the amp. gauge spikes up and down could this mean anything?

 

[pafixitman]

5 - 8 sec is too short. It should be closer to 12. The bouncing amp gauge is normal. The gp circuit will cycle for a bit after the light goes out. If it starts fine when warm (block heater) then it is gp related. Other issue could be losing the prime in the fuel system (air leak). My money says it is gp related. You probably have 1 bad.

 

[lotzagoodstuff]

Did you check your glow plugs with an ohmmeter? 5 to 8 seconds sounds pretty short, should be more like 10-12 seconds. I had three bad ones last year and it was not that noticeable until it dropped below 50 degrees. This year I had only one bad glow plug and I actually noticed it was a little harder starting when it got down to mid thirties. Get out your meter and check the resistance, should be less than 2 ohms when they are cold.

Good luck

R. J.

 

[Mr_Roboto]

Right one of the glow plugs is probably burned out or has a bad connection.

I had a new Beru burn out within a week, it happens.

 

[dairieman36]

i did not check with ohm meter just a test light read some where if the light is bright the gp is still good if dim its bad i will just replace and see what happens thanks for all the advice

 

[Diesel JD]

The light test usually works but may not pick up on too high internal resistance. It always works on the 6.9 system but may not on the solid state, which is highly failure intolerant.