Motor Turns over but doesnt start.

[Fireman Crawler]

I bought an 01 7.3 F-250 Crewcab 4x4. Motor has 195,000 on it. The previous owner told me that it quit coming home from work and would not crank. He had it towed to his house and let it sit for about a year. I contacted the delearship to get some info on it. They told me that they told him to quit driving it because it had bad compression on cylinders 4, 6, and 8. Well he didnt.

I have checked the oil and it looks good. Checked the fuel filter looks great. It will turn over all day long but never get fire. I have checked the fuses and they are great also.

I guess my question is what could cause these three cylinders to have poor compression and shouldnt it still run but just be like crap?

[dray8165]

Yes - it will run on just four cylinders - something that happens frequently when the under valve cover harness gets loose on one side. You need a few things to start. Properly timed fuel delivery, sufficient RPM to fire the injectors, and heat (generated from compression / glow plug system)

Does your wait to start light come on? Are you getting any smoke from the tailpipe when it cranks?

This motor uses the high pressure oil pump (HPOP) to generate the force to activate the injectors. The HPOP uses a signal from the Injection control pressure (ICP) sensor on the front of the driver's side head to determine pressure, which is controlled by the Injection pressure regulator (IPR) - any of these going bad will cause a no start. Read here for more:

http://www.forddoctorsdts.com/public...3HPOPGuide.pdf

The cam position sensor (CPS) frequently goes bad in these trucks. Most people carry a spare. They are about 25 bucks and would be a cheap first try at getting it to start.

Check your glow plug system as well. The tests are free. Read here:

Hard/No Start? Check here first. - Diesel Forum - TheDieselStop.com


I think the best investment you can make at this point would be to purchase a good scanner - AutoEnginuity with the Ford Package - which will monitor all the parameters needed to start and run. It could save you hundreds of dollars as opposed to just guessing and throwing parts at it.

While you are waiting for that to come, I would plug the truck in for a few hours(the cord is on the driver's side of where your front license plate is) and try to start it jumped with good cables to a strong batteried vehicle. You have to have at least 150 cranking RPM to fire the truck. You won't get that with marginal batteries.

[Fireman Crawler]

The wait to start light does come on. It will stay on a couple of seconds and then turn off. It will not crank what so ever and doesnt smoke when turning over.

[Fireman Crawler]

I will check the suggestions you recommended on Saturday. Hopefully this can be something simple.

[dray8165]

No smoke means its not getting fuel. It should puff out white smoke. In addition to everything I suggested, do the obvious thing of making sure there is fuel in the filter assembly.

[Fireman Crawler]

There is fuel in it. I checked it before I tried to start it. That's why I thought it may not be firing.

[Fireman Crawler]

Ok I did the Glow Plug Relay Test. It is reading 11.5 volts. Bouncing between 11 and 12. This appears to be good.

[Fireman Crawler]

Also what is this? It comes on for about a minute when I cut the key on. It sounds like a mini air compressor. It will shut off then come back on for about 30 seconds, then shutting off again.

[dalton1]

Originally Posted by Fireman Crawler

Also what is this? It comes on for about a minute when I cut the key on. It sounds like a mini air compressor. It will shut off then come back on for about 30 seconds, then shutting off again.

vacuum pump

[Fireman Crawler]

Checked the glow plugs they are all in range.