Hi gang;
First off I want to say how much I enjoy this site, lots of great info. I searched around for this and found some great info, but I wanted to run this by you all and see what you thought.

This afternoon I went out to drive the truck, ( 1993 F450, 7.3 non turbo, 167,XXX on the clock that I just got Thursday) and it would crank, but wouldn't fire. When I released the key, I could hear a relay under the hood/dash clicking randomly, and the voltmeter moved along with it. I tried to pop the hood to see where it was coming from, but wasn't fast enough. I tried cranking it again, but gave it a little throttle (probably not a such a great idea, right?) and it started. I've driven it for about 2 hours, with no issues. I stopped by my office, and shut it down. I came back out after 5-10 minutes, and it started right up, ran for 5 seconds, stumbled and died. It will now crank, but won't fire. I haven't tried it again in about 15 minutes, I'm going to let it cool down a little.

I've read it could be the fuel pump getting too hot, among other issues. The starter certainly has plenty of power. What are all your thoughts?

 

Welcome to the besty darn web site I know regarding these trucks! The glow plug system when cold should illuminate the wait to start light for 12 -15 seconds before the light goes out. This indicates all the glow plugs are working. Cranking then results in a start normally, the clicking and volt meter fluctuations are normal, this is the glow plug relay cycling for reasons unknown to me, but its what they do. Stoping after it starts!!- I would check that the IP pump solinoid wire connection (the forward terminal on the drivers side of the IP pump is clean and tight). This keeps the fuel "On". Mine was loose and dirty when I first got my truck, and it would just up and die for no reason until I corrected that problem.

 

Check under the hood and look at the return fuel lines between the injectors. If they are painted gray.... then you have what we call " Classsic fuel line air leak" What this means is the fuel lines develop hairline cracks (from age) allowing air in but no fuel leaks out. If the lines look brittle then this is what you have. Also check under the truck at the lines from the tanks to the engine. I found on my 93 a fuel line was leaking under a clip that holds the fuel lines to the frame. They don't make the line anymore so I used fuel line to bypass the bad spot.

The GP controler is located behind the air cleaner in a black cover. You'll have to remove air cleaner to see it. It will click about 3 times when the system thinks it is up to temp to fire fuel in cylinders.

 

thanks guys. I let the truck sit for about 45 minutes, and went out and tried it again. On the first try it started, stumbled and died. I let it sit a few (<5) minutes, cranked it again, and nothing. Let it sit one last time for a few minutes, and this time held the starter a little longer (10 seconds) and it caught. Whoopee! It did seem that not all the cylinders were firing for a few seconds, then everything smoothed out. She ran just fine after that, as she has every other time I've driven her (I've put about 300 miles on it since Thursday, drove it back to New Hampshire from Connecticut where she came from). I shut it down once home, and haven't tried it again.

As for the relay, I am waiting for the "wait to start engine" light goes out before cranking. The sound did appear to be coming from the area described, but it only did it that once. It clicked a dozen or so times quickly with varing times between each click.

Thanks guys for your help, I will look into this more tomorrow when I can see under the hood again.

 

hi dupesy and welcome to the site. We dont know how much you know about these diesel engines but here goes a quick lesson...
when cold they require glow plug assist to start ... the fuel is injected into a precombustion chamber for pre heating before firing into the cylinder for injection. Wait for the wait to start lite to go out and give a few more seconds after that to allow the glow plugs to heat up enough to fire the fuel. You wont need this much time after the initial start.
Be careful of over heating the starter when cranking ... ;they are susceptible to damage if you crank too long. 20 seconds at one time allowing about 2 minutes to cool down.
take some time to read different forums about the 7.3 engiens and some of the problems that do occur. "hard starting" is one of the major topics and you can learn a lot while reading.

there is always someone around to help with problem solving.
good luck and enjoy the ride.

 

Dupesy sent you and email....... I think you have air intrusion into the fuel system and drain off. If the fuel drains off then there is sufficient in the IP to do a start which quickly runs out causing the stall. The resart will take a long time since you must refill the filter and IP again...... if the fuel lift pump is old and does not allow correct fluid amount and pressure required then it will take forever to start.

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when cranking. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of engine cranking, route fuel to a suitable container with a hose.

There could also be any number of air leak points on the filter header, return lines, steel lines or fittings. You will have to do a process of elimination.........

Visit........ http://www.intellidog.com/dieselmann/idi.htm

 

Dupesy,
Welcome to FTE and the IDI diesel forum.

You have air intrusion and fuel draining back to the tank.
Finding the leak may take a bit to track down, but you have the best support group on the planet to help you find it.
Along with the above mentioned places, the return line from the fuel filter to the number 1 injector may also be the cause of your problem.

 

My dad is having the same sort of problems with his '93 F-250 Turbo. It will fire right off the bat, run for a few seconds, then die. Will not start after that. Must not be as bad as Dupesy's problems though, because once it is warm, it starts fine (fuel does not drain back fast). Thanks for the suggestions guys. I LOVE THIS PLACE!

 

Just be sure not to run starter more than 15 seconds on restart. Starters are very $$$

 

I've limited knowledge of diesels, although I was smart enough to join this site right when I bought the truck. I know that prolonged cranking is bad for any starter, and I never crank for more than 10 seconds on ANY engine.

It's funny that it started just fine the day before, then the next day, these issues. Oh well, just the nature of an older vehicle. As far as leaks, is there anything in particular I should be looking for? I would presume that I would see fuel being pumped out from most leaks, but maybe not.

 

Look at #3 post for your answer first paragraph. My wavy guy.

 

d'oh! Thanks!