The Diesel Garage banner

1 - 14 of 14 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
I bought a non running 1999 7.3 f250 I changed glow plugs, hpop, starter, ICP, UVC, MAP, IPR, CPS and new batteries. It cranks over good and strong but don't fire even with ether. Fuel and oil reservoirs are full. I don't see smoke from exhaust pipe when cranking. The low fuel, oil, tem light comes on when creating. The RPM gauge don't move. I'm thinking maybe injector O- ring but not sure how to test without pulling each one. Or is there something I missed ? It's my first 7.3 .... Thanks in advance. I have read a lot of threads but still fill Lost
 

·
Junior Member
Joined
·
40 Posts
I am thinking for your 7.3 to start it needs three things. Air: Is the cam turning and in time for it to pull air in. Fuel: Ether. Ignition: By compression in this case and ether does not require much. A bad injector o-ring would not cause all cylinders to loose compression and it should fire on ether. Saw a 6.9 sprayed with wd40 and ether at the same time. The oil helped it build enough compression to fire up. It ran a few minutes and smoked out the whole shop. Found out the block heater had fallen out causing it to run so hot the rings were collapsed. Someone else had put an expansion plug in and filled the coolant but could not get it to run. Hope your luck is better.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
Thanks.. how can I check if it's in time or not. This is my first V8 diesel ... My big truck I'd pull the valve cover and it's right there on top.
 

·
Junior Member
Joined
·
323 Posts
This info from Ziggster's files....

You need to line up the scribe mark on the pump flange with the scribe mark on the pump gear housing. That's essentially it to start with. Hopefully the gear housing hasn't been removed, 'cause if it has it is possible the pump timing gear has been moved, and it is very difficult(but not impossible) to get it back to the right spot.

On the housing that's mounted on the top front of the engine where the pump bolts into, There is a small line about 1/4" long stamped into the rear/upper face of the housing just where the pump would mate to the housing. Likewise, on the pump almost at exactly the same spot on the flange of the pump where it bolts to the housing is a similar line scribed into onto the top of the pump flange.

The idea is that when you put the pump into the housing on the engine, and if you have those two marks lined up such that the almost form one 1/2" Long line, then the timing will be close enough that the engine should start and run. This is known as static timing.

Dynamic timing via luminosity is done where a probe is put into the cylinder, and actually sees the light from the explosion of the fuel, and the timing is set accordingly.

Some of us set the timing by "ear". This comes from some experimentation and experience.
I like mine so that when the engine is cold, as the cold advance is on, the engine rattles pretty loud, but once the cold advance drops off, then the rattle smooths out and the engine is much more quiet. If you have it too advanced, then it makes that loud rattle all the time, often accompanied by lots of black smoke, and if too retarded, will sound kinda flat most of the time, lack power, and often not smoke at all, or may even smoke greyish/whitish(unburned fuel).
When you are standing at the front of the truck facing the engine, if you turn the pump couterclockwise(top of the pump to the passenger side) you'll be advancing the timing, and obviously clockwise will retard the timing.

If you line up the gear cover and pump top center lines you will be able to start it.

The marks on the pump to housing are only accurate if it is the original pump from the factory. Turning the injection pump 1/16" to either side (measured at the pump to housing flange marks) that's about 4 deg. Turning IP to pax side is advancing timing, to drivers side is retarding, engine off for all adjustments and tighten nuts on IP before start.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #5
Jasong thank you. Great explanation and instructions on how to set it. I am working long hours this week so I will probably do it this weekend. Thanks
 

·
Registered
Joined
·
9 Posts
Discussion Starter #9
Timing the older 7.3 injector pump seems to be just as described but I have a hpop in that location and so it's not making any sense
 

·
Stuck in Commiefornia...
Joined
·
1,296 Posts
Low compression .... Time to rebuild it
? What ?

No power at the injectors, the injectors aren't firing. If the injectors don't fire, the enjoined won't start. Ether will crack the Pistons on a 7.3L if you use too much, but by the description that it never fired even with ether, the OP either didn't use it right or didn't use enough.

If there is no power to the injectors, and the IDM is good, it has to be an issue in the harness. You'll need to make sure all the connections are good. Start at the injectors and work your way back to the IDM. Take each connection apart, make sure it's clean and that there is no damage. Reassemble with a little dielectric grease and keep moving towards the IDM, if it still won't fire, work from the IDM back to the PCM and power sources making sure those connections are good also. At this point, if it still doesn't fire, it's time to get a DVOM and test each wire in the injector circuit, time consuming, but you may have multiple shorts or opens in the circuit.

Now, in a 7.3, I would start with pulling the computer, looking for an aftermarket chip, remove it if there is one, and see if the truck starts. Sometimes it is really that easy.
 

·
Junior Member
Joined
·
515 Posts
One of your symptoms rings a bell with me. Tach not bouncing when cranking. I am far from an expert but own 2 of them. One bought new in 02. I remember the loss of tach signal being a good indicator of a failed cps back in the day of that debacle. I have rplaced about 4 or 5 and every one failed to have tach signal when cranking. You might try another cps as it is about as easy of an item to swap out as there is. also carefully examine the harness and pigtail related to that. I think that would also explain injectors not firing since cps is what tells idm when to fire. Someone smarter than me may see it different. Guess it could be idm failure?
 
1 - 14 of 14 Posts
Top