my 2000 f250 with the 7.3 in it had a weak battery I jump started it sat. all was fine. tues I put two new batteries in it now it cranks fine but won't fire anyone out there got any ideas

 

Welcome to the site.

Wasn't cabled backwards? Sorry,, the question has to be asked....

In short, the 7.3 needs a 'minimum' of 100 RPM to start (new batteries are at least spec cranking amps?), 500lbs (min) of high pressure oil cranking for injector push, a crank/tach signal from the CMP for the IDM/PCM to fire the injectors electrically and a running fuel pump. Any tach needle bounce during cranking?

So,, whats missing?

If anything was shorted,, does the PCM power relay in the BJB 'click' when the ignition is cycled On/Off. Fuel pump run when the key is cycled On?

If it was all cabled correctly, fuses 'shouldn't' be a probem, but you may want to check the 2 for the PCM power relay just as a precaution and first step. More so if the fuel pump isn't running. One is in the CJB the other in the BJB.

You could insted of checking at the different boxes/fuses, just pull the PCM power relay in the BJB,, check for 12v 'Hot at all times' on one leg (key off) of the relay connector, then, cycle the to ON and check for another Hot in Start/Run supplied there on another relay connector leg. Should be two 12v distributions there, on hot all the time, and the other added when the key is turned on..

If there is 12v on both legs, then the fuses and PCM power diode are good and time to look else where..

 

did some testing hooked code reader to the truck it said the injecter drive module failure. Is there a way to test this befor buying one. and anyone have an idea on why this would just go out? is it something you have heard of?

 

Was there any other codes listed with the P1298?

IDM failures aren't overly common, they do fail though, and mount inside/under the wheel well splash guard and are subject to moisture issues. Sometimes when removed you can hear water inside on a shake test. Connector/pins cab be an issue as well.

Might check the IDM power relay connector for power distributions there. Should be a 'Hot at all times', and a 'Hot in Run/Start' on two legs of the connector..

Odd that the truck was running fine until the battery boost/swap. I'd make sure that current is applied to the IDM relay just in case before moving forward with an IDM

 

checked the relay as descibed have hot all the time one hot when key is turned on and ground tests good there also. all the fuses test fine also. the idm is it in the cab on driver side left of the break peddle on the wall? that was the only code on the reader. thanks for suggestions and ideas

 

Thats the PCM..

IDM mounts nose down between the left side of the cowl and the inner side of the drivers/left fender. The wheel well splash guard needs to be taken loose. Usually you can 'get by' by just taking the the lower/outer screws that attach the guard and 'bend' or bow the guard enough to get in and get the IDM loose and out. Bit of a fight and pinch point that way, but faster than lowering the complete guard, but either way that works for you..