We recently pulled out the gas engine from our crane truck and replaced it with a 96 F250 7.3l diesel. We had some problems with it shutting down once it was warmed up, we repalced the cam sensor and now it won't start. It cranks fine, but it seems as if there is a fuel pick up problem from the filter to the injectors. There is fuel in the top end. There is no smoke at all from the exhaust when we try to crank it over. Any suggestions? We are stumped!!

 

I would still be suspect of your cam sensor. if it wouldn't start up right after you put the sensor in I would guess you got a bad sensor. try puttin the orginal sensor back in and see what happens.

also check the 30 amp fuse in the engine compartment fuse panel. I believe its in the middle row all the way to the inside toward the engine.

also check fuel pressure at the schrader valve on the side of the fuel bowl and oil level.

 

I'll try swapping out the cam sensor again. Where is the schrader valve located?
The oil level is good, I am suspicious of the hpop. We changed it with a used one, how can I check the pressure in the high pressure side?

 

Tried swaping out the cam sensor, no go. Checking IPR.

 

schrader valve is on the side of the fuel filter housing right by one of the engine lifting eyes. The easiest way to check High Pressure oil is with a scan tool with data read out or you need at the very least a 4000 psi gauge to hook up to one of the open HPOP port on the head.

 

I have located the valve, how do I check he fuel pressure there? Is there a tool or can I use the scanner. What does the wire/sensor there do?

The scanner read out from the hpop is about 2500psi, does that seem right?

Thank you for all uor help, we have gotten further with your info than we were with the "mechanic".

 

You can use a tire pressure gauge to measure the fuel pressure. It should be around 50-60 psi. If you are not getting any smoke from the tailpipe you are looking at a fuel problem. The hpop pressure seems ok but you might want to check the oil level in it, it takes an allen wrench. Let us know what you come up with.

 

Thanks for the info. Do you know what the wire does that is on the shrader valve. What should the voltage reading be?

 

I'm not sure it is a fuel problem, I think there might not be enough oil pressure for the injectors to fire.

 

Pressure in the shrader valve reads at 20psi

 

oil pressure is more than enough. 500psi is needed to fire. actually 2500 psi is a little suspect to me. I don't think cranking should produce that much pressure. can you see a data readout of the IPR % or duty cycle?

the 20 for fuel pressure sound decent for just cranking too. 40 to 60 is spec.

Try cranking it with the ICP unplugged. the injector control pressure sensor is located at the front of the drivers side head at the front just inboard pointing upward toward the passenger side at about a 45 degree angle. its a 3 wire connector

The wire you see by the schrader valve I believe is just a sensor for the fuel filter light.

Have you checked the 30 amp fuse I talked about in my first post?

 

The fuse is fine. We already tried to fire with the ICP unplugged, no go. I will check the readout for the IPR % and get back to you.

 

We took another look at the scanner. (Rookies!!) This is how it reads:
Inj Prs Reg % 15
Inj Ctrl Prs (PSI) 204

 

well 15% is pretty good but the pressure is too low. The IPR should be raising the percentage to raise pressure. but maybe the IPR o-rings are bad. it would be worse when the oil is warm which matches your problem. There are 2 o-rings and a backer ring on the IPR. they go bad and start out as a hot restart issue get worse to dieing when hot, then a complete no start. so thats were I would head next. let me know if you need more info.

 

Well, that would make sense. We rebuilt the IPR, but then we replaced the hpop, however we did not put the rebuilt IPR into the replacement hpop. I'll try changing the IPR and let you know how it works, again thanks so much for all your help.