so just put in a used motor in this f-550 tow truck and cant get it to start. found out after taking the fuel filter off and watching the bowl while someone turns the key to the run position the fuel is aerating so fast its like a soda can foaming up with so many bubbles if you get what i mean. anyone have any input on this, we put on a new high pressure oil pump and have great oil pressure readings from the scan tool. we have no codes, and the thing will only run off starting fluid.no leaks in any of the fuel lines. its a 2001 f-550 7.3 auto pos any ideas what can cause the aeration? can it be the fuel filter housing itself? yes we are a professional shop but theres **** out there that kicks our asses too. and the service manager is just throwing parts at it. and of course our diesel tech is on vacation and im tired of working on the damn thing.

 

Get yourself a five gallon jug of diesel, plumb a hose from the jug to the fuel pump and see if the engine starts. If so, then you may have a problem with the pickup in the tank.

 

just a lil more info its the shops tow truck, we were able to get it started enough to drive it inside the shop before I swapped the motor. the old motor had bad injectors and bad high pressure oil pump along with bad glow plugs that had set a p0380 code and well over 300,000 on it. the service manager wanted a new low mileage motor in it, i used the same wiring harness and transferred all sensors over and put new glow plugs and injectors and high pressure oil pump in this pos. only thing i didnt transfer was the filter housing. theirs tons of fuel in the tank too we topped the ******* off. i didnt do the diag on this, im just simply the heavy line tech, o well might have a pink slip coming since all fingers are being pointed my way. their mad for losing money not having our tow truck hooking cars right now.

 

So you're reading high pressure oil off the ICP sensor on your scan tool? What is it getting up to while cranking? Foam in the fuel bowl isn't a great concern, especially if you drained the bowl and are watching it fill back up. Cycle the key and let the bowl fill and the excess fuel will start returning to the tank. Once the air is out of the system, there won't be the foaming issue. But if you're worried about fuel, there are 2 test ports on the back side of the fuel bowl you can plumb a fuel pressure gauge into.

What else have you checked? How long have you been trying to get it started? Getting any smoke out the tail pipe while cranking? I assume the simple stuff like fuses have already been checked out? What is the voltage while cranking? Are you getting an RPM signal on the scanner while cranking? CPS (CMP) sensor is a weak link on these trucks and is what reads the rpm signal.

 

service manager already threw a cmp senser at it. with the key turned on the bowl will keep filling and filling and overflowing

 

How long are you cranking on it when you are trying to start it? When the 7.3's fuel system is drained, it takes quite a while to get it to fill back up and run. When I replaced the injector o-rings on mine, it took us a couple hours to get it to start. We would crank for 20-30 seconds, let it sit a few minutes, and repeat until the batteries started to act weak. Let it sit for 10 minutes or so, and do the process over. It eventually did start and ran like a champ.

 

Moved to the 1999 - 2003 7.3L Power Stroke Diesel forum.

 

The IDM requires 10.5V minimum to fire the injectors, so it might help to monitor the battery voltage while cranking. If the batteries are being drawn down below 10.5V the motor won't start, even though the starter spins fine.

 

Put a filter in the bowl and put the lid back on. The fuel pump is electric and always on with the key. Excess fuel not required by the injectors is returned out the side of the fuel bowl back to the tank. Sounds like fuel is not your problem.

Remember the fuel injectors are HEUI, so they fire off of engine oil pressure on the high side. If you can't hit 500 psi min., the truck won't start.

 

hopefully you guys don't specialize in 7.3's on a daily basis lol

 

bad glow plug relay...diesel tech came back from vacation and took less then 10 min to figure it out