faulty lift pump?
 

1990 F250, 7.3
-the battle continues...
from time to time, this engine fails to light.
let me down again tonight an hour after shutdown.
depressed the Schrader valve...no fuel, bone dry! where does the fuel go?
no sign of external leaks so must be leaking back internally.
where do I start to trouble shoot this baby???

btw, once it starts, it purrs like a kitten...but it only has 350,000 kilometres on it so it's barely broken in.:)

First place to look is the return tee O rings and lines between the injectors.
If the lines are painted grey, they need to be replaced.
Any diesel injection shop should be able to fix you up with the kit to replace them.

By the time you see fuel leaking out of the O rings they are in very bad shape, air will leak in a place that fuel will not leak out of.

with 350,000 kilometers on the engine, even if the return lines are not gray, they should be replaced if you havent had them done recetnly. That would be the cheapest place to start. Look at the lift pump and check to make sure the weep hole isnt damp and also make sure the oil isnt being diluted by leak back fuel at the lift pump. Also look in the valley pan at the top of the engine and make sure that isnt damp from the lift pump weep hole. DONT CRANK ON THE STARTER TOO LONG, it is heat sensitive.

OK...hate to admit it but...
 

...most everthing on this engine (except glow plugs) is original equipment.
Return lines painted grey? Well...they probably were in 1990.:)
Guess it's time to jump in. There is a Navistar shop near me...are they cool for parts/kits or should I try NAPA?
thanks,

Navistar should be good, I just was looking at NAPA online, their price was something like 83 dollars. An injection service price would be in the 30 dollar range for the same return line kit.

injector price? etc
 

90 F250, 7.3

Ford dealer wants $90 each for injectors...is that OK? Also, one hi pressure line may not come off in one piece...Ford wants $90 for each line...sound OK?

Local NAPA was a lost cause on return line kit. Looked at me like I had three eyes!

Navistar dealer was better...no return line 'kit' but can fix me up with all the bits and pieces and says he can make the hi pressure line. He says Ford put on the injection pump and lines etc so these are not Navistar parts...sound right?

I miss my truck...I'm forced to drive an Oldsmobile for now.:)

thanks,

you should be able to get injectors from and injection shop and for the return line kits you can go to a local injection shop or get them on line. The part where ford made the injection lines i am not sure about because i used to haul the complete engines from international to ford factory ready to go.
ford stealerships always add money for handling the same parts that international carries.
YOU will have to be satisfied with your decision in purchases.

A question for the experts along this line.

Should the engine be running when checking the Schrader valve for fuel? Or does depressing the valve without the pump pressure alow air back into the system?

Inquiring minds need to know.:)

any type of "leak" will alow fuel to flow backwards. The pressure should be checked with the engine running or cranking.

bilder12 wrote
The pressure should be checked with the engine running or cranking.
>>>>>>>>>>>>>>>>>>>
I suspected this, so, is it a leap to suggest that the Schrader valve also should be on the list of places where air can get into the system? If we upgrade to a Racor fuel filter mount does this eliminate the Schrader valve? And, if the little devil is on the bad list then is getting rid of it a good thing? If we replace the factory lift pump with an electric do we effectivly solve the air/fuel mix problem?
I know this is a lot of questions, but I'm about to drop a few hundred bucks on fuel system upgrades and just want to be sure that I'm actually improving the system.
Thanks in advance.

90 dollars per injector is rather steep. 30 to 40 each for new or about 30 each to rebuild is my price here locally at a diesel injection service shop.

This is one of the site supporters.
http://www.trademotion.com/partlocator/index.cfm?action=getLocator&siteid=214072&chapter= DN2023&appSectionid=6&groupid=10025&subgroupid=201 70&componentid=60811&make=10&model=F250&year=1990& catalogid=1

You may have to copy and paste the link into a new browser, but Discout Ford Parts in Seattle has them for 36.98 each.

There are several others online unless you are in a big hurry, you could save about 50% of the cost though.

www.mwfi.com comes to mind

You can replace the mechanical lift pump with an electric unit, then it will bleed the system every time you turn the key on. But if you have air leaks, they are going to have to be fixed or the fuel will still drain back out of the system. Eventually the leaks will get bad enough they will start to leak fuel out when the engine is running, but they will be easier to find then.