Completed 1989 F250 4WD gas to 7.3 IDI diesel conversion. Primed the fuel system, (part of the conversion was to put in an electric lift pump). Turn on ignition lift pump does its thing. Crank the engine but she just won't kick over. So I must be overlooking something. Electric is either new or rebuilt, new batteries, glow plug controller Ford OEM new, engine harness new (pacific supply). As part of the conversion changed the fuel filter to different setup due to the problems associated with the OEM fuel filter (air intrusion). I suspect my system still has air in it because the lift pump keeps clicking. Upon looking at the lift pump reservoir there's fuel in it but not completely filled. Is the fuel system not fully primed and purged of air? Or am I overlooking something? I did get fuel seepage when I had the injector connection cracked so fuel is getting up there but may be not enough. Any help or suggestions are most welcome and greatly appreciated.

 

Here's a video of all the things I checked over to get my IDI running on a stand:


about how much diesel is coming out of the injector lines when you crack them? Can you post a video of your cranking process?

Also, these engines need a lot of cranking power. If your batteries are putting out under 12.0V, then you might be able to turn the flexplate, but not get it started.

 

Crack the lines at the injectors and see if you have fuel coming out.

Hobo

 

Thank you for your response. I basically put a vacuum pump on the IP fuel return until I got fuel. Then turned the engine over with the injector lines loosened fuel puddled in some of the glow plug areas but not all . Cleaned it up cranked again no success. So it appears I may need to keep purging the system and connect the batteries (which both are new interstate) to a jump like in your video. Will attempt to do a video of the process but work gets in the way so it may be a day or two. Nevertheless, thanks for your reply.

 

IF you have an electric pump you should have a steady stream of return Fuel.

 

Forget the return........... You must have fuel on the supply side of the injector pump and on to the injectors.

Hobo

 

you will never get fuel to the supply if the Return is blocked


AND you will not get fuel to the injectors if the Metering valve is stuck closed.

 

This^^^^

The injector pump will start returning fuel long before it primes up to the injectors.

With an electric as stated you should have a steady stream of fuel from the filter head and possibly a dribble from the ip return.

 

I figured his metering valve isn't the culprit since in his first post he said there was some diesel dribbling out of his cracked injector ends. Regardless, it could be the metering valve, here's how to fiddle with it a bit to see if that gets you some more fuel to the injectors:

 

fuel can still dribble out of the injection lines even with a stuck Valve... but it will not be enough pressure to POP the injectors. UNLESS it is stuck completely closed .... most the time I see them when stuck still passing a small amount of fuel.

BUT thanx for the video just in case the OP needs it

and I'm not saying it is the issue as I ain't there to see what is really going on.
We don't even know what the inlet Fuel Pressure is at this point.


The other thing here that is being over looked is what is the "NEW FILTER SYSTEM" does it have a return ? if not that could be the issue and most folks think that the Schrader will bleed air off the filter head well WRONG it only bleeds the inlet side of the filter housing... so maybe the OP needs to crack the inlet to the pump to Bleed air off the Filter Head.

 

I'm lazy, instead of messing with the Schrader valve I loosen the line to the ip at the filter head. Helps get all the air out cept the line, but it's also the highest point so it generally starts pumping fuel pretty quick.

Edit: also the part you mentioned about the new filter system is a good point. If it doesn't have some kind of return that ip will have to work through all that air on its own which will take a while.

There's a reason they had either an orfice bleed past or check valve, it makes it prime so much quicker. Lots of people delete them but I don't exactly think it's wise.

I have mine capped on the 85 because the hot pipe for the turbo is in the way, and it takes forever to prime compared to before.....

 

Exactly, you understand it.

the schrader is a test point for lift pump pressure it was never meant as a Bleed port (but it works to some extent) and you are correct the Orifice/check valve is the Bleed point.

it's fine to delete the filter return as long as you understand the downside... I have a prime bulb on mine along with the lever on the mechanical Lift pump that I never use as it is too hard to get to.

using a manual prime bulb works fine because when the Injection Pump is not turning fuel bypasses the Pressure Regulator and fills the housing via the vent wire and will flow out the return when the pressure exceeds the Housing Pressure regulator set pressure or if you enable the cold advance.



AND another thing the DB2 will prime itself real fast IF it has air free supply the suction side of the transfer pump will easy pull 15" Hg and make at least 30 PSI or better while cranking (mine makes 60 psi while cranking) so measuring Transfer pressure even on an engine that is not running is important to understand the Health of the IP itself.

 

May just be my imagination, but ive always had best luck cracking 2 or 3 injectors rather than 1 or all 8. If possible, loosen 3, have someone else crank it. Once fuel is pulsing from the line nut, tighten down while maintaining cranking. Within a few revs it should fire on those cylinders and possibly even run. The extra rpm will help pressurize and get the rest going. If it hasnt been pointed out, all cranking at this point should be done with wide open throttle. Ive run into an issue with pumps that have sat a while, where no matter what the damn thing just wont fire, they will act bled, she will have smoke in the exhaust, not even ether will get it to kick off. In these situations ive actually dumped a few ounces of gas / diesel mix in the intake followed by a snort of ether. I mention this as a last result, catastrophic damage can result if not done correctly, and probably a fair chance of damage even if done correctly. Ive had to do this to two different pumps, both times it worked, it was horrible sounding, but once the engine actually ran a little bit off the added fuel, it seemed enough to "wake up" the IP. Im sure this is due to a stuck something or other in the pump, far be it above my head to know what.