Greetings, Ive had my 89 7.3 for some time and am well aware of the hard start issue... She left me stranded the other day on the side of the road I may have let the fuel gauge go past halfway mark... anyways i switched to my other tank which is full. Long story short after many attempts to get new fuel and bleed the system i decided maybe my lift pump died... I replaced it (straight arm) but still having trouble getting fuel from the tank... if i crack the hard fuel line from the top of the pump where it connects to the fuel/water separator will it squirt fuel after a few 20 sec cranks? because its not... maybe it needs to hold prime or something... anyways how do i know this pump is working... i made sure when i installed it that i angled the arm way down then camp up plus i had to push a little to get the bolts in... sorry for the length im 5 beers into this already...

 

Easy test for your pump, disconnect the line coming from the tank and put a hose into a bucket with some diesel in it. If it pumps it out of the bucket, your pump works and there is an issue with the fuel lines.

Sounds like you installed the new pump correctly.

Good chance you have an issue with the fuel lines somewhere.

 

ah nice thank you

 

so i did the bucket thing no suction at all...i then decided to check the line from the tank to the lift pump its mostly steel covered in oil but i see no holes or anything seemed to be all good so i popped off the line where it connects to the lift pump and blew in it. I heard bubbles coming from the bucket... so im like "i cant believe have to remove this damn lift pump again... " so i did just that and the pump seems to be in working order i pushed the lever nice and firm and i can hear the diafragm (sp?) pumping and the top of the lever had a nice line where the cam was rubbing it so im totally lost.... id rather keep this thing stock but all signs keep pointing to low pressure electric pump... dont know what else to do

 

also i will add that there was (some) fuel in the pump when i removed it... not much at all though...

 

Alright, do this:
1. Pull the intake side off the low pressure pump(that's the side with the rubber hose).
2. Put a 3' piece of 3/8 rubber hose(cheap enough at your local auto parts store) on there, into a bucket of diesel. This eliminates any leaks, any chance of issues.
3. On the filter head, remove the schraeder valve core -- it's just like a tire valve stem.
4. Crank, see if air comes out that port.
If you do not see air coming out, you've got a problem. If you do, the low pressure pump is working.
Remember that the low pressure pump can't /push/ air very well. And there's only a tiny bypass from the filter head to the return system; if it's full of air, it won't be able to push well. Open up the restriction by removing that core, and it should be able to pull/push well enough.

Once you get fuel coming out the schraeder valve, put the core back in. Now, make sure that you have power to *both* of the lines on the top of the IP with the key on, and that you get a clicking noise when you remove/reattach the connector on both of the lines.

If you don't, for this test create a piece of jumper wire and run it from Battery + to both of those terminals.
Now, you have a chance of bleeding things. You will need to make sure that the throttle lever/accelerator on the IP is floored when bleeding. YOU CANNOT BLEED WITH THE THROTTLE AT IDLE.
I would now remove the rubber return line from the top of the IP, and crank until you see fuel there. THIS WILL NOT WORK UNLESS BOTH TERMINALS HAVE POWER.

You can now try bleeding the injectors. Hook the return line back up to the IP, and crack all 8 injector lines at the injector. Crank with the throttle FLOORED until you see fuel squirting out around each injector nut, then tighten them down. You can now try starting the engine.

 

Macrobb, good writeup there, much better at describing what I had meant to do.

Beerme7.3, sounds like you might have a problem in the tank if you can get the pump to work from a bucket. If you hook the hose back up to the tank, can you hear bubbles going into the tank? I had an issue with the pickup rusting out on the back tank of one of my trucks. First I thought it was the tank leaking, but when I dropped the tank noticed how rusty the lines on the sender were.

 

Just going to add you don't have to crack all 8 lines, 2 or 3 will do the trick.

 

Ok so i got fed up with the stupid mechanical lift pump so i went big and replaced the whole thing with an electric fuel pump... works great i have a 30a relay and all that other crap i read off the forum. Fuel pump cover plate installed looks really nice works really nice... anyways i turn the key (circut relay spliced into the Fuel shutoff solenoid) pump starts pumping... boom fuel up to the fuel filter in a hurry.... i push in the pin on top and get some air then a nice gush of fuel im like sweeeettt! so now im wondering how am i supposed to prime the rest of the way... i cracked a couple then all of the lines and held down the throttle while the pump pumped... nothing... not sure what to do now... im wondering if there is some sort of blockage... both wires "click" when i disconnect reconnect. i hope im just not seeing the obvious here. im feeling better though plus miller highlife helps.

 

Did you crank the engine while holding the throttle down and lines cracked? Or just try to bleed through with the e-pump? My understanding is you have to crank the engine....and that it may take several cranking sessions...

What pump did you use??

 

Yeah that was my main question guess I'll hve to wait for the batteries to charge.... I used an airtex I believe here's some pics didn't take more than an hour or two.



Blue is new





Relay inline fuse...





Pump