7.3 non turb.filter not staying full will not stay running

[buckhunter1]

Hi All,91 f250 4x4 7.3,I started up drove to work fine,after work started drove 1 mile it quit,crank and crank started ran 1/2 mile guit,crank it alot start 1/2 mile quit,I took off the filter and it was 1/2 full, [img]/ubbthreads/images/graemlins/shrug.gif[/img] so its not getting its fule,I have a lift pump that has about 600 miles on it,I also have a elec pump I had unhooked,but I even hooked that back up to see if it would keep the filter full it did not, and yes it has a 1/2 tank of fuel,dose anyone have any ideas I am really stumped.
Thanks so much

[arthurgoboom]

You have a stock water separator installed still? You may have an air leak bad enough that even an electric pump won't keep up. You might try doing the flow and pressure tests at the schrader valve just to be sure your pumps are performing well. New doesn't necessarily mean good.

[cdnsarguy]

billy was the manual lift pump the one with the long almost straight arm...........did it come with instructions.......like these.

This info pertains to 88-93 7.3 liter, Carter #M60278 pump.

WARNING

This fuel pump must be installed only at the low position of actuator cam.

If the pump is installed at any other position than low cam, the pump will be ruined, the engine will stall and damage may result.

Incorrect installation will loosen the pivot pin and allows the pin and lever to come out of the pump and drop into the oil pan. This can occur immediately or after several hundred miles. This type of failure is not covered by warranty.

To ensure that the cam is at low position, it is necessary to use a mirror and a remote starter switch. Observe the cam through the mounting port and bump the engine around until a one (1) inch wide machine surface is observed. This is low position of the cam. Now complete normal fuel pump installation.

9502CA
1991

[buckhunter1]

yes the pump was installed right I have been useing it about four mounths scine it was put in ,I also reinstalled the water separator thats seems fine, the filter still keeps going half empty,I can crank it to fill and start but after a min or two it stalls and will not start,remove filter and its half empty,thats with the lift pump AND THE ELEC PUMP hooked up ????

[jackq]

did you check the schraeder valve-just a hunch but the innards of those things are screwed in. If it loosens up, you'll get air no matter what. Need one of those slotted caps to tighten- like on a bicycle. Either that or a loose fitting on top? Hope you figure it out.

[buckhunter1]

Not the valve,its tight,if the filter is going half empty after I get it started and it runs a min or two don`t that mean the trouble is BEFORE the filter,I sure don`t know just pulling at straws? I mean if it was after the filter would `ent the lift pump AND elec pump together keep it full??,

[arthurgoboom]

Have you actually done the pressure/flow tests at the schrader valve? You may have a line blockage or something somewhere that is restricting the pumps.

[buckhunter1]

No Sir,will not stay running long enought for pressure test.

[buckhunter1]

someone said it may be the tank switch so I by passed it ran stright front tank to elec pump no help.

[cdnsarguy]

Check the rubber fuel line at the lift pump to the steel line from the tanks........ could be kinked off if you did not put a pigtail curl in it. Open the fuel cap it could be causing a vacuum.......

[buckhunter1]

OK will Do,sorry men I am just at a lost and can`t put it in a shop to many little birdies in the nest,I can`t thank you enought.

[DSBlack]

Check out this thread.
http://forums.thedieselstop.com/ubbthrea...;gonew=1#UNREAD
It is similar to yours. I did not know about this checkvalve.

[buckhunter1]

Hi All,boy I believe I have about 100 new gray hairs this pass week,now someone says it may be the IP,is there someway to test it ,I hate to buy one then find its not that,Thanks

[DSBlack]

With the filter not having fuel I doubt that the IP is the issue.

This is what I would do.

1. bypass the manual lift pump.
2. install a elect. pump, some will not pump diesel fuel, I had a carter that would pump gas like no tomorrow, and after about 400gal of diesel was shot. I now use a little $40 one from purolator and the local Auto Zone.
3. test the fuel at the fiter input now. Should have a good solid stream, with no air bubbles in it. Pump 4-5 gallons and watch the flow.
If that is good,
4. Hook up to the filter.
5. do the flow and pressure test at the schrader valve.
if all is good,
6. purge the air and start it up.
If not we will go from there.

If you have 2 fuel pumps hooked up in line, the one bad one can still cause flow issues.

If the issue goes away with the elec. fuel pump(differant than the one you have now) then you can decide what to do, go electric, or new manual.
Still sounds like a pump issue to me,
Good luck.

[buckhunter1]

Thanks Mr Black I will try as you said in the am and see what happens Thank You.