Help with 1st start of AZZ/pump problems

[Digital K]

Well, an hour or two ago I was apocalyptically frustrated. Diesel fuel all over my floor. Pump wouldnt draw fuel. Cylinders 2 and 4 would be the only ones that would have even a little fuel come out....

I couldnt get the pump to draw fuel. (this is in a vw pickup that used to be gas btw)

I noticed on the tank the inlet and the outlet BOTH seem to be on the bottom, so I figured no big deal which was hooked up to the filter.

The ONLY way I can get the pump to pump to all 4 cylinders is if I have an air hose hooked up to the filler neck. once I stop that, it seems like the fuel drains out of the lines back into the tank. Without hooking up the air line, no fuel comes out the return at all. once hooked up, and the pump was full of fuel, it seemed to draw down a quart container of fuel just fine. when hooked up to the filter though, it seems like it wont pull.

not sure what to do. also to note, the car didnt start when I tightened down all 4 injectors when it was firing those.

not even sure what questions to ask. Hoping you guys can help me out...

[Digital K]

update, I did get it to run...it runs, if I pressurize the lines on the fuel tank side with an air hose. it will then run until I disconnect the hose. it runs through whatever fuel is in the pump, then dies.

[Powered by Spearco]

I think I would try running the engine on a completly separate fuel supply. Like a small can or jar of fuel right next to the pump and try priming the pump and injectors that way as to eliminate any chance of air in you trucks fuel lines.

[fatmobile]

Clear fuel lines going from filter to the pump,
 when hooked up to the tank?
 How's the air look?

 Don't even worry about what gets to the injectors until you have a good flow going through the pump and heading back to the tank.

If it works great when bottle fed,
 but when you connect it to the tank it won't run?
 
 Hard to tell if the fuel is full of air due to a leak, filter vent not closed/sealed.
 or a fuel line restriction, it could be a clogged intank screen.

[Digital K]

Clear fuel lines going from filter to the pump,
 when hooked up to the tank?
 How's the air look?

 Don't even worry about what gets to the injectors until you have a good flow going through the pump and heading back to the tank.

If it works great when bottle fed,
 but when you connect it to the tank it won't run?
 
 Hard to tell if the fuel is full of air due to a leak, filter vent not closed/sealed.
 or a fuel line restriction, it could be a clogged intank screen.

upon your recommendation I did do a clear line. it basically fills up with air completely almost immediately. after I stop the air pressure at the filler neck.

I dont think there are any clogs in the screen or lines, the truck ran regularly and ran great prior to parking it several months ago.

I didnt try running it out of a can yet. once it fired up and rev'd nicely for a few moments, I decided to end the night on a good note.

I'm going to go through and check all the connections and fuel line clamps tomorrow. I'm also going to replace all the copper washers for good measure.

[JunkcollectorJ]

definitely make sure you've got the inlet and outlet lines correct...but you probably do since it ran.  Dry pumps can be very difficult to prime, so you may just still have air in your pump or the entire system.  I'd agree with trying to use a can/jar of fuel under the hood, and see if it'll run on that.  If it does, then there's definitely an issue between the pump and the tank, could be a simple as air in the lines or filter.  When you force from the tank you don't necessarily get the air out of the system. 

On my previous diesel rabbit we had a horrible time getting it to start (had been sitting  a year)... had to put a mighty vac on the pump return, then crank the crap out of it forever to get the pump to prime correctly and get the air out of the system...then when it did start it took several minutes of messing with the throttle to keep it running and get the rest of the air to purge.

Good call on checking all connection too...any air leak on the inlet side will cause it to never really prime well.

After the pump is primed, then crack your injector lines slightly and crank to get the air out...it makes a mess, but it's the way I always do it.

Wouldn't hurt to verify that the stop solenoid in the pump is working correctly too.

[Digital K]

update:

car idles. basically what I did is run it off a can.... which it does do. I then quickly swapped it over to the filter, and then pressurized it from the fuel filler.

Worked.

It idles roughly, and foam comes out of the injectors. when I pressurize the system the idle rises, and smooths out quite a bit. Not sure what this means. If I increase the throttle it smooths out a bit too. cute little turbo is spooling away....

I changed out the copper washers, and made sure all the fittings on the lines were tight and the clamps were tight.

any input? getting very frustrated now. pump needs a rebuild? Not sure how long it sat with no fuel in it...

[Digital K]

update, runs mint on a quart of fuel set next to the pump w/ the return and in sitting in it.

I sucked on the line from the filter to the pump until there was fuel, then hooked it up to the pump. Ran ok for about.... 30 seconds, then rough, then rougher, then dead.

hook back up to can, runs mint.

:/

[jseeley]

There should be check valves on the send and return lines back by the tank. When I had a similar problem the check valve on my send line was bad (fuel flowed freely both ways). I replaced it with a generic one from ebay as I couldn't find an oem replacement. A mighty vac can be your best friend to prime things and make sure you get all the air out though, form both the lines and the pump.

[Digital K]

There should be check valves on the send and return lines back by the tank. When I had a similar problem the check valve on my send line was bad (fuel flowed freely both ways). I replaced it with a generic one from ebay as I couldn't find an oem replacement. A mighty vac can be your best friend to prime things and make sure you get all the air out though, form both the lines and the pump.

hmmmm would speculating that removing the accumulator and fuel pump from the gas setup removed the check valve as well seem true?

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Don't think that theres any fuel check valves. Its a gas converted todiesel? Then disconnect all the gas fuel lines from the tank to pump to accumulator. Just run new fuel lines from the tank to the hard lines underneath. Trace out the lines if need be to make sure they'er connected to the diesel pump at engine.
I do know that in the tank, there is a pickup screen that can become plugged with some kind of crusty stuff. Drop the tank, pop off the sending unit, use some long needlenose pliers and romve it or just clean it with choke cleaner. Worked for me
When clamping the new lines, use good quality screw clamps.

[jseeley]

hmmmm would speculating that removing the accumulator and fuel pump from the gas setup removed the check valve as well seem true?

What car? Its my understanding that the check valves are usually part of the fuel pump in the gassers.

This is what I got  to replace my check valves->
http://cgi.ebay.com/ebaymotors/One-way-Check-valve-Gas-Diesel-fuel-1-4-Bio-/170622552474?pt=Motors_Car_Truck_Parts_Accessories&hash=item27b9e5899a

Any idea how much vacuum it's taking takes to pull fuel from the tank? Also keep testing with the clear lines, it's really helpful in case you have a leak letting air in somewhere.

[Digital K]

bah conflicting info. someone is telling me theres no check valve on the diesels. kasdjf;laksjdf

this is a 1980 rabbit pickup that used to be gas. I can suck the fuel from the tank to the filter w/ my mouth.... I think. unless I was just getting it out of the filter.

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Gas sure. Diesel no.
Put on in if you want, but they never had them in the lines on MK1's. Maybe in the pump on the feed side?

[jseeley]

They were there stock on my mk2, I didn't know they were there till Giles told me to check them when I was having problems. They are right at the start of the hard lines back by the tank.  

Pic of the stock one that failed on me->