Injector Pump or fuel shut off?
 

Hey folks!

I've got a '93 P30 Van with the 6.2L (I think) diesel V8. I have good fuel at the lifter pump, good fuel at the filter box (black valve top left at the filter mount) and good fuel at some release valve on the front of the motor (I can't tell where it comes from... it comes up from under the intake manifold.)

But no fuel at the injectors. I've cracked 4 of the injectors and no matter how much I crank 3 are dry and one got a tiny bit wet. I pulled the return line at the injector pump and that's dry too. Not even a squirt.

The van ran last year and I had parked it for the winter. The fuel filter is newish.

Is it likely the injector pump is out? If so, can I rebuilt it myself? I've done my own seals on my TDI before.

Is there a fuel shutoff solenoid like on the TDI? Could that be failing to release?

Any other test I can do?

Thanks for your help.

---AutoMerged DoublePost---

PS: The van is for sale — I don't use it anymore. :)

The injection pump could have failed. No you cant rebuild it your self. There is a fuel shut off inside the top of the injection pump. If you unplug the I believe its the red wire from the top of the i/p turn the key on and plug the wire back up you should be able to hear it click. I would take the fuel line off to the i/p and see if you have fuel there. The problem is you will have to remove the intake to remove the line.

2MuchJunk thanks. I don't hear a click from the IP at all.

I have two wires to the IP, both on the passenger side. I think one is green and the other is maybe red. I'll have to look again.

What's the other wire do, and how can I tell which is which? I'd like to jump it directly to the battery to test it but I don't want to damage it. I guess I better check my fuses too. =)

The green wire has to do with cold start stuff and should also be spliced a solenoid that pushes the throttle open a little when its cold. It's the red wire and I think its the one furthest back. It should be fine to jump it right to the battery.

Poke around some more.

Solenoids are good. Both click. Throttle pusher works too. I even pulled the top cover off and examined the solenoids. Both work when powered. There's a little bit of fuel in the IP. It was not full though.

I pulled the box filter and it looks good. Fuel came out all holes.

JUst for laughs I plugged the fuel line from the lifer pump, to the output nipple that the box filter sits on... basically sending fuel right from the lifter pump to the IP. With the IP cover off I cranked the motor. I could see a TINY amount of fuel being delivered... after for or five cranks I had maybe a 1/2 inch more fuel in the IP.

But when I pull the lifter line off and leave it disconnected, the lifter line really GUSHES. I am not getting that level of flow to the IP... it's just a trickle. But, the cracked injectors are now looking a little wet when I crank.

Does this low flow to the IP look right? Is it natural for the IP to only allow a little fuel in? Or do I have a blockage between the box filter and IP? What else could stop me from catching... it's HOT out, do the glow plugs even matter?

Brand new starter... and the batteries are topped off every time I try. So RPMs should be good. What am I missing?

I would guess you have a blockage. You should be getting a good amount of fuel in the i/p. I would check the line between the filter and i/p. There should also be a screen on the inlet to the i/p. You will have to remove the intake most likely to get to everything. The screen if it has one will be in the fitting going into the pump. If you don't have any problems up to the i/p you may have a problem in the transfer side of the i/p.

The glow plugs could matter it just kind of depends on the truck.

Thanks I will tear into the intake tomorrow. =)

Check for kink in the fuel line between fuel filter and IP

No kink. But I ran bio for a year and if it's a rubber line it might have been damaged. Strange to happen now though because I've run regular diesel all last year before I parked it.

I'm going to try to blast out the line from the IP end and see if any crud comes out. If that fails then I have the intake gaskets on order and I will pull it apart.

So what's between the box filter and IP... a nipple, a hose, another nipple, a screen, and a valve? I assume the cutoff solenoid operates some sort of valve because when I pulled the IP cover off I could see it actuated some sort of lever. And the second solenoid, activated manually with the throttle advance, just seems to open up the return line at the IP.

Does the IP regulate its own fuel intake? I see the throttle also moves the same assembly the shutoff solenoid seems to move. Lots of little metal parts and some springs.

It was probably just an airlock. It took days to finally reprime the pump and injectors, now it starts on the first or second crank every time.

How did you reprime the pump & injectors? I just replaced my tank, sending unit, lift pump & filter. It started right up, then quit, it was not running when I parked it. Thanks for your help up front.

Well, you can disconnect the fuel line where it enters the box filter. I believe this is the line on the lower right of the box filter but that depends on where your box filter is mounted. You can pull the box filter and look on the back and it will tell you which port is the input. Pulling the line here allows the lifter pump to pump freely. Crank the motor until fuel spurts from this line, and you know you have prime at the lifter pump.

If for some reason you don't get fuel from the lifter pump, perhaps it is dry or airlocked. You can try pouring some fuel down the line into the lifter pump.

Then there's a air release valve after the box filter. Open than up, and crank the motor until fuel spurts here. Now you know you have good fuel to the box filter.

To check for fuel to the injector pump, you can take the top cover off the injector pump. This lets you look into the top of the pump body and see fuel pumping into the injector pump. This confirms you have good fuel to the injector pump.

And then... crack a few injectors. I use a slotted box wrench. Crack an injector nut enough that the injector line can wiggle free from the injector. Now crank the motor until you have fuel spurting out the injector lines.

The problem with air in the injector lines is that air is squishy. This means the injector pump can compress the air line a spring... but that air then never builds up enough pressure to cause the injectors themselves to open, so the air never leaves the injector line. You can crank all day long and you will just be compressing and releasing the trapped air like a spring. To release the air you must crack the injectors, and then the air has a place to escape to.

TWO WORDS OF CAUTION HERE. One, never crank more than a few seconds at a time, and always let the start cool down between cranks. I burned out a starter last year by over cranking.

Two, the injector pump works at enormous pressures. Be cautious around cracked injector lines. I've heard rumors that a fast pressurized jet of diesel fuel could damage an unprotected eyeball.

I had to crank FOREVER to finally get the air out of the line. I kept my batteries on a battery charge. I would crank, cool down, crank, cool down, for five minutes, until my batteries were drained, and then leave for six hours until they charged again, and repeat the process. This took for days and days of cranking before my motor FINALLY coughed and caught.

Now it will start on the first try every time.

Thank you, I don't know what the FI pump looks like, I know it is located on the front of engine but not sure just where. It is a 1996 Chevy silverado 2500 turbo extended cab. could you help with location?

Well, it's usually called the IP (injector pump). You can find it by following the hard metal fuel lines that come out of each injector. The injectors are the things that look kinda like spark plugs on a diesel. Those fuel lines all head back to the injector pump.

On my Chevy it's on the top front of the motor between the front arms of the intake manifold. Its smallish in size. It will have the eight injector lines running to it, as well as a couple of electrical lines (shut-off solenoid and cold start solenoid wires).

Oh yeah... if you are having trouble getting fuel to the injectors, make sure to check that shut-off solenoid. It should be getting 12v of power, and should click when power is applied.

Thank you!

I have a 1995 chevy one ton with a 6.5 diesel. I was driving to work one day and it started to really cut out, like it couldn't get enough fuel. I took it to my mechanic and he checked it out and determined the IP was bad. I bought a rebuilt IP and installed it and now I am not getting fuel to the injectors. I get fuel to the pump but when I disconnect an injector line no fuel comes out. Thanks in advance for any help you can give me.

jump lift pump
 

Try wiring lift pump direct, you may need the extra pressure to "Burp" it, and Crack 2 or 3 injector lines. The lift pump doesn't engage until there is oil pressure built up so even though there is fuel flowing up it may not be enough to overcome air in the system. I keep a set of jumper wires and a 3/4" wrench handy just in case.
The valve up front should be to drain water from bottom of filter cartrage (bleeding while not running will kill preprime also).