Last night the '89 7.3L diesel died suddenly a full day into a trip. Electric lights etc. looking good, engine cranks fine, but not running. Not even trying to go. Stopped running instantly, no roughness or warning.

We had about 700+ kms on it in the last day, been running OK. Fueled up maybe 90 minutes before it quit.

Thinking it's a fuel delivery problem, cracked #8 injector line and it bubbled out a little fuel, but not spurting like I usually see. Opened the fuel line between filter and IP to see flow there, and the lift pump seems to be working OK... reaching about 5 lbs pressure after cranking it a few times. Flow rate seems OK, 1/3 pint in 10 secs looks like that was being delivered. fuel looked clean and without air.

FSS is being energised, and clicks when power is applied.

IP was rebuilt just last fall, not too many hours or miles on it.

I replaces all injectors last week. Delphi BB, same as what came out.

I've gotten towed to a small shop here in Lillooet BC, being Canada Day the bigger diesel shops are closed down and owners on a cruise. I have some tools, internet, and a yard to work in. And a busy mechanic at this shop that isn't real familiar with diesels but very helpful otherwise.

What should I check or do next? at the moment we're waiting for the batteries to charge so we can crank a little more and see fuel flow at the injectors again.

Thanks!

 

I would say the IP has failed.

-Enjoy
fh : )_~

 

I vaguely remember someone mentioning a screen on the inlet side of the IP. Maybe some crud broke loose in the fuel system and clogged it. I may remember wrong though.

 

Good call on the inlet being plugged... I'll check that out.

After a little more checking, the problem is isolated to the Injector Pump (IP). Good pressure and volume coming out of the fuel filter delivered to the IP, and nothing coming out. disconnected all injector lines at the injectors, cranked and not a drop came out.

Pulled the top off the IP to access Fuel Shutoff Solenoid (FSS). Run a 12V line to it, works fine. Connect the original line from ignition, works fine. Manually operated the plunger inside and it moves freely and easily, with good return.

I'm suspecting maybe a broken shaft or other problem inside the IP and am working to remove it to further diagnose. Right now I'm a bit stuck on the removal process.. there must be some hiding bolts holding this one.

I've removed the cover plate from the front, below the oil fill tube, and removed the 3 12 pointed bolts in there. disconnected all wiring, removed fuel filter + braket, throttle cable braket, fast idle solenoid+bracket. All injector lines are attached to the IP, but disconnected at the injectors. Now what? From reading some instructions on this site I think there are 3 more bolts. I found 3 7/16 bolts deep down (1 road side, 2 curb side, of the IP) and removed them but it's still solid. Do I just need to reef on it a bit to break it free from gasketing?

Thanks for reading this far

 

There are three 3/8" nuts (9/16" wrench) that hold the IP on, one dead center top, one bottom right and one bottom left.

-Enjoy
fh : )_~

 

Thanks Festus! Have the pump off now.

Since FSS seems OK, next thought was broken shaft or gear no longer affixed to shaft. However, spinning the shaft moves the internals.

Well the pump is off, and I'm fairly confident that is where the problem is. Lift pump was delivering and IP was not outputting. Now to wait till tomorrow and find someone to fix this.

Whew, another learning experience!

Thanks for the advice and tips new and old to all FTE members. What a great resource, will be returning the help and advice as I can.

 

Hope all goes well from here out...

Good luck and PLEASE let us know when you're back on the road!

-Enjoy
fh : )_~

 

Bench testing the IP seems like it *is* working.

I've connected a can of diesel to the line in, raised about 5' to give a little pressure. Connected 12V to FSS.

While looking at the shaft, pump to the back, turning clockwise it does spit some fuel out of the lines.

I'm about fit to be tied. Instead I'll head to the local coffee shop for a little break.

Any ideas on what might be happening?? On the engine, it really seemed to be a problem with the IP, there was not a drop of fuel coming out the injector lines, even with good delivery from the lift pump and through fuel filter. Yet on the bench there is fuel pumping through the IP.

Good thing I'm not in a hurry to get anywhere. ha!

 

The gear that the IP bolts onto is not firmly fixed in place. there is some play in all directions - maybe 1/4" or more. Is some play normal? Maybe the engine isn't actually turning the pump.

 

Don't turn the gear that gear ... That will mess the fuel pump timing up if it skips teeth.

Yes, When you unbolted it from the IP it has nothing holding it, That is normal!

-Enjoy
fh : )_~

 

When the IP is removed, the IP drive gear is just sitting on the cam drive gear.
The play you are seeing is how far it is to the drive gear cover in each direction.
I do hope the IP drive gear is still in time with the cam gear, injection timing will be off if it has skipped a tooth.


It does sound like the IP is not building enough pressure to inject fuel though.

 

After all this time and trouble, the IP is back on, and seems to be pumping. as long as the shaft lines up with the metal dowel on the gear, it's fine, right? I mean, it's not like there is 2 rotations to a cycle and chance of being 180 degress out on the timing is there? Pretty sure no teeth were jumped, just double checking.

We think the problem might be a bad lift pump or air intrusion. Although static pressure and unrestricted flow seemed OK, current thought is maybe it isn't performing under operating conditions. I have a Walbro electric pump here that puts out 7.5 psi. I'm working at getting it out (previously installed to pump WVO but I never did get that going) and plumbed in on the diesel side. Any recommendation on placement? There is a clear body fuel filter, maybe 2" diameter, I'll put inline as well.

Does the old lift pump need to be bypassed and/or removed?

 

Had a look around more on these great FTE forums, have purchased a Ch*vy BB fuel pump plate, looks about right -- only block off plate the local parts store has. Will remove lift pump, install block off, and install this Walbro FS pump about mid-frame there is a convenient connector in the line and room on the frame to mount. Literature with the Walbro indicates it is suited to this diesel lift pump application.

Noticed a little dampness around the lift pump lines. Maybe that has been the trouble all along. Might soon know.

 

Yeehaw!! We have ignition!!!

Finally after days of mucking around, learning about the fuel system and trying to get this running, it's running again.

Now to button up the engine, install the electric pump, and hit the road. Electric pump is on the pavement out the front of the vehicle for testing purposes -- wanted to know ASAP if it would work. Still not real sure what went wrong, but maybe the lift pump wasn't working under load.

Thanks for all the assistance and information, in this thread and all the others! I'm now a premium member, well worth the price of admission. Hopefully I'll be in my new home in Vancouver before midnight tonight. My first full day of work is tomorrow, so it's not a moment too soon.

 

Man you sure have been through the ringer on this one.

I would run the electric lift pump off a relay triggered by the ignition circuit.

Sure is strange you were getting the pressure and flow results you were getting and the engine would not run.