View Full Version : Help with 6.9L diesel!!!
11-21-2004, 09:15 PM
I bought a 1986 f350 dually 2wd with a 6.9L diesel and a C-6 auto tranny. I got the truck for 500 so i didn't expect much but it was in great condition for 500 dollars. ok my problem is that it isn't getting fuel. it cranks fine and is getting air fine and will fire with a little ether (just 1 shot). we have been looking at everything. the fuel pump is pumping because there is pressure in the return line. i tried to bleed the injectors but nothing was coming out (tried several times). I am thinking that the fuel shutoff soleniod isn't working right. I checked and it has power going to it. i don't know what to do. i'm afraid if i keep trying i will either burn up the starter or the fuel pump. i give them plenty of time to cool between each try. i put fresh fuel in it with de-icer in case the lines gelled because it set still for 2 years. the lines aren't broken. i also put on a new filter filled with fresh fuel. has anyone had this happen? any suggestions are more than welcome. if any one needs more info. let me know. Please help me.
11-21-2004, 09:50 PM
Have you tried testing the injector pump?? That may be your problem.
11-21-2004, 10:02 PM
If you mean the main pump i am pretty sure it works because of the pressure in the return line. i don't know what you mean by the injector pump. what would it look like? where would it be? and is there a way to test it? thanks for your help.
11-21-2004, 10:09 PM
The fuel injector pump sits on top of the engine right in front. Has a line for each injector. On the injector pump, on the drivers side is the fuel cutoff switch. Its an electrically actuated seloniod. When the key is turned on it should work, if not, you have an electrical issue. Check for power to the switch. If none, check your fuses and wires.
11-21-2004, 10:51 PM
By fuel pump, do you mean the electric pump that moves fuel from the tank to the engine? That is a separate pump from the injector pump. The injector pump sends fuel to each cylinder at high pressure at a precise time. If you are getting pressure in the return line but no fuel to any of the injectors, I agree with the other guys, I think the injector pump is bad. Did the truck run when you bought it? If not, there's the reason it was that cheap, any diesel truck that runs is worth a lot more than $500.
11-23-2004, 11:11 PM
You will have pressure in the return line because of the check valves holding pressure.
11-24-2004, 01:48 AM
That one won't have an electric fuel pump. It is a side mounted manual pump with an arm. You have to be careful when you replace it because the arm will fall into the crankcase and then you get to yank the engine, pull the pan and remove the arm. When you install the pump, the eccentirc has to be in a certain spot as well, otherwise you can damage the arm and the pump can fail prematurely. I'm betting on the fuel pump solenoid like Mac says, or, the transfer pump (side mounted fuel pump) is not working.
Was the truck sitting for a while, or did it run when you got it? If sitting, change the fuel filter.
11-24-2004, 06:49 AM
Dont use starting fluid, use WD-40!!! It works pretty much the same on diesels and is no where near as aggressive.
Make absolutely sure that none of the fuel lines are cracked or old and spongy feeling!
Try and save yourself sometime at this point and pull start the truck, may take 30 miles or more of dragging it in gear. If it starts you most likely have a glow plug problem. Check the voltage at each glow pug terminal, there should be 8 coming out of the cylinder head. If memory serves its a 6-volt system on the 6.9. They will only have voltage with the ignition key in the on or start position and even then only temporarily (30 seconds) and intermittantly. If you dont have voltage to any of the plugs then Chilton's makes a good manaul on that engine (the F-series manual doent cover it, must be the diesel manual) that has pretty detailed troubleshooting. If you have voltage to some of the plugs but not all of them you might have a broken wire trace them out or use a ohm meter to see. If you have voltage at each one then pull the glow plugs out and make sure they arent burned or covered in oil. Clean them up and reinstall. If they all look ok then you have a fuel problem. Disconnect the line going from the mechanical fuel pump on the left hand side (passenger side) of the engine going up to the fuel filter at the fuel filter. Have a helper crank the engine, you should get a steady amount of fuel coming out of the line. If you dont gat any fuel then you have a bad low pressure or fuel supply pump, a bad fuel transfer switch (located behind the cab on the inside of the frame rail) or a clogged feul supply line. Blow the lines out before you replace the pump or transfer switch. If you do trace the other metal line from the fuel filter to the injection pump and disconnect it and again have a helper crank the engine to verify fuel getting to the engine. If you do then your next bet is to make sure one of the fuel return lines is not clogged. The fuel return lines are the flexible hoses that loop between each injector, the fuel tank, the injector pump & the fuel filter. Blow them out with compressed air or look down each one. If all is well and none are clogged leave them off for a minute, disconect the metal fuel lines from the top of each injector and pull of the fuel return tee, they should pop off pretty easily, but some are troublesome. Look down the nozzles that the fuel return lines connected too and make sure they are not clogged, if one of them is try and stick a small piece of wire though it and remove whatever is clogging it out. Also look them over and make sure none of them are cracked. If one is or you break one of them they arent very expensive, $5.00 or so from Ford but bring one of them with you as there are 2 sizes. If none are clogged or cracked reconnect them, but leave the metal fuel lines from the injection pump to the injectors off. Now have a helper crank the engine and verify that you have small bursts of fuel coming out of the end of each line, dont try and touch the fuel as it comes out as its around 2,000 psi. If you dont, disconect the lines and blow them out with compressed air. If one of them isnt clogged and you dont have small bursts of fuel coming out then you injection pump needs to be changed ($800). If you do, then you have either bad injectors or a bad head gasket. The injectors screw out of the cylinder head with a wrench, if you've made it this far then at one point you were only one step away from changing them, keep in mind they are $50 a piece. The head gasket isnt very hard to change either but keep in mind the heads are very heavy, last time I changed one I had three guys and ended up having to get my wife to help too.
11-24-2004, 04:26 PM
Pull it for 30 miles in gear to start it? You are kidding right? :dizzy: :dizzy:
11-24-2004, 04:27 PM
I think he meant pull it at 30mph in gear so it can lock the torque converter to start.
You know like pushing a stick shift off and popping the clutch?
11-26-2004, 11:40 AM
No pull it for 30 miles in gear, it will insure that the fuel ines are bled. It may start sooner, if so good for yo, if not pull for atleast 30 miles before giving up and you spend all day troubleshooting it. 30 minutes of pulling is a lot better than 8 hours of wrenching + parts.
11-27-2004, 12:38 AM
That would tear up a transmission......
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