[dhudge]

Hello all,
I'm new to the diesl forum and writing on behalf of my son who recently bought an '85 F-250 6.9 IDI...I've been an '03 7.3 powerstroke owner (1st diesel) for about a year myself, so I'm afraid my knowledge is very limited.

He was driving down the road the other day when his truck lost all power suddenly. I'm assuming this is a fuel issue, since his batteries are fully charged and he has no problem cranking the engine over. It appears the previous owner replaced the fuel injection pump within the past year...see pic below:

Q: Where to begin troubleshoot?

All feedback welcomed and appreciated...thanks.

 

[bobleny]

The picture is of the vacuum pump, not the injection pump...
When it lost power did it buck and serge? Did it stall, or just feel week?
How does it sound when he cranks the engine over? Does it sound like it is catching trying to fire?
Does it have a turbo?
Does it have dual tanks?

None of these steps will hurt, but depending on your answers to the above questions, these might be unnecessary.
Make sure you have a full tank of fuel, often times the fuel pickups break in tank, and it will just suck fumes.
If you have dual tanks, try the other tank if you haven't already.
Check for fuel leaks around the injectors and under the vehicle. Any fuel leak means it wont run right.
There is supposed to be a fuel water separator on the driver side fender near the brake booster (these are often bypassed or removed). Pull the little ring at the bottom and make sure there is no water in it.
Check the oil level, if it is high or smells like diesel, your lift pump is probably bad.
Check the weep hole on the lift pump (it is bolted to the block under the vacuum pump) while the engine is cranking (If it runs bring the rpms up to about 1,500 to be sure). It should not leak.
Pull the fuel filter off and see if there is fuel in it.
Replace the fuel filter.

 

[dhudge]

bobleny, thanks for quick response...
Re: vac pump...doh! Embarrassed, claim ignorance.
Answers to your questions:
When he began losing power, it was <10 sec before it was completely lost.
Trying to start now produces nothing...does not sound like its trying to catch fire on either front or rear tank. He did not have time, or didn't think quick enough to switch tanks at time of occurrence, but post event start attempts were done on both tanks without success.

He was on his way to refuel when it happened with a 1/4 tank in fwd and approx 1/2 tank in rear (rear tank has faulty sending unit, so not sure of its level).
No leakage around injectors.
Lift pump = supply pump from tanks? (thought each tank would have a separate fuel supply pump?)
Nothing near the brake master cyl vac assist...is this the fuel water separator or fuel filter, behind the alternator? (see attached) It's supplied by the fuel lift pump you mentioned.

...a great learning experience. Please keep it coming.
Thanks.

 

[bobleny]

Sorry, misremembering; the fuel water separator is on the firewall right next to the driver side fender, and the pull ring is on the top not the bottom.
There are no pumps in the tanks, just the sender and the pickup. The fuel is sucked out of the tanks by the mechanical lift pump on the block.
The fuel filter is mounted behind the alternator.

If it died that quick on a quarter tank, I bet you have a broken pickup and you simply ran out of fuel.
Once that happens, they can be a little tricky to start.

I would fill that front tank. (You can try it on the rear tank, but if you are not sure about the fuel level in the rear tank, I wouldn't.)
Make sure your fuel selector switch in on the right tank.
Make sure the fuel filter is full of fuel, just unscrew it, fill it up, and screw it back on.
While holding the schrader valve on the fuel filter head open, crank the engine. (Fuel will be squirting out of the schrader valve, so make sure you have a cup or something to catch it)
It will take several cranks as you purge the air from the system, but if you did just run out of fuel, it will eventually start. It will smoke and run rough for the first few minutes once you get it running. It takes a while for all the air to work its way out.
Once it is running, you can release the schrader valve.

Oh, word of warning, don't use starting fluid in these engines, you can destroy the heads.
Also, it wouldn't hurt to hold the fuel pedal down about half way while doing this, and you may need to work the throttle a bit once it is running to keep it from stalling (they really don't like air in the fuel).

 

[dhudge]

Filled fwd tank with 5 gal of fuel. I didn't take the filter off cause it was on too tight without a filter wrench, and I didn't have one available. So, we just started cranking with Schrader depressed...it did act like there was a little air in system as it took probably 5 sec for the fuel to flow outta Schrader with a strong flow. However, we weren't able to get it started...tried this 4 separate times with no success.
Glow plugs currently non functional, so it could just be having a hard time starting in 59 deg temps.

 

[79jasper]

Plug in the block heater.
Next step would he bleeding the air from the injectors.
Couple ways to do it. My method was to crank, then crack open and close.
Or you can crack open, crank, then close.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[dhudge]

Confused...
With injector pump getting good flow from filter, wouldn't it force any air out of injectors into cylinders?
That's a lot of cranking to bleed each injector...lot of fuel being leaked onto manifold.

 

[dhudge]

Is idea to close injectors while cranking, or just crank then stop to close injectors?

 

[79jasper]

Either. It doesn't really matter.
When liquid and air are contained in a high pressure system, it can't compress the air to push it out. Hard to explain.
What I did was crank with pedal depressed (probably like 10 seconds or so) then I would go down the line cracking and closing injectors. Usually only took 1 or 2 cycles.

You can do them all at once. You don't take it all the way loose. About 1/4-1/2 a turn usually. You will see the nut become wet.

Really no reason to, but if you do take the line all the way off, you will never see fuel "flow out" while cranking. It's just a tiny bit of fuel.

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[dhudge]

Okay, did that...
None of nut threads were getting wet. So, I took one inj nut all the way off...cranked it and no fuel flow at all?

...on another note, I noticed the tachometer is not working. It did so before the incident. Wondering if a bad crank sensor would prohibit fuel flow?

 

[dhudge]

Otherwise, sounds like inj pump is bad?

 

[chuckster57]

No crank sensor on these old beasts. If you know you have fuel to the injector pump, I would check the fuel shut off solenoid.

Standing at the front of the truck, look at the top of the IP. On the Drivers Side there are 2 spade connectors, the front one is the shutoff. Turn the key to the run position and pull the front wire off. You should hear a click as the solenoid shuts the fuel supply off. Connect the wire back up and it should click again. If it doesn't then your issue is either the solenoid or the 12V wire going to it.

 

[dhudge]

Solenoid valve did make a clicking sound when I played with the connector.
Running out of things to check.
You sure the tach sensor, located right in front of the IP doesn't have connection/control to the solenoid valve?

 

[chuckster57]

Tach sensor has nothing to do with no start. These engines are totally mechanical. Just need fuel, air and heat.

If the GP's aren't working, you may get away with a tiny spritz of ether, but I wouldn't use it regularly.

 

[bobleny]

The easiest way I know of to bleed the injectors is to go through and crack all of the lines about a quarter turn.
Then, crank the engine at full throttle watching the lines carefully.
When one or more of them begin to ooze fuel, stop cranking, and close those lines.
Continue until they have all oozed. Sometimes they will foam a little before the fuel comes out.
Depending on how much air is in the system, you may have to do a fair a bit of cranking to clear them.

Also, to clarify my statement about the starting fluid, in light of chuckster57's suggestion, the reason it can destroy the heads is because the glow plugs can ignite the fluid inside the head. So, if the glow plugs don't turn on, they can't ignite the starting fluid.

If the lines all ooze, and it still won't start, make sure you warm it up with the block heater and or new plugs.
If you are convinced the lines will not ooze, replace the fuel filter and check for fuel leaks (just a cheap check before blaming the injection pump).

 

[dhudge]

Thanks for inputs Chuckster...
I mentioned on an earlier post, I bled the fuel filter at the schrader valve (had good fuel flow), but when I tried to bleed air at the injectors, I was getting no flow...even when I removed one of the nuts all the way.
...also verified the solenoid valve at IP was operational.
What else is there besides a faulty IP?

 

[chuckster57]

I'm leaning towards IP. If you do decide to change it, let us know so we can give you helpful advise. Those cheap repair manuals will have you doing things you don't need to do.

 

[dhudge]

@bobleny, I must've been writing my last post the same time you were...
Thanks again.
Changed filter...still good flow at schrader...cracked open all inj nuts, with one completely removed, still no flow after much cranking.
Is there anything associated with IP that should be checked before replacing it, i.e., besides solenoid valve there's lots of other little pieces/parts on top of IP, some connected to throttle linkage and vacuum lines?
Not sure how the IP is connected (timing chain?), but I'm not even sure it is turning...is there a quick/dirty way to verify it is turning?

 

[chuckster57]

IP is gear driven. You can take the oil fill off the front of the IP gear cover if you want to verify the pump is still bolted tight and turning.

There are pictures posted in the 7.3 IDI forum that show the electrical connections, they are the same for the 6.9


The vacuum part on the side is for the transmission. If yours is an automatic it is a C6 and they are vacuum shifted. That piece is called a VRV. Not a common part so treat it like a family heirloom.

 

[dhudge]

Thanks to the help from y'all, I think we've resorted (narrowed down) to it being a bad injection pump...the boy (my son) is headed to the local parts store now to order it. It's $499 including a $400 core charge. Apparently, the one he's planning on is the cheapest available...others were $100 or $200 more expensive.
Are there brand names to be recommended or avoided for the IP???