Help! Vehicle Dies.

[jr1772]

1994 Ford F350
7.3 IDI Factory Turbo'd
5 speed manual

Ok, I have been searching on here and other forums for a solution for quite awhile to no avail. I bought this truck around the beginning of the summer, for a project, but mostly for my kids to learn to drive manual transmission with.
I have went through a bunch of stuff on the truck since then I won't go on with mentioning it all as I don't think any of it pertains to my issue.
The issue is that it will start and run perfectly for a period of time, somewhere around 20-30 minutes or 12-15 miles, and then it will begin to start cutting out like its not getting fuel. Eventually it will quite running, and will not start again. The first thing I did was replace the mechanical pump with an electric pump, put a check valve right before the factory fuel filter, replaced fuel line from selector valve to fuel pump and on to the filter housing. Also replaced all the return fuel line, completely back to the selector valve.
When it dies, I have steady flow of fuel coming out the schrader valve.
If I let the truck sit for a day, you can jump back in and it will fire right back up and run perfectly like nothing is wrong with it. Then repeats the cycle

I'm at a loss, hoping you guys have a solution for me.

Thanks,
Jake

 

[Cubey]

A worn out injection pump can get hot and make it stall out.

 

[divemaster5734]

Has to be at the IP.
You could crack open the lines at the injectors when it's stalled like that and stuff some rags or shop towels under the fuel lines and crank it over a few times.
If the rags stay dry you'll know it's the IP as long as you've verified fuel going to it.

 

[Old Goat]

When it stalls out, pour cool water over the head of the
Injection Pump. If it starts back up, then yeah probably
need to replace pump.

There are 2 electrical plugs on top of the IP.
One to the front is the fuel solenoid that turns the fuel
on and off. With the ignition turned on, remove the connector,
you should hear it click. Was thinking maybe if it gets hot
might turn the fuel off.

How many miles on it?


Goat

 

[jr1772]

When it stalls out, pour cool water over the head of the
Injection Pump. If it starts back up, then yeah probably
need to replace pump.

There are 2 electrical plugs on top of the IP.
One to the front is the fuel solenoid that turns the fuel
on and off. With the ignition turned on, remove the connector,
you should hear it click. Was thinking maybe if it gets hot
might turn the fuel off.

How many miles on it?


Goat

The fuel safety solenoid does click like it is working correctly. I verified that previously.

144k is what the odo shows.

 

[franklin2]

Mine was doing the same exact thing and I started to panic. I too thought it had to be the injection pump, and that is a lot of money to throw out there on a guess.

I kept researching this thing, and people kept talking about this IP will not work if the return line is clogged. Some of the early versions of these pumps had something inside that fell apart, and it would clog the return line and it would act this way. But I do not think any of our trucks have this early version.

But just to be sure, I pulled the return line off the pump, and put a air nozzle to it. It blew back in my face initially, but then I could blow air in the line and hear it bubbling in the fuel tank. I put the line back on it, and it has been running ever since. What was it? I do not know. It may have been something at the sending unit, I was messing with that a month or two before this happened. I know you replaced the return line, but I wonder what would happen if you put a rubber line into a container and let it return into that. Would it run longer? I do not know.

 

[Cubey]

I know you said you did all return lines, but one is very hidden. I don't know for sure if trucks have one here, but I think they do.

The green line is the short piece of return hose (5/16") that vans have in that spot.

You might double check that you replaced that section.

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[IDIBRONCO]

Would it run longer?

That would be a toss up. You might not be able to find out. You'd be pumping the tank dry and filling (probably overfilling) the extra container.

I don't know for sure if trucks have one here, but I think they do.

Yes they do.

 

[KansasIDI]

Dumb effin suggestion I got for ya here. When it dies point a temp gun at the bottom of your fuel tank. Post the temp here. I have a gol danged theory…

How full do you keep your tanks? Does it seem to take longer to die in colder weather or with a fuller tank?

I had rust in one of my fuel tanks, that can also cause issues. But I am on a roll with fuel temp theories. If the fuel gets too hot your IP will start acting weird, usually resulting in hot/warm start issues. That I have determined. I’m sure there are other things that can cause the hot start problems, but I’ve convinced myself that’s one of them.

 

[IDIBRONCO]

I'd think that it would take longer then 20-30 minutes or 12-15 miles to get the fuel that hot. I have been known to be wrong from time to time though.

 

[jr1772]

When it stalls out, pour cool water over the head of the
Injection Pump. If it starts back up, then yeah probably
need to replace pump.

There are 2 electrical plugs on top of the IP.
One to the front is the fuel solenoid that turns the fuel
on and off. With the ignition turned on, remove the connector,
you should hear it click. Was thinking maybe if it gets hot
might turn the fuel off.

How many miles on it?


Goat

Would there be other signs that the injection pump is failing?

Truck gets up to operating temp
~180 and doesn’t fluctuate from there much at all.

I do not mind changing the IP, if that is what the problem is.

 

[IDIBRONCO]

Would there be other signs that the injection pump is failing?

Possibly, but that's the easiest way to tell.

 

[jr1772]

Possibly, but that's the easiest way to tell.

Thanks. Where is the best place to get a new IP and injectors? I see lots of them on the internet, just not sure what’s quality and what is not.

 

[MtnHaul]

Of course I could be wrong here but have you checked the vents on the fuel tanks? I knew someone who was trying to figure out why their chipper would run great for a while and then shutoff and not restart. A simple cleaning of the tank vent fixed it right up. If you do go for a new IP and injectors then most folks would recommend one of the following:

Classic Diesel Designs
Moose Diesel
R&D IDI Performance

 

[KansasIDI]

I'd think that it would take longer then 20-30 minutes or 12-15 miles to get the fuel that hot. I have been known to be wrong from time to time though.

Even with a full tank, mine would get hot very fast. The DB2 pumps process lots of fuel, and return most of it. That’s the reason why they don’t gel as easily as a Cummins, which doesn’t return near as much fuel, typically regardless of IP type.

Not sure if this actually causes problems or is even really a problem, I’ve only looked into fuel temp on one truck. But gonna test my theory on an 85 this weekend.

Max fuel inlet temp for a 6.5, which also uses a DB series Stanadyne injection pump is 140*, which I had been exceeding in my 91 7.3. And since the fuel lubricates and cools the IP, I had theorized that excessive fuel temp wasn’t good to say the least…