[kaya]

are you absolutely positive you were measuring vacuum correctly? this is very important. your gauge must be teed into the supply line between tank and pump, and monitored for a spike just prior to dying.

 

[dellis]

are you absolutely positive you were measuring vacuum correctly? this is very important. your gauge must be teed into the supply line between tank and pump, and monitored for a spike just prior to dying.

All I noticed was the drop in vacuum as soon as the motor shut off. Am I looking for a large spike, that is to say, like one caused by something clogging the pickup tube in the tank?

My gauge is teed into the supply line at the fuel tank sender.

 

[kaya]

Exactly. A spike

 

[dellis]

No spike. I was looking for one too. I understand how the diesel engine works and the fundamentals. This little querp in this 6.7 has me stumped since I haven't seen any evidence of low pressure. The only tool I have to test the high pressure side is my snap on scanner.
It seems that every part has been replaced except the fuel volume solenoid.
The truck died and one mechanic replaced the high pressure pump and it still wouldn't start.
When I got the job, I found that when I exercised the fuel pressure control valve with the scanner, the test would abort at 20% down and 80% up.
I replaced the pressure control valve and it cranked like it had never had a problem. On the first road test, this problem I'm dealing with, showed its ugly head, so here I am.

 

[kaya]

The vcv would have been included with the hpfp.
If the fpl PID is changing from not low to low, as you've described, prior to the stall, the issue should be in the supply side.
Satisfied it's not a restriction, next what I'd do is install a section of clear half inch line immediately after the lpfp, on supply side. Checking for aeration.

The line i made actually has a tee to test pressure, aeration, and if installed between tank and pump, vacuum. All in one.
You will need a male and female quick connect fitting to make this. I robbed them from a core contamination kit. Then crimped them to a foot long section of clear line.

 

[kaya]

The hard plastic u shaped supply line at the secondary fuel filter. I believe it has a male and female end and is fairly cheap from Ford. You can buy that, slit the ends, and remove the barbed fittings to make the line.

Edit: come to think of it, I think that line has 2 female ends. Could zip cut the end off an old secondary filter tho if you have one

 

[dellis]

Edit: come to think of it, I think that line has 2 female ends. Could zip cut the end off an old secondary filter tho if you have one


That's where I got the nipple for my vacuum tester....

There are more tiny bubbles than I can count in the clear line as the pump runs... I have the tubes made into a circle to keep from kinking the tubing. When the pump shuts off, all the bubbles collect at the top of the circle where the tee in installed.

I pulled the sender and found the accordian line for the suction side loose at both fittings. I replaced it with new hose with clamps. There is an occasionnal stream of bubbles after letting it run for 15 minutes.

Now I notice the pump whining and my pressure gauge is rapidly fuctuating between 55 and 65, never steady, whether engine is running or not.
When I engage PTO for RPM increase the gauge will fluctuate from 55 to almost 70, one time it hit 80 for a split second but, after the engine stalls, I have fresh stream of bubbles for a minute after cranking again.

Can air enter the return line without the suction side being at fault? There are no leaks on the suction side of the sender and no leaks visible to suspect the line going to the pump. The reason I ask is because the bubbles dont start until a few minutes after the truck has sat for a bit, if it didn't stall before I let it sit.. driving me batty

Results from repairing leak at sender= gauge going crazy and very few bubbles until rpm increase

 

[dellis]

Recap of the days quest for "Kaya". I got the supply line(the clear tubing) to the point where no bubbles existed even when the pump shut down the fuel stayed in the line. After this, the fuel gauge went practically stationary, give or take 5 lbs but averaged between 60 and 65 lbs. No more big swings of the needle. I attribute this to the fact that all the air is missing from the supply fuel.

Now, though I hoped it was fixed, I can run the PTO for almost 10 minutes before the stall where before, it would only take 2 minutes before stall. Now, when it stalls, it still sets the same p0093 code but, I got the read a difference between the actual and desired on the scanner. It was at 1900 rpm, the desired and actual were both at 11,542 lbs and suddenly the actual dropped to 1,227 and the low pressure dropped from 63 to 0 instantly.

What are the chances that the aerated fuel has damaged the HPFP?

 

[dellis]

Hello Kaya

Hey Kaya, Did I run you off? I was hoping I could get some help to finally come to a conclusion on this problem.

I'm getting the feeling I said something wrong. I apologize if I did....

 

[dellis]

Using data display to find a pressure related problem

Is there anyone here who can help me with a fuel related problem on a 2011 f550 with the 6.7?
I am getting a p0093 code after it stalls. I have noticed a slight drop in the duty cycle % of one solenoid and am wondering what this solenoid was intending to do when the stall occurred.
Dellis

 

[dsmracing1]

Interested to know so I'll comment to refresh the topic. My truck will randomly shut down and have the P0093 code. Only does it once a month or so. Strange issue to say the least. I had that code and the P228F but after throwing a fuel pressure regulator at the truck, I'll only get the P0093 soft code...

 

[dellis]

Interested to know so I'll comment to refresh the topic. My truck will randomly shut down and have the P0093 code. Only does it once a month or so. Strange issue to say the least. I had that code and the P228F but after throwing a fuel pressure regulator at the truck, I'll only get the P0093 soft code...

HI dsmracing1,

Yesterday, while watching the scanners data display, I finally saw something happen right before the stall occurred. There was a point where the desired pressure increased and vollume control solenoid was given more duty cycle (.eg from 37 to 60) while at the same time I saw no increase in pressure. On the graph, the time elapse was only about 3 seconds, but the stall, so I am presuming) happened because the pressure did not increase.

I was hoping to find someone who is familiar with the 6.7 so I could see what normal pressure should be at given rpms. 600 and 1800. Do you know?

 

[dsmracing1]

HI dsmracing1,



Yesterday, while watching the scanners data display, I finally saw something happen right before the stall occurred. There was a point where the desired pressure increased and vollume control solenoid was given more duty cycle (.eg from 37 to 60) while at the same time I saw no increase in pressure. On the graph, the time elapse was only about 3 seconds, but the stall, so I am presuming) happened because the pressure did not increase.



I was hoping to find someone who is familiar with the 6.7 so I could see what normal pressure should be at given rpms. 600 and 1800. Do you know?

Hmm well that's very interesting that you noticed that. My stall only seems to happen when accelerating with light throttle (25-30%). It will stall and then like you mentioned, will fire back up and keep driving like nothing happened. Always happens as soon as the truck hits second gear. I can hook onto my 12K trailer or punch the truck and it won't replicate the issue. It's very strange to say the least. It feels like a complete PCM shut down as there is no notice that it is about to happen.

Unfortunately I am loss for who seems to know any more info about this issue. My tuner at this point is not sure as to what this could be as well.

 

[dellis]

"It's very strange to say the least. It feels like a complete PCM shut down as there is no notice that it is about to happen."

Well, I had to take a break so I could catch up on some other pending jobs. Now I'm back and will be removing the HPFP today.

Whether it fixes or not, I'll post some results.

 

[kaya]

Hey Kaya, Did I run you off? I was hoping I could get some help to finally come to a conclusion on this problem.

I'm getting the feeling I said something wrong. I apologize if I did....

Haha. Sorry buddy. I lost track of this thread.
So you've confirmed that there is NO aeration just PRIOR to the stall?

I think you're focusing on the wrong side of the system by going after the hpfp. The hpfp will not cause the supply side to drop to zero. If the key is on, the supply should remain stable.
Does the supply pump remain running while the zero reading is apparent, immediately after the stall?

 

[dellis]

So you've confirmed that there is NO aeration just PRIOR to the stall?

I think you're focusing on the wrong side of the system by going after the hpfp. The hpfp will not cause the supply side to drop to zero. If the key is on, the supply should remain stable.
Does the supply pump remain running while the zero reading is apparent, immediately after the stall?

Yes, I have confirmed no aeration in supply side.
The pressure drops to zero after the stall and I've posted before, I made the pump run by jumping it to battery all the time and that stall still occurs while the supply side stays charged with pressure.

I have new info that might hopefully help.

I have replaced the hpfp and it still does the same thing with same code, well not exactly. Before I replaced the pump I could count on the stall( every time I used the pto for the rpm increase) to occur within the first two minutes.
I engaged the pto and cleaned all my tools, aired up the two front tires, added water and talked on the phone. probably ten minutes elapsed and no stall. I shut er down and cranked it again, went through the same time frame three more times, still no stall. I shut er down, washed my hands and made ready for a road test. (Note) The motor had more power than ever before. It went from 0-60 in a about 6 seconds. I drove at a level 45 mph for about half a mile and the stall occurred. drop in neutral while coasting, shut key off then on, cranked up, but no power, as in limp mode. Pull into the shopping center parking lot and review codes. The same low fuel pressure code is there and a p1102 MAF out of suspected limit. I clear the codes, restart the truck, still in limp mode, p1102 still there. MAF coming in the morning. All wiring checked good.

Can you help me understand the readings I'm getting on my scanner concerning fuel balance quantity?

at idle cylinder;
1. 1185
2.775
3.-654
4.-514
5.-324
6.-1224
7.665
8.155

Assuming this is similar to short term fuel trim on a gas engine, isn't this a little out of balance?
Which figures represent the use of too much fuel?

HELP PLEASE

 

[kaya]

You have to reset the high pressure fuel tables after replacing an hpfp on these. As well as min/mass adaptation.
So reviewing this thread again, sorry, beating a dead horse, but we must be clear, does the supply drop off PRIOR to the stall?
It can be seconds or milliseconds. But is it prior?

Unfortunately, I don't use injector balance readings on a 6.7 powerstroke, so I have no experience with that. But if your hp fuel tables and min/mass tables haven't been reset, then I wouldn't be looking at them anyways.

 

[dellis]

Kaya asks, does the supply drop off PRIOR to the stall?
It can be seconds or milliseconds. But is it prior?

Answer, NO

Even as I posted before, I have tripped the fuel pump to run all the time and even with fuel pressure still in the low pressure side, the truck stalls anyway. The only pressure that drops is the high pressure side which is normally around 12,000 lbs actual vs 12.000 lbs desired when the stall occurs. (note, these readings vary only slightly at any given time and never more than 100 lbs either way.

 

[dellis]

Kaya says, You have to reset the high pressure fuel tables after replacing an hpfp on these. As well as min/mass adaptation.

Delis asks, Is this something that only the dealer can do?

 

[kaya]

What I'm wondering tho is does the switch change from not low to low prior to the stall, even with the pump hardwired. My thought there is that the low pressure switch may be opening/malfunctioning and shutting down the engine