Cat 3306B Power Loss/Stalling

[funwithfuel]

You need to measure fuel pressure full throttle under load. For example, raise the dump bed at relief to place some load on it. Idle doesn't really tell you anything.

 

[Cory W]

Alright, two more thoughts...the secondary filter is new, but it is a Fleetguard FF5320 2 Micron filter. Is it possible the filter is too restrictive? I wonder what filter CAT specifies and if it's possibly less restrictive. Also, the secondary filter base is bolted to the side of the injection pump. Is there possibly a screen between the filter base and pump housing?

 

[Cory W]

You need to measure fuel pressure full throttle under load. For example, raise the dump bed at relief to place some load on it. Idle doesn't really tell you anything.

Okay, I will try and get a loaded pressure reading. I wish I could raise my bed inside the shop, darn low ceilings.

 

[funwithfuel]

I think we should hope that thepumpguysc sees this and adds his knowledge. I don't think anyone is more knowledgeable with the mechanical fuel systems. That said, a 2 mic filter should pass enough fuel till she begins waxing. I don't think we've been that cold yet?

 

[Cory W]

Yeah I've read some of his posts, I bet he could be quite helpful. Could I message him and ask him kindly to take a look at this thread? Also, more updates. Flow from the tank looks strong. I had maybe 5 PSI on the tank, and had a strong solid stream of fuel coming out of the pickup hose. Just for fun I vacuum tested the air/fuel ratio control on the back of the governor, and it will not hold vacuum. There was also a bit of oil in the fitting. I believe this points to a bad diaphragm in the afcr. I don't know if this is my issue, or a separate one. Interesting...

 

[funwithfuel]

Well, AFC operates under positive pressure not vacuum. I can't say that test or it's results have any validity.
I don't see why you couldn't PM him. In fact he has cryptically given out his email address many times on various threads.
Don't be mislead by flow under pressure, it's different than flow under draw. You wouldn't think so, but it is. You've got all I have to offer, now I defer to the specialist.

 

[Cory W]

Haha fair enough, well thank you for all of your help so far funwithfuel, I really appreciate it! I will try and get in contact with thepumpguysc and see where he leads me. It's been a great learning opportunity thus far, if nothing else.

 

[colson04]

Haha fair enough, well thank you for all of your help so far funwithfuel, I really appreciate it! I will try and get in contact with thepumpguysc and see where he leads me. It's been a great learning opportunity thus far, if nothing else.

Easiest way to get someone's attention on a thread is like this:

@thepumpguysc
@Cory W

Now it sends an alert to him that he was mentioned, and he'll probably come and see what was said.

 

[funwithfuel]

BTW, how did the standpipe check out?

 

[Cory W]

Easiest way to get someone's attention on a thread is like this:

@thepumpguysc
@Cory W

Now it sends an alert to him that he was mentioned, and he'll probably come and see what was said.

Thanks! I wondered how to do that lol

 

[Cory W]

BTW, how did the standpipe check out?

So I wasn't able to remove it for inspection, but I was able to put air through it no problem. I also assumed it was clear after I pressurized the tank and had a solid stream of fuel out of the fuel line.

 

[funwithfuel]

Did you blow through it backwards and see if trash popped out?

 

[Truck Shop]

I just don't see it restarting and back to normal so quickly if it was a fuel restriction.

I've mentioned this one before.

A fleet of grain trucks we took care of all powered by E model and up Cats-one had a issue exactly like
this 3306. Ran great till 3/4 throttle, would idle all day, as long as no 105,500 gvw was put to it-it was
fine. Checked fuel lines, check valves in primer and filter base, checked fuel pressure from lift pump,
checked electrical system, you name it-was all fine.
Let it set idling with gauge hooked to filter base, throttled it up about 7 different times. On the seventh
the fuel gauge dropped engine died.
Went to fuel tank, looked inside with light, a long something was laying in bottom. Drained tank, using
grabber finally got ahold of it. It was the thin 1 1/4 wide micro board from the center if a old tube type
fuel sending unit, just enough suction would pull it to the pickup tube at high throttle. Freak.

I doubt yours has that type of sending unit. But don't go down a rabbit hole installing parts till every
part to fuel system has been checked. Sandwich bags in tank really play hell.

 

[Cory W]

I have to admit, I'm really curious of that pickup tube now too. I couldn't see anything when I put the air to it earlier because the tank is still about half full of fuel. I will try and get it pulled tomorrow for inspection. Unfortunately the tank has to be removed in order to access it, but it'll definitely be worth knowing whether or not the pickup is the issue. Honestly I hope it is, that'd be a nice way to wrap up this problem!

 

[Cory W]

Alright, the results are in! I pulled the fuel tank this morning. Turns out the pickup tube is integral on this tank, so I couldn't remove it. But I was able to shine a light in the tank and look down through the tube and....free and clear, no obstructions. I'm glad I can rule that possibility out though. Going forward, I plan on replacing the lift pump which I received today, and I will clean the fuel hard lines while they're off. Anyone want to take another poke at the pig?

 

[funwithfuel]

So, standpipe is clean as a whistle. Running fuel pressure ~30psi @ idle. AFC diaphragm leaks oil in vacuum test. Fuel filters are clean and new. Pressurizing the fuel system with the return line dead-headed shows no leaks. Running @ 75% or more throttle, she bogs down to the point of dying but continues running. Have you checked fuel pressure at full throttle, loaded?

 

[d9gdon]

It's almost like something that turns the fuel on and off is not working correctly.

 

[Cory W]

So, standpipe is clean as a whistle. Running fuel pressure ~30psi @ idle. AFC diaphragm leaks oil in vacuum test. Fuel filters are clean and new. Pressurizing the fuel system with the return line dead-headed shows no leaks. Running @ 75% or more throttle, she bogs down to the point of dying but continues running. Have you checked fuel pressure at full throttle, loaded?

I like this condensed version, yeah that pretty much covers it. The only thing is once it starts to lose power, it will always die. It never picks back up until it quits and is restarted. I plan on road testing the truck today with my pressure gauge hooked up and see what fuel pressure does. I can duplicate the problem pretty well, bottom of seventh gear with heavy throttle almost always does it.

 

[Cory W]

It's almost like something that turns the fuel on and off is not working correctly.

Most definitely, are you thinking fuel shutoff solenoid or air/fuel ratio control?

 

[d9gdon]

A problem with the AFR will not allow it to build boost pressure. I've never had one affect the idle or make the engine die.

If it's not revving then eventually dying, but will start right back up and run perfectly without cranking and cranking after cycling the key switch then I'd be watching the voltage to the shut off solenoid while you're on that road test.