My truck has a surging/power boost problem like yours... I dont know why it does it, but its caused by the cold advance being on.... Makes it annoying to start in the morning....

It will hunt, but if i switch off the advance it runs smooth instantly.....any ideas? this is a recent (rebuilt) IP...

 

My tach and speedo are the only ones i can rely on.... temp gauge wont move for a 1/2 hour of driving, though i have heat in about 5....

Oil pressure has a mind of its own, as well as the fuel gauge, and who knows about the ammeter....

 

You mean cold fast idle solenoid or cold timing advance?

 

F250, it took a while for me to determine how the tubes are held into the sending unit, but it seems like they have a very fine bead of solder holding them to the sending unit.
I wonder if you could just use a propare torch and solder as you would do so plumbing in a house? Hmm...maybe I'll try it with this spare sending unt I have here. Probably won't be for a long while though, tooo much crap going on LOL

Snapon, you got one of them "fancy" trucks with the working gauges! My buddy used to have a 94 F150 with a 300 I6, auto, 2wd, and all his gauges worked flawlessly also. I think it's an 80-91 issue. I also like that custom dash, I've coped the design for my truck

 

I guess so. My temperature gauge pegged cold, so I swapped the T-stat and it works great. That was the only issue I had but that is common on all cars. Also after hitting a bump, my fuel gauge will move all over but I assume that is the sender in the tank getting knocked around.(?) I buried the needle on the speedo a few times and that hasn't hurt it. Other than that no problems.

 

My IP is 2 years old, with about 30k hard miles on it. Injectors were installed at the same time. How old is your set?
Is your cold timing advance on a toggle switch?

Hahaha, yep...oddly familiar!

Cold timing advance I believe.
On a cold start I have about 1/2" of pedal I can push before the high idle clicks on. That 1/2" is VERY responsive! That's because the cold timing advance is already in effect.
It's the exact same feeling I get with this boosting/surging issue. Except now it's exaggerated because it's at higher RPM's.

I started going back to the dirty CDR today...but then I resorted back to a fuel issue after this diagnosis that left me sitting on the side of a 55 mph 2-lane road.

3rd gear, crusing steadily at 35 mph. (no working tach ) The online calculators are saying that this is about 1826 RPM with 235/85R16's on the rear and 3.55 gears.
Slowly accelerate to 40. Fine, no issues.
Slowly continue to 45, starting to surge a tiny bit...then after about 5 seconds at 45, it starts surging/boosting pretty hard. 2348 RPM according to online calculator.
Accelerate a little quicker up to 55 (only 5 mph more before the governor). This accleration blew a lot of black smoke out of the tailpipe.
I ran it at 55 for about 5 seconds before it began de-fueling. 2870 RPM according to online calculator.
I kept my foot at the same spot int he throttle, and felt the engine die more and more.
Push the clutch in, engine tries to die, downshfit to 3rd...still dying.
Coast to the side of the road and the truck stalls.
20 seconds of cranking with foot at WOT, 2 minutes cool down. Another 15 seconds of cranking at WOT and she fired right back up as if nothing ever happened.

I've ruled out the pick-up tube as collapsing since the 3/8' brake line is not going to collapse on itself.
I replaced the fuel filter about 1k miles ago, maybe I'll try another one in case the new pick-up sucked up some junk from the bottom of the tank now that it reaches that far.
I by-passed the fuel tank selector valve, and the test drive came back positive that it fixed the problem, but it was the same thing last night when I did the brake line in the rubber hose...

Right now, I'm convinced that when I installed the longer pick-up hose, I must have sucked up some junk. I've taken it apart a few times now, and there is nothing in the lines at the sending unit, so maybe there's a bunch of junk in the filter
I'm going to see what by-passing the selector valve does, and probably pick up another fuel filter tomorrow and go that route...
I think I'll dig up one of my spare CDR's and give that a cleaning and put that on, until I can afford a shiny new CDR.

All this because I dropped the fuel tank to replace a rusty brake line, and thinking I did an "upgrade" by putting the rubber hose on so it wouldn't run out of fuel at 1/4 tank. Oh well, I'm glad there are others experiencing this problem...we can work together and fix this!

 

Its the timing advance.

Cant remember 100% (cant remember ANYTHING 100% ) but is been 8 or 9 months for both, and i dont drive it that much.

Its only started this in the last 10 starts or so...

Edit: Yes, toggle sw... got the proper temp sw from a member (Thank You!) but haven't put it in yet...

 

Well I chewed up a bunch more fuel today (@ $4.15 per gallon ) trying to diagnose this ssue further.
Last night I by-passed the fuel tank selector valve using 3/8" rubber fuel hose.
I drove it HARD today and I couldn't get the truck to de-fuel/surge!
It seems that I must have had a small air intrusion issue at the selector valve, and under heavy throttle it must have been sucking air. But I don't understand why extra air in the system would make the truck smoke during that surging and why ti would run out of fuel

Until tomorrow, the truck seems fixed now.

I'm stumped, but also thrilled at the same time now that I'm back to having trust in the truck again.

 

Silly question, but did you clean out that junk that was in the tank in one of the pictures? Otherwise you could be sucking that up against the tubing and blocking off the fuel at high speeds (when the most fuel is being pulled). At some point it stalls, the vacuum in the fuel line drops offs, and the chunk of crap drops off the end of the hose.

And definitely clean/swap the CDR. If you're sucking too much oil through it, that might be causing the surging in a semi-runaway situation. Though I'm not sure how that would cause it to stall afterward?

 

The smoke may come from the governor running out of fuel and opening up and trying to dump what fuel is left to the injectors

 

I need to drop my front take to add something to the end of my rubber hose (I am having the same problem since I added the hose). Trouble is, the front tank is full of fuel.

Does anyone one have any suggestions for pumping the fuel to the rear tank. I want to barely spend a penny, and not spill a drop! I was thinking about those drill powered mini water pumps, or maybe a 12v pump or hand pump.

Who has an ingenious idea? I am tired of siphoning, spilling, dead grass, smelly pants, etc.

 

Pull the bed? Then you wouldnt need to drop the tank....



I love my wood bed I just have to pull 2 boards...

 

Nope, I did one better. I actually swapped in another tank I had, which was brand new and only used for 1 month in my first truck.
CDR is on my "To do SOON" list

But between 45 to 55 mph, I'm still not on the governor yet...

I vote to just carefully use/burn the front tank of fuel.

Wood beds rule!!





And another day of running flawlessly. I guess I can't complain, it's trust worthy once again.

 

Another day of running flawlessly.
I'm now convined that I was sucking air thru the tank selector valve, since my surging issue has stipped since I bypassed it.

Ohtayoni, my best guess is that maybe you have some tiny pinholes in your supply line. Maybe the supply tube on your sending unit has pinholes like F250HDXLT's.

 

Bud, you are talking about the limit part of the governor, The way it works is the foot feed adjusts the governor the gov controlls the fuel. The gov is a set of weights and springs in the pump, its made to run in fuel, when the fuel goes away it allows the gov to open and allow more fuel in(well whats left in the pump) thats the boost you feel.