Weird surging on WMO

[A48WillyzGuy]

Hey guys, just wanted to see if anyone might have some input for this strange occurrence. I've only had the truck for a few weeks and am not particularly familiar with diesel's and especially IDI's. The truck is a 93 N/A, straight-piped, with 255k on it.

When cruising down the road with steady throttle pressure, the truck has randomly revved up and started pulling very, very hard three different times now. When this happened it jumped up between 500 and 1000 rpm and literally felt like someone had hidden some nitrous on it. It runs W80, and I haven't noticed the issue when running straight diesel.

Some other information that may or may not be relevant:
-I have no idea how many miles are on any of the major components.
-The truck slightly hazes at idle on diesel, and hazes a little more on W80.
-It generally feels slow and sluggish (I assume it's just the way of an old N/A diesel).
-Since it has become pretty cold, when initially switching to W80 from diesel it will have a very lopey idle (think top fuel funny car, lol) but smooths out after a minute.
-The W80 makes a noticeable decrease in the sound levels of the engine and exhaust as well as makes the truck feel more peppy and run smoother.

I think that about covers it. Any help would be greatly appreciated!

Thanks,
Jon

(edited some grammar)

 

[idiabuse]

your losing fuel pressure and having air intrusion, that crap happened to me tonight on the way home. I have a pressure gauge mounted on my cowl so I know immediately what is going on. I believe I was low on fuel, so I added 4 gallons of diesel and kept driving home with no more issues for 30 miles.

Cold temps will make it hard to get WMO from the tank to the engine, so you need to either warm it up or use more diesel, or you can add gas to the WMO like 70/30
It is all an experiment at this point for us.


Javier

 

[A48WillyzGuy]

Thanks for the tip! The WMO is blended 80/20 with Regular Unleaded Gas. I had that blended 50/50 with diesel at first and didn't notice this issue.
I have never let the either of the tanks go below 1/4.

Is there a common place where I should be looking for air to be coming in?

 

[idiabuse]

well the shower heads on these trucks are notorious for breaking off and the most common source of air intrusion into the system.
I don't use the OEM pickup at all, I have a hole in the bottom of my tank with a male fitting welded in place, for feeding my fuel pump, even like this I still get every once in awhile a air pocket that makes into the fuel line and makes my truck surge down the road like tonight, but rare it happens, this is because the front tank is long and skinny and the fuel rushes back and forth uncovering my hole momentary. Same thing happens with shower heads.



Javier

 

[bigpanda16]

It sounds more like your injection pump giving you the proper timing advance for a bit thus giving you that power that you never feel because it is so worn out that it never has any advance. my old truck did that a bit before i got a midwest rebuilt pump. It does feel strong but it could be kinda scary if the conditions were wrong. wait until it starts randomly cutting off and then you will know it is time for a new pump for sure.

 

[idiabuse]

It sounds more like your injection pump giving you the proper timing advance for a bit thus giving you that power that you never feel because it is so worn out that it never has any advance. my old truck did that a bit before i got a midwest rebuilt pump. It does feel strong but it could be kinda scary if the conditions were wrong. wait until it starts randomly cutting off and then you will know it is time for a new pump for sure.

Yea that is possible also. Hard to put a finger on it punching on keyboards...

 

[The FNG]

I have experienced a similar issue. Through my experiences, I have found that my truck will do this for one of a few reasons. It could be that my mix is too thick and/or not properly blended, my mix is too cold and/or not properly mixed, or I'm getting an air intrusion. I honestly believe it is that my mix is too thick and cold and the surge is exactly that. It is a surge of fuel caused by a vacuum or lack of fuel that pulls in extra fuel and the truck surges. I will be experimenting with pre-heated fuel in the coming weeks, but for now, I suggest letting the truck warm up on d2 before switching to WMO and shutting down on d2 as well. See if that helps. I should also add that my surging only happens at times of high fuel demand.

 

[phazertwo]

I had the exact same issue when I was running WMO. I always blamed it on the timing advance solenoid in the IP. Turned out, when I had it built into a Moose pump, the advance was jacked, and I had to have Mel replace it. Haven't put any WMO through the moose, just diesel with a shot of veggie oil fur some lube.

PZ

 

[A48WillyzGuy]

Alrighty, thanks for the tips guys. Looks like I've got a bit of investigating to do.

 

[Brad S.]

Just to confirm the air intrusion, the return fuel line on top of the IP which goes to #2 fuel injector, replace it with some clear fuel line and watch for bubbles.

 

[Blind Driver2]

What is your fuel pressure?
What was the temperature?
Are you using the factory fuel filter?

Best thing I ever did was to replace the factory filter and base for a unit that has twice the filter media. No more troubles at 60*.

 

[Josh Carmack]

It's Novemeber, it's cold, and your fuel is more viscous than diesel, and even plain ole deisel can act up in temps a bit lower. Most stations suppliers have not yet switched from their summer blends to winter blends, but they will be soon, especially in the more northern areas. The surging is from the erratic pressure output of the pump caused by air intrusion. Keep in mind that a vacuum created by a slow filter, while is not actually air intrusion, it will cause the exact same symptoms, as air and "nothing" cause pretty much the same things to happen inside the pump.

Blind Driver2, what filter and base are you using?

 

[Blind Driver2]

It's Novemeber, it's cold, and your fuel is more viscous than diesel, and even plain ole deisel can act up in temps a bit lower. Most stations suppliers have not yet switched from their summer blends to winter blends, but they will be soon, especially in the more northern areas. The surging is from the erratic pressure output of the pump caused by air intrusion. Keep in mind that a vacuum created by a slow filter, while is not actually air intrusion, it will cause the exact same symptoms, as air and "nothing" cause pretty much the same things to happen inside the pump.

Blind Driver2, what filter and base are you using?

I don't have the part numbers, but I got mine from NAPA in the Wix catalog.

Anything below 60* is mixed with diesel or K1. Other then that, I run my oil 100% i the summer.

A fuel pressure gauge is your best friend.

 

[96_Bear]

93tubodanimal had this same issue. His problem seemed to be caused by the WVO getting to hot.

 

[Brad S.]

93tubodanimal had this same issue. His problem seemed to be caused by the WVO getting to hot.

Did he have that problem even when the weather was warmer????