Does a diesel "surge" when it runs low on fuel?

[diesel4me]

A gas engine will usually speed up when it gets its fuel supply restricted or it runs out of gas,just before it stalls..a "lean surge",you have probably heard drag cars do it...does a diesel do the same thing too?..

Reason I ask,is my truck sometimes acts weird,like it suddenly got a dose of water in the fuel,or the fuel flow gets restricted,its done it mostly when the fuel tank has less than 1/4 of a tank...a few times in the past it stalled out while cruising along shortly after I put it under a heavier load,like to pull out into traffic or pass someone...it restarted OK though,without a long cranking period..

It had not done this in a long time,till yesterday...coming home from a doctor appointment,I was forced to take a detour due to road construction,and the street I had to use has a rather long and fairly steep uphill grade to it...the truck pulled the hill fine,but as I got just over the crest,I felt a loss of power,like it wanted to stall from lack of fuel--then it suddenly "surged" like it got a dose of nitrous or something,it only lasted a few seconds--then it drove normally the rest of the way home,on a fairly level road..

My theory is the tank was low enough on fuel to allow the fuel to run towards the rear of the tank climbing up the hill,and the sock filter didn't stay submerged,and air got sucked in the fuel lines...??...but I dont understand why the engine sudenly feels like a 454 for a few seconds right after it loses power...(wish it felt so gutsy ALL the time!)...

I stopped at the nearest gas station and put 5 gallons of diesel in it,I live only a 1/4 mile away,so I couldn't really tell if it would have done it again,I tend to think not...

Think I should break down and replace the fuel filter,which has been on the truck since I got it 10+ years ago,but has only been driven maybe 6000 miles since?...and fill the new filter up with some Power-Kleen or similar treatment to help clean out the injectors...I have tried draining both the fuel filter and fuel tank not that long ago and saw no trace of water in what came out,using the factory siphon valve on the tank plumbing and the filters bleeder screw & water drain...hate to toss 20 bucks away if the filter isn't clogged up or waterlogged...

 

[DEMON44]

It's not water. But definately change the fuel filter man. Algae growth. Nuff said.

The governor is trying to maintain engine speed so when the restriction is gone and it's pure fuel. The governor fuels hard to regain lost rpm.

A mechanical governor controls fueling on a Diesel engine. It balances operator input from the throttle peddle and engine load.

As much as you'd like to think you are directly controling fueling with the throttle you are not. The throttle sends an input to the governor. The governor then fuels accordingly based on load. Upto a preset minimum and maximum of course.

 

[DEMON44]

Although. Change the fuel filter. If it does it again. My first though was sucking air from a cracked pickup. Once it's uncovered it get a chug of air. And governor recovers when pickup tube is flooded again.

 

[diesel4me]

The truck needs some maintenence badly for sure--if I had the money I'd keep it full of fuel,but even 20 bucks buys only 5 gallons--my fuel tank weeps some,so I balk at filling it,because I know that will encourage the weep to become a drip,then a faucet..I bet it hasn't been full since I owned it once,and at most it has a half a tank or less..

I have a good used tank I installed on the drivers side last summer,but never got around to swapping the hoses and wiring the sending unit up yet--put it off till warm weather...(truck has dual tanks but someone butchered the fuel selector switches both under the cab and on the dash,and had put some crude manual switch over valve on it when I first got the truck--I just plumbed up the right side tank as a single and got the gauge to work--I am probably going to just extend the sending unit wires to reach the drivers side,rather than have to mess with the original wiring mess..)..If I had a brain I would have just swapped the good tank in place of the leaky one..
I dont think things thru sometimes..

The sensation I described felt like the engine suddenly got a dose of nitrous,I know what you explained about the govenor,and it makes sense...makes me want to override the govenor somehow,it sure would help on take offs from dead stops!..it suddenly felt like I had an engine twice the size under the hood,and it ran very strong--for about 3 seconds..

The engine should have an oil change,and I have to either patch up the oil pan better or have the engine yanked out and put one of the good used ones I have on it--it also needs the exhaust manifolds replaced,I have a decent pair of used ones,it looks to be a miserable job to attempt with the engine in the truck though,if not impossible..for me anyway..

The bolts are practically touching the frame,and they have NO heads left,the manifolds are flaking away in layers and will be all the way thru soon..

I need to replace the front pipes too,and the bolts on the flanges are highly unlikely to come out,they are almost sure to break,and with the manifolds being shot,it makes no sense to try saving them..the inner fenders are junk too,it would be easier to pull the nose off it probably...I cant do that kind of work alone any more though..

I'm thinking about getting my Suburban fixed up,and swapping the plates onto it for at least awhile,so if I end up tearing the pickup apart,I wont have my only daily driver scattered all over the yard,and be in a big rush to get it fixed...if I dont just give up on it period--my back hurts just thinking about doing all that...if I get discouraged enough I might just sell both and look for something less rusty...the Burb needs tranny work,I'd have to pay someone to put a used one in it,I can only do "easy" stuff like brakes now,with no lift I cant work lying under a truck like I once could..thats why everything ends up cobbed and jerry rigged on my truck,I cant work on it long enough to fix it "right"...gets me ..

 

[campfire]

Although. Change the fuel filter. If it does it again. My first though was sucking air from a cracked pickup. Once it's uncovered it get a chug of air. And governor recovers when pickup tube is flooded again.

My thought as well. Although both my '83 and '84 have behaved similarly with air leaks in the fuel line between tank and pump. So it wouldn't have to be inside the tank...

I agree with you, the surging is a bizarre phenomenon.

 

[kennyw]

I always get surging when I am bleeding the air out of the lines after running out of fuel.

 

[ryoken]

get air in a big Detroit system and listen to them surge... garuuummmm garuuuuummmmmm

 

[Russell]

It costs the same amount to keep the tank between 80 - 100% full as 0 - 20% full BTW!

 

[diesel4me]

I know,but when the tank is borderline ,I'd rather have 1/4 tank lost than a full one...filling a 20 gallon diesel tank is equal to the net worth of my entire truck practically too...