Gelled fuel or bad pump?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

SDJunkMan

Full Access Member
Joined
Nov 17, 2017
Posts
1,807
Reaction score
2,653
Location
Black Hills of South Dakota
First Name
Jeff
Truck Year
1978
Truck Model
K10
Engine Size
350
Thursday I was getting ready to put the plow on the CUCV in anticipation of the snow that was coming. Started it up, moved it to where the plow is, and let it idle for a minute while I moved my other truck, and it died, like someone shut the key off. It was in the teens, thought it had winter blend in the tank, but it wouldn't restart, not even a cough. Put some diesel 911 in the tank, and checked tne filter, which was.not gelled. Thought possibly the voltage was low, and caused the solenoid to shut off, so put the charger on overnight and plugged in the block heater. I tried to start it this morning and it doesn't even try to fire. It was down near zero the last two nights and tne highs only in the teens the last couple of days. I opened the drain on the fuel filter to see if it was pushing fuel out, and it wasn't. Hoping its just gelled, and will thaw when it warms up today (supposed to get in the high 30's today).

Is there a easy way to tell if the pu.p we t out, or should I just give it time to thaw? I really need to plow my lot. Unfortunately I don't have a warm place to park it to help thaw it out.
 

59840Surfer

Full Access Member
Joined
Oct 8, 2020
Posts
206
Reaction score
335
Location
Montana
First Name
Joe
Truck Year
1986
Truck Model
K5
Engine Size
350 Stroker to 383 with a 400 crank, Crane Cam, Q-Jet, single 3.5" exhaust..
A few things come to mind --- I worked with the USN in Alaska on the diesels and had a few troubles not unlike yours.

What Grade of Diesel are you running? It should be Diesel #1 per ASTM D4539.

#2 will have the paraffin drop out of suspension and look like the jell you speak of ... but it's really just wax.

No. 1 fuel - which is almost kerosene - has a natural CFPP of -40 °C - which is also -40°F but you can just use a salamander (or torpedo) heater to warm up the fuel tank.

I shoot the exhaust discharge from my Mr. Heat diesel-burning torpedo under my vehicles to get them warmed up for the -5°F temps here where I live.

OR ---> you can just leave the engine idling all winter. That works good too.
 

SDJunkMan

Full Access Member
Joined
Nov 17, 2017
Posts
1,807
Reaction score
2,653
Location
Black Hills of South Dakota
First Name
Jeff
Truck Year
1978
Truck Model
K10
Engine Size
350
Joe, thanks for tne reply. I usually run what I think is #1 diesel without additives (whatever is in the pumps on the regular automotive side, not the truck side, which I think is #2). The local stations usually switch to winter blend in the fall, depending on the weather, but our weatber has been so nice this fall, I'm not sure if the last time I filled up it was winter blend. I do run some bio-diesel inthe summer, but usually stop using itbwhen it cools off.

I don't have a salamander type heater, or would try that (I remember when I was young watching old guys in the truckstop start fires with old pallets under their trucks to thaw them):eek:.

This is the first time I've had trouble with the CUCV, gelled our VW TDI a couple of times and my Powerstroke a time or two. I've been driving diesels for over 25 years, so have a little experience with gelling. In the past tbey either wouldn't start, or lost power and died while I was driving, never just stopped like the key was turned off.
 

backwoodsman

Junior Member
Joined
Feb 22, 2023
Posts
29
Reaction score
26
Location
Idaho
First Name
Dan
Truck Year
1983
Truck Model
GMC Suburban K1500
Engine Size
6.2L diesel
I opened the drain on the fuel filter to see if it was pushing fuel out, and it wasn't.

Do you have an electric pump upstream of the primary filter? If not, that would suck air in, not push fuel out.

Stopping as abruptly as if the key was turned off seems to me to lean away from fuel gelling, and I'm not sure that's cold enough to gel it anyway. I'd be looking first at the injection pump; check that it's still getting 12v and that the solenoid clicks when power is applied. Then crack the fuel line from fuel pump to injection pump and crank the engine to see if the fuel pump is working. Then check the fuel line all the way back to the tank to see if there's a blockage somewhere.
 

SDJunkMan

Full Access Member
Joined
Nov 17, 2017
Posts
1,807
Reaction score
2,653
Location
Black Hills of South Dakota
First Name
Jeff
Truck Year
1978
Truck Model
K10
Engine Size
350
Do you have an electric pump upstream of the primary filter? If not, that would suck air in, not push fuel out.

Stopping as abruptly as if the key was turned off seems to me to lean away from fuel gelling, and I'm not sure that's cold enough to gel it anyway. I'd be looking first at the injection pump; check that it's still getting 12v and that the solenoid clicks when power is applied. Then crack the fuel line from fuel pump to injection pump and crank the engine to see if the fuel pump is working. Then check the fuel line all the way back to the tank to see if there's a blockage somewhere.
No electric pump, unless there was a stock one in the tank. I'll try the wire to the injector pump, forgot about that, but it still should have pushed fuel out of the filter. Maybe I'll pull the filter again and bring it inside to warm up. The fuel in it was liquid when I checked it but it is possible it is still blocked.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,333
Reaction score
8,483
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
No electric pump, unless there was a stock one in the tank. I'll try the wire to the injector pump, forgot about that, but it still should have pushed fuel out of the filter. Maybe I'll pull the filter again and bring it inside to warm up. The fuel in it was liquid when I checked it but it is possible it is still blocked.
I was going to check my 6.2 for you but got busy and forgot,so I'm no help.
 
Last edited:

PrairieDrifter

Full Access Member
Joined
Dec 28, 2014
Posts
3,829
Reaction score
5,597
Location
North Dakota
First Name
Mason
Truck Year
84,79,77,76,70,48
Truck Model
Suburban k10, bonanza k10, k30, k20, c10, gmc 1/2ton
Engine Size
350, 350, 350, 350, 350, 350
Being a northerner. I'm gonna say it's not gelled. It'll usually spit and sputter or sound like it's missing for a little bit. Also I would recommend hotshots secrets products. Winter anti gel for the cold months, it's decent priced. Another project farm test. I haven't had an issue before using that stuff till it gets real cold, farther into the negatives. 0 is getting close to gel zone.
 

backwoodsman

Junior Member
Joined
Feb 22, 2023
Posts
29
Reaction score
26
Location
Idaho
First Name
Dan
Truck Year
1983
Truck Model
GMC Suburban K1500
Engine Size
6.2L diesel
but it still should have pushed fuel out of the filter.

We're talking about the primary filter/water separator, right? Unless someone has rerouted your fuel system, the lift pump is after the primary filter, so it'll suck air if you open a petcock while the pump is operating.
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,186
Reaction score
11,896
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
Whenever I've had cold fuel issues it's been plugging at the sock in the tank. Usually, it becomes an issue at 15°. There's a heater in the box filter, so that shouldn't be the issue. If it's in the tank, you'll have to heat the fuel/tank to get the fuel flowing again.

You should use an additive all year round. Fuel quality today is terrible. The winter formulas of additives like Stanadyne and Alliant Power have an anti-gel built in. But they have to be mixed in the fuel at a temperature higher than when the gelling/precipitation occurs. Regular use will ensure that happens.
 

SDJunkMan

Full Access Member
Joined
Nov 17, 2017
Posts
1,807
Reaction score
2,653
Location
Black Hills of South Dakota
First Name
Jeff
Truck Year
1978
Truck Model
K10
Engine Size
350
I finally got it going, not sure what the problem was, but a new filter and a warm day, and it started. There was a little bit of moisture in the filter, maybe that was the problem? It doesn't have the original box type filter, I was having trouble with it s changed to a spin on, which doesn't have a heater. I did notice that when I was trying to start it, the fuel tank pressurized, I wonder if the vent got some water in it and froze, then wouldn't allow it to vent.
 

backwoodsman

Junior Member
Joined
Feb 22, 2023
Posts
29
Reaction score
26
Location
Idaho
First Name
Dan
Truck Year
1983
Truck Model
GMC Suburban K1500
Engine Size
6.2L diesel
I did notice that when I was trying to start it, the fuel tank pressurized, I wonder if the vent got some water in it and froze, then wouldn't allow it to vent.

That makes me wonder if it was having trouble venting air that got into the fuel system through the fuel return line. That wouldn't usually make it quit quite that abruptly, but it'll sure make it quit, and make it very difficult to restart. If it happens again, take the fuel return line off the injection pump and see if there's air in it.
 

Latest posts

Forum statistics

Threads
43,984
Posts
947,112
Members
36,040
Latest member
75BEASTK20
Top