Dhorn33

I bought my first diesel a year and a half ago - and so far all has been well. The truck was setup to run WVO with a 2nd tank, heated lines, etc - but last weekend one of the wvo tank straps broke and the front of the tank dropped a bit - luckily I noticed right away and was able to strap it back up and drive home. Once I got it fixed and attached with a better setup - I went for a drive and once warm I switched the truck over to WVO. After a short time the truck started stumbling, losing power, bucking and blowing white smoke. I pulled over and was able to get it started back up on diesel. I drove home and swapped out the WVO filter thinking maybe it was plugged - and the same thing happened again. I thought maybe the wvo was crappy so I pumped all that out of the tank and put in some regular diesel. The same thing happened with the diesel in the wvo tank. Each time I was able to get it running again on the normal tank with diesel - but I didn't drive it too far. I parked it and figured something got messed up with the wvo system.

After doing some research I thought maybe I was getting air into the system somehow so I undid the fuel line at the wvo tank at one of the fitting and ran the truck on some diesel that I put the line into (in a jar). After puring the air, etc - it seemed to run fine on the diesel from the wvo line. I was able to rev up the truck to 3000 rpm and it wasn't blowing white smoke or anything. I replaced a section of line and a few fittings and hooked it back up and went for a drive. The truck ran fine with diesel from wvo tank for about 15 miles - then suddenly it started to lose power and stall out again. I switched it back over to the diesel tank and it seemed to run fine - then iwhen I hit 70 mph (about 1900 rpm) it started to lose power and stall! The truck starts to miss - blows a little white smoke and stalls. I pulled over and got it started again - then the same thing happened as soon as I got to 65-70 mph?

The fuel filter has less than 1000 miles on it - and the screen was replaced about 1 year ago (10000 miles ago). The air filter is new.

Being a diesel newbie I am not real sure where to begin. I did some reading on here and I was thinking I would check the pre-filter screen again - probably later tonight. If that is clean - I thought I should check the overflow valve but I have idea how to do that or even where it is? It also soundsl like it could be a lift pump? The pump isn't ticking or anything and it ran great until the wvo tank dropped a week ago. Please help!!

The truck is 97 12v with 132000 miles on it, automatic 4x4. About a month ago I slid the AFC housing and the plate forward but other than that and the wvo system the truck is stock.

Help!!

Dhorn33

I checked the pre-filter screen and it looked fine? What should I do next?

heykw

so the truck misses on either tank?

Dhorn33

Sort of. The truck will idle fine - run and drive fine - and then when I get out on the highway and reach a certain speed it will start acting up. This is on either tank at this point?

Dhorn33

Just to add to the pile here...



When the WVO tank dropped the front end of it tipped - the back was still held in place. The front of the tank has the coolant lines going in and out for the tank heater (heated with engine coolant) and I suppose it was held up by these lines. There is a T right before it where the fuel line comes out from inside the coolant lines and goes back to the tank pickup. I replaced a section of the copper fuel line and a few fittings here yesterday - prior to posting this.



I dumped some Diesel Power Service in the tank last night, checked the fuel pre-filter screen and drained the filter. I primed the system with the plunger - and it fired right up. I didn't drive it - but instead just assumed all was fine and went to bed. This morning I decided to try to drive the truck to work and see if maybe the DPS would clean out injectors or something? Anyway - I had a lot of trouble starting it - I had to push the throttle and it took a few minutes of fiddling to get it started and then it was real rough for 20 seconds before it smoothed out and ran normal. I drove to work never going more than 65 mph (1750 rpm) without any issues.



I too am am thinking their might be air getting in somewhere but I really don't have any idea how to chase that down? I was planning to install a pressure guage on the fuel banjo nut tonight and see what fuel pressure looks like so I will post up the results of that when I get a chance.



From what I have read - the white smoke could be several things:

- low combustion temps (like cold starts, etc)

- air in the system

- water or coolant in the system

- dirty injectors

- ??



As I said - the white smoke only happens when it starts to stumble and stall - it is not constant and when it is running normal it has no smoke or a puff of black when I get on it.



Any more ideas or thoughts guys?

Oh - and I completely forgot to add this little tidbit of info...

When I was under the truck repairing the WVO tank strap I also found a broken strap for my normal diesel tank! The front strap had broken and the tank was slightly leaning and being held in place but the rear strap. I welded up the front strap and put it back together. Needless to say I was a bit suprised that both my tanks had broken straps and I am wondering *** happened? I did go to the compost and it was a bit rough but I can't believe I hit a bump that freaking hard that both tank straps broke! Anyway - I wonder if something came loose on the top of the diesel tank too?

If I install a fuel pressue guage will that indicate any air leaks?

Dan Turner

I had a similar problem once...turned out to be the fuel pick up inside the tank had a crack and would suck air, but was only a problem at higher speeds on the highway. White smoke loss of power, sometimes stalling, etc.

Hope you get it figured out.

-Dan

Dhorn33

How would you figure that out? I assume the tank would have to come out and then the pickup removed?

infidel

You got it.
For leaks in the delivery system outside of the tank you can pressurize the tank with compressed air, 10 psi max, and look for leaks. With two people this can simply be done by wrapping a blow gun with a rag and pressurizing though the fill hole. If you want to get fancy a fuel cap can be drilled and tapped for an air fitting.

Dhorn33

I drove the truck over 100 miles yesterday - some highway and some stop and go - and it ran fine until 1/2 mile from my house when it started losing power and died at the stop sign. This morning I drove it again and it seems to be running fine - until I get on the throttle even somewhat agressively and then it missed and stumbles - but not as bad as before? I swear it feels like it is flooded - but that is based on my gasser experience?



Last night I stuck the air chuck in the fuel tank and looked at the lines and fittings and didn't see any evidence of any air leaks?



I picked up an oil pressure guage that reads to 100 psi in nice increments and I will go find a 1/8" needle valve today over lunch so I can try to install a fuel pressure guage.



There isn't any chance this is a dirty fuel filter - is there? The one in the truck is less than 1000 miles old so I guess I find it hard to believe it could be clogged at all but are any of these symptoms possible from a clogged or bad fuel filter?

infidel

If you buy clean fuel there's no reason your filter won't go 50,000 miles but if you get dirty fuel it's possible for the filter to clog every 25 miles.
Big no-no is to fill up while a fuel tanker is filling the or has just filled the underground tanks. Adding fuel stirs up sediments from the bottom of the tank that can cause long lasting plugging problems.
A fuel pressure gauge will defiantly tell you what's happening.

Dhorn33

I think I will pick up another fuel filter tonight and after I install the fuel pressure gauge I may replace the filter and see if that makes any difference.

I have a strange feeling that my last batch of WVO may have been really bad or something? Maybe it was enough to plug the filter or something.

Dhorn33

Alright - I installed my fp guage tonight and once I got it going I started the truck and at idle the pressure was only around 10 psi. At 2500 it was slightly higher. I pinched the return line and the pressure shot up to 65-70 so I assume that means something is up with the overflow valve?

I removed the overflow valve and stretched out the spring a bit- then reinstalled and at idle the pressure was 40-42. When I throttle to 2500 rpm the pressure drops to 24-28?

In both cases when I drive the pressure drops to 0 and stays there until it go back to idle? Is that normal? I also replaced the fuel filter and it seems slightly better - but still stumbles when I get on it at all. I am not seeing white smoke and it didn't die -but that could be just me figuring out how to drive it with this issue?

What does this all mean and what should I do next?

Dhorn33

This morning the truck fired right up - and the fuel pressure came up to 40-44 at idle. When I drove it on the highway I noticed that the fuel pressure would sit at 12-14 if I kept the speed at 65 - as soon as I hit a hill or got on the throttle at all it dropped to 0.

Also - the gauge was bouncing at 40-44 this morning - but when I give it gas or drive the needle gets solid and drops to under 30. When I pulled in to work the needle was solid still and reading 10-12 psi at idle and 20 at 2500 with no load? This thing is all over the freaking place?

When I changed the filter I drained it first (I make a big enough mess as it is - I can't imagine if I left it full!) so I can't say if there was air or not but the filter was much dirtier than I expected with some nasty sediment at the bottom?

PLEASE HELP!

infidel

You have some kind of restriction in the supply system.
Need to first check the prefilter then move on to kinks in the the supply hoses and finally the in tank filter.

Dhorn33

I assume that I also have a bad overflow valve? When I pinched the return line the pressure shoots to 65ish - does that indicate it is bad?

I guess I might try dropping the tank tonight - but can I blow air through the fuel line to try to blow out the restriction before I drop the tank? Should I replace the overflow valve first and then see what happens? If not - how to I get to the screen in the tank? The fuel filter is brand new and the pre-screen in the heater is also clean.