Truck wants to stall after you nail the throttle

[spencnaz]

Truck engine wants to stall or die when you nail the throttle. Is this another issue with the air leak I've been having in the fuel system?

Only started doing this like last night.

 

[Exekiel69]

Well You run veggy so this could be related to fuel temps as well. You can fix the air leak and run #2 for some time to see if it makes a difference. Also think how old is You fuel filter. Do You use the stock lift pump or electric pump?

 

[spencnaz]

1. I'm not running veggie, it's biodiesel.

2. Been running #2 lately as it's been too cold to use biodiesel.

3. I changed the fuel filter a couple months ago.

4. I replaced the stock fuel pump this last summer.

 

[towcat]

1. I'm not running veggie, it's biodiesel.

2. Been running #2 lately as it's been too cold to use biodiesel.

3. I changed the fuel filter a couple months ago.

4. I replaced the stock fuel pump this last summer.

After working on Evergreen Ranch's rolling french fry vat, I can definitely tell you that b100 flows like warm molasses compared to regular #2.
Ok...feul filter may have been changed, how's the feul quality been since?
Lastly, how old is the air filter?

 

[spencnaz]

As stated before, I've been running #2 diesel fuel for the past 2 months.

Fuel is flowing fine. Biodiesel flows fine if you're above about 38F when using a soy oil based biodiesel. If its made from canola oil, the gel point drops to about 25F.

New fuel filter last month.

New air filter last month.

I'm beginning to think that it may be the check valve on the fuel return line on the IP that is giving me fits. It's looking like it's weeping or at least sweating fuel. Is it possible to use something like a teflon tape on the threads, making sure none gets into the fuel system itself?

I just want to find the damn air leak so I can get this truck running smoothly again.

One question, I know that there are leak detectors for A/C systems. Is it possible to put this dye into the fuel and then look around the fuel system for the dye with an ultraviolet lamp?

 

[towcat]

As stated before, I've been running #2 diesel fuel for the past 2 months.

Fuel is flowing fine. Biodiesel flows fine if you're above about 38F when using a soy oil based biodiesel. If its made from canola oil, the gel point drops to about 25F.

New fuel filter last month.

New air filter last month.

I'm beginning to think that it may be the check valve on the fuel return line on the IP that is giving me fits. It's looking like it's weeping or at least sweating fuel. Is it possible to use something like a teflon tape on the threads, making sure none gets into the fuel system itself?

I just want to find the damn air leak so I can get this truck running smoothly again.

One question, I know that there are leak detectors for A/C systems. Is it possible to put this dye into the fuel and then look around the fuel system for the dye with an ultraviolet lamp?

I was just adding comment to the french fry feul. I saw your earlier comments.
Pull the check valve off and take a look through it. If you can't see through it, its time to change it. If you suspect it, change it. Those valves do real funny things to timing advance on the pump when the low pressure side of the pump is overpressurized from blocked flow. Iirc, its no more than $30usd at the stealership.

 

[RLDSL]

2. Been running #2 lately as it's been too cold to use biodiesel.

3. I changed the fuel filter a couple months ago.

Regardless of which fuel you have in there, it only takes one real bad batch of fuel to clog a filter.
Back when I drove a big truck, I can't count the number of times I filled up somewhere and found myself on the side of the road every 30-50 miles changing the fuel filter till the next fill up.

----------Robert

 

[tonkadoctor]

Is it possible to use something like a teflon tape on the threads, making sure none gets into the fuel system itself?

Don't use teflon tape on fuel or hydraulic systems, bad JUJU if it gets in and messes up the pump or injectors, use an liquid teflon sealant sparingly if necessary on any tapered pipe theads. If you have JIC flared fittings or fittings that use an o-ring leaking you should replace the problem fitting/o-rings as sealant usually won't work, if it does it'll be temporary at best.

Permatex makes it and you can get it at any decent autoparts store...NAPA definatly carries it on the shelf. I'm sure there are a few other brands out there but I've used the Permatex for years with no problems.

 

[spencnaz]

I'm going to take another look at that valve this morning as soon as my back loosens up a bit.

I have another line to check as I see a dark spot on the hose that may indicate a pin hole on the intake line to the fuel/water separator. It's right on the junction between the rubber line and the steel fuel line. If it is bad I'll just snip out the offending section and try again.

Also is there supposed to be an o-ring on the return line fitting at the top of the IP? I took this off earlier this year to check but couldn't see an o-ring in there, I did notice that it had a flared end on the line so I didn't think of it having an o-ring at the time.

 

[yARIC008]

Truck engine wants to stall or die when you nail the throttle. Is this another issue with the air leak I've been having in the fuel system?

Only started doing this like last night.

Isn't this problem usually a sticky metering valve in the pump? Overdose it on dieselkleen or the like.

 

[DeepRoots]

its also a symptom of an air leak.
small enough it doesn't bother you, full throttle however pulls more air in....
also kinked/deteriorated fuel lines will do the same thing

 

[spencnaz]

Well I just got in from taking off the check valve, I can see through it and the little glass ball in there looks good, so that wasn't the problem.

I tightened the injector fittings just in case, some were a little loose but not bad. I checked the seal on the return line to the fuel filter head, it was a little chewed up, but didnt' look like it was weeping fuel. I put a wrap of Rescue Tape around it for another layer of sealing.

Last of all, and where I think the leak was coming from, the inlet line from tank to separator looked like it might have had a pin hole on the area near the hose clamp. I took it off, cut off the offending section. I think put some vaseline on the outside of the steel fuel line and pushed the hopefully hole-free section of line onto the steel line. I have to say its a challenge to get down to that area of the engine bay to tighten the hose clamp.

I should mention that I had a remanned IP put in this last September, as per my signature. So I'm pretty certain it's an airleak(s).