First off I will say the truck has been running great up until today. I will also say that I have no been listening to people about running HOT veggie oil through my stock lift pump. Also, I DO NOT have the capability to test fuel pressure, it has been on the to-do list for a while.

Anyway, today I needed to go somewhere 40 miles out and took the thruway. Like usual I waited until the truck was warmed up running on diesel and then switched over to veggie. I had it on cruise the whole way and made it 30 miles to the final toll booth, payed the man at the booth and the truck ran at idle.

I then noticed I was very low on veggie and switched back to COLD diesel. Well the truck did not like that at all, had very low power and would only work at 1300+ RPM. At first I was sh*tting bricks because I was in the middle of nowhere with this thing on the side of the road. I finally figured out that it would indeed move around at the high RPM (thank goodness for having a manual). As soon as I realized it would run like this I headed straight back for home ON DIESEL THE ENTIRE TIME.

Luckily I made it the entire 30 miles home. And I must say it performed alright on the freeway. I was cruising at 65 but it didnt have any power to really accelerate and hills were a bit troublesome but it made it. Another thing to note is that it is NOT smoking at all.

At this point it it will start if you throttle it good and keep it at higher RPM but will die out instantly otherwise. It also has significantly decreased power. But on a straight away it runs pretty much fine.

Whats going on here? I think the lift pump may have finally bit the dust by running all that hot veggie oil through it? The whole thing is ironic because im in the process of buying a raptor pump right now to move the veggie oil and keep the stock lift pump for diesel.

Please help! Thank you!!!!

 

I'd check the easy things first, any fuel line leaks, and especially the shut down solenoid, make sure it is pulling all the way up. Sounds like you gotta rent/borrow/buy a fuel pressure gauge too to see if the lift pump is checking out.

 

Where is the location for connecting the fuel pressure gauge?

 

Google must not be working today.

http://www.cumminsforum.com/forum/94...-12-valve.html

Floyd

 

UPDATE:

I took a look at the fuel shutoff solenoid and it is in rough shape. The rubber was completely tattered and nearly all gone. The two screws that hold it in place... well the left one was loose and the right one looks like it was snapped off by the previous owner so the whole solenoid was loose. So that definitely needs to be fixed.

However I pulled UP on the arm the solenoid is supposed to pull on and tried to start the truck. It seemed to behave the same way. My question is.... those two screws that hold down the solenoid, it appears to hold down half of some sort of housing... since one screw was loose and other gone, is it possible that the housing is not clamped down all the way and sucking air? Is that even a possible problem?

 

Not even possible, no fuel flows though the solenoid.
It just activates a lever.

There is actually a third bolt that holds the solenoid bracket down.
Some people get lazy or can't find the lower bolt and bend the bracket in order to access the fuel plate.
Sometimes this gets things out of alignment so that the solenoid binds and won't lift all the way.

 

I didnt mean the solenoid, I meant the housing that it bolts to. When I tightened the loose bolt a little bit of engine oil (or of that consistency) weeped out of the bottom of that housing from being clamped down tight.

 

are you talking about the afc housing?

 

Be careful overtightening the AFC cover bolts that also hold the the solenoid.
It's just aluminum and strips out very easily. People come here all the time asking how to fix their stripped out threads.

There is an o-ring under the AFC cover that might be out of it's groove or tightened down on so hard that it's squished out of place causing the oil leak.

 

Thats really weird that you switched back to #2 and it performed worse. Never had that happen.
Im assuming that source and feed were switched so that you arent dumping veggie into the diesel tank, right? You have veg fuel in the pump and lines and it needs time to purge (chances are youre doing this I just want to be sure).
not that it would do this sort of thing right away, but over time some veggie could clog the #2 system which is unheated.
Id get a fuel pressure gauge on there just so you have something to go on. Id also look into adding a clear sight glass to the system, just before the lift pump so you can see air in the lines. I used a furnace sight glass from mcmaster-carr with 3/8 npt push-lok fittings on either end.
Its possible something got loose and youre pulling air in the lines.. thats what it sounds like to me anyhow. With that sort of temp change it is possible something cracked or split.. who knows. The sight glass will help a lot with diagnosing air problems and its safe for a permanent install.

 

Problem solved.

I removed the stock fuel lines and installed rubber. There was a crack in the line very near the top of the tank, she was sucking air.

I appreciate everyone's help, thank you!