Losing prime

[Mark P]

He’s not running a VP44, he’s running a VE pump.

And after stopping the leak at the T…… it doesn’t start. Time to get the tractor and the bed puller. I’ll keep you posted!

 

[petersonj]

He’s not running a VP44, he’s running a VE pump.

I understand that he is running a VE pump. Instead of a constant pressure valve in each of the high pressure pump outlets, there is a delivery valve. I think the principle would be the same - how would fuel drain back?

- John

 

[BigPapa]

I don’t think it’s draining between the IP and the injectors. When the return line rotted on my truck, the fuel between the IP and the tank would drain. It’s like the finger on a straw, liquid won’t drain until you remove your finger.

 

[Mark P]

OK........ so the bed is off. Took me about 45 minutes to pull it with the help of a tractor, pig pole, and a home made bed puller. I pulled the fuel canister out of the tank, and the port that I'm using also has a tube (black in the picture) going to the bottom of the tank. Everything looks good, but I can see that the original port goes into a valve or crossover of some sort, connected to the fuel supply line for the original in-tank pump. I'm wondering if the "valve" has some sort of purpose in this?? I'll include some pictures of it, and if anyone has any suggestions, I'm all ears. I don't see an issue at the tank. I even considered separating the return from the VE pump and the return from the injectors, and running a new line from the tank to the back of the head. OR...... hook the original clear/yellow line from that valve to the port that I'm actually using. Your thoughts? I'm scratching at straws at the moment.

 

[BigPapa]

There was no in-tank pump, it was on the side of the engine. All that was in the tank was what you have.

Explain again how you have the FASS plumbed, please. I recall you said something about not using the return line. If you bump the starter and let the FASS run a couple of cycles, does it start?

 

[Mark P]

If you look at the picture, the yellow pieces have arrows on them. One in and one out, and below those wires is an electric fuel pump...... approximately 2" in diameter. First one like it I've ever seen. Could this have been off a gas truck???

As for the FASS, I wish I had taken pictures of it. I didn't install it. It was on the truck when I bought it 2 1/2 years ago. From looking at the pictures above, one line come out of the front of the pump and goes to the engine. The other one on the front is fed from the pick up tube in the top of the tank. The one attached at the back of the pump, goes to the back side of the pick up tube on top of the tank.

I just tried to tighten the banjo bolt on the back of the head, but couldn't budge it. I tightened the T fitting, and cleaned it with brake cleaner, and it still looks dry. There is a push lock fitting just below the T fitting, that seems a bit loose. It's where the metal line, attaches to a plastic line. I have a plate in my neck, and 2 sets of rods in my lower back, and I'm having a tough time just reaching them. I don't bend too good now. I am sure I can't get to them to change them out. This one may have to go to a shop. We have a local Cummins "guru", so I may give him a call. I haven't driven the truck on the highway since I swapped the VP44 for the VE, but I'm getting ready to now. I'm sure I lost some horsepower, but I haven't made any changes to the VE yet. I have a Denny T fuel pin, and I'll be adjusting the AFC for a quicker boost reaction, and turning up the fuel. I've had VE's before. Good pump, and normally, easy starting.

I remember reading a post about NOT plumbing the FASS return line in with the return line. I'm assuming he is referring to the line from the back of the head. It said it can cause issues. I think it was on Mopar1973man.com forum. I've tried to get back on it since then, but it's been down to transfer to a new server.

 

[BigPapa]

What about cycling the FASS a couple of times and then trying to start it? Will it start then?

 

[Mark P]

I have to bump the starter to cycle it. I’ve tried that and it doesn’t seem to make a difference. I just drove the truck and it has no boost pressure??????? Not much power. Not sure what that could be. I don’t know of anything on the engine to cause it other than maybe the waste gate. It had good boost before the swap. WOW

 

[BigPapa]

May have something to do with the 1K psi difference in Pop Pressure on your injectors. The 1st Gens pop at 3550psi, the 24-Valve injectors pop at 31,026kPa (4500psi).

 

[Mark P]

I thought of that, but I know guys that made this swap and didn’t have the pop pressed changed. It idles fantastic, but doesn’t have any power. I removed an Edge controller, but I don’t know of any sensors that would make a difference with a manual pump. Timing is advanced a little. One tooth on the gear. That should only be 10 degree. I’m going to check the waste gate, and pull the hose off between the turbo and the intercooler. See how much air it’s moving.

 

[Mark P]

Ok.. figured the power and boost out. The VE pump was backed out completely. I gave it about 4 turns and it’s a totally different truck. 30 psi boost now and 900 degrees at 60 mph. I backed the idle down all it would go and it’s still idling at 875. With the pump advanced, it has fair bottom end and great top end. More tuning….

 

[Ozymandias]

I've another idea to rule something out. Order a cheap in-line check valve for the feed line to the VE pump, install between VE-pump and fuel filter.
That is easy to do and gives you the proof that you aren't draining the fuel back that way. We had another case here in the Forum not to long ago where exactly that happened.

 

[Mark P]

There was no in-tank pump, it was on the side of the engine. All that was in the tank was what you have.

Explain again how you have the FASS plumbed, please. I recall you said something about not using the return line. If you bump the starter and let the FASS run a couple of cycles, does it start?

I did a little reading. (ok... a lot of reading), and there were some with in tank pumps.

 

[Mark P]

I've another idea to rule something out. Order a cheap in-line check valve for the feed line to the VE pump, install between VE-pump and fuel filter.
That is easy to do and gives you the proof that you aren't draining the fuel back that way. We had another case here in the Forum not to long ago where exactly that happened.

I never gave that a thought. Great idea!! I'm also hoping that turning the fuel up may help the prime issue. Find out tomorrow morning. I've done a little adjusting on the pump, and I'm really happy with the power, especially the top end!!!

 

[BigPapa]

Order a cheap in-line check valve for the feed line to the VE pump, install between VE-pump and fuel filter.

Wouldn't the pressure regulator valve in the FASS work the same way?

I did a little reading. (ok... a lot of reading), and there were some with in tank pumps.

There were no 2nd Gen diesels with in-tank lift pumps. The 12-valves used a mechanical piston pump in the side of the block above the starter and the 24-valves had an electric pump mounted on a block-off plate in the same location.

 

[Mark P]

Wouldn't the pressure regulator valve in the FASS work the same way?



There were no 2nd Gen diesels with in-tank lift pumps. The 12-valves used a mechanical piston pump in the side of the block above the starter and the 24-valves had an electric pump mounted on a block-off plate in the same location.

I just found a couple articles on Diesel Bombers and also on Cummins Forum that said some 2nd gens had the in tank pump. These were a Carter in-tank lift pump. One article said that the in-tank pumps were retrofitted at the dealer per TSB.

 

[Mark P]

Wouldn't the pressure regulator valve in the FASS work the same way?



There were no 2nd Gen diesels with in-tank lift pumps. The 12-valves used a mechanical piston pump in the side of the block above the starter and the 24-valves had an electric pump mounted on a block-off plate in the same location.

Mine definitely has one.

 

[Ozymandias]

The in-tank was a retrofit design from MOPAR to get rid of the problematic Carter pump at the side of the engine. Same as with the early Gen. 3

 

[NIsaacs]

I just found a couple articles on Diesel Bombers and also on Cummins Forum that said some 2nd gens had the in tank pump. These were a Carter in-tank lift pump. One article said that the in-tank pumps were retrofitted at the dealer per TSB.

Yes, the first link is an in tank pump module, second link is the module with fuel level only.

https://www.moparpartsgiant.com/parts/mopar-modul-kit-fuel-pump-level-unit~4897667ad.html

https://www.moparpartsgiant.com/parts/mopar-modul-kit-level-unit~4897668ae.html

 

[BigPapa]

That part in the first link certainly doesn't look like what you have in your pics.

There should be documentation if your truck was retrofitted. Why would it have both in-tank and a FASS?