andyr354

the fuel line that runs from the filter to the inj pump is crimped/twisted almost shut right above where it screws into the pump. Looks like somebody overtightened it or something causing the line to twist.

I was trying to decide if there was enough room back there to get the line out and a new one in?


Anybody know if this line is a part I can buy or just have to make one?

Ggg

I believe D/C can get it if the truck is less then 10 yrs old. Cummins will go farther back then that, but you will need to give them the engine s/n. They will not be able to do anything with the Dodge truck info, just engine info.
Then again if it isn't causing any problems you might consider leaving it alone, just a thought.

Monty

If it is almost completely shut. Definately replace it. A crimped line to the injection pump can cause rapid wear of the pumps internals, high fuel temp, low power. It basically makes the pump work harder with less fuel for lubrication.

Cummins lists the fuel pump supply line as 3918641 (probably superceded so dont be suprised if they give you a different number). However, this should get you started.

Here is a link to the breakdown of the fuel line and fittings. https://www.dieseltruckresource.com/...cat/500/page/1


Using the numbers assigned to each part, refer back to this so you can see what part number corresponds to each part.

1. 3908988 Tube Fuel Supply

2. 3905351 Seal, Grommet

3. 3918641 Tube Fuel Supply

4. 3905351 Seal, Grommet

5. 3908985 Union, Male 9/16-24 x 9/16-24

andyr354

Anybody know if it will wiggle out in one pice?

Or do you have to get it taken appart in the middle somehow?

Thanks for the part#s and diagram BTW!

andyr354

I got the new line, but can't get the old one loose from the pump. Is seized in place very tight. Have been putting PB on it this week to see if it will loosen up by the weekend and try again.

Any other tips? Can the large fitting in the pump be removed with no problems instead and get it appart on the workbench? Could cut the line and screw the larger fitting out?

Denis

That is the part I replaced tonight, Andy. It's a tight fit but the fitting that screws directly into the injection pump requires a 17mm wrench, the brass portion that screws into THAT requires a 14mm wrench. That one comes with the part 3918641 that Monty mentioned.

YES, you can remove it easily and get it apart on the workbench. Above the filter/separator there's a nut that I think is something like a 17mm as well. Once these are undone, the entire line assembly can be removed by finagling out from above and to the front of the injection pump.

The two lines are connected by a brass coupling. 3918641 comes with a rubber grommet at the coupling end and a compression fitting at the injection pump end. From Cummins is't about $21. Make sure to order a rubber grommet for the other coupling half and the two brass and rubber washers for the end of the line that screws into the casting above the filter/separator.

Hope this helps!

Bushy

I really suggest using some anti-seize on the tubing body where it enters and remains inside the threaded nut. This is a fairly decent way to help prevent problems just like yours.
The threaded fitting doesn't really need much torque either. Just snug it up and check for leaks/weeping after a test drive.....if it looks wet then loosen it off and re-snug it again only a bit tighter.

pb.....

loch

Might i add one thing to, never take risks with fuel systems on our truck, i wont even let mine get low in the summer, without the full fuel flow the cooling effect of the fuel in the injector pump drops fast, my boss replaced to pumps for that reason, a line is cheap insurance.

andyr354

I will get it this weekend somehow. I got the new line and a couple of seals for the union. Also have a new banjo to put in with a pressure guage fitting tapped in it.

Just that we are expecting a high of 10 degrees today doesn't make me to excited to go try it right now.

Denis

Andy,
Mine runs now after cracking a couple of the injector lines to the cylinders. Air in the fuel was the problem.
I HAD to get it done in case the weather system you guys are having moves east!

andyr354

I messed with it again today. That fuel line is really stuck in the fitting on the top of the pump. The flare wrench was gonna round it off so I stopped there since I need the truck running this week.

Where could I get another fitting for the top of the pump via mail? I would like to have an extra one on hand in case I can't get it appart.

The assembly the fuel line screws into that has the 17mm hex on it and screws into the pump.

I have nothing local here to get the part unless CaseIH would have it.