Cat c15 MBN

Do C15s actually have an injection pump. Thought those went out with the 3406C hybrid mechanical electronic pumps?

 

It is probably posted under the the search block, top right.
Poor mans way connect a hose to the filter head and hang a gauge on the mirror. Probably looking for 100 Lbs, or at least 80.
First sign is often surging power under load uphill.
So what is going on with your truck?

 

Others much more qualified than me around here. A scanner hooked up under load is probably a good place to start. Maybe some inexpensive code readers are available.
Sounds more like a sensor or harness problem to me.

 

I have a BXS that missed under load and had a difficult time getting my boss to understand that it is an issue that is still on going (Been that way for the year I drove it) and needed to be fixed.

The engine would either have power or half power. No engine lights coming on.

I just rebuilt the engine, has only 400 miles on it so far.

Problem is that the truck sounds good and runs good to him when he uses it.

But he hauls light loads (10 tons at least) while I haul loaded B-trains up to 50.

The truck will miss a lot under load, like it was going break something.

Several weeks ago I had the truck taken to a shop that has a Cat ET.

He did the injector cut out at idle test. 1 turned off at time.

Said there is no noticeable difference.

I ask him to turn them all off but one.

He said the engine won’t stay running if we do that. I said it’ll run on one cylinder.

Sure enough, #1 and #6 couldn’t keep the engine running but #2,3,4,5 kept the engine running smoothly by themselves.

So I replaced all 6 injectors.

The truck hasn’t been on the road yet with the new injectors as it’s getting other work done at the moment.

But I sure hope the problem is fixed.

The current truck I’m driving now has a 3406E with over 1 million miles on the near original engine. This summer it had a missing under load with occasional missing at idle. The engine for years always smoked white when started up but always cleared up and went to work.

We pulled all the injectors out and had them tested.

5 tested low flow and one was non responsive.

So all 6 injectors were put in. Fixed all the issues the engine had. Back to being smooth.

 

Injectors can miss under load but not when idling. You can cut out 5 cylinder and see if it runs on one like @Shawn2130 did.
If it passes that you will have to take a laptop for a ride and cut out cylinders as the miss is happening.

 

To answer your question on testing pump. Plug return line and hook gauge up. Idle engine..DONT REV IT UP ! Watch fuel pressure. Then unplug return line and run engine again. At low idle then high idle.. Checking pressure. Your miss sounds like a weak injector. Do manual cutout test and watch fuel flow rates for each injector.

 

vise grip on return line and watch pressure