I need some help. I have a 4ISBE cummins. That's the engine that comes stock in ford F250's in Brazil. I believe it to be the same base design as the 6 cyd. Cr, but just with two less cylinders I have about 100k miles on it. Anyways, it started having problems last week. I drove into town, everything was normal. Got back in to go to the farm, started normal, ran 20sec. Then died. Cranked it over, wouldn't start. I primed the fuel filter a little with the plunger on the side. It took, and it ran great for 40miles to the farm. Next morning, started fine, ran 25 miles, I turned it off, went to start 20min later, ran 20sec and died. I tried priming the filter again, and wouldn't even act like it wanted to take.
Soooooooooo, I pulled it into town to a diesel shop. Put the computer on it, and said the high pressure pump wasn't making enough pressure. Took the pump off, put it on the stand, it would hold pressure for a few seconds, then psi would fall. He said normal psi would be around 26k psi, but this pump was only making 5k or so. I fought with the mechanic for a while and told him that doesn't make sense, because it was just running fine, why would it go from 100% normal to 0 in a second if it was the pump? Wouldn't it get sluggish over time?

Anybody have any thoughts here???

 

an ip pump can go bad in a blink of an eye i had a cp 3 go out while goping down the highway. if its not passing a bench test then its got to be the pump

 

Does this shop have the correct test equipment or are they doing some fancy rigging on just any old test stand? How is fuel delivered to the cp-3 on that truck? Lift pump? Pulling its own directly from the tank? I ask because when you say you can reprime it, it makes me think theres a possibility its losing prime,either from inadequate supply(failing lift pump) or pulling air into the system(example:cracked pick up tube in the tank).

 

I believe the shop has proper equipment, I think. The pump was on a stand with a line going to a rail, then a gauge was on the end of the rail. So it was a little rigged.
I'm told this truck doesn't have a pump in the tank, but that it has a lift pump mounted on the back side of the High psi pump. Not quite sure how that works. To me, it seemed like the symptoms said there was no fuel getting to the high psi pump. That's why it would run for 20 sec then die. But the shop feels differently.
When I said I primed it, on this engine, there is a spin on filter mounted on the side of the block with a plunger at the top of it to bleed. All I did was give it about 10 pumps, and it took that first night. I thought it could be a loose fuel filter, so i tighten it some, but not hardly any. I pumped a lot the second time this happened, and had no positive results.

 

possible it may be the lift pump and its blocking fuel flow altogether.

 

I wonder how they are testing the CP3 without some type of control over the FCA (Fuel Control Actuator).

First item to look at is the lift pump.

MikeyB

 

i had a bosch rep. tell me that only 2% of the CP3 pumps that they got back as "bad" where really bad 98% of them had a problem that could have been easily fixed or had a problem not related to the CP3

 

Well, it's fixed. They rebuilt the pump. Has pressure again. Cleared the codes. Runs normal. I still don't understand why though. They tell me there is no lift pump. That the high pressure pump sucks and pumps all at once. I can't say they're wrong. Frustrating.