Engine Missing

[CUMMINS]

My engine is missing/sputtering at about 1100 to 1400 rpm while under no load and at 2400 to 2600rpm while driving in overdrive, I have had my injectors rebuilt ,but my intank pump isn't working, I figure the high rpm stuttering is from starving for fuel, but why is it stuttering at only 1100 to 1400rpm, could this also be caused by the intank pump.

 

[DDoyle]

yes

 

[jwaller]

your intank pump would not cause that studder. I'd suspect fuel filters, air leak in the lines or something else.

 

[WillWagner]

Sounds like a low fuel pressure problem..filters...low PSI pump. Are yop using straight diesel? Mine will act like that if I have too much gas in the tank.

 

[DDoyle]

I'd agree that an air leak may be at fault - but were the intank pump working this likely would minimize the air leak - by making it leak fuel. Why is the in-tank pump not working? Did it get fouled with crap? Is the screen on the intake plugged? Have you checked the rubber hose that goes from the bottom of the tank to the top?

Regards,
David

 

[CUMMINS]

The filters should be good they are only 8 monthes old and only have about 1800 miles on them, I only run clean diesel, and I have checked and rechecked for air leaks,I have had the pump apart several times, the impeler section of the pump spins very freely but the motor screams and howls like the bushing are worn, It will blow a 2 amp fuse imediatly, I have been running a 30 amp fuse just to keep the pump alive a little longer, I just don't understand why if the pump was causing the sputtering at 1100 to 1400 rpm and run smoothly up to 2400

 

[TacticalTruck]

I had a deuce do a similar thing. It was a sticking by-pass valave in the mechanical transfer pump on the side of the injection pump. It was stuck partly open. At lower rpms it would bleed off too much fuel causing it to run bad but if I could get past it, at higher rpms the pump was spinning fast enough to make up for the bleed off and the engine ran fine.
Jeff

 

[cranetruck]

This is the valve Jeff is referring to. If the plunger is stuck, you may have to remove the assembly from the hydraulic head and tap it free.

Pardon the condition of the parts, it's from a "scrap" engine.

 

[CUMMINS]

I pulled the valve off and it was free and clean, I even rechecked my overhead valves adjustments and it is still missing I don't know what else to check, I'm about to go crazy with this thing.

 

[red devils dude]

ok I'm going to chime in, in AG diesels(tractors) injectors and fuel are the big one's to look for your fuel looks ok so that leaves fuel injection
one pull the injectors and have them checked one bad tip and it can miss any where in the rev range two clogged injector
lines I donr think that's your problem but I'll add it and then maybe a problem in your injection pump but if it was
that it would run bad all the time from what I know. this is just my but I have fixed problem's like this
where when the tractor took load at low revs and then again at high revs it would miss the culprit was a bad injector.

 

[CUMMINS]

Well today I rigged up a working fuel pump to the truck and I got a good amount of fuel pressure to the injector pump and the truck is still missing, Could the hydraulic head be the cause of the missing, but wouldn't it miss at all rpm, I'm stumped,

 

[CUMMINS]

My engine is now missing at idle up to 1500rpm, and 2100 to 2300 rpm but above that it still runs smooth, a 12 point 7/16 bolt on the side of the hydraulic head seems to be seeping fuel it is very tight but has no gasket, I don't know if it needs one though, I pulled the bolt out and there was a small spring that came out, I put it back in and tightened the bolt very tight but it still seeps a small amount of fuel. do I need to pull the hydraulic head and look for something in particular, Thanks for the replies.

 

[DDoyle]

That spring is part of a check valve - the tiny plunger that spring pushes against is precisely matched to the hydraulic head, and according to Bosch if you lose the plunger, it cannot be replaced and the hydraulic head is scrap.

Regards,
David

 

[CUMMINS]

I didn't lose the plunger I put everything back together and it still seeps fuel and misses, do you know if there is supposed to be a washer type gasket on the bolt, because I don't have one on the bolt and no matter how tight I get the bolt it still leaks. Thanks