cat loader running problem

fiddleman

Member
I'm an off-road mechanic.Been workin on a 1991 cat 950f wheel loader with 3116 engine. Complaint was that it lost power.Upon checking it out,I found that it starts right up smoothly and sometimes can throttle up,but then starts sputtering and dies within 10 seconds.it just had a remanned head put on about 35 hrs ago, and ran fine till now.I changed fuel filters twice,drained about an eigth cup of water off the bottom of the fuel tank,rebuilt the fuel pump,checked for a restriction in the intake air,spun the turbo,blew out the fuel lines and passages in the head,checked fuel shut-off solenoid, and injector rack for binding or sticking,even hooked up a remote fuel tank directly to the pump to eliminate the possibility of it sucking air in the fuel somewhere. still does it.I did not try another governor yet,or pull the turbo to check for an exhaust restriction,which i think seems very unlikely.I'm baffled.any ideas? Thank you in advance.
 
Sounds like you've run into a good one there. I've had some like that myself over the years, and as much as I wish I could give a new suggestion, it sounds like you've covered all the bases, but the governor, already.

The bad thing is when you find the problem it will probably be something really simple. I'll look tomorrow, but think I've got a service manual. If so, I'll see if it shows anything with those symptoms, and get back with you tomorrow evening.
 
I appreciate the reply. After further testing,I suspect the problem may be a compression/combustion leak pushing air up past an injector. didn,t get it apart yet to verify.gonna try to get it trailered to the shop.
 
Yup. Number 6 injector wasn't quite tight. air was gettin pushed into the fuel gallery, and the fuel enters the head in that end,sending the air downstream to the rest of the injectors.Runs now! Thx.
 
I had a CAT 3054 (Perkins branded CAT) doing something similar about 15 years ago. In that case it was a turboed engine, and when you put a load on the engine and the turbo build enough boost pressure, it would force air past the check valve in the intake heater.

I did everything from changing fuel lines to pulling the injection pump and having it gone through, and couldn't figure out what was going on. The way I finally figured it out was the line going to the heater was the only place to tap into the fuel system to check pressure. When I pulled it lose, and hooked up a guage, the problem went away.

I all but pulled my hair out trying to get that one figured out, so I know exactly where you were at. Glad to hear you got it figured out and running right.
 

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