McCormick loses power as you run it

   / McCormick loses power as you run it #1  

Greg Hollinger

New member
Joined
Nov 6, 2011
Messages
5
Tractor
McCormick
Hello folks,
My neighbor has a McCormick (50-60 hp) we've been trying to repair. Dealer said it was injector pump and had it rebuilt - did not fix. Problem: as you run the tractor under load, approx. 10-15 min. into job, it starts acting as if it's grasping for power and struggling to keep up the rpm's (like water or air in fuel). If you stay on the load (cutting moderately heavy hay), it will eventually choke itself off. Seems obvious to be fuel related. Other things done already: Tank drained and new fuel, injectors bled. If you wait 30 minutes, tractor will start back and resume work until it eventually happens again. You can hear the fuel pump kick on when key is activated, but it sounds "bubbly", like it's sucking air into the system. I really think air is getting into the fuel system, but I just don't know where. Any leads?
 
   / McCormick loses power as you run it #2  
Fuel filter? Pleated filters can collapse slowly under suction. This reduces their area and worsens til engine starves. When you let it sit the filter opens back up ... repeat.
larry
 
   / McCormick loses power as you run it #3  
i would blow the line out between the filter and tank.then change the filters.some mccormicks have a little filter before the lift pump.
 
   / McCormick loses power as you run it
  • Thread Starter
#5  
Well, we replaced the filter yesterday. The old filter did not look as if it had collapsed from suction. Everything looked pretty normal. Bled air at the injectors, then at the pump, then at the injectors again. Tractor performed as it ever has. The longer it runs, the more it seems to starve for fuel. However, while bleeding injector #1 (the one closest to the pump), when I cracked the nut, it did not seem as if it affected the function of the machine like the other two. Almost like that cylinder was not working anyway. We are going to pull that injector today and look at it. Thanks for the replies folks...please keep them coming!!
 
   / McCormick loses power as you run it #6  
Hi
Is there a filter/screen actually inside the fuel tank. Does it have a tap on the outlet from the fuel tank.
I had an old International that got a tiny tiny pebble lodged in the fuel tap.
When it was stationary and I checked the flow through the tap it was fine....After 10 or 15 mins use the power would slowly diminish.
Cleaned the tank, filters etc etc could not find the fault.
Finally found it when the pebble got lodged hard in the tap and cut the fuel off completely.

Just a suggestion.
 
   / McCormick loses power as you run it #7  
A slight positive pressure on the tank might show a small draw side leak.
 
   / McCormick loses power as you run it #8  
Its an obstruction in the tank bottom or in one of the lines. When the fuel in the bowl or filter is used up it cant draw enough to keep running.
Remove the tanks flush shake dump. incredibly common on tractors that sit a lot or get fuel poured from can or jugs. remember a small piece of plastic or foil is all it takes....
 
   / McCormick loses power as you run it #9  
hi guy's
One thing not discused here, is the fuel cap vent clogged ? you may want to check that 1st. before pulling the fuel tank. just my :2cents:
david
 
   / McCormick loses power as you run it
  • Thread Starter
#10  
Pulled the #1 injector and it tested O.K. In the A.M. my neighbor is draining the tank and blowing out the lines. I thought he did this already, but apparently he just drained the fuel and replaced it with new. A clog sounds as good as any other right now. Hopefully this will do it----I'll keep ya'll posted. We had checked the fuel cap...o.k. there. One thing, this tractor did sit a few years at the dealership as a trade in. Good call rdbigfarmboy, we shall see....
 
 
Top