Injection pump issues

[charleyman39]

Having a mare with an old 780 fiat. Tractor sits around yard and does very little most of the year. Started losing power recently, and won't hit top revs, or if it does it dies out again. Figured fuel issue so replaced filters. Still nothing so replaced fuel lift pump. Still the same issue so took off fuel tank and cleaned it out, blew out fuel lines and put back on.

Whilst bleeding the pump, an old CAV, have noticed the diesel running freely through top bleed point, however when bottom bleed screw is taken out it's barely a dribble coming out with lots of air. This is after new filters, tank cleaned etc.

Have I got a blockage in the valve inside the injector pump? Hesitant to take it off but seems like I might have to to get it done.

 

[marshfarmer]

Is there a gauze filter in pump inlet?

 

[startinghandle]

Air filter?

 

[charleyman39]

Is there a gauze filter in pump inlet?

Haven't loosened that yet to check, if there's a steady stream coming from top bleed point would that not suggest the issues past the gauze anyway?

 

[charleyman39]

Air filter is 100 percent. Issue is the bottom bleed screw

 

[Mur Huwcun]

Is the tank higher than the pump? If not it sounds like it’s drawing in air from somewhere.

Best bet is start from tank, open and check every connection for dirt or blockage, replace any sealing washers etc as you go along. Did you replace all the orings on the filters?

 

[charleyman39]

Is the tank higher than the pump? If not it sounds like it’s drawing in air from somewhere.

Best bet is start from tank, open and check every connection for dirt or blockage, replace any sealing washers etc as you go along. Did you replace all the orings on the filters?

Had tank off, spent a day cleaning it as there was alot of debris in it. Flushed out fuel lines. Replaced filters and o rings, lift pump clean.

The diesel is flowing strongly to the injection pump inlet, bleeding on top screw but not bottom one.

 

[Mur Huwcun]

You may well need to clean the inlet section gauze then, if it's the CAV pump it's under the union the inlet pipe is screwed into. It's held in by a spring and a plunger and another spring down the bottom that need to go back in the correct way. Sometimes I take the whole end of the pump off, remove the four 5/16" head sized bolts and dissasemble on the bench

 

[agrimax]

If the gauze is clean,you may find the delivery valve plunger is stuck. The gauze sits around the valve body. When you lift of the top union,then a heavy spring,then a small plug(that needs to be installed the right way up),then sometimes another spring inside the tube and followed by the plunger. A small thin screwdriver inserted into that tube will determine if the plunger is stuck.Should be able to gently press down and feel if it comes back up again as there is another fine spring underneath it. If all's well in there,the pump likely needs to come off and be overhauled.
Had a MF35 with the same problem a month ago. Fuel at the top bleeder and nothing at the bottom and hence no injection. Pump needed overhauled.

 

[Mur Huwcun]

If the gauze is clean,you may find the delivery valve plunger is stuck. The gauze sits around the valve body. When you lift of the top union,then a heavy spring,then a small plug(that needs to be installed the right way up),then sometimes another spring inside the tube and followed by the plunger. A small thin screwdriver inserted into that tube will determine if the plunger is stuck.Should be able to gently press down and feel if it comes back up again as there is another fine spring underneath it. If all's well in there,the pump likely needs to come off and be overhauled.
Had a MF35 with the same problem a month ago. Fuel at the top bleeder and nothing at the bottom and hence no injection. Pump needed overhauled.

A good glug of ATF oil into the fuel filter will sometimes help with this and let it run through. Have heard of others using two stroke oil as well. Can do no harm anyhow!!!

 

[Farmer_Joe]

if you cant get it to work from the above blow compressed air in at bottom and open top, years ago i successfully cleared out a fuel pump doing this after someone clogged it, think i also turned it over with no injector ipies on to clear it out, when its pump off job you got nowt to loose.

 

[charleyman39]

So I took out the gauze inside the inlet and it was indeed well and truly clogged. Cleaned it and put all back together and got diesel coming out both bleed screws. Thought great job, bled the injectors and away she went. Revved up all seemed fine. Went and hooked on the tanker and was pulling it up a small hill in the yard and she started struggling in high first gear. Tanker was empty. Obviously still not getting enough fuel when under pressure. Any ideas where I should look now?

 

[charleyman39]

Also forgot to mention, when I dropped the revs she cuts out. Wondering is it the stopper shaft

 

[fiat 9090]

Also forgot to mention, when I dropped the revs she cuts out. Wondering is it the stopper shaft

It sounds like its drawing air ,if its grand when you bleed it and then it acts up then its hardly the pump

 

[charleyman39]

It sounds like its drawing air ,if its grand when you bleed it and then it acts up then its hardly the pump

If there was a valve in pump jammed would it not restrict pressure?

 

[avag]

Had tank off, spent a day cleaning it as there was alot of debris in it. Flushed out fuel lines. Replaced filters and o rings, lift pump clean.

The diesel is flowing strongly to the injection pump inlet, bleeding on top screw but not bottom one.

Had similar on a ih 475 Perkins engine losing power so changed filters plenty of fuel in top bleed screw not much in bottom screw after trying all basics I eventually removed injection pump and turned out the cam ring inside had cracked so I fitted a new copy pump from Romania at half price of original pump overhaul, it starts a lot better aswell after new pump

 

[Wisconsonian]

You've already said the tank was full of crud, and the injection pump inlet filter was full of crud, which means the whole of the system had crud through it, as it never should have reached the inlet filter. I'd take all the lines off and blow through them with water, then air, put a wire through everything you can, look through every fitting, then see what it does.

It could be internal to the pump, but eliminate the obvious first. Good flow when priming by hand is not the same as good flow at full load.

 

[charleyman39]

Had similar on a ih 475 Perkins engine losing power so changed filters plenty of fuel in top bleed screw not much in bottom screw after trying all basics I eventually removed injection pump and turned out the cam ring inside had cracked so I fitted a new copy pump from Romania at half price of original pump overhaul, it starts a lot better aswell after new pump

Old thread, but just wondering where you ordered the copy pump from?

 

[avag]

Old thread, but just wondering where you ordered the copy pump from?

Sparex were cheapest at the time but most aftermarket parts suppliers sell the same pumps from Romania, must be 5 years since I fitted it and been trouble free it sits on a scraper all winter so clocks hours regularly