MF1085 injector pump

CBBC

Member
I had my injector pump rebuilt...previously posted a question about advancing and retarding by rotating the pump mount. Thanks Dieseltech for confirming that information.

My problem is now it really doesn't run well under load. When it starts it actually seems like it is putting out unburnt fuel- white exhaust, but not steam. Once it is up and running at 1500-1700 rpm it clears up and sounds pretty smooth.

I put the brush cutter on it and tried it out, bogged down and struggled even to get back to the shop, exhaust looked blacker...almost like the air intake was plugged, filters are ok.

Rotating the pump didn't seem to make much difference. Is it possible that the timing gear lifted out a notch while I was attaching the pump back to that gear?...it can only attach onto that gear in one position. Does that gear just float in there when the pump is not attached tight?

What else could I have done??

Any help would be appreciated. Thanks, Grant
 
The pump drive gear can't jump teeth inside the cover as it fits tight enough even with the pump off, it can't move around. Once it clears up at 1500 and is slowed back to 800, does the white smoke return, or still run OK like at 1500? Also some air filter assemblies have two filters, the outer main and an inner safety element which can't be cleaned like the outer can. Did you try with both out to see how it runs? I've seen the inner one be the trouble before even though it doesn't look bad. The injection pump on that model has a retard start advance box, meaning it stays retarded for starting then moves to full four degrees pump advance and stays there at 800 RPM and above. One more thing to check, if NAPA/WIX brand fuel filters are used MAKE SURE the filter top outer fuel inlet groove DOES NOT have an O ring in it by mistake. I've seen that happen a lot. Usually the engine won't even run, but sometimes just enough fuel gets past the restriction for running, but the pump advance won't work right. Original CAV filters don't have this problem..
 
I will pull the air filters tomorrow and see if it is better.
I think the white smoke did return when it idles back down, I will verify when I run again.
When I tried the brush cutter out and it bogged down, it sounded like it was missing...like only running on 3 cylinders???

Exhaust temperature was very high, the plastic shrouds / casing around the wires going to the starter started to melt- they are close to the manifold / muffler. I ran it the first few times without the muffler - I was waiting for a new one to come in. The new muffler is on now - at least its not as loud.

The water temperature was 185. I just put a new temp sender and readout gauge in. I could touch the hoses and while they were all hot, they didn't burn me.

It runs better in the counter rotated direction (retarded). In the center where it was before was worse and I didn't move it to advance.

Always frustrating when something is worse after the repair. I will try without the air filters probably Saturday and post back with a new thread. Any other thoughts...maybe the shop mess up...

Thanks, Grant
 
Well it appears worse than I thought. The head gasket appears to be blown...again I know this is a common problem with this engine A318. Leaking coolant out the sides where the head gasket seals.

I assume this is the "white" smoke mixed with unburnt fuel? When I went through and cracked each injector with running it seemed like one cylinder was defiantly not firing and the one beside it probably is loosing a lot of pressure.
Would this make the exhaust temperature very high? As I said the coolant is only up to 185-190 but the exhaust manifold / muffler is really hot - melting the plastic wiring on the starter.

It starts slow at the 800 rpm with white smoke and when the throttle was put up nothing was really happening...and then suddenly the rpms went up, the white smoke cleared...the exhaust still didn't look like it should though. When throttled back it idled down and then started chugging and the white came back.

I pulled both air filters out. Fuel coming into injector doesn't seem to be a problem, and the injectors are squirting ok when the lines are cracked. I had the injectors serviced and tested last winter so I don't think that is the problem.

Any thoughts??? especially why the exhaust is so hot? Thanks, Grant
 
White smoke is unburned fuel due to low compression heat. The smoke will lighten up or go away completely when fuel is taken away from the bad cylinder with the injector line loose. Let me know if you want a head gasket as I have extra since I stopped using them in my Super 90 puller. And make sure it gets retorqued when hot after replacing it..
 
Thanks DieselTech. So I fiddled with it again today ... somethings just not right in my mind. That high exhaust temp. I pulled the muffler off and I have pulsing flames coming out burning fuel when it gets up to the higher rpms.

So are my valves suddenly so worn that it is creeping past or it the pump timing out so that the injectors are squirting in late as the exhaust valve is just opening? I don't know how this is possible as you said the drive gear cant move in the housing and the pump only bolts on in one position.

What about the pump rebuild...could the timing be off somehow inside the pump?

Sorry I don't really understand the workings inside an injector pump. This tractor was running fine - well ok - before I had the pump taken in. It was just leaking so much and sucking air, I had to use the lift pump to re-prime every now and then. The pump shop said they were amazed it ran at all and completely rebuilt it...did I get taken here? Should I take it back and get them to check again?

I have other things to do so the head gasket is going to need to wait until winter...but if there is a pump issue I don't want to let it go on.

Thanks, Grant
 
Make sure that you are not off one revolution on the crank. Make sure both valves are closed on #1 cyl with the pump and timing marks aligned. Some engines will run 1 off, some won't.
 

I'd call my Massey dealer and have them look at it before you really tear something up......plus they have all the service manuals for it too! No substitute for old experience!
Good luck
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top