Diesel Surging Issue minimec pump

OzMF35

Member
I've got an old Ford 2712e 4 cylinder diesel engine on an irrigation pump. I purchased it from a clearance dealer not going (radiator was holed, no fuel tank etc.) but was told it should go.

I've managed to get it going but it wont hold a steady rpm. It surges continually. Revs climb - then drop - then climb, over and over again. It has a 'minimec' injection pump. So far I have:

- Removed the injection pump side cover and verified that the metering rack moves freely.
- Drained and refilled the injection pump oil.
- Checked for any fuel restrictions to the pump.
- I can dampen the surging by moving the fuel shut off lever over to a point where it restricts the rack movement and it will hold a steady rpm but this is not a solution.

I'm starting to think its an issue with the actual governor operation but that's about where my knowledge ends, I am not sure what to try next?

Anyone with some knowledge of these pumps have an idea what it might be?
 
Make sure the fuel supply lines are good as David mentioned, no air leaks in the supply side. Next could very well be the internal governor assembly causing the surge trouble. Is the surge at all speeds, or mainly at idle? If low idle is set too slow most Minimec pumps will surge, but settle down around 800-900 RPM.
 

I've been over the fuel lines a few times and don't believe there's any leaks or restrictions, but will check again. The surging starts as soon as it fires up and there is no load on the engine. Doesn't seem to matter at what rpm?

Here is a video I took if its helps anyone:

https://vimeo.com/239227188
 
my 6610 was doing that, was combination of leaking suction lines, broken return springs on plungers and rust on them
 
Just saw the video, that pump has the leaf spring governor. There's a SLIM chance it may get better with use IF it's been setting awhile. There's a lever inside that pivots on a support shaft that MIGHT be rusty, and an oil change and some use may free it up. Leaf spring governor is generally more sensitive than the two legged coil spring like most Ford tractors use. Might come out of the surge as a load is applied too. Perkins V-8 510 and 540 had the same type leaf spring governor that are known for low speed surging, but revved up some they come out of it.
 
Simms mini pumps dont like old fuel. If this engine was laid up for a extended time the plungers will get sticky. It may feel free to your fingers, but to the trained finger it may be sticky. Roll the engine by hand until you see each plunger just start its way up, then use the tip of a dental pick to push n pull on the foot of the plunger. it should move a few thousands each way. Most surging on a simms pump is from lack of oil. This is a problem that takes years to have happen. Most guys never knew these pumps need oil, let alone change it once in a while. Might be a good time to have it checked out. These pumps are not expensive to go though unless you wait until there is a full blown train wreck. Fixing one that has been run dry for a while will cost much more. I did one a few weeks ago that was just a check out n reseal for a over haul job 3cyl. 520 with new lisft pump n springs. This week I did one that was run dry long enough to wear out the gov. unit. new springs, lift pump n bearings 645. No oil is bad, no oil but full water even worse. Sometimes spending a few bucks now saves you a ton later. Al
 
Thanks guys, I'll go back over the lines looking for leaks and try the other suggestions and hopefully it comes good.

Otherwise it might be off to the injector pump specialist.
 

Make sure the return line is clear and unrestricted,,, or it will not let it get fuel into to the pump correctly????
 

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