Fordson Major Diesel Simms pump repair or scrap?

[dukeyfox]

Hello out there. I feel like I am alone. For the past nine months I have had nothing but Major problems - forgive the pun - with my FMD. First it was the brakes and cables and the shoes and the fittings and that still remains unresolved. Then without warning whilst testing the brakes it gave up the ghost. First it started to rev and then died. Since then I've tried everything, but it looks like a new pump is on the cards. I am told that they can be repaired. My Simms pump (the one without the lift pump on the side) is pumping minimal amounts of fuel to one injector only, but not enough to start the engine. At the other 3 injectors, there's just the slightest trickle but again not enough to get through to the injectors. I've replaced the fuel tank tap that was leaking, changed the lift pump, changed the filters and for some unknown reason soaked the whole pump in petrol for a few days in the hope that it was dirt that needed dislodging, but to no avail. I'm no purist when it comes to the Major which is a workhorse - or was - but is it feesable to rebuild the pump yourself? I notice there are repair kits for sale, so is this a regular thing to do? The cost is prohibitive in buying a new pump and the risk involved in buying a used pump could just be throwing good money after bad. I also want to eliminate all other possibilites before replacement. In short, first, is it the pump? and secondly if it sounds like it is, why not just go ahead and pull it to bits to see if there's anything obvious? Am I being meccano-ish and going back to my childhood? Can anyone throw a ray of hope out there that the pump may be okay and that it could be something else? Or is it D-Day for the pump?

[oehrick]

Unless you can buy a known working pump from someone you know / trust privately you are probably best to send yours off to have it tested, at best adjusted / calibrated at worst quoted for a rebuild.

When you prime / bleed the pump are you getting floods of diesel out of the bleed screw hole as you operate the lift pump ? if not you have a lift pump or fuel line restriction or leak up stream of the injection pump.

Before that,

Newer diesel may have skinned or waxed in the tank tap filter or damaged rubber somewhere, if you take the pipe into the lift pump out and open the tap does diesel pour out of the pipe ?

Have you taken off the pipe into the filter or the input side bleedscrew out and cranked the engine over ? if so does plenty of diesel come out of the pipe ? if not you may have a worn cam or drive lever on the lift pump, a damaged diaphragm or non return valve.

Ditto but taking the output side bleedscrew out of the top of the filter - does it match the input side flow ? if not clogged, collapsed or wrong pattern filter might be the culprit

Same as above but at the bleedscrew on the injection pump - same flow ? if not something clogged inside the pump.

Do you know anyone with the same engine? if so a loan of the pump would prove finally that it is what is wrong

Hope that helps

[shepp]

If your engine was starting and running fine before the episode you describe, then it is unlikely that there is a major failure with the injection pump.

You have replaced the lift pump and filter. As oehrick has suggested you need to check the flow of fuel coming out of the injection pump bleed screw when the lift pump is operated. If this is a strong flow free of air bubbles then the fault lies within the injector pump.

If there is a good fuel supply situation to the injector pump I would say that for whatever cause the control rod in the pump is stuck at the fuel cut-off position or very close to that position. There are a number of possible causes for this.

Face the injector pump and check that the fuel cut-off lever is in the forward position and not in the "stop" position i.e. not stuck on the cable.

If it is not stuck on the cable disconnect the cable and move the fuel cut off lever to the rear slowly and carefully by hand - do you feel any resistance to this movement or is the lever "sloppy" without resistance? If there is no resistance then the control rod is stuck in the fuel cut-off position.

Does you tractor have the push button for the excess fuel setting or the early pump where you have to pull the stop lever towards you to set the excess fuel cold start setting? In either case engage the excess fuel setting then move the fuel stop lever rearwards and check if the button pings out or the stop lever clicks back inwards. If these happen then the excess fuel mechanism is operating correctly and the fault is elsewhere on the control rod.

At the front of the pump on the vacuum governor housing under where the two vacuum pipes go in there is a screw held by a locknut. This is the damping valve screw, the damping valve operates on the diaphragm which in turn operates on the control rod. Back the locknut off a few threads and move the screw a few turns inwards and then the same turns outwards a few times, this might free a stuck damping valve which would be preventing the diaphragm and hence the control rod from moving. With the locknut still loose and backed off but the screw in the original position try and start the engine. If it starts and runs then the damping valve is where the problem was, it will be necessary to remove the governor housing which is held by 4 bolts and dis-assemble the governor with it's diaphragm and spring and damping valve and clean everything up so that it moves freely - it is fairly logical but might help you if you get one of the inexpensive manuals such as the I & T one to help you. I would fit a new diaphragm at the same time.

If this does not work then there is the possibility that the governor spring has snapped leaving the control rod set in the fuel cut-off position, again it will be necessary to remove and dismantle the governor housing to check this. Replace the spring and fit a new diaphragm at the same time.

Finally, it is possible that if all these components are intact and working the control rod is simply stuck in the bores in the pump body in which it runs. If you remove the side cover which is held by four or eight bolts (CLEAN OFF BEFOREHAND!) you will see the control rod and can attempt to move it by hand. If it is stuck try WD40 or penetrating oil to free it.

Do the first checks and report on what you find.

Good luck!

[oehrick]

As Shepp said but I would like to emphasise how important it is to check lift pump output when the engine is being cranked rather than just using the manual lever, not on a Major but I have known these where the operating lever linkage has worn so it skids off the cam or even weakens and bends so there is no pumping action.

Happy hunting, you'll crack it

[dukeyfox]

Thanks Oehrick and thanks Shepp. It WAS the cut off 'gate' - as I call it - preventing the fuel from going through. to you both. Started first punch after a good dose of deblock. Really pleased. Now it's back to the old problem I had with the brakes some months ago.

[oehrick]

Excellent news - now to apply the same logical approach to the braking problem...................

[shepp]

That's a good outcome! Check that the pump has lubricating oil in it by removing the pigtail overflow pipe and banjo bolt, and using a pump oil can filled with clean engine oil pump say less than half a pint of oil into the injection pump through the hole that the banjo screws into. When oil starts to flow out freely when you remove the can let it drain to the level of the hole then refit the overflow pipe and banjo bolt. Pumping a decent quantity of oil in will help displace diesel that may inevitably have leaked off from the pumping elements over a long period of time.