LarryH57 Posted December 8, 2014 Share Posted December 8, 2014 (edited) On a Hillman Tilly we are working on it doesn't pick up fuel when turned over and the engine died on a day out and would not start. The pump has been stripped and a new diaphragm put in it and all the other parts seem OK. However the engine runs only on the fuel pumped in by hand, and I'm wondering if its the cam on the engine that's worn or not engaging. How would we know if its the cam on the pump not seated correctly or if the cam on the engine is worn down too far? BTW in this respect I was looking at the exploded diagram of the Hillman Tilly engine trying to work out where the cam on the fuel pump is driven from, as the fuel pump rocker arm only goes a little way in to the engine - unless the engine cam shaft sits to one side of the engine near the fuel pump?. Has anyone got a drawing showing where it sits? Incidentally the new diaphragm that has been fitted had a smaller 'metal disc' in the centre of the diaphragm and I'm wondering if the size of the disc has any bearing on the suction? Also on the body of the fuel pump below where the diaphragm sits there was what looks like a recess for a rubber gasket and one was even supplied in the refurb kit but was not fitted as its not shown as fitted in the manual. If the engine cam shaft is worn would an electrical pump be the easier option than a new cam, and if so who makes one? http://hillman.tillyregister.com/downloads/replacement.pdf Edited December 8, 2014 by LarryH57 spelling Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted December 8, 2014 Share Posted December 8, 2014 I have not got my manual to hand but it looks like there is a pushrod (listed as Plunger rod) that runs through the block horizontally to run off the cam. The rod could be worn (shorter) or the internals of the pump could be worn. Check the suction and pressure on the pump with hand primer first to rule out problems in the valve department. Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted December 8, 2014 Author Share Posted December 8, 2014 Thanks Richard. The exploded diagram of the engine cam and the fuel pump were on the attached link but it didn't explain to me how the cam on the fuel pump was driven by the engine cam shaft. Any help greatly appreciated. I think the pump is by AC and is the same as fitted to an Austin Tilly. Quote Link to comment Share on other sites More sharing options...
paulbrook Posted December 9, 2014 Share Posted December 9, 2014 To test the pump slacken off the banjo union on the carb, then turn the engine over on the starter and there should be a definite pressure at the carb end. If required take the spark plugs plugs out so the engine spins over quicker. If you have good pump pressure then suspect the valve at the top of the carb float. If not then the problem is back along the pump system somewhere. Did you change the little valves in the pump as well? To test undo the feed side of the pump (the one that comes from the tank and gently blow back down the pipe that runs to the carb. You should not be able to blow backwards as the valves should be shut. You should be able to suck but unless you are keen on the taste of unleaded I would take care with that one (I would try but I am old and daft) Assuming that is OK then look at the suction (ie tank) side. Does the pump have a sediment bowl? If so make sure the gasket at the top is in good condition and the bowl is properly seated and tight. If air leaks in there it will destroy any "suck". Also check any lines (especially rubber ones) between the tank and the pump. Splits will draw in air under suction but not necessarily leak fuel out the other way (trust me I was fixing this very problem on Saturday morning at the side of the road on an Armstrong Siddeley car) Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted December 9, 2014 Author Share Posted December 9, 2014 Thanks Paul One thing I should have mentioned is that the pin holding the fuel pump cam in place was half out of the hole on one side. If you see the Tilly manual you will see that a circlip holds each end in place but one was missing so the pin was on its was out of one side, and would surely have fallen out altogether on the road. I'm thinking that with the pin half out, it may have then allowed the cam in fuel pump to be 'moved aside' by the engine cam. The Hillman has an AC type fuel pump without a sediment bowl and has the gauze inside but this was not blocked. All the pipework to the pump and the carb is metal and showed no signs of leaks or holes. The diaphragm was changed and the springs and valves inspected and appeared to be in good order. With the fuel pump primed by hand the engine starts and can run as long as the pump is 'hand pumped' which leads me to believe its either a worn engine cam as above or we have not put in back on correctly! Quote Link to comment Share on other sites More sharing options...
paulbrook Posted December 9, 2014 Share Posted December 9, 2014 A good question to ask is "what has been disturbed....?" It is always good just to go back and check! Does it pump with the engine turning over? Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted December 9, 2014 Author Share Posted December 9, 2014 (edited) Paul, As soon as the hand pumping stops so does the engine after it's used up the fuel. Going back to the problem as it occurred, the Tilly drove along quite nicely then suddenly stopped, and turning over of the engine on the starter never got it going. The AA was called and they thought it was fuel pump too and possibly a split diaphragm. The fuel pump was then removed back at base as related above and the old diaphragm changed for a new one, even though I thought it was OK. So if the diaphragm didn't fail on the road, it must surely be related to the cam, as we can run the engine with hand priming but it won't run on its own. This surely discounts any leaks and blockages? By the way has anyone rigged up an electric pump on a Tilly as I'm told a Morris minor one may do and be easily available. Edited December 9, 2014 by LarryH57 Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted December 9, 2014 Share Posted December 9, 2014 Thanks Richard. The exploded diagram of the engine cam and the fuel pump were on the attached link but it didn't explain to me how the cam on the fuel pump was driven by the engine cam shaft. Any help greatly appreciated. I think the pump is by AC and is the same as fitted to an Austin Tilly. Larry, You have to read the parts list as it is not all shown in the pictures. It is obvious that the lift pump is on the opposite side of the engine to the camshaft. There is a pushrod (not illustrated but listed) that follows the cam lobe and in turn operates the pump. I explained this before that it could be worn or broken. The Hillman AC pump is similar to an Austin tilly but the method of operating is different, Austin having a lever that follows the cam directly. It could also be part of the cam operated linkage in the pump is worn or adrift because the and primer generally has a longer stroke on the diaphragm hence why it runs for a bit on hand priming. Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted December 9, 2014 Author Share Posted December 9, 2014 (edited) Richard, You'll have to forgive me I'm not mechanically trained so sometimes I don't explain myself or pick up on what others are posting. Anyway this explains things a bit better but as for a cure, if the push rod is broken then the engine needs to come apart, more than just taking a rocker cover off I presume. BTW if you have also looked at the parts list can you say what the part number is or rather its number in the list from 1 to 178 on the pages 5 to 12 covering the engine parts? Lastly what do you think about my suggestion for an electric pump? Edited December 9, 2014 by LarryH57 Quote Link to comment Share on other sites More sharing options...
paulbrook Posted December 10, 2014 Share Posted December 10, 2014 Paul, As soon as the hand pumping stops so does the engine after it's used up the fuel. Going back to the problem as it occurred, the Tilly drove along quite nicely then suddenly stopped, and turning over of the engine on the starter never got it going. The AA was called and they thought it was fuel pump too and possibly a split diaphragm. The fuel pump was then removed back at base as related above and the old diaphragm changed for a new one, even though I thought it was OK. So if the diaphragm didn't fail on the road, it must surely be related to the cam, as we can run the engine with hand priming but it won't run on its own. This surely discounts any leaks and blockages? By the way has anyone rigged up an electric pump on a Tilly as I'm told a Morris minor one may do and be easily available. My Armstrong Siddeley experience at the weekend was a timely reminder that assumption can be the mother of all - er - mistakes. In my case hand priming ran the engine - stopping pumping caused the fuel to run dry. The reason for this is that the hand pump works over a much greater stroke and this can mask other issues, particularly duff valves. Now internet diagnostics are notorious but the sequence described previously will determine more precisely where the problem lies. Fitting a 12v pump of modest output will do the trick for sure, but to be honest the original set up (when working correctly) is more than up to the job and if there are issues with leaks and splits then pressurising the pipes may not be a great plan. We have a Leyland fire engine in at the moment with a standard MGB electric pump and it seems to work a treat. As for the cam, take the top off the pump (the ring of screws) and turn the engine over. If the cam is OK you will see if the diaphragm is lifting as the cam goes around. Be aware though it does not move all that much - maybe 1/4 inch or so. And check that the two valves are seated properly, undamaged and the right way around... Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted December 10, 2014 Share Posted December 10, 2014 Richard, You'll have to forgive me I'm not mechanically trained so sometimes I don't explain myself or pick up on what others are posting. Anyway this explains things a bit better but as for a cure, if the push rod is broken then the engine needs to come apart, more than just taking a rocker cover off I presume. BTW if you have also looked at the parts list can you say what the part number is or rather its number in the list from 1 to 178 on the pages 5 to 12 covering the engine parts? Lastly what do you think about my suggestion for an electric pump? Larry, Page 17, last item with a Hillman part number is a push rod. Also, a clue you gave about the pin coming out, if it had come out far enough for Item 16 to drop out, the pump lever may not be aligned with the push rod as it is a spacer to centralise the lever. As for fitting an electric pump, well you can if you wish but nothing wrong with AC lift pumps if in good order, it is yours or the owners choice. regards, Richard Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted December 10, 2014 Author Share Posted December 10, 2014 Paul & Richard, many thanks for your replies. Yes, it was the case that the pin was nearly coming out, and one of the washers (number 16 on the diagram) had drop down inside the rocker arm link (number 11 on the diagram), so the rocker arm was probably misaligned. But when we put it together properly we thought that would be the end of our troubles!!! So the next thing we will do is take the top off and watch to see if the diaphragm moves when the engine is turned and after that check the alignment the rocker arm and the push rod. I will also turn the engine over on the starting handle to see the action of the engine push rod if I can through the hole. I'll let you know how I get on and if web diagnostics is worth it! (I have so far had great help from this and other forums, so keep posting) Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted January 22, 2015 Author Share Posted January 22, 2015 Regarding the Hillman Tilly, the fuel pump is actually OK and in good working order. The problem is with the push rod bar that's driven from the engine cam shaft, in that it appears to be worn down at each end so that when the engine is turned over there is not enough of a push on the push rod for it to move the rocker arm on the fuel pump sufficiently to pick up fuel. This problem is apparently typical for Hillman Tillies. A replacement part was sought from a firm called Speedy Spares IIRC but one has not been found as yet. Presumably the push rod which can be pulled out of the engine block (and replaced the same way) is made of hardened steel so could be made up quite easily but does anyone know the correct length, as at the moment we are guessing ours needs 1mm added each end. Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted January 27, 2015 Author Share Posted January 27, 2015 (edited) Can anyone say whether the push rod needs to be made from hardened steel, if we decide to make one up? I suppose it would not harm the engine if we made several and tested them for size and ability to push on the fuel pump cam and then had the best one hardened? BTW - for anyone with a Hillman what length is the push rod, even approximately, as without an exploded diagram its hard to know if the push rod we have of about 7 inches long is the full length or (fingers crossed) not just half of one, with the other bit still in the engine! The push rod just pulled out by hand once the fuel pump was removed. The end that was in the engine didn't look as if it had broken off another bit of metal. Edited January 27, 2015 by LarryH57 Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted February 5, 2015 Author Share Posted February 5, 2015 Any help on the length of the push rod gratefully received. Quote Link to comment Share on other sites More sharing options...
LarryH57 Posted February 5, 2015 Author Share Posted February 5, 2015 Ok more help needed; according to a brief description on the Hillman Tilly Register these vehicles should be 12 volt negative earth, yet the one we are working on is Positive Earth. Were any made like this or is it a bodge being positive earth? The AC fuel pump doesn't work because the cam on the engine is worn, so we want to fit an electric pump for now - which needs to be positive earth as the positive terminal on the battery is connected to the bulkhead. By the way does any one know the pressure of the standard AC pump as we would like to fit one from SU that's 1.4 psi. Is that good enough? Quote Link to comment Share on other sites More sharing options...
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