Author Topic: ST1 will not start  (Read 165 times)


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ST1 will not start
« on: September 07, 2022, 09:10:28 PM »
I have a late 70's year ST1 that is made onto a LIMA 3500 generator, I love running this generator set.  This engine has done got hard to crank, the last time it was run it was making oil so i have fuel getting in the oil somehow, i put a new injector in and that did not solve the problem with it cranking.  I used to could crank it with the handle in a couple of turns, not anymore, i hooked the electric start up and it will not start with it either, maybe smoke just a little while trying to crank on it but its not getting fuel.  I don't know much about this engine but i am mechanically inclined i can do the work, does anyone know where i should start to find the problem.



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Re: ST1 will not start
« Reply #1 on: September 08, 2022, 05:48:49 AM »
G'Day Mate,
Sounds like you have a possible problem. Firstly check the engine oil level and make sure it is oil only and no more fuel in the mix. Trying to start it like this is going to cause serious damage to bearings. Fuel could be entering via the fuel pump not the injector so that needs to be checked and fixed if needed.
If the pump id found to be the problem while it is away being repaired or while waiting for a new replacement this is the time to drop the oil mix from the sump change the oil filter and use new oil. I would also suggest that both air and fuel filters be replaced so that when it does start up and run again all will be ready for work.
Do not force the engine to turn over especially with the electric starter motor as it may burn out so go back to using the crank handle and the decompression lever. Which leads me to ask will it crank over by hand when decompressed?
We need to go through things step by step to try and source the problem/s. So start by checking the condition of the fuel pump and go from there.
Coopernook - the centre of our Universe.


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Re: ST1 will not start
« Reply #2 on: September 08, 2022, 12:47:26 PM »
G`Day to you both. I totally agree with Cobbadog that you need to work through this problem logically, so there are four things that diesel fuel systems hate: dirt, water, air and leaks.
Start at the fuel tank, drain the tank and flush out the detritus, blow out the fuel line to the fuel filter. strip and clean the fuel filter assembly and replace the fuel filter. Follow the fuel pipe from the filter to where it enters the crankcase, remove the adjacent cover plate to expose the fuel injector pump. undo the banjo bolt on the front of the injector and remove the fuel supply pipe, be careful not to loose the two dowty washers or the small neoprene crankcase seal around the pipe. Blow out the pipe. Just above the banjo bolt you just removed, there is a bleed nipple, remove it and check the condition of the seal.
On the top of the fuel injector is a high pressure fuel pipe that runs up to the fuel injector, undo the pipe at both ends and remove it, blow it through.
Now put everything back together starting at the fuel tank, do not tighten the high pressure injector pipe where it connects to the fuel injector. Fill the fuel tank and bleed the fuel filter using the two bleed valves on top of the filter. Next is to bleed the fuel injector pump using the bleed valve above the banjo bolt. Let the fuel flow until you get no bubbles. Now (with the injector pump rack fully open)crank the engine over until you get fuel leaking out around the loose fuel injector pipe, when you do, tighten the nut.
Once you have checked everything is tightened (rocker cover and injector pump cover still removed), with the fuel pump rack fully open, crank it over while decompressed, look for fuel leaks around the banjo bolt and high pressure fuel injector pipe. Also check the fuel injector return pipe to the fuel tank.
If everything looks good try to start it with the rocker cover and injector covers still removed, don`t wear your best suit and please wear safety specs while doing this, you may get a bit of oil spray. If it starts have another good look for leaks, especially around the high pressure line between the fuel pump and fuel injector. If it starts and everything looks ok, turn it off and replace the covers, I recommend some gasket sealer around the neoprene fuel inlet pipe seal.
If it still won`t start after all your efforts I suspect that the fuel injector pump is worn and will require a new element. When they are worn they do not produce enough pressure for the fuel injector to spray diesel into the engine, they also tend to leak fuel out from the bottom of the pump into the crankcase. I hope this is not the case. Injector pump elements are readily available but I do not recommend you try to replace it yourself unless you are a Gun mechanic, take it to a diesel service specialist and have them do it. If you do have to remove the fuel injection pump be very careful to keep the shims that are between it and the crankcase, these determine the fuel injection timing.
Good luck, let us know how you get on,