Hello, my name is Mark and I will try help you with this.
If this is a diesel engine then the first thing you need to check are all the glowplugs are working ok.
Yes they are
Did you measure how much current they were using?
no what should that be?
Initially about 60 Amps and reduces as they warm up
How did you check them?
Someone else checked them for me
how do you recommend I check them?
With an ammeter.
An induction amp clamp meter is easiest.
The other way is to remove them from the cylinder head and connect them to a battery using jump leads to see if they glow or not.
OK I can do that
Appart from the glow plugs what else should I look at?
Water in the fuel filter.
Wrong or contaminated engine oil.
Starter current draw being too high.
Air in fuel system.
there is no water in the fuel
Did you bleed the filter to check?
there is no air in the fuel system. I bled this. No signs of water or air
oil is only new and the problem existed before the oil change
Did you open the drain of the fuel filter and capture what came out?
starter current, do you know what that should be?>
What size engine?
About 200 Amps
I think you need to go back to the glowplugs and have them rechecked.
When the glowplugs are out it would be a good idea to check the cylinder compressions.
OK I will check them. It will be tomorrow when I get to do that
Have a happy new year when it comes.
Please remember to rate my assistance.
How did you get on with the testing?