Universal diesel M 18 surging

[Chawes]

My Universal M18 surges under load. Rena up and down no problem. But under load it surges as soon as I put it in gear. High range les noticeably. I have changed fuel filter on engine. Checked Racor which looks fine. What could be the issue. It runs , does not stall but annoying. Any suggestions where to further investigate would be appreciated.

[Hesti]

Governor / injection pump. On some Diesel, the injection pump has its own little oil reservoir, if that is empty, it could be one reason. Beyond that, the pump or governor mechanism if seperate may need professional help.

[donradcliffe]

Surge under load usually means partial fuel starvation. If both filters have been changed, you could explore for partial blockages in pickup tube, elbows, or valves. Consider it the warning signal that you are going to lose power soon.

[Stu Jackson]

https://forums.sailboatowners.com/th...hlight=obscure

[Chawes]

Ok it sounds like fuel starvation. I will start at the tank and inspect each connection and line. Thanks for all your input I will follow up with what I find.
Thanks

[Chayal]

Does the exhaust smoke any specific colour when it’s surging?

Might be worth changing the racor out if you don’t know when it was replaced last.

[boatpoker]

Fuel restriction or small air leak between the tank and injection pump.

[Chawes]

In answer smoke is normal. I will inspect everything. I may bypass Racor to test.
Thanks all for your insight.

[Gavino]

after checking theres no trouble with the tank pick up pipe....try blowing back down the fuel pipe from the first filtre.....have a look at the lift pump....theres a sometimes a small filtre in the top of the lift pump.....which collects a lot of fine gundge....which could slowing / partely blocking the fuel supply.....just had the same problem...the engine would idle ok but start surging when rev higher than 1200rpm......
good luck with finding the fault...