Redwood

Where is the engine located?

Check the shaft seal and gasket on the transfer pump as either one will allow fuel to enter the pump housing. Redwood

Old Iron, Check out the attached link https://www.ebay.com/itm/Caterpillar-Crawler-Dozer-International-headlight-Brush-Guard-new-in-box-Tractor/254847107203?hash=item3b56124083:g:bHQAAOSwNM9gEZzu

Just sent you a PM with all the gory details

Might have some bits and pieces left over. I will PM you with details. Gene

Saw this on E-bay and thought someone may be interested https://www.ebay.com/itm/IH-International-UD-18-UD18-TD-18-TD18-Engine-Head-Gasket-Set-Assortment-259893/154172774052?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649 Gene

Fill the fuel tank to the point that you can gravity fill the primary filter then fire up on gas bleed the secondary filter, crack the throttle and bleed the injectors. good to go. You might want to change the fuel filters at this time as who knows what you might have sucked up from the tank. Gene

When you call Associated Tractor ask for Tom - Owner

I have also used Manila file folder paper for the thin gaskets with success. Gene

Attached is something that I downloaded from Red Power a number of years ago. I believe from MB Cat. Hope this helps. Gene

If you are getting fuel coming out of the fuel pump top cover it is most likely the gasket that goes between the auxiliary pump and injection pump. this gasket has to seal the return flow of fuel coming from the injection pump. Be careful when putting in a new gasket as there is nothing to hold it in place so one side must be glued. The shaft seal could be the culprit but it would have to be severely damaged. Gene

Sending unit should be located at the back of the head

PA, Keep in mind that the UD-16 is the 6 cylinder version of the UD/TD-9 engine so they share a lot of common parts. Gene

Appears to be a UD18 stationary engine. Could you please post a photo of the back side of the engine? Gene