Oil & Fuel Diesel fuel line restrictions Chinese tractors

[Chris D]

I know this has been covered before but I'm running it through again because it is a common problem and may prove frustrating for owners.

The fuel system on most of the 2, 3 and 4 cylinder diesel engines used in Chinese tractors is pretty much of the same generic design across all brands and it has been used for a long time. Essentially the fuel flows from the fuel tank, via a shut - off valve to a sight glass to indicate if free water is present (often the shutoff valve is incorporated within the sight glass assembly). From here, a hose goes to the lift pump attached to the side of the main fuel pump, and from there it is pumped to a filter before it goes to the main fuel pump with an overflow line back to the lift circuit again. All this has been well covered and there are some pretty good photos uploaded elsewhere that illustrate this. The fittings used are standard issue "banjo" fittings swaged to rubber lines often covered in stainless braid.

Here's my point. In many cases, the swaging is a bit overly done and may well result in restriction or even blockage of that line. In most cases, a little eventual swelling of the rubber hose may cause a delayed problem in constricting the fuel lines a little or a lot with reduced engine power. Usually it is displayed by normal running for a while and then reduced power, "missing", and ultimately stalling of the engine.

The correct fix is to replace these problem hose assemblies and there are plenty of diesel service outlets that will make these for affected owners. There is another way for those of you who are hands - on. Since the pressures in these hoses are only relatively low, you can rebuild restricted hoses yourself. Simply cut the swaging rings from around the hose ends and discard the old hose and check that the banjo fittings are unmarked as you will be reusing them. Then purchase some good quality diesel injection hose (it does not need to be steel braid as it's not close to hot exhaust surfaces) of the correct size and some good quality hose clamps and remake the hose(s) yourself. Blow out the finished hose assembly with compressed air and get them as clean as you can and then install them with new copper washers, check that any filter gauze inserts are back where they should be, flush the system using the priming pump and bleed valves, start the engine, check for leaks and get back to work.

Good luck.

 

[bjr]

Your right in that fuel flow issues has been covered. And having said that I'll recover my fix. I changed out the tank valve sedimate bowl with a 1/4" needle valve bought from hydraulic shop. I run just the standard spin on filter. That was THE FIRST thing I did on building up my crate bought Jinma JM354. It has been a very good starting engine, EVEN, in the coldest weather (modification done 12 yrs. ago). I agree that fuel restriction is a major cause of woe in these Chinese tractors. Those factory tank valve have tiny orifices that plug all to easy. bjr

 

[Bob Rooks]

...with an overflow line back to the lift circuit again.

My dozer had that setup and I found that it was aerating the fuel, which will also cause the lack of power symptoms you described. This was done, IMHO, as a cost saving measure so a fuel return line wasn't installed back to the tank. I found it necessary to tap into that "overflow" line and install a return line to the tank. Eliminated the aeration problem. I used a refrigeration line tap.