air fuel problems

[logonberry]

Hi, Aussie JCB owner and self mechanic here, I am having trouble keeping my JCB 3CX running. It has a Perkins 4236 engine with Lucas CAV injector pump. I usually have no trouble bleeding the system when I ocasionaly run out of fuel, but this time the machine runs for about a minute and then stalls again. this has happened five times and I am sick of bleeding it. I assume that air is being drawn into the system as there seems to be plenty of fuel to all points in the system. I have dismantled the whole fuel line and filter assembly and have found that the lines have rubber rings/seals on them . they are not O rings. Thing is some of the seals are at the front of the flare and some behind between the nut and the flare. Where should these seals be ? Should the (fuel line ) joint/seal be metal to metal ? Hope you can help , Cheers, Roy.

 

[Fixingfarmer]

Do you loose a fuel standpipe (often it’s just a rubber hose) in the tank? How much fuel did you put in does it have to be pretty full? Sounds like you have fuel too the pump though does it have an electric charge pump or small mechanical one that feeds it? Could be it’s getting enough to start but not run full throttle I’ve seen specifically skid steers and terra gators be able to pump fuel for awhile off the injection pump only drawing the fuel in. But then if you run out you will have problems problems problems getting it to work right again. Specifically I remember an ethanol plant skidsteer where the fuel pumps on those models were loud enough you could hear them key switch on in the cab with the door shut clattering away. this one didn’t do that. Ran great they used it every day didn’t bother them at all. When I go to change the fuel filter would have a heck of a time starting it. The last time I did it I ran it for a full hour after I was done just to make sure it would stay that way. It wasn’t a concern to management as they didn’t have to change the filter. Would be about the same as running out of fuel. Just a couple things to try hope you get it figured out! Oh and if it didn’t have an o ring no o ring needed

 

[Jim.ME]

Hi, Aussie JCB owner and self mechanic here, I am having trouble keeping my JCB 3CX running. It has a Perkins 4236 engine with Lucas CAV injector pump. I usually have no trouble bleeding the system when I ocasionaly run out of fuel, but this time the machine runs for about a minute and then stalls again. this has happened five times and I am sick of bleeding it. I assume that air is being drawn into the system as there seems to be plenty of fuel to all points in the system. I have dismantled the whole fuel line and filter assembly and have found that the lines have rubber rings/seals on them . they are not O rings. Thing is some of the seals are at the front of the flare and some behind between the nut and the flare. Where should these seals be ? Should the (fuel line ) joint/seal be metal to metal ? Hope you can help , Cheers, Roy.

Welcome to the forums.

You might have better luck getting answers if you post this on the Crawlers, Loaders, Dozers and Backhoes forum. (Or you can use the report button and ask a moderator to move it to that forum.) There are a couple guys that check that forum that don't often appear on this forum. Here is a link to it.

Crawlers, Loaders, Dozers and Backhoes Discussion Forum

I looked for a parts book or service catalog online but haven't found one. Do you have the manuals for your machine? There should be info on those line seals in the parts book and maybe the service manual. Perhaps you could post some pictures of them which might help. My first thought is they should be on the tube in front of the flare, so they compress and seal to the tube. That is just a guess based on your descriptions and no visual reference. If you have had them apart in may be wise to get new ones and replace them.

 

[Dieseltech]

Most Perkins have the line rubber sleeve BETWEEN the line end flare and the line nut. When the nut is drawn tight it squeezes the rubber sleeve for a good seal. On the final filter Perkins uses a constant bleed orifice fitting that must NOT be plugged as it allows air to be removed from the filter base BEFORE it can get into the injection pump where it WILL cause shutdown, and bleeding again. Orifice might be a straight fitting or a banjo bolt, but either type will be hooked into the return line across the injector top. Also, if NAPA/WIX filters are used MAKE SURE there's no extra O ring placed in the filter top OUTER groove just inside the base sealing lip. That groove is the fuel INLET passage on that style filter and must not be blocked.

 

[Fixingfarmer]

Most Perkins have the line rubber sleeve BETWEEN the line end flare and the line nut. When the nut is drawn tight it squeezes the rubber sleeve for a good seal. On the final filter Perkins uses a constant bleed orifice fitting that must NOT be plugged as it allows air to be removed from the filter base BEFORE it can get into the injection pump where it WILL cause shutdown, and bleeding again. Orifice might be a straight fitting or a banjo bolt, but either type will be hooked into the return line across the injector top. Also, if NAPA/WIX filters are used MAKE SURE there's no extra O ring placed in the filter top OUTER groove just inside the base sealing lip. That groove is the fuel INLET passage on that style filter and must not be blocked.

Ahh I understand his question now I missread that he has the square edged round packing. He is correct it is not an o-ring and it should be put into the line nut when installed. Probably have to pull some out with a pick if you are replacing them