Loss of power

[fingers]

Hi All

I'm new to this site and my knowledge of JCB's is limited so go easy on me !

I have a 3CX sitemaster 1984 which ticks over OK but when I put a load on the engine it die's down to idle even with my foot flat on the floor. I suspect it fuel starvation related but I have fuel coming out of all the right places, I've change both air and fuel filters but still no joy,

I see on older threads with similar issues that people have had problems with lift pumps and air locks

Can anyone give me some things to try

Thanks

[agrimax]

Try running with the tank lid loosened? Or have you checked the gauze/filter in the end of the injector pump, and the lift pump filter?

[Jeremy Rowland]

Try running it off a straight through feed in other words get yourself a small container with some diesel in it and put a pipe from the filter to this drum. If the engine runs fine then you either have no ventilation to the derv tank or something in the tank thats stuck to the fuel pick up in the tank.
It could also still be the lift pump itself but thats the way in which I would proceed faced with your problem.
Hope that helps you.

Jeremy

[martyn williams]

Looks like fuel starvation,re bleed fuel system,check flow from tank.You have changed the filters so may be lift pump defective.Or the fuel injection pump may need a service.As poited out make sure that the filler cap is not causing a fuel flow problem by not venting, check tightnes of feed pipe connections.Is the fuel tap partly blocked or not fully turned on ? Some taps have an internal strainer. This was a common fault on the MF 50 B's
Some times after a filter change its best to fill the tank to at least two thirds full as the lift pump may be weak so not delivering enough fuel when above idle therefore loss of power.
Martyn

[fingers]

Thanks all for the info,

So far it's not the fuel cap as taking this off made no difference, I removed the top of the lift pump and the filter was completely blocked and after cleaning it was better for a few minutes then went back to no power, I took the hose off to the filter and put it in some direct fuel but this seemed to reduce the tick over speed as if air was present, tried to bleed the system with the pipe in the bottle but without success.

I think i'm going to drain the tank at the weekend and remove the round plate just above the pipe outlet which seems reasonably accessible and see what the state of the tank is, I will also remove the lift pump and clean as well, I'll look at the injection pump but I don't know much about them.

thanks

Fingers

[FOWLER MAN]

Hi Fingers,
It's always a good idea to clean out the tank.
The injector pump inlet filter is easy enough to clean. Follow the pipe from the filter and you will see the pipe connected to the pump. It's screwed into a large nut on the end of the pump, I think it's a 15/16 A.F.(24 mm.) spanner size.
Carefully clean around the nut and connection and remove the feed pipe, then undo the big nut.
There is a spring and plunger behind the nut, be carefull not to drop them and note the way the plunger is fitted for reassembly. There is a small nylon filter in there about the size of your small finger tip which can be gently hooked out, remove it and blow it out.
Be sure to keep it all clean,reassemble it and bleed the pump.
Good luck.
Fred
P.S.
There is one other thing you might check. If the triger arm on the back of the lift pump is worn or damaged the pump may not be getting a full stroke, I have known that cause fuel starvation in the past. If the lift pump is weak a full tank may help??

[fingers]

Hi all,

Thanks for all your help, cleaned everything and it's working fine now, turned out to be a blocked up filter in the injector pump. couldn't have done it with out you as i didn't know it existed.

I managed to replace the seals on the boom ram as well as a couple of others last week and none of them leak so I'm chuffed to bits with my new toy and it all ready to go!

[FOWLER MAN]

Hi Fingers,
Glad to help.
Don't worry lots of fitters miss that filter too. It often only gets serviced at pump overhaul time.
As you know now, it can cause power loss without actualy causing an airlock.
Fred

[Johnno]

'afternoon chaps, well, I had her running to dig a gatepost hole over the weekend, still got that low power and smokey running as soon as it gets warm, but keeps running and working if not under too much load. Misses more whn you try to increase the engine speed, or stops if you return it to tickover, but runs somewhere inbetween, allbeit smokily.

The more I look at the injector pump, it almost seems as if the main feed and the return are on the wrong way around on the connections to the pump. The pump is on the left of the 4/98 Leyland Engine (as viewed from the driving seat) the distributor part is on the rear (transmisssion end) of the engine. The inlet pipe is connected at the front if the pump, nearest the drive, fan etc, with the return on the rear nearest the distributor/ transmission end *is this the right way?* Would the engine even run if they were the wrong way around?

Thanks in advance for your input lads.

[Johnno]

PS, how do you thank someone on this, the statistics thing I mean?