Bosch CAV Pump

[RS1600BDA]

Hi Everyone, I have a IH 684 that has now stopped. Revs kept dropping, then occasionally over fuelled and Rev’ s increased. Rev’s dropped and now won’t start. Fuel from tank is ok. Undone feed line into the pump can’t get fuel to show. No fuel at injector lines.
Could the pump just stop?
Is there any basic tests I could?

Happy to take the pump off, not sure where the timing marks are though.
Any help is really appreciated.
Thank you.

 

[Wisconsonian]

Revs dropping and then increasing sounds like running out of fuel. When were the fuel filters changed last? Take apart the next joint past the tank and see how far the fuel gets. Usually you'll find some trash collected in a fitting, or a collapsed soft rubber hose, or something blocking the fuel somewhere.

Don't touch the injector pump until you're sure the fuel supply is good to the pump.

 

[Ukjay]

Hi Everyone, I have a IH 684 that has now stopped. Revs kept dropping, then occasionally over fuelled and Rev’ s increased. Rev’s dropped and now won’t start. Fuel from tank is ok. Undone feed line into the pump can’t get fuel to show. No fuel at injector lines.
Could the pump just stop?
Is there any basic tests I could?

Happy to take the pump off, not sure where the timing marks are though.
Any help is really appreciated.
Thank you.

Are you sure you have no air lock or blockage in the fuel pipework as you say fuel ok out of the tank, but nothing into the pump?

If this was mine, I would open the feed pipe to the pump, then try and pressurise the fuel tank slightly using an airline to help force fuel through the pipes. You may have had some debris sent down the pipes when you ran empty and bridging the flow.

 

[RS1600BDA]

Are you sure you have no air lock or blockage in the fuel pipework as you say fuel ok out of the tank, but nothing into the pump?

If this was mine, I would open the feed pipe to the pump, then try and pressurise the fuel tank slightly using an airline to help force fuel through the pipes. You may have had some debris sent down the pipes when you ran empty and bridging the flow.

Thanks for the reply, I will take the main feed line in from the filters off and have a look.

 

[RS1600BDA]

Revs dropping and then increasing sounds like running out of fuel. When were the fuel filters changed last? Take apart the next joint past the tank and see how far the fuel gets. Usually you'll find some trash collected in a fitting, or a collapsed soft rubber hose, or something blocking the fuel somewhere.

Don't touch the injector pump until you're sure the fuel supply is good to the pump.

Thanks, Fuel is definitely flowing into the last filter before the feed line out to the pump. I hope this pipe is blocked. It is strange I have no fuel out of the pump at all, which points towards a blockage rather than a weak pump,

 

[Ukjay]

Thanks for the reply, I will take the main feed line in from the filters off and have a look.

When I was reading up on my pump, on the CAV pumps there is reported that on some of them, there was a threaded pressure regulator / gause / plunger in the inlet that gets bunged up, so worth while checking that too, if you have fuel to the inlet of the pump, as that would stop fuel getting in.
Also - check the fuel shut off is not sticking, as some people advised that they can stick and gentle tap with hammer can free off.

 

[Gapples]

Hi Everyone, I have a IH 684 that has now stopped. Revs kept dropping, then occasionally over fuelled and Rev’ s increased. Rev’s dropped and now won’t start. Fuel from tank is ok. Undone feed line into the pump can’t get fuel to show. No fuel at injector lines.
Could the pump just stop?
Is there any basic tests I could?

Happy to take the pump off, not sure where the timing marks are though.
Any help is really appreciated.
Thank you.

684 with fuel tank at the back of the tractor ?
They also did a 684 with a flat deck cab.
Anyway I'll work on it been a 684 with tank at the back, those fuel taps under the tank are well worth cleaning out as they are prone to blocking, from there simply move forward but take out every banjo bolt in the feed line to make sure all are clean !
Remember you need a minimum of 5 gallon diesel in the tank to bleed the system, preferably a full tank.
Once you've got fuel going into the injection pump undo the pipe on the return side, see if you can get a bit fuel coming out of that.
Undo the injector pipes on the pump & turn over the engine until fuel is spitting out on all delivery valves.
Move up to the injectors & do the same, if all is well in the pump & injectors it should start.

From description though it could be a pump fault, if you can't get it started message me & I'll send you details on how to time the pump, it's MUCH easier to time the engine/pump before you take it off rather than faf about trying to do it afterwards.

 

[RS1600BDA]

Great, thank you. Yes it is rear double tank. I will fill them right up. Taps seem to be ok, good flow to filters. Hopefully have some time later today to look further. Fingers crossed it’s not the pump but will definitely not take it off without setting the timing etc.

The good thing is I have taken the opportunity to replace the water pump gasket as it was weeping every so often which means I have good access to everything at the mo.

 

[RS1600BDA]

I took off the main feed pipe to the pump from the filters. It was a little bit flat on the braded part but not pinched or has ever been pinched. I cleaned it up and blew it out as best I could. (No air line) I put it back on filled her up with fuel managed to get fuel at the pump side, bled the pump and bingo she fired up and is running like a kitten.
I will assume the pipe could do with replacing and I will try and get one or have one made. I also think as the pipe is not great and probably restricted, coupled with the fact that the tank was low on fuel it was just not getting enough fuel. I will keep the tank topped up and see how we go.
I can't run her up for too long at the moment as I am waiting for a new water pump gasket.
Fingers crossed and a big relief I did not take the pump off or apart

Thank you for all your help.

 

[Gapples]

I took off the main feed pipe to the pump from the filters. It was a little bit flat on the braded part but not pinched or has ever been pinched. I cleaned it up and blew it out as best I could. (No air line) I put it back on filled her up with fuel managed to get fuel at the pump side, bled the pump and bingo she fired up and is running like a kitten.
I will assume the pipe could do with replacing and I will try and get one or have one made. I also think as the pipe is not great and probably restricted, coupled with the fact that the tank was low on fuel it was just not getting enough fuel. I will keep the tank topped up and see how we go.
I can't run her up for too long at the moment as I am waiting for a new water pump gasket.
Fingers crossed and a big relief I did not take the pump off or apart

Thank you for all your help.

Great to hear you it running, those braided pipes do have a habit of degrading over time & are well worth replacing.