Series 3 Had fuel pump off and now won't pull fuel through...

Hi everyone. In the process of trying to find out how fuel was getting into my oil sump (mentioned in another thread) I've had the fuel pump (petrol) off and replaced the diaphragm, but now I've got it fitted again it doesn't seem to be pulling any fuel through, either by hand priming or turning the engine. The glass bowl stays very much empty and there's not any sound of liquid moving etc. The tank is probably quite empty but I put a jerry can's worth in so there's a little in there. Is it likely to just be an air lock problem? And if so does anyone know of any tricks for sorting it? Cheers, Pete.

When You removed the pump, did you line up the actuating lever with the cam properly, it has been known for peeps to put them back on wrong.

Col

Oh right I hadn't thought of that... Must admit I just assumed it would all fall into position when the pump was refitted. Would that affect the hand primer too though? When I was pumping the lever it sounded like the diaphragm was working as it should.

Loosen the union out of the pump, put a short peice of garden hose in the filler cap, stuff rags around it and then blow as hard and long as you can.

Harrris303 said:

Oh right I hadn't thought of that... Must admit I just assumed it would all fall into position when the pump was refitted. Would that affect the hand primer too though? When I was pumping the lever it sounded like the diaphragm was working as it should.

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I think the hand lever should work regardless but if the fuel Iine is empty it takes ages. I must be getting weaker with old age cos my hand gives up before I can pump fuel through. Are you sure the diaphragm is located ok, when I did mine it was a right pain to get it in, it was if the new diaphragm was a couple of mill bigger than the old one.

Col

Hand lever only works if the lever internally is not on the highest point of cam shaft.
Try turning the engine a little either by putting in gear and rocking landrover forward a little or with cranking handle.
Another problem could be if the fuel union is letting in air.
When you serviced the pump did you just do diaphragm or valves as well.
Was the lever on the diaphragm the same as the one removed as two types available.

Tried to post this morning, but looks like I forgot to click 'Post'!

I had a very similar problem. Unfortunately, I can't tell you exactly what I did to solve it.

I ended up taking the pick-up out of the tank, looking for air leaks, etc. I didn't find any, but when it went back to together again, it just worked. Very odd.

The only hints I can really offer are to be absolutely sure you have enough fuel in the tank, and try manually priming it at a fast rate. You could also try turning the engine over a bit, and then manually priming it again. The cam lobe that drives the pump may stop in either high or low position, and if it's high, you won't get as much effectiveness as you can from manual priming.

Good luck.

Thanks for the input everyone. Gives me a few things to look into at least. I did just change the diaphragm as I was being lazy and couldn't work out how to do the valves! But I sort of just assumed they'd still be working fine.... I definitely got the diaphragm with the correct fitting (on the 2nd attempt!) and got it fitted so it was properly located and locked in place, although it was a real fiddle to get it in position compared to the original one. I got an aftermarket one and as Col said it was just slightly different.

There was enough charge on the battery to turn the engine over briefly which didn't bring any fuel through, although maybe it just takes quite a while for it to work its way up to the pump.

I think today I'll just get it off again and check the diaphragm is still locked in, maybe turn the engine to a different position and try refitting, and stick another can of fuel in the tank! Then just pray it randomly starts to work as TheMegaMan said. Cheers guys. Fingers crossed!

Interesting about the position of the cam changing the effectiveness of the hand primer too... I'll definitely bear that in mind.

Harrris303 said:

Interesting about the position of the cam changing the effectiveness of the hand primer too... I'll definitely bear that in mind.

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I *think* there is enough movement on the manual lever that it'll move the diaphragm even if the follower stops on the peak of the cam lobe, but you definitely won't get a full stroke.

You should be able to put a finger over the inlet and outlet ports to check the pump is working, before fitting it. I checked the valves using a short piece of hose over the valves when the top of the pump was off, and checked I could/couldn't suck/blow through each as expected. And you can also feel for a slight vacuum from the pump inlet after installing it, but before connecting up the inlet pipe.

I think @rob1miles suggestion to pressurise the tank slightly, is a good one. If you can somehow get fuel into the pipe to the pump, then the pump will have a far easier job getting pulling the fuel through with less 'spongy' air in there.

TheMegaMan said:

I *think* there is enough movement on the manual lever that it'll move the diaphragm even if the follower stops on the peak of the cam lobe, but you definitely won't get a full stroke.

You should be able to put a finger over the inlet and outlet ports to check the pump is working, before fitting it. I checked the valves using a short piece of hose over the valves when the top of the pump was off, and checked I could/couldn't suck/blow through each as expected. And you can also feel for a slight vacuum from the pump inlet after installing it, but before connecting up the inlet pipe.

I think @rob1miles suggestion to pressurise the tank slightly, is a good one. If you can somehow get fuel into the pipe to the pump, then the pump will have a far easier job getting pulling the fuel through with less 'spongy' air in there.

Click to expand...

if its on the cam the diaphragm is at full stretch you wont get any further with the priming lever

All sorted! Thanks for the input everybody. I took the pump off again and made sure the diaphragm was positioned properly, and turned the engine on the handle to change the cam position before refitting it. Also what I found really useful was to refit the bottom half of the pump before reassembling it, so then was able to see the movement in the diaphragm and turn the cam position until the hand primer was getting optimum action. This still didn't quite do it so in the end I got underneath and sucked on the inlet pipe and got a tasty mouthful of petrol, but quickly got it back on and Bob's your uncle. Quickly filled up the bowl with fuel so and it was a welcome sight! Thanks again. Landyzone saves the day once more!