mechanical fuel pump / cam lobe

[jimbob-mcgrew]

my car conked out last night. checked the usual things by the side of the road and found I wasn't getting fuel from the pump.

ive never had a mechanical pump just stop on me like that. is it normal for them to suddenly die ?

im worried if its not the pump, the cam lobe has worn out. is there any way of measuring the cam while its still in the carrier box to rule this out ?

cheers for any help :thumb:

[John]

Yep of the diaphragm is goosed it'll just stop. Remove the pump and turn engine over to check lobe.

[Novasport]

Are you getting fuel to the pump? Little 'S' pipes kinked? Any fuel in the tank?

[jimbob-mcgrew]

Yep of the diaphragm is goosed it'll just stop. Remove the pump and turn engine over to check lobe.

ok, will check cheers (any idea what the tolerances are on it ?) ill use a length of pipe or something to see how far in and out it moves on rotation


Are you getting fuel to the pump? Little 'S' pipes kinked? Any fuel in the tank?
yeah fuels coming thru, as I got a mouthful of the stuff thru the pipe (mmmm... tasty unleaded) the pumps doing nowt unfortunatly.

[mk1nova_rich]

I doubt the issue will be a worn cam lobe...the diaphragm is far more likely. Just replace the pump, they are cheap enough :) I'm gathering its not been replaced recently anyway so a tenner well spent either way

[mowgli]

just remember to keep the plastic spacer, cos they don't get supplied with them.....

[L14MNP]

Remove the pump and check if the diaphragm is OK. Operate the pump by hand to see how.it reacts.
There should be a noticeable resistance.

My money is on a ****ed pump. Nothing more serious.

[jimbob-mcgrew]

I knocked up a make shift measuring device to check the cam lobe, and turned the engine over via the crank bolt.

give or take, I measured 8mm's push from the cam, does that sound about right ?

[meritlover]

ye thats about right. its not a device where the stroke is highly critical. the pump arm is sacraficial and will wear before the cam. as long as it's turning the pump should work. get a new pump.

[jimbob-mcgrew]

forgot to update this : the internals of the pump turned out to be fine, but the larger of the 2 pump pipe's (the fuel in side) had split its seal from the pump.

when I tried to remove the fuel hose, the pipe end (very easily) snapped out of the pump head... no wonder it suddenly went kaput, it must have been sucking mostly air in.

fitted a new pump, and bled the fuel thru (another mouthful of petrol... mmmm).
I didn't want to kill the battery any further with lots of cranking, so I poured fuel into the float chamber, and then turned the throttle linkage several times to get several squirts out the jets and she fired up with a few turns.

she made a 300 mile trip to Newcastle the following day after fitting, and back a few days later, so she's good again :thumb:

[mowgli]

sorry to upset your mouthwashing habits, but you can prime the pump by connecting the pipes to it before you bolt it onto the head, and then pump it by hand...

[jimbob-mcgrew]

doh !

ill remember that in future lol