mechanical fuel pump reinstall 72Z

[siteunseen]

Here's a good read, couldn't find a photo of the actual cam washer it rides on. Yes you can take the valve cover off and see it riding on the lopsided eccentric I think it's called on the nose of the cam.

 

[swflaz]

Thanks for the "good reads". several very helpful comments. one of which was making sure that the fuel pump arm is riding on the offset cam lobe and not below it. one of my concerns was  whether i had just incorrectly installed it in the block. i'll probably still remove the valve cover just to learn more. Thanks to all. i'll report back when i fix it.

[dutchzcarguy]

If you remove the valve cover and set the cam lobe in the far off position you can simply "pump"the pump by hand and see if it pumps fuel..

(I got a original new in box pump from nissan if you need one but it'll cost yeh 250 euro.. excl transport/shipping.) 

[swflaz]

Thanks, i'll try that when i get the valve cover off. Probably this morning. Don't need the new pump but thanks for the offer. 

[swflaz]

A god news, bad news day. i removed the valve cover without destroying the gasket.  Was able to see exactly how the fuel pump arm is supposed to sit on (and not under like i may have had it) the cam off the end of the camshaft. also checked the direction the pump was pushing. (you can actuate the level and feel a puff of air coming from the carb feed side). that was good so i reinstalled the pump and hoses. then put the input hose in a small bottle of gas and tried to start with no luck. then it ran for about 10 seconds using starter fluid but quit after that. 

SO, i still can't get fuel to the carbs and feel like i'm back to square one. Anyone with new thoughts?

 

[jitenshakun]

Try to get another mech pump and try it. 

[swflaz]

Good idea. i have some aftermarket models in my notes back before i decided to just rebuild mine. they are not that expensive and it should solve the "is the pump the problem?" issue.

thanks for checking back in.

[dutchzcarguy]

9 hours ago, swflaz said:

SO, i still can't get fuel to the carbs and feel like i'm back to square one. Anyone with new thoughts?

It can also be a clogged needle in the float chamber.  you can check that with a piece of hose and blow through them.. ( the chambers have an air outlet and you can hear the air blow when you do it with a compressor!) 

If you can't blow through them with your mouth then use air from the compressor and afterwards you can blow through them with your mouth! Now they are open. (no fuel in the bowls is also a clue.)

Check your pump first with a bottle on both sides and let the pump put in from one to the other.. if the pump does work your carbs are clogged up or have worn needles in the bowls.

[dutchzcarguy]

If it was the needles, clean the carbs with carbcleaner and/or replace the needles..

[swflaz]

Thanks for the ideas. i have noticed that the fuel bowls were empty but just blamed it on the fuel pump, not thinking about clogged needles in the float chambers. i've actually added fuel to the fuel bowls with a syringe and it will run for a minute or two until the bowls are empty again. Bottom line is that i will try all the above recommendations and see how it goes. grateful for everyone's input. What a great site .

[jitenshakun]

Have you ran the pump into a bucket to capture the gas yet? That'll completely answer if it is a pump issue. 

[swflaz]

yes, i have. first pulled off the two fuel hoses that come off the fuel rail into the carbs and was able to blow thru both. So, no clogged needle valves. 

next i removed the fuel pump (didn't do it on the car for several reasons) to do a manual operation check. with a fuel hose on the entry side in a small container of gas  i manually pumped a bunch of times and it was not delivering fuel. so that's the problem. Before i replace the pump i'm taking it apart to see what the problem is. Might have to replace it but it was rebuilt a few months ago. Maybe the diaphragm got compromised some how. More later.