jchristians Posted April 14, 2011 Report Share Posted April 14, 2011 I'll be installing a new fuel pump in a couple of days on my '71 521...any tips?? I know it is mechanical...have no idea how these babies work. thanks! Quote Link to comment
izzo Posted April 14, 2011 Report Share Posted April 14, 2011 lol.. undo the 2 gas lines, unbolt it. Put a new gasket on the new pump, shove it back on, bolt it down, install the 2 gas lines, done. About a 10 minute job if you take your time :lol: Quote Link to comment
Eagle_Adam Posted April 14, 2011 Report Share Posted April 14, 2011 you gotta love the simplicity of a datsun!!!!!! :D Quote Link to comment
jchristians Posted April 14, 2011 Author Report Share Posted April 14, 2011 wow, I was hoping that was the process! thx! Quote Link to comment
68Datsun510 Posted April 14, 2011 Report Share Posted April 14, 2011 Dont forget the spacer that goes between the head and the pump! Should go in this order. Left to right looking under the hood. Pump->Gasket->spacer->gasket-> head. dont overtighten, just snug it down Quote Link to comment
jchristians Posted April 16, 2011 Author Report Share Posted April 16, 2011 How does the "arm" set against the lobe? That pushes the arm? My new pump is not pumping fuel. No blockage in line. Fuel in the tank. Anyone ever have a worn lobe that pushes on the arm?...I am not familiar w/ what it looks like inside there and am tempted to pull the valve cvr and see how this arm is supposed to seat. Help! Quote Link to comment
jchristians Posted April 16, 2011 Author Report Share Posted April 16, 2011 Pulled the valve cvr...so, now I know how this guy works...seems like it doesn't push out the pumps arm far enough for an adequate pump...is it a BAD idea to remove that spacer between the gaskets to pull it closer to the "lobe"?? Quote Link to comment
nismo dr Posted April 16, 2011 Report Share Posted April 16, 2011 is it a BAD idea to remove that spacer between the gaskets to pull it closer to the "lobe"?? yes, very bad idea, it will damage things. can you take any oics of the problem area? the eccentric is on right? Quote Link to comment
jchristians Posted April 16, 2011 Author Report Share Posted April 16, 2011 Sorry, what do you mean by eccentric? Thanks much for the reply. Will try and get some pics. Quote Link to comment
Roger Posted April 16, 2011 Report Share Posted April 16, 2011 Sometimes the lever part will go right in and sometimes it wont. The fuel pump operates off a cam lobe and when the lobe is sticking up the lever wont go in. Rotate the engine about 45 degrees and it will go in. If you can do a water pump you can do a fuel pump. 1 Quote Link to comment
jchristians Posted April 16, 2011 Author Report Share Posted April 16, 2011 Yeah, it goes in...and I see how it works and everything. Just doesn't seem like the lobe is thick enough or large enough to push the pumps arm enough to pump. Hard to explain! Quote Link to comment
banzai510(hainz) Posted April 16, 2011 Report Share Posted April 16, 2011 why you changing the fuel pump? Its bad? and the new one dont pump either? then I would look else where. also another thing once the carb is full the pump arm does go limp. But if it were me doing this I would leave the intake hose hooked up and see if gas come out the output hose. If yes then the pump is good. or put your finger over the intake and pump the arm and you sould feel suction. The ecentric is at the end of the sprocket. its a round OBLONG round thing that pushes the arm. do not ever run w/o a spacer Koyosan are the stock pumps or nikkei Quote Link to comment
wayno Posted April 16, 2011 Report Share Posted April 16, 2011 As long as the arm is touching the lobe all the time it should work, there should be a little resistance when you push the fuel pump all the way down to the spacer. If the arm doesn't touch the lobe, then you more than likely have the wrong fuel pump, or it is not being installed correctly. Quote Link to comment
jchristians Posted April 16, 2011 Author Report Share Posted April 16, 2011 One thought...do mech. Pumps work as a siphon? So, needs fuel in the filter and all the way up to pump? If so, what is the trick to getting this fuel in place??..does that make sense?? Lol. Thanks much all you Ratsun dude men! Quote Link to comment
DanielC Posted April 17, 2011 Report Share Posted April 17, 2011 The pump should not need to be primed. Eccentric means something round, but off center. It can be hard to see it if the engine is not running. The pump has a chamber with a rubber diaphragm on one side of the chamber. There is a check valve on the input side, that only lets gas go into the pump. There is a check valve on the output side that only lets gas go out of the pump. The eccentric pulls the diaphragm, and this sucks gas into the pump. There is a spring that pushes the fuel out of the pump, when the eccentric turns half way. You should be able to take a short piece of hose, hook it up to input side of the fuel pump, and put the end of the hose into a gas can, and it should suck gas just by moving the lever with your hand. Quote Link to comment
Datto521 Posted December 4, 2022 Report Share Posted December 4, 2022 Hi all, first time inquirer. Does the arm that makes contact with the eccentric on the cam need to be greased at all? I installed the pump, gaskets spacer and all without using any sealer, permatex etc for a dry run. The pump works and the engine runs but I couldn't help but notice a small rattling noise, typical for metal on metal. I had an electric fuel pump before this install so maybe I am just not used to the new sound. Quote Link to comment
datzenmike Posted December 4, 2022 Report Share Posted December 4, 2022 1 hour ago, Datto521 said: Hi all, first time inquirer. Does the arm that makes contact with the eccentric on the cam need to be greased at all? I installed the pump, gaskets spacer and all without using any sealer, permatex etc for a dry run. The pump works and the engine runs but I couldn't help but notice a small rattling noise, typical for metal on metal. I had an electric fuel pump before this install so maybe I am just not used to the new sound. They should be installed without sealer with dry gaskets. You could put a dab of grease on just to start but once started it's well oiled by spray from the timing chain. Is this an Hitachi stock fuel pump? for L series. I don't know what after market generic pumps sound like. The pump arm rides on the pump side of the eccentric not under it. Quote Link to comment
Stoffregen Motorsports Posted December 4, 2022 Report Share Posted December 4, 2022 Do you have the spacer between the pump and cylinder head? This is important. Quote Link to comment
datzenmike Posted December 4, 2022 Report Share Posted December 4, 2022 16 hours ago, Datto521 said: Hi all, first time inquirer. Does the arm that makes contact with the eccentric on the cam need to be greased at all? I installed the pump, gaskets spacer and all without using any sealer, permatex etc for a dry run. The pump works and the engine runs but I couldn't help but notice a small rattling noise, typical for metal on metal. I had an electric fuel pump before this install so maybe I am just not used to the new sound. 1 Quote Link to comment
Datto521 Posted December 4, 2022 Report Share Posted December 4, 2022 Yup! Using the Carter mechanical fuel pump. https://www.rockauto.com/en/moreinfo.php?pk=296166&cc=1212321&pt=6256&jsn=1848 Does the job, just not used to the new sound. Thanks! Quote Link to comment
Datto521 Posted December 4, 2022 Report Share Posted December 4, 2022 Ah, If you're doing this I recommend taking the head cover off and making sure the rocker arm is properly engaged. It looks like the Carter pump has a tendency to skate over and scrape against the timing sprocket. I am going to bend the rocker arm slightly on this to avoid further scraping. Quote Link to comment
banzai510(hainz) Posted December 5, 2022 Report Share Posted December 5, 2022 (edited) I hope yu keep the orginal spacer in between had and the fuel pump. should just ride on the round offset lobe in the center. Cam eccentric or what ever they call it I have 2 of these Carter mechanical I assume its the stock clone looking pumps. I never heard ofscaping against the timing spocket but these are CHINESE made clones. I have heard issues of the arms falling abart at the pivit joint/spring falling out. Also sold under the Spectre Band also I think Edited December 5, 2022 by banzai510(hainz) Quote Link to comment
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