Fuel Pump 101

[bossbob]

So, I had the engine running great in the driveway, no stumbling, revving up great, thought I had all 96 hp. Took it around the block and it crapped out on me. I just replaced the fuel pump, but my filter is empty, so under load the pump is failing. At least to the best of my knowledge, I also see air bubbles going through the glass filter. So???

Pump on the top right is the original pump, can't see spending $200+ on a the correct fuel pump, so I replaced it with the pump on the top left which is a Autozone A1173MP supposed to be a cheap replacement for it, although the arm is a lot longer, I have a replacement arm that Lorna gave me. The original pump has a 2 piece arm, the one Lorna gave me is a 1 piece arm which is still a little longer than the original, but is arches like the original and not nearly as long as what is in the picture. I also have an electric pump that I haven't done anything with.

I was thinking should I install the electric pump on the inner fender between the glass filter and the battery and by pass the mechanical pump, leave the mech. pump there, maybe remove the arm so I have a block off on the block.

Any thoughts on this, you know when you think your there, and your not, so a little discouraged, but wanting to move forward.

What suggestions do you have?

Fuel Pumps.jpg

[Linda]

If you have the glass filter those are notorious for having the gasket dry out and suck air....then poor running. When I had a 67 that happened to me and a trick was to dip the cork gasket into the gas in the bowl to plump it up then reinstall it. Worked several times. Otherwise get rid of that fuel filter and get a new plastic one, even if just to check if that is the problem. I use the cheap small VW filters and toss them frequently.
I would be worried about any fuel pump arm that is not correct. It rests on the cam and you don’t want to screw that up somehow.
Also that pump may not have the correct pressure, likely too much, which is not good for the carbs.
You can rebuild your stock pump. I think Sin City Datsun has a rebuild kit.
Otherwise be sure all connections are tight ...fuel filter hoses, pump hoses, carb hoses, carb fuel bowl screws.
Then be sure there is not a blockage in the gas tank. Blow some air back to tank to dislodge any blockage, listen for bubbling.
Good luck, don’t get too discouraged, you have some new things to check.
Linda

[Curtis]

I had trouble with the glass bowl filter. Took the bowl off and put a piece of 600 grit wet dry sandpaper on a piece of glass. Ran the sealing edge of the bowl around on the sandpiper until it was smooth. Put it back on with a new gasket and no more air leak.

[Nissanman]

The alloy tops of the glass filter have a nasty habit of warping over time if the clamp is done up too tight.
Make sure the sealing surface is quite flat against the cork gasket and follow the advice Linda gave.
I used the rebuild kit specified for the P510 car [L series engine] and it fit perfectly

[C.Costine]

Air bubbles would tell me that the pump is sucking air from a loose fitting so most likely the pump and glass bowl are innocent. They are simply hanging out in the open available to shoulder the blame. I would be looking up stream at the tank connection and at the mid point connection. First try just loosening then retightening. At the coupling you can take it apart and put a tiny bit of grease on the sealing surfaces. This can help it to slip by a resistive point that keeps it from actually tightening.

[theunz]

A couple of things to consider if you decide to use the electric pump. First, most electric pumps are much better at pushing then pulling, thus the pump needs to be located close to the fuel tank. Second, if you don’t install some kind of inertia cut off switch then if say, you are in an accident and a fuel line gets cut gas will continue to escape. If you are not able to turn off the ignition than you could have quite a bonfire. Maybe tape a bag of marshmallows to your steering wheel which could double as an air bag and a source of entertainment while watching your car roast

[redroadster]

A couple of things to consider if you decide to use the electric pump. First, most electric pumps are much better at pushing then pulling, thus the pump needs to be located close to the fuel tank. Second, if you don’t install some kind of inertia cut off switch then if say, you are in an accident and a fuel line gets cut gas will continue to escape. If you are not able to turn off the ignition than you could have quite a bonfire. Maybe tape a bag of marshmallows to your steering wheel which could double as an air bag and a source of entertainment while watching your car roast

Yes the fuel pump relay alternator tie in....a little bit of knowledge can be dangerous

[bossbob]

Thanks all, it wasn't sucking any air before replacing the fuel pump, I have already been through the fuel lines and feel confident they are clean and leak free. I did remove the glass bowl to dump some crud out of it, so I'll check the seal there. I guess I'll also look into the correct fuel pump or repair kit for it, maybe install the electric pump as temporary test to see how it does under load.

Thanks again everyone.

[Linda]

We keep you busy, don’t we, Bob? LOL
Sin City Datsun:

http://sincitydatsuns.com/store/p54/OEM ... uded..html

Linda

[zippy67roadster]

We keep you busy, don’t we, Bob? LOL
Sin City Datsun:

http://sincitydatsuns.com/store/p54/OEM ... uded..html

Linda

Thanks Linda!!

[bossbob]

Well hit my head with a hammer......

Thanks again for all the input. I installed the electric pump to test things out, with no change. I was standing at the back of the car looking at the gas tank, and thought what the hell. So as I was tapping around the tank it sure sounded empty, even though the fuel gauge showed 1/8+.

A quick trip to the gas station and add 5 gallons, and it is no longer sucking air, only fuel. Still need a little fine tuning on the carbs, and hook the mechanical pump back up and get rid of the electric pump.

Here it is, it's the best it's ran since I've owned the car. Test drive is next.

[Linda]

Bob!!
OK, I’ve made that mistake too. LOL
Gotta cap off those smog plugs..... plumbing caps as a temp fix.
Or Dean sells some inserts so you can rid of them

Linda

[bossbob]

Test drive went great, clutch is releasing quite high on the pedal, brakes feel great, got some thumbs up on this short drive.

Now I have to burp the cooling system again, typical hot upper hose, cold lower hose, temps at the top of the gauge.