78' 280Z stumbles under throttle application

[FastWoman]

Hi Kelly,

As I recall, black is gnd and blue/green (?) is hot on my '78. You should double-check the + and - markings on the fuel pump to be certain you've got the polarity straight. We're all prone to mistakes.

To see if your pump is pumping, do as Zed suggested. Just connect a length of fuel line to a convenient point (e.g. main fuel filter outlet), and drop the other end into a gas can. Crank the pump, and see whether fuel comes out.

FAIW, I think I filled my new fuel pump with gasoline before installing it. Your new pump might not be getting gasoline and might just be whirring the air around.

Oh, and it's perfectly safe to hold the key in the start position (with the starter wire removed) as long as you wish. Nothing will burn up.

Edited July 7, 2013 by FastWoman

[Virto]

ZH - I agree. I actually called the local AZ about a loaner, but they did not have one in-stock. I'll need to break down and just buy my own, since it's so useful.

I filled the tank and made no progress otherwise. I have a feeling that fuel isn't even reaching the pump - but I have to wait until I get my second pair of hands back to help me get it back in the air and get under it. Looking at the little in-line filter should provide some insight - if it's full of gas, then there should be gas reaching the pump. If it's dry, then I'll know why it's not pumping.

I'll double-check the wiring as well, once it's in the air. Wouldn't be the first time I was certain of something that I turned out to be wrong about.

When you primed your pump, did you just pour some gas into the inlet? Once I know the pump has fuel reaching it, I'll worry about testing flow.

[FastWoman]

Yes, I just poured gas into the inlet until it was full and then kept it "upright" until I could get the hoses on it.

[siteunseen]

Make sure the arrow on the clear filter coming out of your tank points towards the fuel pump. Silly I know but I bought a 240z and the plastic fuel filter in the engine compartment was backwards, car ran good until it got down to half of a tank then it started acting weak like it was running out of gas. I caught that and it hasn't done it since but I try and keep at least half full anyway; do not need any damn rust!

Looks like the top or larger cap goes towards the pump.

Edited July 8, 2013 by siteunseen

[Virto]

I've considered that as well, . Since I mounted it up where the fuel hose passes through the frame, I can't see it without jacking the car up. I don't trust my floor jack too much, so I make it a two-person job.

Again, it's one of those "I'm sure I did that" things that you keep thinking about until you can't remember one way or the other.

Worst case, since this is a POS autobest/airtex/delphi generic pump, it's an out of box junker - I may try wiring the stock pump up to 12V with a hose in a gas can to see if it's still whining after I unblocked the inlet.

[Zed Head]

Did you do anything else while you were working on the pump and fuel lines?

Maybe you're subconsciously avoiding the smell of gasoline, but with a rag and a screwdriver you can determine if you're generating fuel pressure or not. Wrap (edit - not Rap) the rag around the hose end that feeds the fuel rail, after the fuel filter, and loosen the clamp. If you have pressure you'll get some fuel leaking out. If you have pressure you won't have to do all of the lifting and looking. If you don't have pressure you can pop the line off and stick it in a container and run the pump to try and prime it. Could save you a lot of of time, you can do it all standing up and leaning over the engine bay.

You might find that you have pressure and something is stopping your injectors from spraying or that you've lost spark.

Edited July 8, 2013 by Zed Head

[madkaw]

A lot of this guessing would be eliminated with a fuel pressure gauge.

Did you ever pull the sending unit to look at it?

[Virto]

I changed the front fuel filter at the same time we did the pump. So really, if I pull the line off the rail it should be empty, provided no fuel is flowing, as I suspect. Easy test, though - worth doing.

I agree, a fuel pressure gauge would be helpful. I tried to rent one this weekend but it was already out on loan. I'm going to just have to buy my own and keep it on-hand.

I wonder if I can find my little inspection mirror...I could tell easily if there's any fuel in the pump inlet line if I could get a view of the clear filter I installed.

The fuel sending unit? I haven't pulled it for any reason before.

[Zed Head]

Just trying to simplify.

I think also, that if you get your lines switched at the fuel rail the pump will be pushing against the outlet of the FPR. This will give maximum pressure in the lines up to the pump, but no fuel in the rail. Another possibility. Be careful with loosening the lines since the aftermarket pump can generate 90 psi.

[madkaw]

The unit that sits at the top of the tank that has the wires for your fuel level and also the return and outlet lines that go into your tank.

[Virto]

No, no, I appreciate it, honestly. I hope it doesn't sound like I don't.

I didn't pull the lines off of the FPR, but I'll double check the lines to the front filter - maybe I've got one kinked or twisted.

[Zed Head]

It would be the lines to the fuel rail, by the filter. One of them comes from outlet of the FPR and the other feeds directly in to the rail. The line from the filter should feed directly to the rail.

If you didn't pull both lines from the fuel rail then that wouldn't be the problem.

Fun, fun, fun. And you were going to sell the car.