changed fuel filter, no start

[h4nsm0l3m4n]

Hello, I have a 1975 260z. It drives fine around town but on the freeway once I get to about 55 the rpms start slowly dropping until eventually I have to pull over. I turn off the car, turn it back on and it runs ok again. My first guess was that it was a bad fuel filter so, feeling confident, I went out and bought a new one and changed it out. The car started right up at first but eventually it sucked up all the fuel in the lines but no new fuel is coming from the tank. I know I installed the filter the correct way, so that cant be it.

Is this due to air being in the fuel lines? Or did I break the fuel pump? Maybe both? Any help would be great.

[zbane]

My guess would be crud in the lines. Have you taken a peek inside your gas tank? I wouldn't be surprised if there is all sorts of stuff in there...

Before you go and spend more money, check the tank.

[beandip]

First off , if the car is a 260 it is a '74, that is in the U S A , '75s are injected. Is this an injected engine or carburated? There should be a fuel filter back by the gas tank . Change it also. If this doesnt help have the fuel pump checked for flow and pressure , especially if it is a injected engine. Gary

[h4nsm0l3m4n]

It is the carburated model, and actually it was the back fuel filter I changed, sorry if I was unclear. As far as the year I couldnt say exactly, but the serial number is that of a '75 260z if this website is correct:http://www.300zx.cl/ga/300zx/images/serial%20number%20Datsun%20Z%20Car.htm

Is it possible that I damaged the fuel pump by forcing it to suck on air for a while?

Thanks for the help

[sblake01]

It is the carburated model, and actually it was the back fuel filter I changed, sorry if I was unclear. As far as the year I couldnt say exactly, but the serial number is that of a '75 260z if this website is correct:http://www.300zx.cl/ga/300zx/images/serial%20number%20Datsun%20Z%20Car.htm

Is it possible that I damaged the fuel pump by forcing it to suck on air for a while?

Thanks for the help

Allow me to help rid you of that misconception. That website is WRONG! It's not only wrong about the 260Z but also in other areas. All USA 260Zs are 1974 year model. Some inadvertantly have been registered as 75s because of the late build date. That would have made it tough to pass the smog check since the computer would try to test it with lower limits as if it had fuel injection. Nissan was late in the development of the 280Z so they built the late 74 260Z with the 280Z body minus the fuel injection and attending electronics that go with it. But they are all 74s. And your problem does sound like your pump is trying to pull fuel through clogged line or a clogged tank.

[sleepyzzz]

are you running the original pump? it might need cleaning out also. i didn't trust my old pump after sitting for twenty plus years, and changed out the original for a Holley from MSA. it is noisey, but has never given me any problems. i only hear it when sitting still.

[h4nsm0l3m4n]

Allow me to help rid you of that misconception. That website is WRONG! It's not only wrong about the 260Z but also in other areas. All USA 260Zs are 1974 year model. Some inadvertantly have been registered as 75s because of the late build date. That would have made it tough to pass the smog check since the computer would try to test it with lower limits as if it had fuel injection. Nissan was late in the development of the 280Z so they built the late 74 260Z with the 280Z body minus the fuel injection and attending electronics that go with it. But they are all 74s. And your problem does sound like your pump is trying to pull fuel through clogged line or a clogged tank.

Well that will sure make smog a breeze, 1975 is the first year they require smog checks in oregon, if I can get it running again. IS there is a way I can reregister it as a 1974 I wont need to take the test?

are you running the original pump? it might need cleaning out also. i didn't trust my old pump after sitting for twenty plus years, and changed out the original for a Holley from MSA. it is noisey, but has never given me any problems. i only hear it when sitting still.

The car has the original pump, both electric and mechanical, from when I bought the car (recently). Theyre probably due for replacement but the car was working ok at low speeds before.

I am hesitant to think something clogged the lines, at least in any major way, since the car would, at least, start up before. It was only after I changed the rear filter it actually stopped starting up, which leads me to believe I broke one of the pumps. Is there any easy way to quickly test both pumps to see if they are running? If the pumps work then that will at least let me know there is something in the lines I need to clear out, right?

[sblake01]

Well that will sure make smog a breeze, 1975 is the first year they require smog checks in oregon, if I can get it running again. IS there is a way I can reregister it as a 1974 I wont need to take the test?

So it's currently registered as a 75? I don't know how Oregon works (even though I was born there) but in California it would be difficult but do-able . We start with a 'Statement of Facts' form and go from there.

[kenz240z]

You mention that you changed the back fuel filter. Are you refering to the filter that is located inside the electric fuel pump mounted back by the fuel tank? If so, was it caked with silt-like crud? If you didn't replace the fuel filter in the engine bay it is probably clogged up with the silt, too. I had this happen on my '73, which performed similar to what you describe. Once BOTH filters were replaced it ran great!

Had your Z been sitting for an extended period of time without being driven? Anyway, I'd recommend checking the inside of the fuel tank for rust & sediment. Replace both fuel filters (the one in the electric pump & the one in the engine bay)...since you already replaced one of the fuel filters now replace the other so they are both new. Replace all flexible fuel lines at the tank & electric fuel pump, at the mechanical pump and at the carbies & fuel rail.

[beandip]

Your pump mounted on the engine runs as long as the engine is turning over. It might not pump gas but it must turnover because it is mechanically attached to the engine . The Electric pump. The year model you have can be set up in different ways . One the pump runs at start up , or it runs any time the key is in the start of on position when the engine is running. My '73 the pump runs at start and in the run position until I turn the key to Acc or off . How close to Cedar Mill do you live. Gary

[h4nsm0l3m4n]

i finally got it started again, the line was clogged with a piece of the dowel i used to plug it when changed the filter (im not too bright) that had broken off somehow. After I cleared it out it still wouldnt start. I had to pour some fuel into the fuel line right before the mechanical fuel pump to get the car to start for long enough so the electric pump to kick in (since it only works when the engine is running correct?) and send some fuel from the tank. After that the car idles fine.

You mention that you changed the back fuel filter. Are you refering to the filter that is located inside the electric fuel pump mounted back by the fuel tank? If so, was it caked with silt-like crud? If you didn't replace the fuel filter in the engine bay it is probably clogged up with the silt, too. I had this happen on my '73, which performed similar to what you describe. Once BOTH filters were replaced it ran great!

Had your Z been sitting for an extended period of time without being driven? Anyway, I'd recommend checking the inside of the fuel tank for rust & sediment. Replace both fuel filters (the one in the electric pump & the one in the engine bay)...since you already replaced one of the fuel filters now replace the other so they are both new. Replace all flexible fuel lines at the tank & electric fuel pump, at the mechanical pump and at the carbies & fuel rail.

This is kind of an odd thing about this car. It actually didnt have a front fuel filter, it just had the one in the back. I havent worked on the car much but I do plan on replacing the rubber fuel lines, and putting in a front fuel filter. I bought the car from a dealer which sold old cars, the guy there told me the car was given to him but had been in storage for a while and he had gotten it into semi-running condition. As a result the tank probably does have some rust and sediment in it. I'll check the tank as soon as I can.

So it's currently registered as a 75? I don't know how Oregon works (even though I was born there) but in California it would be difficult but do-able . We start with a 'Statement of Facts' form and go from there

Yup, it says 1975 Datsun on the title. I'll check around to see if changing the year on the title is possible.

Your pump mounted on the engine runs as long as the engine is turning over. It might not pump gas but it must turnover because it is mechanically attached to the engine . The Electric pump. The year model you have can be set up in different ways . One the pump runs at start up , or it runs any time the key is in the start of on position when the engine is running. My '73 the pump runs at start and in the run position until I turn the key to Acc or off . How close to Cedar Mill do you live. Gary

I live over by PCC Sylvania, near where I-5, Barbur Blvd, and Capitol Hwy cross.

[sblake01]

Yup, it says 1975 Datsun on the title. I'll check around to see if changing the year on the title is possible.

You might find this scan interesting. It's from the Nissan 'Outline Specifications 1975 Models' publication. Note the catagory your car falls into: