Hello everyone, I changed the gas filter and the car is running better without the no power problem. Thanks 2manyzs. However, my mechanic said that I should get a new fuel pump because the diaphragm is letting in some air. He said that it is an easy job since my car has a mechanical fuel pump. Would this solve the problem with my car all of a sudden idleing too low? Should I get a new fuel pump? Is it easy to install?

There is also another problem with my car. The engine is dieseling. I looked at previous threads and I could not seem to pin point what it could be. My car is definately not idling to high, it just had a tuneup so that cancels out a lot, but I remember something about my intake not being sealed. Does this ring a bell to anyone? I just want everyone to know that I am a newbie to fixing engines. I am willing to learn and if you could be patient with me I would really appreciate it. I don't want to have to go to the mechanic every time my car needs something.

Thanks in advance,

Ben

Mechanical pump is an easy job, couple hose clamps, couple bolts, gasket and that's all there is to it. A leaky pump diaphram could cause quite a few things, including putting air bubbles in the fuel, which could cause erratic idle and even vapor lock type symptoms.

"Dieseling" can be caused by a few things, one of them is a bad vacuum leak. Another of the usual suspects is too fast an idle speed (even as little as 100 RPM's over the "standard" of 750-800)and last but not least, timing that is too far advanced. Of course, excessive carbon buildup in the cylinders or on the piston crowns can do it also.

Those are the usual causes, there are more but usually they are a combination of things.

Thank you Keith. I guess I will get a new fuel pump. Here is one that is on ebay. Does anyone know if this an oem fuel pump? Do you think it is a good fuel pump? Is it a good deal?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33555&item=2469468841

Thank you,

Ben

Looks OK to me, and the price is about what I'd call average for a mechanical pump, anything less and I'd start to wonder about the quality of the pump. Looks to be a stock aftermarket replacement.

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Originally posted by v12horse

Thank you Keith. I guess I will get a new fuel pump. Here is one that is on ebay. Does anyone know if this an oem fuel pump? Do you think it is a good fuel pump? Is it a good deal?

Victoria British offers one for $44.95 in the new catalog

MSA's website offers one for $49.95 (listed as high quality, aftermarket unit. (They'll usually give 10% discount to us)

Chloe has OEM ones listed for $92.93

Keep in mind that SOME of the stuff on eBay has been sitting on shelves for a LOOOONG time. I bought a NOS fuel pump on eBay (different seller) and it did not work at all.

Call Chloe at Midwest Z. That fuel pump is already up ehere I wouldn't mess with it. VB only wants $44.95 for it.

Ben

What year is your Z? If it is a 73 or 74 you have a elec pump in series with the mech. pump. If so, the mech pump could go out and you would still be ok I'm sure. I would like to know how you tell if if you are getting air bubbles? X-ray vision? Why would mech. say filter is ok? Did he take it off and blow thru it? One thing about the 240Z fuel filters is they are extremely effective. When they are bad you cannot blow thru them. They will hardly pass water if at all. You cannot tell by looking at them either.

The mechanic took the fuel filter out and started tapping it on the concrete. Rust and a whole bunch of sediment started to come out. This has happened before about 2years ago, but the tank was blasted out.

Okay, so it is a no go on the ebay fuel pump. I am pretty sure you are right about the mech. and elec. fuel pump working in circuit on late 73-74 Z's greyghost, but I am convinced that the mech. fuel pump is one of the problems because he took it off and then put it back on and the car idles lower than before. I know I can change the idle on the carbs to raise it, but I want to fix what is wrong. I am at school, so I don't have my car here or my service manual, but in a few weeks I am going to go back home and I will look at the car. Hmmm, now I am utterly confused about the fuel system. If the mech. pump is bad, the elec. one will be running and everything will be fine. Hmm, I should be asking these questions when I am with my Z. Okay, I must go. Hopefully I can fix all this myself with the knowledge that everyone has given me. I'll keep you guys posted.

Thank you,

Ben

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Originally posted by v12horse

The mechanic took the fuel filter out and started tapping it on the concrete. Rust and a whole bunch of sediment started to come out. This has happened before about 2years ago, but the tank was blasted out.

If this is true, he (or you) should replace the filter. I can assure you that he did not knock all of the rust and crap that was in the filter out of that filter. Buy a Fram G3359 fuel filter at your neighborhood Kragen and replace it. Costs next to nothing to do this, and eliminates any question as to whether the filter is plugged. THEN, cut the old filter in half and see for yourself what is inside.

If there is rust in the filter, something (tank, metal lines, or whatever) is still producing rust. Was the tank sealed (internally coated) with a material to prevent water from coming into contact with the interior of the tank? You may want to inspect the tank to check it's current condition. The metal lines could be corroding also. no way to tell without examining.

Don't worry, the gas filter is changed. I will have to do some inspecting of the lines and the tank like you said Carl.

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Originally posted by v12horse

Don't worry, the gas filter is changed. I will have to do some inspecting of the lines and the tank like you said Carl.

IF/When you have time and tools to do this, let me know. Perhaps I can find time to lend a hand.

Thanks Carl, I will hopefully take you up on that offer. It won't be for a while though. Prolly in the summer is when I will tackle that project. How is your car looking these days Carl?