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240 runs out of power under load, i.e. going up hills

Don East

Have you had up hill power loss?  

8 members have voted

  1. 1. Have you had up hill power loss?

    • power reduction of load
    • power reduction up hill
    • power reduction on level
    • power reduction from ingnition
    • power reduction from fuel

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I have a 72 240Z. I thought I had a fuel starvation problem. I've installed a new mechanical fuel pump. Blown out all lines, Removed the gas tank and had it refurbished by a professional, replaced all hoses and made sure there are no restriction in the lines. I just installed an electric fuel pump near the fuel tank. I have not field tested the electric pump while driving as of yet. I'm waiting for a replacement fuel indicator.

Here is my question what else could be causing the problem? The distributor has been replaces with a newer electronic distributor. My Son did this and I believe it was from a 260Z. The car also has a MSD ignition system and Coil. On level ground the car runs great. I can rev it up to 5,500 rpms in all gears no problem. I start pulling a hill and it just runs out of power. Anyone out there have any ideas?

Thanks Don

Just thought I'd and a note: I've had this car since it was new.

Edited by Don East
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Not sure why you started a poll for this issue.

It helps us diagnose issues with a detailed history of any engine work or engine status; I.e. Any recent work done? Did this issue just start recently?

Did you make sure that your coil and dizzy are impedance matched?

Why an electric pump and a mechanical?

What kind of carbs?

Engine rebuilt?

Compression check?

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A "dizzy" is shorthand for a "distributor".

On the subject of the dizzy having been swapped for a "newer" electronic one, it is possible and more than likely probable that the replacement came from a boneyard car, which would make the Vacuum Advance Bearing Plate (under the "points" plate) questionable. Both the electronic and points dizzies use that bearing plate to allow the points or sensor to be rotated by the Vacuum Advance Diaphragm. When it goes bad, due to lost ball bearings, or rust, it causes the vacuum advance to operate erratically. One time it will advance properly, but not return to un-advanced normally, other times the other way around.

When mine went bad, years ago, it would not let me accelerate properly, it would take slow and careful throttle action to get the car up to higher speeds. Once up to speed (and therefore no or very little advance being required) the car performed normally.



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It's a simple check.

Disconnect the vacuum hose, remove the dizzy cap and look at the points plate. Then (sorry about this) suck on the vacuum hose to simulate engine vacuum. The more vacuum you generate, the more the plate should rotate. Then, release your hold on the hose and the plate should counter-rotate SMOOTHLY AND PROMPTLY back to it's zero position. Repeat a couple of times, try to emulate a sudden vacuum to see how well it reacts. Both on the intake and release it should have smooth and prompt response.

If it hesitates, or seems sluggish, check the plate.



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