Engine losing power

[Casey]

My 1973 240 starts to lose power after 10 minutes of driving. It gradually slows down to a crawl and then quits. I had the fuel system checked and it is OK. Any suggestions? Casey

[Zedrally]

When you say you had the fuel system checked, what was checked?

Pump, filter etc???????

Need you to be more specific, does your 240 have an electric pump or is it manual, all information you can provide the list members with will assist in getting a quick concise answer.

Mike

[Casey]

Thanks for the reply. The car came with a mechanical fuel pump, an electric fuel pump was added by Datsun in 1982 to fix the vapor lock problem common with '73 240Z's. (They also added asbestos around the fuel lines, which I would now like to have removed.) The mechanic checked both the electric and mechanical pumps, and the filter, and all checked out OK. He did hook up a bypass to the mechanical pump, took it for a test drive, and if worked fine for him. When I took it on the highway however, it gradually slowed to a stop, but not for 50 miles. Any suggestions ? Casey

[2ManyZs]

I'd almost suspect a fuel pickup problem caused by rust and crud in the tank.

Does it restart OK after it quits or doesn't it completley quit?

I'd pull the drain plug on the tank after you run the tank down as low as you dare just to see what comes out. If you get a lot of crud, you might need to flush and blow out the fuel lines.

The second thing that comes to mind would be the water control valve may be stuck open and overheating the intake manifold and it is trying to vapor lock. Easiest way to check this is to block off the water line that comes around the back of the head and connects to the intake and take it for a drive.

If these ideas don't work, let us know and we'll give you some more work to do....:devious: