Fuel consumption and Hesitation

[Glliw]

Wires.

Steve

Right. I just went back over your procedure. When checking with a multimeter I guess the car needs to be in the "on" position, or no?

[biddljj]

Were the spark plug wires checked/replaced ?

Not just a Z - zdisease

[Glliw]

Were the spark plug wires checked/replaced ?

Not just a Z - zdisease

They have not been replaced, but they have been checked to a degree. Each plug looks fine. Each wire looks fine. Each wire when pulled from the plug fires decently well.

[Glliw]

Update:

Installed a 0-15 psi fuel pressure gauge today right after the pump. After installing it, I saw the needles bouncing radically from 2-3 psi, and 3-4 psi when I revved and held the motor at a higher rpm. However, I had forgotten to close the gas cap.

So, after closing the gas cap, I saw a reading of 0-1psi at idle and 1-2 revved up. With the choke out I would see 1-2 at idle and 2-3 revved up.

[doradox]

Right. I just went back over your procedure. When checking with a multimeter I guess the car needs to be in the "on" position, or no?

When checking the resistance of the wires with the DMM the car would be off and the wire removed from the engine. Positive DMM lead on one end of the wire, negative on the other. Doesn't matter which end.

[Glliw]

Ok, cool. DMM is just shorthand for digital multimeter yes?

[doradox]

Ok, cool. DMM is just shorthand for digital multimeter yes?

Yes, and an analog one works just as well.

Steve

[Glliw]

K I'll do it within the next hour. Have to wait on a friend so I can borrow a multimeter since I'm 400 miles from mine. I'll post up ASAP when I get the numbers.

[Glliw]

Got the numbers on the wires for ya. These were with the DMM set to 20k ohms

Coil wire: .49

From front of car to rear:

.82

.77

.87

.87

.89

.94

These are Taylor Spiro Pro 8mm wires.

[doradox]

Got the numbers on the wires for ya. These were with the DMM set to 20k ohms

Coil wire: .49

From front of car to rear:

.82

.77

.87

.87

.89

.94

These are Taylor Spiro Pro 8mm wires.

Those look fine. Check the boots for cracks/splits. If all is good then I would say that was a dead end.

Steve

[Glliw]

Nope, couldn't find any cracks splits. I referenced the Taylor website, and they said 350 ohms/ft. So I believe I'm well within spec.

Looks like a dead end to me, thanks for the idea though.

Next thought?

[monkeyman]

You were planning to check something: the float setting. Have you done this yet?

My understanding is that a surging engine is often due to a lean mixture.

This sort of matches the 'it's fine until it heats up' scenario. An engine runs hotter when the mixture is lean, and I think it is this heat in the cylinder that affects the way the mixture burns (I am happy for anyone to correct/clarify this).

I have recently experienced something like this. I have a 260Z with 240Z SUs and it was all running well, the carbs were adjusted and balanced, then one day it started running like a dog (but it wasn't surging). I found the three rear sparkplugs were black with soot. The rear carb was running much too rich. I tinkered a few days, in the process I adjusted the rear float to run a bit leaner, but in the end I realised it was jus that the choke was stuck, this is why it was running so rich. (Why didn't I check the choke first?!) So now I have my rear carb back to normal but with a leaner float setting. My car surges a bit now. The hotter it gets (ambient or engine temp) the worse it gets. The temperature guage shows normalish temperatures, but I can feel a lot more heat under the bonnet. Everything seems hotter. It is raining today but I want to get the float back to normal.

Sounds like you have the same problem.

Make sure that when you find the problem you let us know. It will help the next person with a similar problem when they do a search.

Good luck