Engine running backwards?
04-26-2004, 09:43 AM
#1
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Engine running backwards?
I drove to my brotherinlaws house the other day, my z was a little hard to crank but not bad ran fine the whole way there. But when i tried to come back the car will not start. My brother and i checked the spark plugs (fireing just fine) Check the disturbitor (sp?) and it hasn't been changed from the stock setting. Unpluged the fuel line to see if it was flowing (it is) and filled the tank with 93 octane and put in octane booster. Brand new battery and starter, all gagues read normal. The engine turns over shakes really hard. Maybe once every 30min we can get to run for 10 sec. then it dies no matter how we play with the throtle. It sounds like it backfires when we can get it running. We pulled off the rubber hose from the airbox to the intake and sprayed some starting fluid into it, wiped off all the overspary and tried to start it. A flame came shooting out of the intake. If this was my heavy equipment i would think it was drawing air in the exhaust and sending exhaust out the intake. But can a car engine do this? I've checked everything i can think of. Anybody else ever have this problem?
04-26-2004, 06:11 PM
#2
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Originally Posted by '76Z
I drove to my brotherinlaws house the other day, my z was a little hard to crank but not bad ran fine the whole way there. But when i tried to come back the car will not start. My brother and i checked the spark plugs (fireing just fine) Check the disturbitor (sp?) and it hasn't been changed from the stock setting. Unpluged the fuel line to see if it was flowing (it is) and filled the tank with 93 octane and put in octane booster. Brand new battery and starter, all gagues read normal. The engine turns over shakes really hard. Maybe once every 30min we can get to run for 10 sec. then it dies no matter how we play with the throtle. It sounds like it backfires when we can get it running. We pulled off the rubber hose from the airbox to the intake and sprayed some starting fluid into it, wiped off all the overspary and tried to start it. A flame came shooting out of the intake. If this was my heavy equipment i would think it was drawing air in the exhaust and sending exhaust out the intake. But can a car engine do this? I've checked everything i can think of. Anybody else ever have this problem?
My $.02
04-26-2004, 08:08 PM
#3
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Originally Posted by OlderThanMe
I have the problem where when I turn my engine off it deisels and runs backwards after a long time of running. When it happens I put in 4th and release the clutch to stall it. I think it has somthing to do with the advance. Try using regular (87 octane) gas and see if you still have the problem. I run my z on plus (90 grade fuel) and it deisels a little bit but not much. usually I can stall it before it starts running backwards.
My $.02
My $.02
04-27-2004, 06:55 PM
#4
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Originally Posted by theramz
You might have a bad ecu or ignition module on the distributor is bad. You could hook up a timing light to each plug wire to see if you're getting fire on time. Check your coil and coil wire too.
04-27-2004, 10:30 PM
#5
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Originally Posted by OlderThanMe
On my L26 I have new ignition except for the base of the distributer. what is the ecu? plus I have dual SU carbs from a 240z. And performance stuff in the engine (I was told a it has a camshaft and "other equiptment inside the engine")
04-29-2004, 06:17 AM
#6
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Originally Posted by theramz
You say L26 so I assume your engine is a '74. You don't have an ECU or ECM. If your car is a '76 it has or did have an ECM. Starter fluid is to hot to fill the manifold when you are getting intermitent spark which is why it coughs flames. Check for spark at each of the plugs and work from there. Sounds like your car is a mix of years so it could be hard to find the problem without the right test equipment.
04-29-2004, 09:28 PM
#7
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ahah
Originally Posted by OlderThanMe
the z is a 74' 260z with several engine mods and 240z carbs. I dont think it is belching fire but it used to belch gasoline at the hood through the overflow on the bowls of the carbs. I made it deisel less by turning the left adjustment screw out and lower my idle to ~800 rpm (was at 1100) and now it shuts off fine
Once you've got you timing correct it probably won't idle good. Next adjust the linkage (left screw) using an air flow gage, MSA sells them. Next, at idle turn the thumb screw (idle fuel mix) in until it starts to run rough, then back it out until it smoothes out, repeat on both carbs at least twice.
04-30-2004, 01:58 PM
#8
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Originally Posted by theramz
The over flow as you call it is a vent. There is a vacuum hose that goes from each carb bowl to the back of the air cleaner to prevent engine fires. If you are blowing gas then your carbs need some work, maybe only clean the seats in the bowls. It should never squirt gas. No properly tuned car will diesel. If your vacuum advance isn't working, the previous owner may have advanced the timing to get top end perfomance. This will make it ping at low end and diesel. It will also burn your valves. The left screw you turned is the front carb air flow balance linkage. This linkage is meant to even the air flow of both carbs at idle. The fuel mix ratio is adjusted with the thumb wheel under the carb.
Once you've got you timing correct it probably won't idle good. Next adjust the linkage (left screw) using an air flow gage, MSA sells them. Next, at idle turn the thumb screw (idle fuel mix) in until it starts to run rough, then back it out until it smoothes out, repeat on both carbs at least twice.
Once you've got you timing correct it probably won't idle good. Next adjust the linkage (left screw) using an air flow gage, MSA sells them. Next, at idle turn the thumb screw (idle fuel mix) in until it starts to run rough, then back it out until it smoothes out, repeat on both carbs at least twice.
thanx
04-30-2004, 02:30 PM
#9
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Originally Posted by OlderThanMe
I set it up good where it won't spit gas anymore or deisel after shutoff, I had set the timing at about 14*btdc but it was at 6-7* btdc so I think I will go back to about 10-11*btdc to keep from burning anything up.
thanx
thanx
08-01-2004, 07:35 PM
#10
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it sounds like your timing chain slipped.. This would cause the valve timing to be off and would cause backfires out the intake. If you haven't messed with anything, then your ignition timing is probably not off. That could be easily checked with a timing light, even though your car is not running. A timing chain usually slips when the engine is shut off.. It runs good then won't start the next time you what to drive it. It would be easy to check, by taking off your valve cover. Look at the chain and gear and check for excessive wear and looseness. Good luck!
-jeremy-
-jeremy-
08-02-2004, 10:27 AM
#11
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Originally Posted by zguy36
it sounds like your timing chain slipped.. This would cause the valve timing to be off and would cause backfires out the intake. If you haven't messed with anything, then your ignition timing is probably not off. That could be easily checked with a timing light, even though your car is not running. A timing chain usually slips when the engine is shut off.. It runs good then won't start the next time you what to drive it. It would be easy to check, by taking off your valve cover. Look at the chain and gear and check for excessive wear and looseness. Good luck!
-jeremy-
-jeremy-
08-04-2004, 08:02 AM
#14
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join z club
Originally Posted by dr. buddha
dam my bad did not see date. sorry i hope you have got it fixed already.
328-1401 8 AM-3PM Ted Christianson
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