wobbedennis Posted January 3, 2014 Report Share Posted January 3, 2014 My old Datsun 210 is having some issue. I reconnected the smog pump, and it hasn't run right since. When I have to get on it, which now is all of the time, and I let off, it back fires through the carb. It also is really easy to flood out, and if it stays under a heavy load for a while, 30 seconds or greater, it begins to flood out, and it cuts power. and misses, it now has a miss, but it jumps from cylinder to cylinder, so it's not just on one cylinder. Plugs are getting carbon fouled out, and I have yet to disconnect the pump to see if that changes anything, but the idle has changed, the whole running characteristics of the car has changed. It sat for a week and a half after I lost the thermostat (it stuck open)and found a crack in the housing. hasn't run the same since I got it back on the road. Quote Link to comment
datzenmike Posted January 3, 2014 Report Share Posted January 3, 2014 My old Datsun 210 is having some issue. I reconnected the smog pump, and it hasn't run right since. When I have to get on it, which now is all of the time, and I let off, it back fires through the carb. Often one problem can hide or produce other symptoms. Other than a slight load on the motor to drive the pump, it shouldn't have any effect on the running. After all... all it does is puff air into the exhaust ports. How is that going to affect the running motor ahead of this? It also is really easy to flood out, and if it stays under a heavy load for a while, 30 seconds or greater, it begins to flood out, and it cuts power. Hard to say with certainty it's flooding if you are driving it at the time, don't you think??? This sounds to be like a classic plugged fuel filter. You give it the gas and the motor runs great until it uses all the gas up in the float chamber and the pump can't suck more in fast enough because the filter is part clogged. These things are only a few bucks so... Change the fuel filter. Even if it does not help it's probably due. ....and misses, it now has a miss, but it jumps from cylinder to cylinder, so it's not just on one cylinder. Plugs are getting carbon fouled out, and I have yet to disconnect the pump to see if that changes anything, but the idle has changed, the whole running characteristics of the car has changed. Carbon fouled plugs. Now this could be the cause of you miss. Check the choke is shutting off once the engine warms up... usually about 8-10 min. The choke plate should be fully open. Is it??? Check the fuel level in the float chamber by looking at the glass bull's eye on the front of the carb. Fuel should be at or near the dot. Is it??? It sat for a week and a half after I lost the thermostat (it stuck open)and found a crack in the housing. hasn't run the same since I got it back on the road. Stuck open by itself is no big deal, many wouldn't even notice it. However some thermostats are designed to fail in the open position when over heated. You also mention a cracked housing. Leaking??? So I have to ask... did you over heat this motor? Because this can cause major problems. The head is aluminum and they can warp and allow the gasket to blow out inside. Perhaps between two cylinders which disrupts everything including a bad idle from poor intake vacuum and possibly backfiring through the carb. Quote Link to comment
wobbedennis Posted January 3, 2014 Author Report Share Posted January 3, 2014 Trust me, I had to go through this engine cause the previous owner overheated it and warped the head. I have never let this engine over heat, it had tried to come close when I first got her on the road, but it never did. It was a cold morning and all of a sudden the heater wasn't blowing very warm air, and I looked at the temp gauge and it wasn't warmed up. Went to replace it a couple of days later, and that's when I discovered the crack, and it was JB welded back into service. Fuel filter was replaced about 3-4000 miles ago, and I have plenty of gas, and once I remove the load from the engine, it sputters back up to rpm, and clears it self out, and this is not driving, this is just trying to load the engine more so it warms up a little faster. I plan on converting the car over to a manual before to long, so I don't really care about this auto trans. I have check the choke, it fully opens, however, on the secondary side of the carb, (by the way, it's the factory Hitachi DCH 306-63) the carb looks to be drenched in gas. and it doesn't dry up. Also, I played with the carb and most of the issues went away, except it back firing through the carb when I'm pushing the car, like I would to merge onto the highway, or to climb some of the mountain roads we have around here. Quote Link to comment
datzenmike Posted January 3, 2014 Report Share Posted January 3, 2014 Check the valve lash. A tight valve may not be closing fully and under heavy throttle can't contain the explosion in the combustion chamber. It squeaks out past a valve and explodes the intake fuel/air mixture. Quote Link to comment
wobbedennis Posted January 3, 2014 Author Report Share Posted January 3, 2014 just for laughs I removed the belt from the smog pump, The back fire went away. car's running dead smooth at all rpms, the smog pump was causing most of my issues, carb coming out the rest. Quote Link to comment
datzenmike Posted January 3, 2014 Report Share Posted January 3, 2014 Wonder how that was? Quote Link to comment
wobbedennis Posted January 3, 2014 Author Report Share Posted January 3, 2014 you have me, I don't see how a smog pump could cause a intake back fire, I can see exhaust, but not intake. Quote Link to comment
datzenmike Posted January 4, 2014 Report Share Posted January 4, 2014 The smog pump on the A series doesn't go to injectors on each exhaust pipe does it? Doesn't it go to something on the head itself? Quote Link to comment
wobbedennis Posted January 4, 2014 Author Report Share Posted January 4, 2014 yeah, it goes through a one way valve on the thermostat housing, and from there into the exhaust, but I don't know where it's put into the exhaust at. Quote Link to comment
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