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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 46binder on January 29, 2014, 09:34:44 am
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Hello, 1984 K30, 350 goodwrench engine, quadrajet I just rebuilt. Haven't had good luck, not able to test drive it yet. To top it off, was negative 17 below, 37 below with the windchill yesterday. New float, electric choke, pulloff during rebuild. Then I had to replace the tank selector valve. It starts, I try to get it to warm up, and before the choke opens, it starts to stumble and die. Then I squirt some gas into it, still nothing, barely tries to fire. I try to pump the accelerator by hand, and I don't see any gas squirting in the carb. New filter, I unhooked the fuel line and turn engine over, and its pumping. Its been too cold out to do anything, but It starts, stumbles, dies, won't start, but next day it will start right back up again and do it all over. I thought it could be bad fuel and a clog, but with it starting again after sitting, it sounds like it floods, but I don't smell like there's a bunch of gas, and like I said, I didn't see it squirt gas when I tried the accelerator. I'm going to remove the filter, put in a clear plastic inline one, try again. I have to check fuel pressure, see if it starts to drop off before it stumbles, but it a new pump. I also thought of blowing out the lines, thought there might be a clog in the pickup tube in the tank. I need to get this running so I can drive again, but the weather hasn't been helping my ambition. At this point, I don't even know if the electric choke is opening yet.
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Sounds like you have two issues. Follow this in order.
First, the choke. Check that you are getting 12V to it in IGN ON only (when you switch the key on to crank). If you are then proceed to checking that the choke flips open slightly when you start to crank. It should open anywhere from 1/8 to 1/4 inch. This is the vacuum pulloff. If not, crank the engine and open it some manually by hand. If it continues to run good then you need to adjust the vacuum pulloff, which isn't opening/not opening enough and is choking the engine out. You can bend the linkage from the dash pot to adjust. Do not try to fix by adjusting the choke spring.. that won't work as that only changes the duration the choke is on.
Second, the fuel. When you pump the gas you are squirting gas in from the accelerator pump circuit. Once cranked, your carb pulls from the idle circuit. If you do not get any squirt/at idle, you could have a bad accelerator diaphragm or you have created a vacuum in the fuel system somewhere. Take the gas cap off both tanks, crank the engine. If it runs good then you have a vacuum in the fuel system somewhere. Did you hook up the return lines correctly on the selector valve? Is a rubber line collapsing? Are the vapor lines hooked up from both tanks? What shape is your vapor canister in? If all that check out ok, you could have a bad needle/seat in the fuel bowl or a sunk float.
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I had checked the 12 volt to the choke prior, and yes I have 12 volt at the wire. Choke is closed when not running, and when first started, about 1/8" gap. Have not seen the choke light turn off yet, replaced the oil pressure sensor, now that works. Have not seen the choke open completely yet either, but temps have been below freezing.
You brought up vacuum in fuel system, that sounds possible, PO removed any charcoal cannister, and checked old photos of carb before rebuild, large vacuum ort that went to it was left open and I had put a plug on it. Course I couldn't run it now, battery is dead, belt to alternator tore off. Will be able to fix it this weekend and try. Here are some pics of the truck, and carb vacuum lines.
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Forget it, cant post pic, says its too large. I tried.
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Post the pics to image host like imageshack or something. , or post to Facebook and hotlink from there.
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On the driver side of the radiator, right next to the frame, there should be a metal line. Is there a rubber hose from that to something? Is it capped?
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My son had to show me how to upload the pics.
Yes, there is a tube coming out by the frame by the steering box, not plugged, nothing hooked to it.
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truck
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carb
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if you can after it warms up and the choke opens then it stalls put your hand over where the choke is and suffocate it and get your boy to turn it over. see if it will start.
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You should run a rubber hose from that metal line up to the carb. Preferably use ported vacuum so you aren't introducing gas vapor during idle. Also it looks like you have a lot of vacuum leaks, although maybe you just took them off.
1- I assume that the air tube (the metal tube on rear passenger valve cover) no longer hooks into the air cleaner? You should get a breather cap to replace it.
2- I see you still have the cruise check valve but you no longer have the servo. You should cap the line that is open going to the firewall that is just laying there.
3- is your choke properly grounded?
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Another 4" of snow last night, still had some flurries but in between shoveling took some more pics. The air tube does hook to the stock air cleaner, along with a smaller vacuum line going to the top middle rear port of the carb. I did remove the cruise, but lines going up the firewall connect to a vacuum switch on top passenger side, and the other goes to some 'ball' cannister, gas recovery? I have pics of both. Large port on front top of carb was open when I bought it. I capped it, but when I removed it some gas came out of it.
Pic 1 shows front of carb with 4 vacuum ports. Lower left is capped, top left is capped, lower right goes to dizzy, top large is capped. lower large middle goes to drivers side valve cover.
Pic 2 shows lower small port going to pulloff, top middle not currently hooked up but goes to air cleaner, hard line goes to one way valve that I hope isn't backwards and to brake booster. Then theres a tree off the manifold, goes to pic 3 and 4, and I believe a vacuum switch for the trans. Maybe previous pics will show some of that.
I hope I got the lines right?
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This is really turning into a big turd, and is about to be tossed out. Won't start at all now, don't know what is wrong now. It turns over, I added a clear fuel filter before the carb and I can see fuel pumping, of course now it leaks where the line goes threads into the carb. No EGR, but where it was is a plate that looks factory, with two brass or copper tubes, one sticks out. Are these open holes into the manifold? Doesn't look at all like the EGR blockoff plates I've seen before. Cruise check valve, is that the white one? It goes to the ball shaped vacuum canister and the other vacuum switch it the pics#3 and #4. Any help before I throw in the towel?
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This is really turning south, and is about to be tossed out. Won't start at all now, don't know what is wrong now. It turns over, I added a clear fuel filter before the carb and I can see fuel pumping, of course now it leaks where the line goes threads into the carb. No EGR, but where it was is a plate that looks factory, with two brass or copper tubes, one sticks out. Are these open holes into the manifold? Doesn't look at all like the EGR blockoff plates I've seen before. Cruise check valve, is that the white one? It goes to the ball shaped vacuum canister and the other vacuum switch it the pics#3 and #4. Any help before I throw in the towel?
Walk away for a couple of days and let the dust settle and your blood pressure return to normal.
Seal the fuel line nut with Teflon tape. The tape won't seal the threads, but will allow the nut to tighten more effectively by lubricating it. And, use a 6-point 5/8" tubing (flare) wrench or you'll have even more problems to solve due to a crushed tubing nut.
In addition, that steel vacuum line off the back of the carburetor that connects to the brake vacuum reservoir should be replaced next Summer, since it's crushed. But, don't worry about it until the weather warms.
The "EGR block-off plate" is actually the hot air choke stove. The tube just makes a u-turn in the exhaust cross-over passage.
Exactly what is it you want to know about the check valve?
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Thanks, its getting a little frustrating here. Below zero again when I woke up, and my lower back is sore from almost slipping on the compacted snow all around the truck yesterday. No ambition to work on it, but this was supposed to be a winter beater for now, and its not on the road yet. It was running before, only thing I did was added a filter before the one in the carb, removed that one, and air cleaner is off. There was a vacuum 'tree' right behind the carb, split off between the items posted in pics#3 and#4, and I plugged it, and a new line and valve for the brake booster. I do need to know the routing for the vacuum cannister, trans switch by the brake booster, and the other vacuum switch in the pic. Can I just connect them all? And where should the one way valves go? I need to go charge the battery, and see if it will fire again after sitting. Then I think I will go work on my IH Scout, that might be on the road sooner.
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46 ,I know lots of cold weather tricks out here in Montana and they might be dangerous but lots do use them. get charcoal briquettes and get them goin right under the oil pan if you got no block heater,2nd gas in that cold don't vaporize so you can use starting fluid and need the choke held a little open with screwdriver in the carb.i know this isn't the norm but in a place where death by freezing can happen in minutes you need to know how to get going.once going set timing and check for vac. leaks.in that cold those magnetic heaters do not,DONT WORK, unless the motor is warm to strat with. do you have fire at the plugs,are the plugs clean,very important to starting
in cold.pour some oil or even tranny fluid down carb and that will up the compression also batt. probs are from dirty posts and seem to lose connection in the cold also put vasaline on them after cleaning. is starter cable loose and also check if float is hung up.when you get going keep high octane gas in it and heet .in older motors fresh oil keeps up compression and lastly rubber to metal line connects could shave rubber lines and stick the needle and seat. throw gravel ,kitty litter or dirt where your working we call it big sky garage-ing it,luck to you
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So it started again, runs about 30 seconds, stumbles and dies. Second start it runs even less and dies, third attempt and it won't fire at all. Pulled spark plugs, all wet. Took carb off to local carb shop, multiple problems. If I got this right, it had a bad needle seat, some tubes were plugged, needed some adjustment on linkage. Bad part was he said there was water damage, there had been alot of water, and there still was some in there when he took it apart. Choke works fine, carb will be run on a dyno and guaranteed. Choke problem is on my end, lite comes on, 12 V at wire, new oil pressure unit, theres something else behind the dash? Don't want to drop the tank, hope all the water is out or thinned out after I fill the tank.
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If water is accumulating in the carburetor you need to drain the fuel tank. The longer you wait the more likely you'll compound your trouble with rust forming in the tank.
Are you using a voltmeter or test light to check power at the choke stat? Have you checked/replaced the Choke fuse?
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I think I figured out why my choke light is on. Carb was rebuilt, again, and new choke confirmed works. 1984 K30, 350. Light stays on, and choke wasn't opening. 12 at wire, traced it right back to the firewall connection. New oil pressure switch, but its single prong. Light blue wire for choke should go to a two prong switch, which I dont have. Should I put a T in the port for the one prong switch, and place another 2 prong switch there and wire the blue wire to it and then to the carb choke? When I got the truck the wire was just frayed and cut, not hooked up to anything. And I can't find a part # for it on Rockauto or autozones site.
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Use this 2-prong oil pressure switch (http://www.autozone.com/autozone/parts/Duralast-Oil-Pressure-Switch/1984-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ik3mfZ8znc6?itemIdentifier=123893_652058_9889_5835) and connector (http://www.autozone.com/autozone/parts/Duralast-Oil-Pressure-Switch-Connector/1984-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ik3mfZ9cjre?itemIdentifier=518356_0_9889_) for the electric choke. Look at page 9 of the 1983 Wiring Manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST386_83_1983_GM_Wiring_Manual_CK_P_G_10_to_30_and_ST.pdf). Three wires connect to the OPS. Pink/white (ckt 350) from the firewall plug connects to one terminal of the switch. Dark blue (ckt 931) from the firewall plug AND light blue (ckt 78) from the choke thermostat connect together to the other terminal of the switch.
You can use a 11/2 to 2" long x 1/8" pipe nipple and tee fitting to connect both OPS's into the oil pressure tap next to the distributor OR you can thread one of the OPS's into the oil pressure tap in the left side of the block above the oil filter. I prefer the latter arrangement to decrease bulk at the back of the intake and eliminate the possibility that the pipe nipple might snap off flush with the block in the future.
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Wound up installing new tank, sender, new lines all the way to the carb, and 3/8" line to brake booster. Got rid of second tank, wires for Pollak valve are just hanging for now. Will have to figure out what wiring to cut, hook up later. Found wiring boot for oil pressure switch above oil filter just hanging there, PO installed a plug instead of buying a new $6 switch. No spark from three plugs, so got new ones, and engine was really flooded. Smelled some gas in oil, REALLY flooded, and changed oil again and turned over engine without plugs and fuel line disconnected briefly to clear gas out. Now the truck starts, and choke opens up like its supposed to with no dash light! Only thing left to do is the vacuum wiring, what are the two vacuum switches on the firewall, pics on first page, and do I need them.
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There are alot of pics on the first page, which one specifically?
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Well, looking at past posts and google images, one vacuum line is an esc tip switch, on the right side of firewall, and I guess I need that. Second is a switch behind the brake booster, and thats for a trans tc, but it sounds like its for a 700r4, but I have a 400 trans. Then theres a vacuum 'collector' ball on the drivers side, and that sounds like it hooked up to the cruise control that I removed. So I don't need that. I only have one more vacuum line on the back by the dizzy, and its a metal line, possibly from the trans? Don't know what that was.
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if you want to post a pic right click on it, then properties. then copy the address (url) and paste it on here with the img code so it looks like [img]address(url)[\img]
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well I went on a short vacation, South, away from the cold and snow. Took the truck for a short spin, and it stumbles when accelerating. So bad I can't drive it yet. Will have to check the timing now, and see if I have a possible vacuum leak. Fuel system is all new, and I did new plugs, wires, rotor, cap. Truck idles great, choke opens as its supposed to. Didn't have this problem before, but I do know carb before rebuild was set extremely rich, and had no working choke.
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Some more success, found a vacuum leak, I think I fixed the vacuum line routing. Drove the truck, still a slight hesitation, but seemed to go away the more I drove. Switched the vacuum line for the dizzy advance to manifold vacuum not ported on the quadrajet. I also have only 10" vacuum on idle, and when I give it some gas it goes up to 20-21. I don't think the choke was open all the way at that point though. Still, its good to go on driving.
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"You should run a rubber hose from that metal line up to the carb. Preferably use ported vacuum so you aren't introducing gas vapor during idle."
Isn't that the tube that runs to the fuel pickup/sender? I thought that was to vent the fuel tank, wouldn't hooking it up to vacuum cause the tank not to vent correctly??? I just stripped all my smog crap off but I thought I should leave that unhooked?
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Drove the truck to work yesterday, and went to drive it again, and it wouldn't stay running. Then I saw gas on the ground, the external fuel filter I put before the carb was empty, and when I started it again, I saw the gas was squirting from the bowl vent, which is not hooked up, I am missing the charcoal canister it goes to. I just had this rebuilt, new lines, tank, etc. Called the carb guy, he said most likely its contamination between the needle and seat. Sound likely? Guys at work are now giving me more crap, since the mechanic here told me to toss the quadrajet from the beginning. The carb guy said bring it in and he'll fix it no charge. Any opinions?
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Charcoal canister or no, there should never be fuel coming out of the vent, just vapors. The quadrajet can be a good carb when working right. Sounds like maybe your float isn't working. Older floats can start to take on fuel and then they won't work properly. Best way to tell, is to take the float out, put it in a can of gas for a few hours and see if it sinks to the bottom. It should stay floating on top of the fuel, if it sinks then it is bad. The old brass type floats can get pinholes in them allowing gas to get inside. the new black foam ones have a coating on the outside that wears down and then the foam soaks up fuel.
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tell the "mechanic" hes not a good mechanic if he want to just toss a quad. most back yard mechanics go by hearsay and if someone automatically judges the quad by what they hear instead of witness they arnt a true mechanic. the quad isnt a bad carb its just an O.E. carb. so it has some years and miles on it. just like any other carb you put on there give it 20 years and it will be running like crap also. you can rebuild one for way less then a new carb and yet it will be tuned in to your truck no need to change needles or jets cause its set up from the factory unlike holley and edelbrock. but it does sound like a float problem
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tell the "mechanic" hes not a good mechanic if he want to just toss a quad. most back yard mechanics go by hearsay and if someone automatically judges the quad by what they hear instead of witness they arnt a true mechanic. the quad isnt a bad carb its just an O.E. carb. so it has some years and miles on it. just like any other carb you put on there give it 20 years and it will be running like crap also. you can rebuild one for way less then a new carb and yet it will be tuned in to your truck no need to change needles or jets cause its set up from the factory unlike holley and edelbrock. but it does sound like a float problem
^ x2
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Well the carb guy came to his shop on a Sunday for me. He had said over the phone probably contaminants, I watched him take the carb apart, sure enough, some small pieces that looked like metal shavings. He put in a new needle and seat just in case the old one was scarred, cleaned and blew it out, new filter, and ran it on the engine while I watched. Took the carb back to work where the truck was, and it runs great. Don't know where the sediment came from, new tank and lines, he said it doesn't take much.
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could of been just in the fuel bowls. even with fuel filters we had to rebuild a couple carb because when mudding all sorts of stuff gets mixed up