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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: dvdswan on December 19, 2013, 11:07:02 am
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Ok, so I went out the start the truck yesterday and I'm pretty sure I flooded the dang thing. lol The last time I owned a vehicle with a carb was in 89 so I guess I've forgotten how to start it.
when its running its smooth and idles around 800, it does have a choke, when I started it 4 days ago it warmed up at around 1400-1600 rpms, tap the throttle and it dropped to normal.
so I'm pretty sure I flooded it, battery was getting weak so I put it on rapid charge which allowed it to crank fine but it just wouldn't catch. it tried twice but after that just turned over.
any tips? It's a 350, 4bl carb(don't know if its original or aftermarket, Q-jet or holley, etc.), 4sp, no emissions,. I was going to give it a tune up this weekend but want to make sure I know how to start it when its cold out. low 30s and below.
thanks for any tips.
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Mine LOVES gasoline, so it may not be flooding, but....
Best starting procedure for unknown carb vehicle is probably: push the pedal all the way to the floor, wait three seconds for the accelerator pump to run out, and release. Without your foot on the pedal, try to start it.
Mine actually likes two pushes to the floor with the three-second wait, then fires on the first turn of the crank.
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Mine is 1 Pump always starts right up Unless its cold in the morning which then 2 pumps.
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I did a couple pumps before I tried to start it. but pretty sure I held it down after that. >:(
thanks for the replies.
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you sure its getting fuel and spark?
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I will be checking that. I did a quick look yesterday and realized the pos and neg cables were really corroded. after seeing that did a little more investigating and found things just are not how I like to see them. old plug wires laying on top of each other, I'm sure the plugs are not in the best of shape as well. I had planned on doing this anyway so it will give me some old training that I've long forgotten. lol
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so I did the tune-up and it seems that one was done within the last 10k I would guess. cyl #5 is burning a little oil, nothing too severe. tried to start, no go. pulled the fuel line off at the carb and cranked about 3-5 seconds, which I think would be enough time to have fuel come out but nothing, its dry.
am I correct in assuming the pump has gone south? or should I have to crank longer?
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if it sits for a while the fuel can drain back to the tank, you have to re-prime it. i usually get a can of starting fluid and run her off that for a couple seconds, by then fuel should be up to the carb. get a clear/glass fuel filter so you can see if its there or not
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it runs with starting fluid.
well, I wasn't getting any fuel from the pump and it looked wet so I replaced it. I'm still not getting fuel. I have dual tanks and have heard that the selector can fail. I'm puzzled by this as I'm not sure how the selector works. it has one wire (yellow) going to it I've checked the connections at the selector and another one like 6" from the selector. is the body the ground. it looks original as do the fuel hoses as they have those spring clips and some type of undercoating on it.
I am showing just over 3/4 full on the l/s tank and almost empty on the r/s tank. it was on the l/s when I drove it home and I haven't tried to run in on the r/s as it looks empty. I did find a ground very loose by the selector, it looks like it would be for the tank sender (I'm guessing) and I tightened it up with no change. it also looks like new fuel caps. I'm still puzzled how the selector could do this.
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The selector has one wire to it from the switch. This powers the solenoid inside the switch. If the solenoid fails, the spring loaded switch will fall back to the rest position and whichever tank is connected to the rest position.
Also, the solenoid has a wire to ground. This comes off the solenoid and connects to sheet metal ground. No ground wire, the solenoid will fall back to the rest position and whichever tank is connected to the rest position.
Any bets the RHS tank is the rest position?
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how do I find out which tank is in the rest position? and what does rest position mean? the dash switch seems to switch between the two tanks
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OK, a solenoid has two positions, right? When you put electricity through the solenoid, it goes into one position, the energized position. When you don't put electricity through the solenoid, the spring pushes it back into the other position, the rest position, or default position.
The dash switch in one position energizes the solenoid. In the other position it does nothing.
I think you have been running on the RHS tank all along, because the solenoid is not being energized, or has failed.
So, basically, you're out of gas.
Put a couple gallons in the RHS tank and see if the truck runs.
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got it. we'll try that. if that's the case then I need a solenoid. correct.
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got it. we'll try that. if that's the case then I need a solenoid. correct.
Well, you need to see if the existing solenoid is getting power, and has a good ground. If it has power and ground, and does not switch, then either the solenoid coil is open-circuit, or the internal valve is jammed too tight for the solenoid to move it. In either case that means a new valve.
First, though, is to make sure it has power and ground.
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this might help you out
http://i333.photobucket.com/albums/m387/rebel_cowboy_83/Diagram/fuelvalve_zpse5885df3.jpg
the two ports on the top front side are the mains from your fuel tanks. the port thats closes to the solenoid is your main/rest tank. follow that line see which tank is your main/rest
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this might help you out
http://i333.photobucket.com/albums/m387/rebel_cowboy_83/Diagram/fuelvalve_zpse5885df3.jpg
the two ports on the top front side are the mains from your fuel tanks. the port thats closes to the solenoid is your main/rest tank. follow that line see which tank is your main/rest
thanks that makes sense. incidentally, I don't have a return on my system. that picture looks like the selector valve I bought for my Nissan dual tank system.
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Did you try putting a 2-gallon can of gas in the empty tank and see of that solved the problem starting the engine?
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Did you try putting a 2-gallon can of gas in the empty tank and see of that solved the problem starting the engine?
actually, that's is exactly what I did. 2 gal. (fuel gauge didn't move) and cranked a little to fill the line up to the carb and then pumped the gas once and tried again. it cranked 3 seconds and fired right up. I did flip the tank switch to see if I could hear the solenoid switch... I do hear something, not sure if its a relay or the solenoid but didn't go any further than that. tomorrow I'm taking a short day so I will climb under the truck again and see which tank is the closest to the solenoid and test for power, I'm guessing its the pass. side. I don't know how long the gas has been in the left tank either.
being the truck is 35 years old and it has what looks like original fuel hoses I'll test for power and get new fuel hose and possibly a selector valve. I would think 2 gal. would move the fuel gauge, am I wrong in thinking this? its a 16 gal tank, so 1/8 of tank, maybe I'll go fill it up and see if it moves then. when it was empty it showed between E and 1/8 tick mark and still shows the same. I'm just typing my thoughts here.
I am sort of glad I wasn't going insane... lol. the fuel pump was wet so I believe it was weeping and on its last leg, certainly not helping with the quick start. thanks for all the advice.
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OK. Excellent. So we know the solenoid isn't switching. And for now you can just drive around like you only have one tank.
Note that some wiring diagrams show the solenoid switching the sending wires, and some show the dash mounted switch switching the sending wires. I don't know which applies to what years or models.
As for the gauge, I have one that will not move off full for the first four gallons, and then falls 1/8 tank per 1.5 gallons until Empty. I have a second gauge (in the blank instrument slot where the clock goes) for the other tank. It starts falling off of Full right away, and falls 1/8 tank per 1.5 gallons to Empty, at which point you still have four gallons left.
So, yes, some of the gauges are idiosyncratic. By my experience, you could put four gallons in there and still maybe not move the needle. After that though it should show up on the gauge.
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so a little update. the truck starts now on the 1st half of a crank. so most of the hard starting was due to the fuel pump. i installed a new selector valve and it seems to be working. I put some more gas in the right side tank so I'm showing 1/2 tank in each side. I drove it yesterday on the left side tank so I know that side sender is working cause I started with 3/4 tank. just need to switch over to the right side now. the new selector made the l/s tank the main tank as its nearest the solenoid now.
question: can i flip the switch while driving or do i have to be stopped with the truck off? I know this is really a basic question but tried it while driving and the engine didn't sputter a bit between the 2 tanks switching like I would think it would.
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You can switch them while driving. You are correct that there is a little gap in fuel delivery to the carb while the fuel pump gets flow going from the other tank, but the carb has internal fuel reservoirs (the float bowls) that hold more than enough gas to tide the engine over that short gap.
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got it. thanks Rich.