VT80

Hello fellow first gen enthusiasts. I picked up a 1980 longbed with a 20r and have been working on it for the last two months. When i got my hands on it she hadn't run for about a year.. the gas tank rotted out and the PO parked it when he couldn't find a replacement. so i hooked up a five gallon can, charged the battery, and drove it home (luckily not very far). it ran horribly and stalled out a few times on the way, so i began trouble shooting and doing a basic tune up. This helped a little and got it to at least idle in my driveway so i could continue diagnosis. I discovered that i had an exhaust leak at the bottom of the header and the heat shield had been removed, so it had been pulling exhaust through the Hot Air Intake which explained why the entire intake and carb were thickly coated in carbon buildup. So i rebuilt the carb and reset the idle mixture and speed per my chiltons manual instructions, now she was running awesome!! Took her for a test run only to find that every time i break 3000 rpms it would sputter and eventually stall out upon deceleration. Every time this happens it wont stay running unless i let her sit for 10-15 minutes, if i try to start it right away it will rev up then sputter and die.. So i drove her home and began trouble shooting again. I decided to de-smog it in order to make diagnosis easier, looks way cleaned under the hood now but the problem persists. She runs great when she's running but every time i drive her she will sputter and die eventually, when it sputters the truck will hop violently if its in gear and rpms will jump up and down until is dies.. Also occasionally on initial startup it will skip when i hit the throttle, i have found this coincides with the eventual sputter and stall.
So far i have done:
Basic tune up
De-smog
New (used) gas tank
Rebuilt carb
Fixed vacuum leaks
Unhooked HAI
Changed all fluids

This forum has been extremely helpful to me and I am amazed at how much good info has been compiled here, however i have done hours of searching and have found nothing that has helped me with my sputtering problem. I LOVE this truck but am getting very frustrated with this problem.. Any input from you Toyota experts would be greatly appreciated. Unfortunately im a bit of a newbie with Yotas and could be missing something very simple. At this point I'm willing to try anything you guys suggest to get this fixed. i will post anymore information about the truck that you need to help diagnose this, but im afraid i have already created a very long first ever yotatech post and don't want to waste anyones time with unnecessary info.
Thanks for reading.

igotit

are you using the trucks fuel lines going back to the tank?
odds are if the tank was rusty,the lines may be obstructed.
i disconnected my lines from both ends,filled with water,then blew out with 40 psi air untill it was clear.
my 81 was doing a similar sputtering/dying thing.
also check the fuel pump.

also on my 81 .....if the battery is dead,and i jump it off...she runs very badly,pops through the exhaust,sputters and dies.
my 81 wont run on just alternator alone.

VT80

I have blown the lines out with air, but I had my regulator down to 15 psi.. I will go try with 40 psi and check my fuel pump, just disconnect from the carb and crank over? If I get fuel I can assume its working right? Also I replaced the fuel filter after i had run a few gallons though the new tank so I know the filters good.
The battery was new when the PO parked her, i have checked it multiple times, funny thing is sometimes i get 15 volts but usually 13.5

VT80

Just blew the lines out with 40 psi and checked my fuel pump. I undid the fuel line at the carb inlet and put it in a glass jar then cranked the engine over for about ten seconds. The gas that came out was murky at first but then cleared up. I started it and she still skipped at initial throttle.. but hasn't sputtered out yet after going over 3000 rpm. I will take her for a test drive later and run some fuel system cleaner through it.

igotit

glad everythings working out for you!

VT80

Unfortunately my test drive didn't go very well.. she skipped on initial throttle again and about a mile away from my house i hit 3000 rpm in third and as soon as i let off to go into fourth she started sputtering. She jumped from about 1500 to 500 rpm a few times and stalled out. After letting it sit for a few minutes she fired back up and i drove her home. Any other ideas on this??

igotit

i would thouroughly clean your fuel tank/system,new fuel filter...ect.

i know how you feel....my 82 left me in the rain on the side of the road today,due to a weak fuel pump.

VT80

I cleaned the new tank out as well as i could before i put it in, so i cant see how it would be coming from the tank. I will pick up another fuel filter this afternoon and see if that gets me anywhere, I'm also thinking about replacing all of the hard lines in the fuel system (I have already replaced all the rubber lines) although the hard lines really dont look bad from the outside.. I tried to check the output pressure on my fuel pump but i dont have a gauge that goes low enough. My chiltons manual says it should be 2.8-4.3 psi at 2500 rpm, hopefully my buddy has a gauge that will go that low and i can borrow it. Also the PO said this problem had happened to him a few times before he parked it but it was very random when it happened to him.

4serge

VT80, did you make it work after all ? I also have 80 Pickup but it dies on deceleration..

VT80

Yeah I ran new hard lines and got a new fuel pump, it was running great for a while... but, now she keeps flooding. I've adjusted the float multiple times but the fuel level just keeps rising over the glass and eventually it starts to flood into the secondary barrel. I'm at a loss again, I've checked the cut off solenoid and my adjustment screws everything seems right but i cant get her to stop flooding. Anyone else have this problem or any idea what's going on here?

neockder

I'm having similar problems.. picked mine up a few months ago, and she had been sitting for 5+ years. Ran a ton of seafoam thru everything, 2 fuel filters, valve adjustments, timing, plugs, fuel pump, and now its down to the carb.

The carb wont take an adjustment for idle speed, and I can't get it to run without cutting out unless its running rich. My next step I think is a new carb, and finger's crossed it'll make it through the winter!

Could yours be the carb as well?

VT80

After rebuilding the A-2 once and adjusting multiple times, Yes i think it is the carb. My Chiltons manual says it could be the fuel pump operating at too high pressure, I have ruled out everything else.. I'm planning on buying a weber but was hoping to wait until spring. At this point I have put far too much time into the stock Aisin carb, I had it apart yesterday too adjust the float one more time. The smallest adjustment i can make brings it from flooding to getting no fuel and vice versa. It is so frustrating I almost threw it at the shop wall. So I will be ordering a weber 32/36 once I have the money, meanwhile if anyone has any suggestions or input on this any advice would be greatly appreciated.
Thanks for reading.