Sputters or dies after running a while.

[Mogordo]

Hey everyone,
I've been having some issues with my '83 SR5 and I'm looking for ideas. The car came with Weber and I got the vacuum sorted out to what is recommended on here in FAQ. After that I got it timed to around 10* BTDC. I plugged one port on vacuum advance (two port unit) as appeared to leak.It was running well then overall. No stalling (unless I messed up driving...), quiet, and fairly smooth at idle, a little noise that might be valves.
I was only driving it maybe once or twice a week most of the summer, making it a point to take it on some longer trips to get it good and warmed up and aired out. No issues until toward the beginning of winter last year.
It started hestitating or kind of sputtering sometimes then. It would lose power and the accelerator pedal felt like it wasn't doing much. It happened in the rain the first time but it happened not it the rain also after that. The first few times it happened the car was in motion and when I downshifted one gear and the RPM went up a lot something changed and the accelerator pedal did what I expect it to again and it went back to running normally. I think it only did it once in those trips. Then it happened while stopped at a light and without the car moving I couldn't save it by downshifting and it stalled and would not run again. I got it towed home, rolling it down the hill at the end of the drive way to park in front of the house. I had replaced the fuel pump in the spring of last year. Knowing they don't always last as they should I didn't rule that out. But I looked at the fuel filter and found the cartridge inside was cracked so I thought it wasn't filtering and maybe something in the carb. got clogged. Probably a week or so later I replaced the fuel filter but then the car started and ran and I parked it in the garage as I figured that wasn't the end of it as the filter wasn't clogged so it didn't make since to me that replacing it would fix the stalling problem. A friend suggested a way to probably clear out anything that might be blocking in the carb. without taking it apart which was to start the car then disconnect at the carb. the fuel line coming from the fuel tank, then let the car run until it died from lack of fuel, the theory being the floats would then be open and allow carb. cleaner in, and then to spray a lot of carb. cleaner into the inlet port on the carb. I did that and thought maybe that would be the end of it. The car ran fine one thirteen mile trip, sat a few hours, then a mile or so in on the return trip it sputtered but as it was in motion the downshift method kept it going and it ran fine the rest of the way home. I thought maybe it was something in the distributor and tested the one on the car and the primary coil resistance was within the range specified in the '85 FSM, I couldn't get a reading for the secondary coil resistance and I thought maybe it was because of the corrosion on the high tension terminal, there was something incorrect in the readings for the igniter though. I don't remember now if was in the power source line or transistor and I only did test (a) for the transistor because I was concerned I would apply voltage too long and ruin the transistor but whatever reading wasn't right I decided it was enough for me to try a different distributor. I got a used off another '83 and did the same tests I did on the original. The primary coil resistance is supposed to read 0.3-0.5 with an ohmmeter and it read 0.7 and I hoped that was close enough, the igniter readings were pretty close to 12 volts but I don't remember the number exactly. I still didn't do test (b) for the transistor.
I didn't have the distributor lined up correctly the first time I drove the car. I drove it a few miles then left it running a while before checking the timing with the vacuum advance lines plugged but because I didn't put the distributor in lined up right I couldn't time it as it wouldn't advance to better than about 5*ATDC before hitting the end of the adjustment. After I played around with it and figured that out the car stalled and then wouldn't keep running. I thought that odd as it had run 15-20 minutes with the timing that off but thought maybe the timing was still the issue. I figured out what I did wrong with the dist. and today I went out and took it back out, re-found TDC on the compression stroke, and installed the dist. correctly. I started the car and let it run a while, the fan had just kicked on before I checked the timing, I plugged the vacuum advance lines again, I turned the idle down slightly to from around 1000RPM to 800-900, then set the timing at 10*-13* BTDC. Just as I tightened the dist. bolt the car stalled. I started it and it stalled again. I put the idle screw back to where it was to start with. I was able a couple times to start it and rev it a little before it stalled again but then it just seemed to be done running.
I was talking to a friend who said he had a truck with similar issues and when he replaced the igniter the issues went away. He suggested testing the voltage on it just after the car stopped running so a couple hours later I went out and started the car. It started then died, then I stepped on the gas then turned the key to start a few times without it starting then it started and ran. It took around 15-20 minutes again for it to stall and not stay running when I re-started it. I did just the igniter tests I did before and got a reading of 11.55 volts for positive and negative and that seemed close enough to right to me especially since the voltage in the car's battery was only reading at 11.80 volts.

Does anyone have ideas as to what the problem is? Or things to check to get a better idea?

[Mark]

I'd park the car, take off the air filter cover, start the engine, wait for it to seem like it's about to stall and then spray something like carb cleaner down into the carb. If the engine starts running again while you're spraying then I'd suspect a fuel delivery issue. I don't know if the Weber carb has a little window where you can see the level in the float bowl. In the stock Tercel carb, the fuel level should be in the middle of the window. If the level drops, leading to the engine stalling, then you have a fuel delivery issue. I doubt the fuel filter is clogged since you changed that. Does the Weber carb use the stock fuel pump? There are cheap ones on Rock Auto and they are quick to replace so it might be worth swapping the pump out to rule out a defective pump. There might be holes in the fuel line from the tank, which would allow air to be drawn in instead of fuel, making the pump loose it's suction. I've never had that problem yet, but others on this forum have.
Anyway, if it still stalls when you spray carb cleaner down the carb, then it probably isn't a fuel problem although it sounds like it is.
Another thought...does the Weber carb require a fuel pressure regulator to drop the pressure? If it's missing or defective, would this result in too much fuel in the carb leading to flooding? I've never had anything but the stock carbs, so I'm unfamiliar with the Webers.

[Mogordo]

Thanks Mark. I took too long between logging in and writing the long reply I wrote out and I got logged out and the reply didn't save. I'm heading into work so short reply is: Thanks, That helped. Your ideas gave me more ideas.

[dlb]

I agree with Mark. To answer the Weber/fuel pump/fuel pressure regulator questions, yes the Weber uses the stock fuel pump but it does require a FPR because the stock pump puts out a pressure of 5-6 psi and the weber likes 2-3 psi, IIRC. Mogordo if that's something you're going to look into you should double check my numbers. I know it's been mentioned here on the forum before but it was long ago so I'm not super confident I have the numbers exactly right.

[Mogordo]

Thanks also dlb, I am going to look into the fuel system as a source of the problem when I next have enough time free. Putting a FPR in was on my to do eventually list but eventually didn't come yet. If that is the issue I don't know that it is directly the problem or if there are some issues in the carb now from too much pressure in it.

[dlb]

I don't believe the higher fuel pressure would cause damage to the carb, I think it would just cause it to flood or run rich at times. I never ran into that though so I can't say for sure though.

[Mogordo]

Well that would be helpful if the higher pressure doesn't actually mess the carb. up. It seems to me I read something on here about affecting something in the carb. long term but maybe not. I'll read through more posts about it when I have more free time and see what I find.

[Mogordo]

One other thing though is that I changed the fuel pump in spring of last year and the car ran fine until around the end of fall last year. If it was just a fuel pressure problem I think it would have started at least when I changed the pump.

[NWMO]

Mogordo,

It may be a fuel delivery issue. I don’t have experience with the Webers, but it sounds like it’s starving for fuel. Blockage or possible leak in the fuel supply side allowing the carb to suck air.

Chris

[Mogordo]

Thanks Chris, I think I'll have time to look at it this weekend and I'm to going focus on determining if I can affect the issue by affecting things in the fuel system. See what I see and then see if I am more confused or less (:

[Mogordo]

Well, It does act kind of fuel related but it isn't quite making sense to me. I went out yesterday and let it sit running until it stalled. Took 25 minutes that time. I started it a couple times and it would stall and then it wouldn't start. I put between a tsp and a tbsp of gas in the carb. and it still wouldn't start. Talking to a friend later he asked if I checked for spark when it wouldn't start at all. I had forgotten. Reading through some Weber related posts I found two threads about similar but a little different issues. One didn't have a post telling of a resolution and the other I think in the end was fixed by replacing the fuel filter. I started the car again today and let it sit but after half an hour it still hadn't stalled. Since another similar issue was happening for someone else mostly under load even though mine was happening at idle too I tried driving the car up the fairly steep hill right in front of it that is part of the drive way. It went all of maybe 20 feet and stalled. I let it roll back down the hill and started it again. If I stepped on the gas pedal it would rev the engine a little and then hit a point where it was as if the gas pedal lost all effect and the engine would stall. I did that a few times then the car just wouldn't start anymore. I dumped gas in the carb and the car still wouldn't start. I pulled a spark plug and checked for spark. Yes, it had spark. I pulled the line to the fuel filter coming from the gas tank and there was gas in it.
I don't know why, if fuel just isn't getting into the carb like it should, the car still won't start after I dump gas in the carb.
Does anyone have more ideas with that information?

[dlb]

If pouring gas down the carb when it stalls doesn't help, it's not stalling due to fuel starvation. Might be due to flooding which I mentioned could be due to running it with the wrong fuel pressure for that carb.

[Mogordo]

I still don't know why it would suddenly start flooding when it had the same fuel pump on since spring and ran fine until fall. I could try putting a FPR on it since even if the pressure isn't causing it to stall it would still be good to have one in but I can't figure how that would suddenly be an issue.

[NWMO]

Mogordo,

Does the fuel boil when poured in the carb? I’ve experienced times when less than perfect fuel delivery would combine with a “hot” carburetor and it would have to cool down some before running again. Dieing as you start uphill points to inadequate fuel as well.

Chris

[Mogordo]

I don't think the fuel boiled but it did smoke. But when I looked down the barrels and there was some fuel down there I think it looked calm. Is it normal for it to smoke or is even that an indication of too much heat in the carb.?