strange event

[stomper]

This happened to me this AM also. I had some water in the fuel line. Purged it, and continued on my way to the store.

[siii8873]

I'm thinking the same, got it home and in the garage. Going to let it warm up a little and try it again.

[SafeAirOne]

I dunno---It really sounds like an obstruction in the fuel supply system to me. I probably asked this way back when, but does it start right up normally an hour or two later?

[siii8873]

It does seem to start and run normal for a very short ways after it sits. When I got back to it today ~1 hr it started fine and went for about 100yds then went bad again, could hardly idle it.

[SafeAirOne]

It does seem to start and run normal for a very short ways after it sits. When I got back to it today ~1 hr it started fine and went for about 100yds then went bad again, could hardly idle it.

Well...OK. That doesn't describe what I had in mind. You've got a bit of a mystery on your hands, I'm afraid.

[stomper]

If it were me, I think I would change the fuel line, and install a cheap electric fuel pump. You could even do this as a temporary diagnostic if you choose, much like printjunky did to get his rover home.

For some reason, you are not getting enough fuel to the carb. either a drop in fuel pressure, or a failing pump, or a blockage in the line.

[jimrr]

at first it sounded like ignition prob but what you describe on the last couple pages is definatly fuel and you get enough to fill the fuel bowl but when you start working the engine it eventually runs out.........
ususally, almost always, this indicates insufficient flow to the carb. plugged intake, pump issue etc.

[siii8873]

I decided to top off my tank and add some drygas as a first thing to try before I go crazy changing parts. I may have found something while doing this. When I removed the gas cap there was quite a vacuum in the tank. I had replaced the cap a while back. Law of physics can only pump out what air is allowed in. Not sure why the cold weather would make this worse. Is there a good way to vent the tank? I know the siii's originally had a vent system of hoses, charcoal canister, etc. What did the older vehicles use before this system?

[bkreutz]

I decided to top off my tank and add some drygas as a first thing to try before I go crazy changing parts. I may have found something while doing this. When I removed the gas cap there was quite a vacuum in the tank. I had replaced the cap a while back. Law of physics can only pump out what air is allowed in. Not sure why the cold weather would make this worse. Is there a good way to vent the tank? I know the siii's originally had a vent system of hoses, charcoal canister, etc. What did the older vehicles use before this system?

They used a vented cap.

[siii8873]

what's the best way to "vent" a newer style cap? The old style cap will not fit on SIII.

[LaneRover]

Did releasing the vacuum solve your problem?

Cold would make it worse because cold air makes everything smaller (anyone who swims in the ocean off of Maine can vouch for this). Not so much the gas itself but the air in the tank really contracts.

I would try driving with the cap a bit loose - or get a 2nd cap and drill a small hole in it. That way in the summer you can still have a nicely sealed gascap.

Think of the good part of this - now you know your cap seals well!

[SafeAirOne]

If it's a 2-priong cap, a replacement vented cap is only $8 if you shop around.

Looking at the picture of an un-vented 3-prong cap, you may be able to drill a small vent hole through the center of the inner liner and it'll vent through the channels on the outer shell, just like the vented 2-prong cap.

[siii8873]

I did exactly as noted I drilled a small hole in the center of the inside of the cap. Still need to test drive to confirm (if there is such a thing with these intermittant things). There was enough of a vacuum in the tank that I have some confidence it could have overcome pump capabilities.
That's a good idea to get a second cap for summer.
BTW this is a SIII with the three prong sealed cap. I checked they don't make a vented cap in three prong.
Hope it all was this simple!!

[siii8873]

Took the truck for a drive tonight all was well. Last time I said this the problem came back..... I think this was it this time.

[bkreutz]

I did exactly as noted I drilled a small hole in the center of the inside of the cap. Still need to test drive to confirm (if there is such a thing with these intermittant things). There was enough of a vacuum in the tank that I have some confidence it could have overcome pump capabilities.
That's a good idea to get a second cap for summer.
BTW this is a SIII with the three prong sealed cap. I checked they don't make a vented cap in three prong.
Hope it all was this simple!!

How is the vent system on your tank currently configured? Stock there should be a plastic line from the tank to a canister on the drivers side of the frame, then a vent line from that forward. I would think that system is presently blocked if you're building up a vacuum in the tank, maybe you could repair (or modify) that system to function.