Runs smooth, then sputters, then smooth, then sputters

[DoubleDingo]

It'll clear out eventually. It's getting better each time I drive it and we aren't getting more rain right now. This is the dry season here.

 

[Radiohead]

Lil Nissan farm truck is getting better too. Danged ole water anyway...

 

[82sbshortbed]

Just talked to Pop about this. He said it sounds like the power circuit has a clog. We discussed that there is probably water in the fuel because of all the rain we got during the winter months. He said to get a bottle of HEET, and do the Mexican (to some)/Italian (to others) tune-up. So, I will grab a bottle of HEET and fill up the tank again. I have used a half tank since Saturday trying to get it to clear and to diagnose the problem.

This was my first guess but seems as that water in gas wasn't the problem.

 

[DoubleDingo]

This was my first guess but seems as that water in gas wasn't the problem.

Pretty sure it is water in the tank. It's clearing up more and more. Added one gallon of rubbing alcohol this morning, it ran better at lunch. Topped off the tank with 8 gallons of 93, and it has cleared up more. Soon it will be running normal again, but I still have stuff to replace to make sure it runs at peak efficiency.

 

[82sbshortbed]

Good then it won't be expensive to fix.

 

[DoubleDingo]

Good then it won't be expensive to fix.

Except for the fuel

 

[DoubleDingo]

On top of water being in the fuel, I found a couple vacuum leaks last week. Going to add spring clamps to all connections that get manifold and carb base vacuum, as well as replace the hoses and those runs I haven't replaced yet.

 

[DoubleDingo]

Yesterday replaced some vacuum hoses, and found two sources of vacuum leaks. One was the hose going to the modulator valve. The other was a block off plate gasket. Decided to check the vacuum advance can with the vacuum pump and it leaked down pretty quickly. Going to replace that, as I'm sure it's not supposed to lose vacuum that quickly.

I can hear air on the drivers side of the engine. I suspect it's one of the emissions things, I have no idea what it's called, it has electrical connections on it, and a vacuum hose on the opposite side of the electrical connections, and an open port next to the electrical connections. I assume that port is designed to go to atmosphere, and I suspect that is the cause of the air sound I hear. Not sure if it's supposed to be drawing air in at idle, but I think it is.

After fixing the vacuum leaks, sans the thing with the vacuum hose/electrical connections/open port, I took it for a test drive. Ran considerably better but still stumbled some under load, and then runs strong again.

Stopped at the station on the way home and topped off, as it then started running worse than it did before I fixed the vacuum leaks.

Back to square one.

 

[DoubleDingo]

The thing I mentioned in the previous post with the electrical connections and vacuum ports, one being open, I see it is the TRC VLV. I guess the port under the electrical connections is supposed to be open, it always has been except for when I put a plug on it. I eventually took off the plug. It looks like it should have a hose connected to it, but it doesn't show anything on the diagram.

These images are all that I have on hand to share at this time, they are from a few years ago, but the routing is the same even though the carburetor on it is not the warm air choke carb shown, it's still a q-jet now, just with an electric choke.

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[DoubleDingo]

Maybe I have this correct, maybe I am completely wrong.

Whatever the EFE is, the EFE TVS(Thermal Valve Switch?) opens and closes the EFE once the coolant is up to temperature? My guess is the EFE operates the butterfly on the exhaust?

Whatever the Spark TVS is, the Spark TVS opens once the coolant is up to temperature and then allows full vacuum to Check Valve?

What does the Delay Valve do in all of this?

The Throttle Lever Actuator and TRC VLV and air pump DVTR VLV all work together for what purpose?

The label on the lower portion of the air cleaner housing says to set timing at 6 degrees BTDC, I have it set to 10. The truck runs better at 10. However, if all of this stuff is supposed to work in conjunction with each other, would it be better to set the timing lower than 10?

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[Snoots]

Here ya go . . .

G30 van question

thats my problem too. broken tubes. i guess i head to the yard and CAREFULLY try to pull one. If i knew so many people were after them i woulda pulled every one i saw and helped yall out!

www.gmsquarebody.com

 

[DoubleDingo]

Here ya go . . .

G30 van question

thats my problem too. broken tubes. i guess i head to the yard and CAREFULLY try to pull one. If i knew so many people were after them i woulda pulled every one i saw and helped yall out!

www.gmsquarebody.com

Thank you. That answers the one question about how TLA/TRC VLV/DVTR VLV work together. I don't know if the TRC VLV is supposed to draw air in or not, but I definitely hear air at idle. I brought my service manual cd to work after lunch, was going to look up some stuff, but they replaced our computers recently and the new replacements don't have a cd/dvd drive. CRAP!

 

[DoubleDingo]

Maybe I have this correct, maybe I am completely wrong.

Whatever the EFE is, the EFE TVS(Thermal Valve Switch?) opens and closes the EFE once the coolant is up to temperature? My guess is the EFE operates the butterfly on the exhaust?

Whatever the Spark TVS is, the Spark TVS opens once the coolant is up to temperature and then allows full vacuum to Check Valve?

What does the Delay Valve do in all of this?

The Throttle Lever Actuator and TRC VLV and air pump DVTR VLV all work together for what purpose?

The label on the lower portion of the air cleaner housing says to set timing at 6 degrees BTDC, I have it set to 10. The truck runs better at 10. However, if all of this stuff is supposed to work in conjunction with each other, would it be better to set the timing lower than 10?

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Did my own research, the delay valve keeps the timing advanced when cold. Once the engine warms up the vacuum advance works normally. So, if my feeble brain understands this correctly, the spark tvs controls the vacuum signal for this delay valve to release when the engine is warm. If that is true, then I guess the efe tvs has the same function but for a different system.

I'll research this stuff further later on and report back what I learn. I'll figure this out one way or another.

 

[82sbshortbed]

Sucks you can't just take all that off.

 

[Ricko1966]

Efe is the valve on the passenger side exhaust manifold. The vacuum switch applies vacuum when cold to close the val e and push air through the heat crossover that you don't have to help with cold weather drivability. The factory timing specs are no longer relevant you no longer have a factory engine. Acquaint your self with minimum best torque. Google. You want the minimum timing you can run before power falls off. It's a balancing act you want as much as you can give it until your not making anymore power,then back down but not enough to lose power.I told squirrely brother how to do this a long time ago. If you make equal power at 34 degrees as you do at 36 degrees at, 34 degrees your pistons are fighting to over come the expanding air and fuel for 4 degrees less time. Equal power,but less fuel consumed to make it. That's why I'm a fan of fast burn heads.Closest way you have to check it without a dyno, find 2 landmarks you can from a dead stop get most of the way through second gear. Set your timing on the low side check your speed at the 2nd land mark,bump the timing 2 degrees keep coming up until your speed starts to drop or plateau then back it off 2 degrees. Your using speed not time,it's more accurate.