Weird Dying or sputtering at highway speeds

Hey Everyone,
Have not been on in a while cuz i sold my van. But I now have a new one! here it is..


Its a 69 108 with a 318 and three speed tranny. 2 bbl carb. I am having a weird problem that just started.. when I drive at normal speeds it runs and drives fine lots of power no problems at all. But one I get on the highway at speed after like 5 to ten min then it starts to die. I can pull over and drive slower and it will run fine again and go as long as I want. but the min I try to get it back up to hyway speeds again it starts to die???

I have replaced
carb
fuel pump and filter
fuel lines
coil
wires ,plugs, points, condensor
alternator, battery

what else could be causing this? anyone else ever have this problem?

thanks

Here are some better pics of it..

Heres a shot in the dark: fuel tank venting? Proper gas gap?

Ok well I will look into that when I get it back to my place. but... I dont know if this is related but now I have another problem.. I was driving down the road, came to a stop and the van was idleing but shaking like crazy I pulled away from the light and about 1/2 a mile or so up a hill, all of a sudden the van backfires twice very loud! It dies, so I pull over and now it wont start. It turns over fine and normal, but I can hear this like compression sound like whooomp, whoomp out the exhaust avery few cranks. I have spark and fuel did a valve drop or burn? timing chain? Any Ideas

That happened to me before, and the tang on the distributor was bent. It was one of the oil type that had the flip up lid on the back so that it could be oiled. I'm with the other guys on the fuel issue being the sock in the tank.

You mean it backfired like that? Then you took the distributor out and found that? well its worth a try.. I would hate to have to tear into the motor so I hope its something that simple. Its was never noisy and ran really good other than the fuel thing. So hard to believe that the timing chain could go like that. But you never know...

Yeap, I was going about 45 and it back fired through the exhaust once and then trough the carb and quit. So I went with an electronic igniton from summit and it runs like a charm now. When you take the Distributor cap off, roll the engine over to #1 TDC and the rotor on the Distributor should point at the very front intake manifold bolt and your timing marks should align on the front cover.

Ok so here is what I have found so far. Turned it over with the cap off and the rotor turns, so thats good. also got it to what looks to be top dead center. I can´t hold the pressure from 1 cylinder compression. but when i get it to compression stroke and the timing mark right at zero (middle of the timing hole) the rotor is pointing straight forward, not to the left or right but dead ahead. Which is very close to where it should be for plug wire #1. Do you think this means that the distributor broke a tooth or something? Or still timing chain? When I bought the van the previous owner said (as they all do, but this pretty old guy was the original owner) that the engine was rebuilt about 15,000 miles ago. He said he rebuilt it because he needed to tow his new boat. but stopped using it because it would not stop very well. And there it sat till I scooped it up. That explains how the pickup sock could be clogged... Why did i just say all that? Because could it really be the timing chain that early on? Yes but unlikely, no? Anyway those are the findings I have right now. What does everyone think I should do next? take out the distributor? The front of this engine is a flippen pain to get to so I don't want to pull the cover off unless i really have to.. At that point I don´t know any of you in the area, but I am happy to host a help me out party with pizza and beer at my house or warehouse! Thanks so much everyone!

I think that it might be starving for fuel like Donivan65 said. Some times people put a fuel filter in front of the gas tank. Have you checked to see if there is one there & replaced it?

Ok well cap looks suspect.. i Can´t see any cracks but it has seen better days for sure. in fact when I pulled the coil to cap boot off it crumbled and pieces fell off..



So that will be getting replaced first off..

Another thing I just noticed is that the vacuum advance is pointing straight back and the vacuum line is pinched against the back wall of the doghouse. when I suck on it to get it to advance I get nothing. I never noticed it before as As I said it ran fine. started up first time every time without barely turning the key.. Never pinged so I thought it was timed right... Then this happened... So the fact its pinched..that just does not seem right... I tried to turn the dist by hand but would not budge.. so the hold down is tight.. could it have moved while driving and cause the timing to go out? Broke a tooth? Could that be why it is not pointing to the number one plug wire? At tdc it should be,, correct? or is it ok. If the tube is pinched and not getting vacuum it could not advance it.. so... WTF?? The vacuum line should not be pinched. so should I turn it so that when at rest the rotor is in line with plug wire #1 and try to start it? that looks like it will un pinch it and the rotor will still not be facing to the front right but will be facing to the right plug wire... Or first pull the dist and check it?

Pull the dist & start looking. Then if alls good redo everything.

Check to see that the bolt that locks the distributer in place hasn't loosened up causing it to turn, this has happened to me once.

Ya, that's where my vaccum advance ended up. My advance is between 8 and 9 o'clock, here's a pic.



Get the rotor to point at #1 on the cap, and #1 @ TDC, then pull the distributor and look at the distributor drive gear to see where the slot is pointing. Here is a pic from the service book.

tuneup 101 here, gotta start with the basics.
1. bring it back up to TDC #1, ONLY rotating it clockwise. This is lining up the marks on the crank. We will get to timing later.
Now, with someone watching, rotate it backwards (counter-clock-wise) slowly until the dist rotor starts moving. You can see how many degrees of slop there is in the timing chain by the marks on the crank. under 10 is great, over 15-20 is bad.


2. If the chain is okay and you have compression, the next thing to check is timing and ignition. turn the engine back to TDC #1. The rotor should be pointing toward #1 wire. The rotor spins clockwise. Try twisting it counter-clock-wise to check the mechanical advance. It should move a bit (about a 1/4 inch at the tip) with spring tension and spring back to the same point each time you release it. Without this, high RPM spark timing will suffer. You can also 'dead time' it by removing the coil wire from the dist cap and connecting it to a spare spark plug. Ground the base of the plug (lay it on the intake) then turn the key on. Loosen the dist. hold-down and rotate the body by hand. It will spark at the point where the points open (point style) or when the reluctor aligns (EI style). As you turn it back and forth, note where this happens. Turn the key off and move the body to the point where it sparks. This will get the timing pretty close. Replace any bad/worn stuff. Once this is all done, start it and check timing with the vacuum line off and plugged. Set if needed. Now, rev the engine up to about 2400 RPM. The timing should advance. This is the mechanical advance. It should return to the same point when back at idle. If not, something is sticking. Next, check that vacuum hose at idle. If it has strong vacuum, it's connected to manifold vacuum. If it only has strong vacuum above about 1400RPM, it's ported vacuum. I won't get into the M. vs P discussion here, but you need to know which you have. raise the idle speed to about 1500 RPM. If you have a choke, it will probably have a fast idle cam which can be swung up and hold this speed.
Connect and disconnect the vacuum line, which should have strong vacuum no matter what. The engine should speed up and the timing advance. If it doesn't you need to replace tha vacuum advance. This will also affect cruising at speed.


3. So now you have compression, spark and timing. All that's left is fuel. remove the fuel cap, and drive it. If it's still acting up, it's going to be something it the fuel delivery. This is (back to front) the sock, rubber hose, fuel line, pump, more hose, filter, more hose, line and the carb inlet and float system. Inspect the hoses, filter and lines for damage and plugging. The next most common thing in old vehicles is the sock. If none of that is it, check fuel pump pressure and volume. You are going to need a service manual for that.

Above all, if you start with 10 fingers and all your hair and skin, try to finish the job the same way. Try not to burn the van down while messing with gas and sparks. It's better to let it sit until you can take it to a shop or a good friend than to catch you and the van on fire.

i had to go out of town to San Fran and just got back. I plan to take a look at it tonight. will let you all know. I am dying to know myself!

I guess I'll throw my two cents in as well.

I had a pair of similar problems with mine:

1) It would, at seemingly random times, just sputter out and die. Sometimes it would restart, other times it would have to sit for hours. It turned out to be a bad ignition coil and condenser. When the coil/condenser would get hot it would die, no problems after replacing them both.

My brother had the same problem on his '68 Mercury, turned out to be the condenser.

2) Before I had my fuel tank vatted and replaced my complete fuel system it got where it would run down the road a mile or so and then die for a bit and eventually start back up.

after putting clear filters on it I figured out that the filter sock was rotted off the pickup tube in the tank and the lines were partially clogged. It would let "some" fuel through but not enough to run highway speeds.

My fuel tank filler line had rotted away on the inside and it dumped a bunch of ground coffee size rubber particles into the fuel system.

Well i think i found the culprit. I did get it on tdc and it was not pointing to plug one. I saw a picture of the way it should be set up. When I turned the distributor to mimic this set up, #1 plug came up and lined up with the rotor. I also found that the return spring would not return the rotor if turned by hand.(hard to do by hand, had to really force it!). I just yanked it and the distributor does not at all turn freely, so i know its shot. And most likely turned the distributor while driving. which cause the timing to go out and the backfires plus no start.. Off to the parts store to pick a new one up. will keep you guys posted! thanks for all the suggestions so far! wish me luck!

that was it distributor was screwed.. it did what i thought it did. Put a new one in and fired right up!