brown7373

My 72 350 has been running perfectly until Tuesday. I filled up the other day at a Mobile that I haven't been to in a couple years. As far as I know, my ignition is all good. I replaced a coil, cap, rotor and ignition module about 6 weeks ago and it has been running better than ever...until Tuesday.


How can I test for water in the gas? Is there an additive (Dri Gas) that will absorb water if that is my problem.


I haven't ruled out something in the distributor, but it started almost immediately after the fill up at not my regular station. It starts fine, idles correctly, but falls flat when you try to accelerate...even just speed up a little. The carb was rebuilt with a kit from Cliff a couple months ago, so it isn't the accelerator pump. It stumbles badly even on slight acceleration, that doesn't even use the accelerator pump.

oldcutlass

Disconnect the fuel line and the coil wire. Grab a glass 16oz jar, and have someone crank the engine so you can collect a sample in the jar 3/4's full. Let the jar sit for about 30 minutes and the water will separate and fall to the bottom of the jar. Gas line antifreeze or dry gas as they used to call it, is basically alcohol and will help burn the water in your gas tank. It can be had at any auto parts store, just follow the directions on the bottle.

Note, if there is a lot of water in the jar, you need to drain the tank, the alcohol will not work well.

Charlie Jones

When you look for "dri-gas" , try to find a product that contains Isopropyl alcohol . Rather than Methanol alcohol.
Isopropyl alcohol will mix gasoline with water and get rid of it.
Methanol will only keep the water from freezing.

I wouldn't bother to test for water in the gas . Just pour a bottle of Isopropyl in the tank , wait half an hour and then take it for a drive for a half hour.
If that doesn't take care of it , then you have other problems.

Professur

Do yourself a favour and check the gas filter.

brown7373

Thanks guys. I have a friend who had his brand new Ford 1 ton Super Diesel Pick-up get a tank of Shell that had a LOT of water in it. Supposedly it is supposed to have sensors to shut down when it detects water. It didn't, or didn't in time, and destroyed the engine. His truck has been waiting for parts and insurance settlement for over a month. Dealer is doing a total rebuild. Not sure which parts needed replacement.

brown7373

Check filter as in water will ruin it? It is only a couple months old.

Professur

The bad gas may have had more than just water floating in it. Urban myth holds that you never gas up during or immediately after a fuel delivery. The dump from the tanker stirs up any sediment at the bottom of the station's tanks and it can get delivered right into your tank. Or even the sediment from your own tank can get sucked up if you let it get too low. I know I had a great running car heading out on a long run. Let it get lower than normal to get me across the border to where the gas was cheaper. Immediately there after, any more than half throttle and she bogged. When I finally go to check the filter ...


P1020038_zps0e0eb25f.jpg

She'd been running like a top before.

Charlie Jones

The water won't "ruin" the filter. Just use the Isopropyl .
It may be good to check the filter . Just to make sure there isn't dirt in it.

jaunty75

I second the fuel filter idea. The symptoms you describe could easily be caused by a partially clogged one. I had a similar issue with my '67 Delta 88. It would start and idle just fine, but it had no pep on acceleration and would not maintain highway speeds. Changed the fuel filter, and problem gone.

It's a $3.00, 10-minute effort, so you're not out much if it doesn't solve the problem, and if it does, you save the bother of disconnecting fuel lines and collecting gasoline samples and worrying about whether or not you have water in the tank.

oldcutlass

That's not an urban myth. Getting fuel at the same time as the tanker is filling the tanks can provide misery. Since the fuel is drawn from near the bottom of your cars fuel tank at all times, if there is dirt in there it does not matter what the fuel level is to collect it.

brown7373

Okay, it wasn't the gas, it was the distributor module. That is the first failure of a Pertronix I have had in 6 cars and tens of thousands of miles each. I had another distributor with points that I popped in and it ran fine.


This problem started a week ago. I have an aftermarket cruise in the car that has worked fine for 7 or 8 years. It started disengaging after a minute or so. Looking back, it was a more severe "jolt" than you get if you tap the brake to disengage. But it kept getting worse, and it became obvious that something else was wrong. Yesterday, I tried to drive it and could hardly get up to 35 or 40. Terrible bucking and stumbling, but a different distributor and it ran fine, as did the cruise.

Professur

Sweet.

Charlie Jones

Just another point for points (pun intended) . In the Points vs. Pertronix argument. (On another thread)

Fun71

Agreed. Running the tank low would only be an issue if there were crud FLOATING on top of the gasoline.

Professur

Hence me terming it Urban Myth. I don't claim it to be fact ... but I've heard people swear it's happened to them for decades. And the one time I had a filter do that to me ... I'd just let it run as low as I've ever gone, and I didn't see a tanker when I filled. It might be when you reach a certain amount of gas in the tank, the lack of weight lets the bottom oil can up with a pop, shaking loose sediment ... I dunno. I just lay it out there and let everyone draw what conclusions they will from it. I didn't believe it myself, and changed out every inch of old vacuum hose under the hood first.

brown7373

I have had ONE Pertronix module go bad in 6 cars, and as many as 40,000 miles on one of them. I have had points go bad several times. I have had bad condensers. A set of points might last 12,000 miles with multiple dwell adjustments along the way. One failed module doesn't prove points are better in my book. I have a new Pertronix unit I am going to install tomorrow.

White_Knuckles

I'm certain your branded module is fine. However after too much reading on HEI goodness I've gone back to genuine A/C Delco modules. The legend that they are bad due to low rev limit yielding RPM breakdown is false. The modules were improved from first the generation buggers that started the tales. The aftermarket modules are touted to have goodness that may work for your application but I find the Delco's very reliable.

One tip that may be the secret to any units life is to use killer heat-sink compound. I read this in an HEI tuner article and now use computer CPU compound available at Radio Shack. It's called Arctic Silver and is way superior for transferring heat away from the module. Don't apply it heavy read the instructions.

brown7373

UPDATE Actually, the problem persists, so it is not the distributor or the module. The car ran fine for a day, then started all over again. Last Sunday, I made it 1/4 mile from my house, top down and it started bucking and stumbling and then it shut off and I couldn't get it to restart. Within about a minute, a fellow Olds with a '70 442 stopped to help. Together we agreed it wasn't getting sufficient fuel. He took me home and my wife and I were going to use a tow rope to pull it home. When I got in the car, for grins I tried to restart, which it did. I managed to get it back home and in the garage. I a replaced the fuel pump and it didn't help. But very little fuel flowed from the tank when I disconnected the line, so I think it is a restricted fuel line to the pump. All the rubber hoses on the vents and the pick-up and the splice on the passenger frame rail are a year old and they are the proper fuel injection or aviation rubber for fuel.


I dropped the tank yesterday and the pick-up sock is brittle and collapsed, and I think that is my restriction. I have a new sock, an plan to blow out the fuel line before I put it all back together. I don't see any areas on the metal fuel line that appears to leak or have a pin hole. Any way to check for small pin hioles that show no evidence of leaking? Anything else I might be missing?

Charlie Jones

The new sock will probably take care of your problem.
However, before putting it all back together. Check inside the tank with a flashlight and make sure there is no rust, dirt, or other debris, such as pieces of that old sock, in the tank.

brown7373

I did that yesterday. I inverted the tank and sloshed around the gas that was left. I saw zero rust and very little dirt of any kind. I am thinking there may be dirt and pieces of the sock in the fuel line, or in the carb filter. I will replace that filter and blow out the line.

Koda

On an old system, there will be the problem, and a lot of stuff that is marginal. Fix everything involved and do it once.

My grandfather's advice was: Never fill up when the tanker truck is there, or just after it left. My dad's comment: How do you tell when the tanker truck was just there if it's already gone?

classicmuscle442

Don't bother with filter sock in tank, not needed, fuels are cleaner now, easier to clean filter at carb than tank, new cars do not have filter(sock) in tank.

Charlie Jones

Not true. The newer cars still have a "sock" or some kind of strainer.
It is usually attached directly to the electric fuel pump.
Fuel,then as now, was always pure and clean when first refined. It's the stuff that gets in it during transportation, storage, and dispensing into the tank that is the problem. And the reason for the sock.

Fun71

I don't know what gas stations were like in the 60s but the ones I use these days advertise they have filters on the pumps to remove any particulates BEFORE they can get into the tank.

64Rocket

On my '70 Supreme did just about the same problem.
What I found was the old rubber fuel line joints, some had cracks and would suck air. You might replace all the rubber hose joints.

Gene

brown7373

I replaced all the hoses last year. But I dropped the tank. The inside looked pretty good, but I cleaned the outside and painted it with Eastwood Tanktone. It is not as good as a new, galvanized tank, but it looks a lot getter than the surface rust. The sock was brittle and collapsed on itself, but otherwise the inside of the tank was clean and rust free.


There was no evidence of water in the gas, and this did not correct my problem, som I move on the electrical side of the issue. Long story short, I was also considering a bad Pertronix module, so I put in a new points distributor I had on the shelf. If ran for a couple day fine, then crapped out and got REALLY bad. But it was my own stupidity. When I replaced the distributor, I forgot and also hooked up full time 12 volts that was there for the Pertronix. Just a bone head play by me, and it either destroyed the points or the condenser. When I put another set of points in and removed the full time 12 volts, it started instantly and has run perfectly.


Thanks for the help and ideas.

White_Knuckles

Is there a ceramic ballast resistor (12V+ series) now in the points circuit? Modules don't require them and most yank the resistor as unused. Your points can fry without it.

brown7373

All the original wiring is intact. The black & pink resistor wire and the yellow wire crimped together on the same connector is part of the original wiring harness. The 12 volt wire was installed for the Pertronix unit. The Pertronix was already installed when I bought the car in 2007. It has worked fine for 7 years and 20 or 30,000 miles. I have installed Pertronix in other cars a half dozen times and also had ZERO problems. However, I never installed a full time 12 volt wire to the Pertronix. I have always just used the factory wiring. I ran a Pertronix in a 455 Pontiac for 12 years and over 50,000 miles.

64Rocket

On one of my install of a pertronic unit, ran fine for a few days then ran somewhat bad. like it had a miss. Got checking and one of the magnets on the ring fell out. Might look at that also.

Gene

red70442

Actually the sock is a necessary component in the fuel system...The sock holds fuel when the tank is low allowing the vehicle to run while the last of the gas is sloshing around...My 68 impala sock fell off due to clamp rotting while sitting and I ran out of gas with 1/4 tank left going up a hill killing the engine just before the top of a bridge...The gas sloshed around but did not get pulled into the line...With a sock the gas is always available to be pumped out of the tank...Bottom line is the sock is not just a screen but a holder of fuel...I never, ever run a car without a sock and actually used one from an electric pump because it fit better than the original one and reached the very bottom of the tank...