Slant Six Bogging Down!

-
LeaningTower

LeaningTower

Active Member
Joined
Jan 8, 2015
Messages
27
Reaction score
0
Location
Georgia
Having some issues recently with my engine bogging down and eventually dying. It will start up just fine but it seems to be when I am under any sort of load that it will sputter and run very slow. For example I will be on the gas and it will start to sputter until I let my foot off to 10% throttle or less. I ended up going 20mph all the way up a hill with a huge line of traffic following. I have had a misfiring issue that seems to have been getting worse over the past few months, don't know if that would have any effect on my problem. I have changed out the ignition coil, plugs but not wires. Not sure exactly whats wrong (If it is a fuel issue, ignition problem or something else), I have look at other threads but can't seem to find the answer. Any help would be appreciated.
 
Sounds like either a fuel supply issue or exhaust restriction. If your air filter had gotten wet the paper fiber often becomes too dense to pass air in its original efficiency. Year model, type of ignition and any mods? Try it with the fuel cap loose. Or when it does this see if there seems to be pressure of vacuum in the fuel tank.
 
What year of car? We may need to know if it is a points ignition or electronic system.

If points, have you adjusted the points gap?

Fuel delivery is the most likely issue. What have you done to the car as far as fuel filter changes, cleaning the fuel tank out, etc.? Did this car sit for a long time at any time in its life?

Also, check the rubber hose coming out of the tank to the hard fuel line and form that line into the fuel pump. A crack in either rubber line will suck air instead of fuel.

Do you have:
- Voltmeter
- fuel pressure gauge
- access to compressed air
- a place to drop the fuel tank
 
nm9stheham said:
What year of car? We may need to know if it is a points ignition or electronic system.

If points, have you adjusted the points gap?

Fuel delivery is the most likely issue. What have you done to the car as far as fuel filter changes, cleaning the fuel tank out, etc.? Did this car sit for a long time at any time in its life?

Also, check the rubber hose coming out of the tank to the hard fuel line and form that line into the fuel pump. A crack in either rubber line will suck air instead of fuel.

It is a 67. I have not adjusted the points. I have recently changed out the fuel filter but have not removed the tank. As far as I know it is the original tank and has never been removed. Also no crack in the hose running to the main fuel line or to the pump. Could it be that the lines are clogged with debris?
Click to expand...
 
I know it is a stupid question but is there any specific compression tester that I would need for my engine?
 
UPDATE. Now I am not even able to make it 10 feet without the engine completely bogging down and dying! It will crank back over and idle but when I give it any gas it chokes and dies.
 
something similar happened to me, check if your carburetors float has a hole in it, I got stranded because of this.
 
I had rebuilt my carburetor, but I neglected to replace the float because it tested fine; That was a mistake, as the float had developed a leak. As I was driving in the car started to bog down a little at a time, it would run, just not well. I kept going and eventually the car wouldn't start because it was completely flooded.
I had to call my dad to get the trailer and come get me out of a chinese restaurants parking lot at 1 AM. Not fun.

Im not sure thats your problem, but it sounds similar to what happened to me, so it would be something to check.
 
Personally I'd dump the points and upgrade to a Pertronix. It's one less POS item that you have to deal with. You have enough help on your problem so I'll keep quite. Good Luck
 
spark plug wires, have at minimum a 1/2 tank gas, try no gas cap, test with any compression tester with 3/4" threads
 
To the OP: Let's find out some basics and the general area of the problem before you make any big changes. You need spark, fuel in the right amount, and compression. The fuel supply is the main suspect based on what you have said; testing for that and spark are pretty easy so do those before messing with compression.

- Does the car start fairly reasonably? If not , please describe
- When it idles, does it idle fairly smoothly or is it very ragged or just barely running?
- If you give it gas gradually when sitting still in neutral, will the engine speed up?
- Is there any particular smell of gas around the engine?

Do the following:
1. Pull off the center spark plug wire from the distributor cap (the one from the coil) , and place the end of the wire 1/4" from metal and crank the engine. You should get a regular sequence of good, blue sparks.
2. With that spark wire still off, do the following 3 fuel system tests:
a) Remove the line to the fuel pump coming from the tank and put on a longer hose, and see if you can blow any air back into the tank. Remove the gas cap first. It may have some resistance, but you should be able to push a fair amount of air back if you have decent lungpower.
b) Reconnect and then disconnect the fuel pump outlet line and connect it to a fuel pressure gauge. Crank the car and see if you get 3-5 psi pressure. If you get pressure, then it should hold for many minutes after you stop cranking. (A simple fuel pressure and vacuum gauge is easy to find and not too expensive.)
c) Then take off the pressure gauge from the fuel pump outlet line and put the line into a can. Crank the engine and see if it pumps a pint to a quart of fuel in 30 seconds of cranking.

Let us know what you find.
 
nm9stheham said:
To the OP: Let's find out some basics and the general area of the problem before you make any big changes. You need spark, fuel in the right amount, and compression. The fuel supply is the main suspect based on what you have said; testing for that and spark are pretty easy so do those before messing with compression.

- Does the car start fairly reasonably? If not , please describe
- When it idles, does it idle fairly smoothly or is it very ragged or just barely running?
- If you give it gas gradually when sitting still in neutral, will the engine speed up?
- Is there any particular smell of gas around the engine?

Do the following:
1. Pull off the center spark plug wire from the distributor cap (the one from the coil) , and place the end of the wire 1/4" from metal and crank the engine. You should get a regular sequence of good, blue sparks.
2. With that spark wire still off, do the following 3 fuel system tests:
a) Remove the line to the fuel pump coming from the tank and put on a longer hose, and see if you can blow any air back into the tank. Remove the gas cap first. It may have some resistance, but you should be able to push a fair amount of air back if you have decent lungpower.
b) Reconnect and then disconnect the fuel pump outlet line and connect it to a fuel pressure gauge. Crank the car and see if you get 3-5 psi pressure. If you get pressure, then it should hold for many minutes after you stop cranking. (A simple fuel pressure and vacuum gauge is easy to find and not too expensive.)
c) Then take off the pressure gauge from the fuel pump outlet line and put the line into a can. Crank the engine and see if it pumps a pint to a quart of fuel in 30 seconds of cranking.

Let us know what you find.
Click to expand...

Working on getting the car back, due to the fact that it died in a parking lot. I will definitely let you know the results.
 
nm9stheham said:
What year of car? We may need to know if it is a points ignition or electronic system.

If points, have you adjusted the points gap?

Fuel delivery is the most likely issue. What have you done to the car as far as fuel filter changes, cleaning the fuel tank out, etc.? Did this car sit for a long time at any time in its life?

Also, check the rubber hose coming out of the tank to the hard fuel line and form that line into the fuel pump. A crack in either rubber line will suck air instead of fuel.

Do you have:
- Voltmeter
- fuel pressure gauge
- access to compressed air
- a place to drop the fuel tank
Click to expand...

Ok, I think I have solved the problem. The fuel pickup in the gas tank was clogged from rust and a lot of other garbage. My guess is that the pickup was getting clogged with all the trash causing the engine to be starved of fuel, misfire constantly and eventually die. So for the time being I am replacing the tank and the sending unit. Along with completely blowing out the gas lines.
 
LeaningTower said:
Ok, I think I have solved the problem. The fuel pickup in the gas tank was clogged from rust and a lot of other garbage. My guess is that the pickup was getting clogged with all the trash causing the engine to be starved of fuel, misfire constantly and eventually die. So for the time being I am replacing the tank and the sending unit. Along with completely blowing out the gas lines.
Click to expand...

I'd do a rebuild on the carb as well.
 
My 69 slant did that on a cross-country trip in 1989. It would start stumbling above 55 mph on the flats and less up-hill. Seemed worse in the afternoon and especially as we drove into NM on a hot day. I found the fuel inlet hose at the fuel pump was soft and thus collapsing at higher flows. Swapped in new hose in the parking lot and drove the rest of the way to CA at 65 mph, and smiling. One of the few times my wife thought I was a genius. Our 2nd boy might have even been conceived that night. That was about the time they started putting ethanol in the gas, especially as we went west. Use only "fuel injection" hose today or will have problems. Also check the fuel hose at the gas tank. But could be any of the fuel problems mentioned above. Too much spark gap can do the same, but you changed plugs.
 
UPDATE, I have replaced the points along with the condenser, rotor, distributor cap and distributor gear (since it was split in two!) This provided me with NO change with my problem, but needed to be done. Thought I would throw it out there.
 
Did post #15 fix your problem?
It sounds like post #18 was just to elaborate, not that you still have the bogging problem.
 
BillGrissom said:
Did post #15 fix your problem?
It sounds like post #18 was just to elaborate, not that you still have the bogging problem.
Click to expand...

For the time being yes changing the tank and sending unit has fixed my problem and I can see how much gas I have:D. And post #18 was just to let you guys know that fixing those things did not help fix the problem.
 
Very good... hope it is pretty well licked now. From the symptom description, it was a bit hard to say if it was one thing or another; with general symptoms, there are usually several possible causes and you just gotta go through each, one at a time. With an old car being resurrected, all those checks and many of the parts replacements are necessary anyway for any reliability.

What particular test or check did you do to finally key you in on the tank and pick-up being the problem?
 
Well when I removed the fuel filter and found large deposits of rust and gunk. So I bought a new filter because I was not sure when it was last replaced. I then after a week of driving I pulled out the new filter to see if it had picked up anything and it turned out to look just as bad as the old filter that I had pulled. When I got to thinking about what could be in the tank I knew that the original owner of the vehicle was an elderly woman who had let the car sit for long periods of time in between driving. This causing oxidation in the tank #1. Also the gas gauge did not work which was either do to a rusted sending unit or a broken or dissolved float or both #2. So I decided to remove the tank and sending unit to see what was living in there and I found the sock around the pickup was clogged with junk that was in the tank. As I said in another post, I then went on and replaced both the sending unit and tank and have yet to have a problem.
 
Great you're back on the road! On a side note, thanks for following through on your thread with what ended up being the problem, and solution.
 
UPDATE! Still having fuel issues, (or at least that is what I think the problem is) not as bad as it was before the new tank was put in but still laggy. I think it has to to with the fact that the car misfires really bad. It will misfire at idle quite bad, also when I drive but I can't hear it after a certain point, but when I let off the gas I can hear it still misfire. Was wondering if it could be the valves or the fuel pump? Any knowledge would be very much appreciated. The misfiring issue has been continuously getting worse over the past few months.
 
If it is just an erratic misfire, then I would be inclined to look at the ignition system.

The description of 'misfire' needs some more explaining. Is it erratic, or steady, like consistently on one cylinder?
 
You must log in or register to reply here.
-

Back
Top