Hey guys,

73 280sel 4.5 we're dealing with. Basically, the car sat for maybe 2-3 years before I got it last year. I never cleaned the tank, and I don't know if that is what is causing this problem:

Basically, the car has run fine all winter long, but has always had a little problem with hesitating on acceleration. Just today, it was about 85 degrees, and the car has EXTREME hesitations where the car will basically just does nothing, but I get backfiring in the intake and in the exhaust. The car will do this until I kick the pedal a couple times usually. If that doesn't work, I pull the car, and restart it. In between these hesitations, the car will run flawlessly. I am going to be replacing the points soon, but I have already replaced the wires, plugs, and cap, as well as the fuel filter. It is my 2 cents that I am having problems with a bad fuel tank sending in bad gas, or even just getting clogged. One thing I noticed is the fuel gauge has recently been getting a little nervous twitch right when the car starting having these hesitations. The needle will only bounce, and then go back to the correct position.

Any hints? I was hoping the jumping fuel gauge needle would be a tell tale sign of something, but that is where you guys come into play!

Thank you very much.

Sam

I had that with my 4.5 before. A new cap cleared it right up. I would suspect the cap or the rotor first. If you're backfiring through the intake and/or exhaust, it means you're getting fuel but not burning it.

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

That could work... I never did replace the rotor, but the cap and wires are brand new. I'll give it a try and get back to you. Thanks.

Sam

backfiring through the intake is often a sign of the ignition timing being off as well.

may want to check your centrifigal and vaccuum advance (retard) mechanisms while you have the distibuttor cap off. might be a good idea to check the trigger points as well for oil fouling.

if you have a fuel pressure gauge, you could also "T" this in and watch it while the car hesitates; then you can at least determine if you've got a fuel delivery issue or ignition issue.

just a few more ideas...

P.S. did you get your windows working?

This sounds to me like classic fuel starvation. I would start by replacing the fuel filter and cleaning the strainer in the fuel outlet from the tank.

If you find a lot of rust in the strainer, you will need to find a tank in better condition, or the existing one boiled and coated or the problem will keep coming back. That's been my experience with cars that have sat for long periods.

A lean condition will also cause a backfire.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Fuel filter is new, and I believe if it was caused by rust in the gasoline, it would happen more consistently, rather than specifically on acceleration. It very well could be the timing... I am going to be checking all this this coming week. Can anyone explain the recent bouncing of the fuel needle? I would not think that it is coincidental that the two happen at the same time.

I think one way or another, I should get the tank cleaned, just for good measure.

Ozawa:
switching in your prongs didn't do the trick, so as soon as I get a free minute, I will switch the entire unit in and see if that doesn't work.

o, and how would I go about getting the strainer out of the tank? That could help if it was tank related.

Sam

Fuel needle bouncing is a sensor issue. I had that a while ago, but it seems that 2 tanks of fuel system cleaner and sitting a while with an empty tank resolved that. At one point, I had to go off mileage because with a full tank, my needle would bound between full and R...

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

What I think is happening is that the tank screen is clogged, reducing fuel flow. When you try to accelerate, more fuel is needed, but not delivered, so you go lean and backfire.

When you pull over, you allow fuel to drain from the tank into the filter and accumulator, so the car runs OK for a while.

You may also have some crud in the fuel distributor and injectors. Some Techron or BG-44 in the tank, once you get it squared away, might help.

The bouncing fuel gauge is probably as sticking sending unit. You can remove the sender from the tank through the trunk floor, and soak it in a can of carb cleaner overnight. Flush it out and put it back in and it should be OK. You can also get a good look at the inside of the tank through the hole.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Here's how I do it. Pic #1, hex head drain plug in bottom of tank. Pic #2 inverted spark plug socket and pipe wrench, pic #3 is self explanatory.

The plug is a soft brass alloy so make sure the socket fits tight. It's better to give it a quick "rap" on the pipe wrench than to slowly increase torque. There is an "O" ring which seats between the tank and the plug. make sure it is clean and apply a light smear of petroleum jelly to it when you re-install.

There will still be fuel and some sludge in the tank no matter how empty you think it is. Have a drain pan ready.

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Couple of thoughts...

On the tank drain, good idea for the drain plug. Here's a suggestion: take the spark plug socket and slice out the rubber plug-holder insert with an exacto knife. Then you can use a standard socket extension inserted backward through the hole into square extension slot. Use a Tee bar on the extension to give slow steady two-handed twisting force on the Tee bar to remove the plug. You won't need a pipe wrench, which gives you unbalanced force and tends to slip on a good day.

On the gas gauge, it may or may not be relevant. Does the needle jump when you knock the dash gauge with your finger? If so, it is probaby a bad gauge. If not, look at the sender, but not until after you have done the strong fuel cleaner bit. My Costco has 4-packs of Techron fuel system cleaner for less than $10. Many folks think it is the best cleaner.

230/8

Just got off for spring break today, so I now have time to do all of this. The inverted spark plug socket is a great idea! Is the strainer accessible near the drain plug? should I do anything to drain the excess gunk out of the tank?

Thanks for the help guys, as I said, I will keep you up to date.

ftp://members.aol.com/ajdalton7/Tank-Hex.jpg

nice! thanks for the picture. Tomorrow, the tank.

By the way, how amazing is it when you drive your car knowing that you have to waste gas?? hahaha

Someone stuck a ping pong ball in the gas tank.

When you ask for lots of fuel, the ball would drop down, stop the flow and the car would stop.

Take it to have it checked out, and it would drive around the block just fine..