The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Coughing Fit

My wife and I were were cruising to Truro in our '65 C20 (292) on Sunday, a beautiful fall day, when she (the truck, not my wife) started to cough and sputter and lose power. We stopped a few times for the truck to recover and I added gas treatment to no avail. With some backfiring and smell of gas I am thinking it is either the plugs, fuel filter, or fuel pump causing the problem. Any ideas regarding possible cause as well as the best plugs and pump to use would be appreciated. Thank you.

Don't think a bad plug, does sound like fuel delivery maybe. A few of the normal tests will find it. I hope it's not the beginning of a timing gear/chain slip. (that's the backfire part). But could be carb/choke thing. Not enough concrete info yet to determine what of many things it could be. Time and/or testing next. Do you know the procedures/tell tales?

Points? How do the points look?

I am less than a "backyard mechanic" so this is all new to me. The truck doesn't have any points as I had an electronic ignition installed a few years ago.

Are you in the mood to dig in or just want some possibilities for pricing a shop? It does take some knowledge and some tools. But we are all glad to try and help. It's going to be questions, observations and tests. Can be anywhere from "out of gas" to dirty air cleaner to valves at this early stage. Recover? Did it "recover"? What did it do on the way home and at home? What is recent history of work done? Starts? Idles? backfires a lot? did it once? more? For now, Visually check for loose or burnt plug wires or ignition wires. See if choke butterfly is stuck. Any gas leaks at carb or other, leave gas cap loose next drive. Observe any other info you can give. Backfire is a good clue so describe specifically how often and if "backfiring" at carb or tail pipe or both. And do you really mean backfiring. Chitty Chitty bang bang?

Thank you for your help and interest. I would like to fix the problem myself but it doesn't take long before it is beyond my expertise. By "recover" I mean that I was able to restart the truck with some difficulty after letting it sit for a few minutes. It ran well for about 15 miles and I thought that I had solved the problem with the gas treatment. Then it started to sputter again and backfire (not often though) through the exhaust pipe. I stopped again for a few minutes then got home. I haven't started the truck since. The air filter is an oil bath one but the oil looks pretty clean. The truck was in the body shop being restored for almost two years which probably didn't help the gas.

Trash in the gas tank blocking or partially blocking the fuel line.

1. When did truck come home from shop?
2. How many drives/miles since coming home from shop?
3. Was gas in tank those two years?
4. Backfire is not a symptom of fuel shortage. It's a symptom of too rich or no. 5 issues.
5. You may want to check plug wires for cracking, distributor cap crack, timing if you can, choke operation, idle speed, vacuum hoses, carb hold down fasteners.

My current best guess.
You did say you smelled gas= Scenario of: carb sending too much gas to manifold.. backfire.. flooding then stalling, waiting for drain off, restart, re-flood.

Which possibly is:
Carb float/needle valve not shutting off gas or wrong/too strong/"custom" fuel pump.

This is more likely than timing but there is Murphy's Law to consider.

What recent work done?

I have read where "backfire", better known as spitting/sputtering/coughing fit thru carb, can be too lean....but so far you say tail pipe. Aye? Bang bang shotgun pow!?

If it has been sitting in a shop for two years I would start by draining the gas tank, then change the fuel filter, drain and clean the air filter. If that doesn't clear the problem, check the vacum advance on the distributor along with plugs , wires,and rotor. As far the timing, there is no timing chain on that engine, it is gear driven, unlikely that is the problem. If the gas was in the tank for two years sitting in a shop the carb. could need a good cleaning also. good luck finding the cause of your trouble. We are all hear willing to help you, just let us know what you find.

Thanks guys for your advice. The truck was in the shop for almost two years with gas in the tank. I didn't realize it would be there that long. However, I drove it all summer with no problems whatsoever. I checked the plugs and wires tonight. The wires look fine as they are fairly new. The plugs look OK (they were installed with the wires) but I may still change them. The fuel filter is the type which is located at the bottom of the carburetor. Do you know if this filter is still available?

Yes it is still available.

OK so I guess the answer to my no. 2 is you have driven it all summer. I will assume, since you didn't say how many miles (question 2), that you have filled up the tank several times and have driven a good amount of miles with NO problems until now. You have probably diluted/absorbed the bad gas. It could be that you have absorbed the residual bad "gum" into the carb, the filters, the gas tank pick up screen and maybe the fuel pump. This ain't good. I don't think clogging is your problem but it MUST be eliminated post haste. So, new filter(s) everywhere, new pickup screen or clean, a carb rebuild and I guess a fuel pump. Then see what happens. I think it is unknown if this backfire, stalling is every time you drive now or not. Not trying to tell you to just throw money at it in a shot gun way of solving the issue but these things should be done anyway for the most part. If you decide to do some of it (the easy parts) you may clog up the new parts and be back at square one. This advice is just my best judgement using your money.

Thanks Tommy. I drove the truck all summer, probably about 500 or so miles. Definitely quite a few tanks of fresh gas.

Sorry, was still typing when you posted. Better re read my post if you care.
Good luck.

I understand what you are saying and I appreciate your input. If all these items need to be addressed it is definitely above my pay grade. Obviously I have to do what is best for the truck.

Very nice looking truck and home.

if you are getting gas and spark it should run, nbut somewhere in there the system is breaking down. usually it is a systematic process that things have to be checked. putting in gas treatment will just take your money. compression check will tell an ideal of how the top end on your engine is. burnt valves will cause backfiring as will ign timing. you say that someone installed a HEI system in your engine. a lot of people over look one item when they installa het in these vehicles and that is that they do not remove the resistor wire or resistor coming to the ignition that was used with the original system which supplied 9 volts(resistor knocks it down from 12). HEI requires a full 12 volts. you eliminate that resistor or resistor wire with a new 12 guage wire.
.finding these kind of problems are just a process of elimination. if you are going to keep the truck, buy s few tools that will let you check things for yourself. if you have any interest you will learn. most of these testing tools do not cost that much, but thety will simplify the process. timing light , compression guage and a pressure guage foe checking fuel pressure from the pump.
Bart gets a little exuberant sometimes
.your diagnose doesn't really give anyone really the info to give you an answer online other than a guess
sometimes you just have to get a little grase on you
ron

Thank you Bart for the compliments. The truck looks much nicer now that it has been restored. Ron, thanks for your input. I have a friend who is a fantastic mechanic (he installed the HEI) who has all the tools. I will probably ask him to look at the truck. I don't mind doing some work but I do want to get to the root of the problem.

is he a backyard mechanic or a real one. ids he a friend who just knows a bit. there are a lot of younger real mechanics out there who have never worked on a points ignition who are ignorant of them. they wouldn't be aware of a resisted wire or resistor in these vehicles
ron

Oh, he is a real mechanic alright. He is very, very good and really knows his stuff.

How old is this real mechanic?

Points gone after 1974.

Last year non-computerized carburetors 1980.

Last year computerized carburetors 1988 Chevy, 1990 Buick and Cadillac.

So if your mechanic was born 1982, grad HS 2000 chances are he does not know $h!t from shinola about the old cars because schools stopped teaching points and carbs long before he entered HS shop class. And Chances are good that in his career he may of not got to work on cars older then 10 years when he started out.

Not saying he or you can not learn.

Why are you attacking a mechanic without knowing who he/she is or knows? Nothing here indicates he/she did anything wrong. This is a normal engine problem question which needs troubleshooting.
Easy boyz. I'm getting exuberant.

Not attacking. I do not doubt the OP's word. His friend can be good. And I closed with no reason why the OP or his friend can not learn.

Though being if the OP's friend is 34 years old and had no prior interest learning about old cars he may not have the knowledge or experience. This is why I asked how old his friend is. Jeffrey

He is probably about 50 or so (like me) and is a master on classic vehicles.

We have many younger mechanics who frequent these pages. For the most part they are competent and proficient on these old vehicles or they are smart enough to ask questions of us older and maybe more knowledgeable folk. For you just to assume that anyone younger than 40 has no knowledge or experience is just plain insulting.
If you had taken the time to read Cape65C20's posts you would have found out the truck had been changed to HEI some time ago, therefore no points or condenser to worry about.
Take a step back Jeffrey and try to be more nurturing to the younger generation and not try to run them off with offhanded remarks. They are, after all the future of our hobby.

if he has a good mechanic then it shouldn't be a problem
I only brought up the resistor wire as it is a common overlooked item and it does cause a problem
A lot of people also say somebody is good when they do not really know what good is. I see it in my business constantly and it is the same in the automotive industrty.
there are always good young guys out there who can figure things out, but thyere are also a lot of young and old that can't
ron

fuel filters are aviable at napa