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1974 Fleetwood died on me

Started by ithaca1230, June 02, 2017, 11:18:17 AM

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ithaca1230

Was driving the girl yesterday and she backfired once then drove fine 10 miles later she just quit. checked all the wires jiggled them and started up drove about a mile quit again started back up and drove fine all the way home about 20 miles. gonna repace all wires plugs cap rotor and coil. wondering if any of you can give me some insight as to what else to look at. Thanks

Billy Epthimiatos

Jeepers Creepers

G'day Billy,

My advice would be, don't just replace everything you've suggested straight away.
Try to go through each item on its own and try to decipher and diagnose the problem if you can.

Its an old drag racers tip, one change at a time.
If you change everything and fix it, you won't know what the hell was wrong in the first place.
If you change everything and make it worse, you won't know what the hell was wrong in the first place.

I'd be looking for something loose.
Kevin and Astrid Campbell
Australia

35-709

Right, some good old diagnostic work might bring up the problem without using the "shotgun" approach and save you some money.  Don't forget to check the condenser while you are looking for the problem and also look for a broken wire making intermittent contact.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

V63

74 could be points? Or the new electronic ignition?

As already mentioned, I would check for lose connections at coil. Check for clean internal ground strap on ignition coil (electronic) . If the tune up items are questionable and old...I would simply replace it all post haste.




35-709

Ooops, oh yeah, HEI.  No condenser to check.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

bcroe

Quote from: ithaca1230
Was driving the girl yesterday and she backfired once then drove fine 10 miles later she just quit. checked all the wires jiggled them and started up drove about a mile quit again started back up and drove fine all the way home about 20 miles. gonna repace all wires plugs cap rotor and coil. wondering if any of you can give me some insight as to what else to look at. Thanks  Billy Epthimiatos 

It does sound like ignition.  But make sure the timing chain is OK; it should
have been replaced by now.  Bruce Roe

Rich S

In addition to the suggestions made, consider whether your fuel pump is working properly--when was it last replaced? Just another consideration.
Rich Sullivan CLC #11473

1971 Eldo Conv., 2013 CTS Cpe

Glen

Back fire is a symptom of lean fuel.  One possibility is restricted fuel flow.  It is OK when idling but when driving the fuel in the carb is diminished until the engine dies.  Restarting refills the carb.   
Glen Houlton CLC #727 
CLCMRC benefactor #104

Scot Minesinger

1974 Cadillac the HEI was optional, points standard.  My friends 1974 Cadillac did the exact same thing, and it turned out to be the coil had to be replaced in the optional HEI.  There are also two wires that are inside the ignition that can break and cause this problem too.  The problem is likely confined to ignition, not fuel or unlikely been a backfire.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

EAM 17806

That same type of problem has happened to my 76 deville. The wire connection from the HEI kept slipping out as I drove a few miles when again I had to stop and push it in. I was on the highway and didn't have any tape to hold it attached so I had to keep stopping and push it together for another few miles until I got home and repaired the attachment.  Just make sure all the electrical connections are securely attached first of all.  EAM
Ev Marabian

1976 Cadillac Coupe DeVille, 1989 Chevrolet Caprice Classic, 1990 Pontiac Bonneville and 1996 Buick Skylark

ithaca1230

Thanks for the response! I changed the coil coil wire cap rotor and little round thing on top of coil. I was told I need a dwell meter to set points so I didnt do that yet and ran out of daylight last night so didnt change plugs, wires or fuel filter. It ran fine after that with no backfire. I have not changed timing chain yet or the fuel pump. They are on the to do list. Was hoping to do one thing at a time and still drive it around. Will let you guys know if it happens again.

Thanks again

Billy Epthimiatos

V63

It sounds like your 74 fleetwood is an early production as electronic became standard fare soon after.

Point ignition get 'pits' on them...and likely the problem. I would abandon that system and swap out the whole distributor to the electronic version. You 'might'  need the air pump tube that encompasses the larger assembly?

It's a world of difference in performance, reliability, economy and starting.


ithaca1230

I will have to look into this thanks!!

Billy Epthimiatos

35-709

#13
Billy,
Changing the "little round thing on top of the coil" will net you zero results with your problem.  All that is is a capacitor to help reduce radio static.  If it is bad all you will notice is more static on your radio, especially on the AM dial.  What you should be concerned with is "the little round thing" (the condenser) inside the distributor next to the points.  When this component fails it can cause some different ignition symptoms, one of which could be similar to what you are experiencing.  Sometimes the failure will cause the engine hardly to run at all, other times it will let the engine run fine at lower RPMs but will cause misfiring and backfiring when higher RPMs are attempted, etc., etc.

GMs HEI ignition is great, but a much easier and probably less expensive route would be to convert to a Pertronix II system with their coil.  http://www.pertronix.com/  I haven't taken notice lately but there has been a vendor in the Self-Starter advertising Pertronix systems at a discount for CLC members for quite some time.  I have done several of these conversions and they have always been trouble free for me.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

V63

I have used pertronix...and its 'ok' but no comparison to the OEM electronic system introduced as standard fare in 1974.

It's fairly easy to 'swap' systems. The whole distributor is replaced, wires and plugs. A heavy gauge wire is required to supply the power.

Even a novice should accomplish in an afternoon. An expert in 1.5 hours.

Most important to research exchanging distributor and maintaining the timing....that will cause you the most grief.

ithaca1230

Thanks for the recommendations. I am going to look into this stuff. A buddy gear head was saying something similar. For now just gonna change all the existing stuff. Next big repair is the timing chain and fuel pump. Oh and get the radio to work on more than one speaker so kids will ride with me.

Thanks

Billy Epthimiatos

ithaca1230

Well figure out the problem. As I drove the car to my buddies house to finish the tune up she backfired so hard it blew the muffler open at the seam. Scare the crap out of me. Started pulling wires and plugs and there was a couple real bad ones. I cant believe I didnt start with that when I first got the car but it was running fine. Having a new muffler put on her now. If I figure out how to get pics on here I will show you the muffler it is impressive.

Glen

In my earlier post I assumed the backfire was through the carb.  Obviously, I was wrong. 
What you have is unburned fuel getting into the exhaust.  My father had a Buick that exploded the muffler in the same way several times.  Usually when starting the engine. He finally figured out what was wrong.  It was a burned valve.  We never figured out the mechanism as to how that worked, but the older parts guy at the NAPA store told him it was common. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

Jeff Rosansky CLC #28373

It's possible you also have a sticking valve which would be similar to the burnt valve mentioned above.
Everyone has there own idea on freeing them up but some good old fashioned Marvel's in the oil mite help....... Can't hurt.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

V63

#19
The carburetor could be 'overflowing' causing raw fuel to accumulate in the exhaust system. Are your spark plugs or tail pipe coated in heavy black soot?

FYI Did the fuel go fuel 'stale'? .a very common occurrence after 4 months with alcohol blended fuel. Very first thing I check on any old car...is I remove the fuel cap and sniff for stale fuel. People do not realize  stale varnish gas it is like having sugar in the gas. It WILL stick your engine valves open or cause them delayed action. Dilution is not the answer...REMOVE it! Needless to say it also causes havoc in the carburetor and everywhere else. Typical of a stuck valve, in this varnish gas scenario , is the car will still run when it's warm...and your compression test would be ok. Once the engine cools the valve guide seizing is in place. The next morning the engine has a dead miss (minimumly) or won't start at all.