: Help! My hearse is killing me!

05-01-11, 08:22 PM
Hey! So, I'm having a rather irritating issue with the 81 fleetwood superior. I can drive for a good while, and she performs absolutely flawlessly-but, after a while, I end up with a serious issue. It chokes out as I accelerate-like its not getting gas, but doesn't die(unless I peg the throttle). At first I thought maybe the carb or fuel pump were the issue, but it doesn't happen all the time. Same with a vacuum leak-if that were the problem, I assume it would happen immediately upon ignition, and would affect the idling. It's like it only does it around the top end of 2nd or 3rd gear.... AnyOne familiar with these 8-6-4 motors? Any ideas at all?

05-01-11, 08:37 PM
Maybe I'm wrong, but my guess is your cat is plugged up... I don't know what state your in, but what I have done is this... Measure the cat body and by a muffler that is the same size... Then take off the cat and cut the bent pipes off and weld them to the muffler so it fits right in and looks like a cat..or you could just have a test pipe made ... but then again maybe I'm wrong and it's not the cat....

05-01-11, 08:41 PM
I'll definitely look into it. TX only does emissiOns testing in the bigger cities, and it's over 25 years old so it's not required. I might just hack it all off from the cat back... Thanks for the suggestion!

05-01-11, 08:48 PM
Does the V8-6-4 still work?

When it happens, can you smell gasoline?

05-01-11, 09:01 PM
As far as I know, and judging by gas consumption, I'd say the 8-6-4 has been disabled. Had the mechanic make sure it was disconnected.And there's no gas smell, but a rough idle...

05-01-11, 09:36 PM
How long into a drive does it act up? On the highway or in the city?

05-01-11, 10:00 PM
That's the tough part. It started to after about 150 miles of straight highway the first time. The second time, I had ran quite a few errands in the city(put about 45 miles on the odometer). I had shut it off and started it 3 or 4 times.

05-01-11, 10:33 PM
Sounds like a heat-sink problem. When electrical components (such as the fuel injectors, spark plug wires, ignition coil, or distributor) get hot, the resistance increases and the component begins malfunctioning. Cadillac used throttle body injection for 81 (check to make sure yours still has TBI) and if the injectors are old, they could be heat-sinking. Have a reputable garage test the resistance of the injectors when they are hot.

05-02-11, 12:15 AM
I didn't see injectors when I was going through it-granted, the valve covers on the 8-6-4 are ENORMOUS, but I thought the commercial chassis was carbureted. I'll definitely look into it. I appreciate it.

05-02-11, 10:06 AM
Not all hearses were built on the commercial chassis. If it had the V8-6-4 connected to the 368, then it is (or was) fuel injected.

05-02-11, 11:10 AM
Good to know. Thanks for the help!!

05-02-11, 09:40 PM
Ok. Drove it today, and it started acting up after maybe only ten minutes, so the problem's getting worse. Would this still be the heat sink issue?

05-02-11, 10:51 PM
Not if the engine wasn't hot.

If you can, pull out one of the spark plugs and see how cruddy it looks. The car might need a tune up.

You could also try cleaning the throttle body and linkages. They could be binding or sticking.

05-02-11, 11:37 PM
It was warm, but not up to full temp.(the guy before me installed a water temp gauge). It had been sitting for two years before I got it, so first thing I did was change the oil, plugs, wires, distributor cap and rotor-so I know that's all new. I can use carb cleaner on the throttle body, yeah?

05-03-11, 12:16 AM
Yeah carb cleaner will work.

05-03-11, 12:26 AM
Ok. Thanks. I hate chasing down gremlins- I'm much better at just replacing parts!

05-03-11, 01:08 PM
Oh, could it be the fuel pump or filter??

05-04-11, 01:56 PM
Can we see a photo of this hearse, and engine? Especially if it's a commercial-glass '81 Superior, I am convinced the motor is a 4bbl 368, not 8-6-4. If it's a standard roofline chances are it's not a Z-code commercial chassis and then could indeed have the V8-6-4. Comm. chassis were carbed 368's up until 1984.

05-04-11, 07:43 PM
absolutely. Should be able to upload pictures tonight-if not, tomorrow. And again, I appreciate any help I can get-this is my daily, and I can't afford to pay a mechanic to track this down. Plus, most mechanics don't have experience on a car this old-and especially this model. I'm pretty sure it's not a standard roofline, and I swear I saw an intake manifold... I'm hoping it might just be a dirty/bad carb, or any kind of fuel flow issue. But why only when it gets warm?

05-05-11, 10:49 AM
ok, so here's the external shot. I'll get one of the engine shortly....

05-05-11, 08:09 PM
Looks like a de Ville... All commercial chassis were Fleetwoods. Some of the coach builders used de Ville bodies to make hearses, limousines, and flower cars; these would have the base engine for that year (the V8-6-4 in your case).

05-05-11, 11:58 PM
Well, the VIN contains a GEeZ.... Wouldn't that make it a commercial?

05-06-11, 12:24 AM
Post the entire VIN...

05-06-11, 11:44 AM
No dice.
I decoded the VIN myself, and this is what I get:
Year 1981
Make Cadillac
Driveline RWD
Model Fleetwood
Trim Level Ambulance
Engine Type 6.0L V8 OHV 16V

05-06-11, 09:11 PM
Then it is a commercial chassis... The VIN is 1G6AZ906#B91#####, right?

cadillac kevin
05-06-11, 09:18 PM
there isn't an ambulance trim level or body style. caddy didnt make ambulances then. thats what a conversion/ coach company did. and as far as I know conversion companies dont alter the VINs to reflect what they made out of the car (if car is a hearse, limo, etc., VIN will bring it up as a sedan or commercial chassis, whichever one it left the factory as).

05-07-11, 12:45 PM
that's just what popped up on the VIN decoder I used. the VIN is a 1GEEZ906#B92####. Regardless, I'm convinced That it's a commercial chassis, and therefore carbureted. since that's nailed down, Back to the issue @ hand.... I'm unable to drive it for much more than short errands until I figure out what's wrong with it and fix it.

05-08-11, 10:25 AM
I still sounds fuel related. Does it have throttle position or idle control sensors? I've been told that, when a motor is starving, you can spray starter fluid down the carb and it will act better. So next time it starts acting up, you could spray some fluid down the carb and see if it brings the idle back to where its supposed to be. Or put a fuel pressure gauge on it and drive it around until it starts acting up again.

05-08-11, 08:18 PM
I honestly don't know if it has those sensors. I'm looking thru the haynes now, and will get back on that. I'm replacing the oil pressure gauge in the cluster with a fuel pressure gauge(on payday, of course). got some carb cleaner, though, and am going to thoroughly spray it down tomorrow. also gonna put in a clear in-line filter to see if there's crap in the gas. I REALLY don't want to have to drop the tank and change the pump-it still has @ least 16 gallons left in it!
Anyway, thanks to everyone for the assistance, will post results soon....

05-08-11, 09:47 PM
The pump is on the carburettor; it's mechanical not electric.

05-09-11, 03:25 AM
in that case I believe I'll install an electric one.

05-09-11, 02:16 PM
You would need to install a pressure regulator into the fuel line and there would probably be issues with it flooding until you got the pressure right.