My limo won't run

[1975 Fleetwood Limo]

I have another issue with My 1975 Fleetwood limo. Over the past winter I removed the heads,to drill out broken exhaust manifold bolts. Once it was all reassembled, I went to start it, and all it wants to do is backfire thru the carburetor, sometimes will also belch a little fire. The distributor was not touched,and all plug wires were marked and installed in the correct firing order. I ran the firing order several times and it is correct.

When it would actually run for a few minutes it would barely make 200 RPM with pedal to floor,and would backfire before it quit. I also took the gas line loose,and pumped some fuel into a jar. It looked brownish in color. What in the world is wrong? I missed another summer of cruising, what do I do next?

[LorcinLS1]

Mine for awhile did the exact same thing. I found 2 wires reversed and a few other things that needed attention. I'd guess you installed new plugs since you had the heads off. You also have checked the firing order that all wires are correct. You may want to check the contact points on rotor and cap, mine needed to be cleaned. May want to check the points too, if it applies to your motor. From there I'd give it some fresh gas. I just went thru some similar things with my 84 not running correct and it was mulitple problems. I did all I mentioned and even had to drop the fuel tank and found the pick up screen clogged as well as the check valve on the new fuel filter wasn't opening properly. Carb also got rebuilt and car is running fine. Sometimes its best to walk away for a few and then recheck.

[travlinman]

The 75 should have an HEI. If Your'e convinced its wired right, I would get a long piece of 3/8 hose from the fuel pump inlet to a gal jug of gas and see what happens. Check the filter in the carb too. Doing this eliminates the fuel tank and lines. You can also pour gas thru the vent tube and it should start right up and take off.

[1975 Fleetwood Limo]

Yes, mine has HEI, I installed new cap,rotor,module,and pick up coil. I will get a gallon of gas,and try that. I know the previous owner for some reason spliced in an inline filter close to the carb inlet. Maybe the gas has something to do with a stalling issue when hot I had last summer

Thanks for the info and help, hoping to get a little cruising in before winter

[Dickey]

What you're describing is often experienced when the distributor is installed a single tooth out of phase, so your wiring can be entirely accurate but the distributor itself is 15 degrees one way or the other. A timing light will determine this absolutely without too much hassle. I suggest turning the engine over without any fuel being available (carb bowl needs to be empty as well) so that you don't risk a backfire doing the check. With a freshly charged battery, you should be able to turn the engine over 2-3 hundred rpm in order to get an idea where the timing mark is.



edit - My bad, I totally missed the detail where the distributor was not touched. I'll work on my reading comprehension but I'm leaving the above in case someone with a similar issue should stumble across this thread. That said, I still suggest a timing light just for shits and giggles to make certain your number 1 is firing when you expect it to be.


btw - how is it that a distributor is not touched but you've installed all new components in it?

[Morella]

Brown gas may be part of the problem. Does the gas smell like shellac? If so, you'll have to drain the tank and get some fresh gas in there. Fuel filters could be clogged. There is one inside the fuel inlet at the carb, if you have the original Quadrajet. The tank might be full of rust, which will come loose and clog your filter.

I don't quite understand the distributor issue either. HEI distributor are usually trouble-free. Checking the timing, and running it from a fresh can of gas, sound like good ideas. Any time you pull the heads off, you should do a compression check, and pressure test the cooling system.

[1975 Fleetwood Limo]

Dickey, that ddistributor work was done in 2009 when I first got it, untouched since then

[Dickey]

I gotcha. Also, as a diagnostic aid for chat forums, you can snap a pair of decent resolution shots of the engine (pullies to firewall) from each fender with the air cleaner removed. Sometimes the details like disconnected vacuum lines and unplugged ports are easier to spot with fresh eyes is all.

What did you do with the carburetor while the heads were off? What steps did you perform when you installed it back to the engine? Clean it out with brake cleaner, full on rebuild, just bolted it back in place after sitting on the shelf, that sort of thing. If you hit the carb primaries with a shot of ether, does the engine fire up right away like it should and then begin to act up or does the stumbling/misfiring remain?

fwiw the inline fuel filters are an excellent method of debugging fuel delivery woes. I have always kept a clear plastic or glass filter within eye sight of the carburetor on all of my carbed mobiles. For the three q-jet rides, I have also tossed the inlet fuel filter. It will only serve to hurt your feelings and with an inline filter ahead of the carburetor you are good to go just the same.

[1975 Fleetwood Limo]

I stored the carb in the trunk, wrapped up in a plastic bag, Once I got things all together, I took it out of the bag,and bolted it back on. If I recall correctly, I shot some ether in,it fired up,then started acting up

[Dickey]

That's not good for them. The gasoline will start to gum up the passages within the carburetor after only a few months. In my experience, just a fresh supply of fuel to the carb is enough to clear this out after a minute or two of rough running unless it has been sitting for a year or more. Even then though, the only issue I've seen is that the idle sucks. Stomping the gas causes the accelerator pump to squirt raw fuel directly into the manifold and even if the main jets were hosed, there would be a brief rev of the engine before it started acting up. I believe you might have something else amiss and some pics would be a good place to start.

What did the timing light show?

[1975 Fleetwood Limo]

The timing light showed it right on 6 degrees BTDC as called for on the emission decal

[travlinman]

That was with the vacum advance disconnected, right? Just checking. Now hook it back up and make sure moves. If the advance is not working, all You will have is the 6 and not the about 26 You should have. Also ruptured diaphrams will cause a vacum leak. A vacum gun will pin point this. Now We getting it step by step. 1 more thing, where are You getting the vacum from, My 72 ran better with the vac advance teed off of the tranny line instead of the carb. Good luck.

[Dickey]

The timing light showed it right on 6 degrees BTDC as called for on the emission decal

That should make for easy cranking and idling. Even if that's with the advance connected, flooring the engine would put you in the 15-18 atdc range which wouldn't rev up very well but shouldn't cause any manner of misfires back through the carburetor either. I think a picture or two and a vacuum reading as Travlinman suggests would be a good next step but given the hassles you're having, I'm not sure that you'll be able to get a valid reading on the engine vacuum since it won't idle with the throttle plates closed. With the engine floored, regardless of rpm you wouldn't have much of a vacuum signal at all.

[1975 Fleetwood Limo]

That was with the vacum advance disconnected, right? Just checking. Now hook it back up and make sure moves. If the advance is not working, all You will have is the 6 and not the about 26 You should have. Also ruptured diaphrams will cause a vacum leak. A vacum gun will pin point this. Now We getting it step by step. 1 more thing, where are You getting the vacum from, My 72 ran better with the vac advance teed off of the tranny line instead of the carb. Good luck.

Yes, was with the hose disconnected
I had the vacuum coming off the thermal vacuum switch that is on the left front of the engine block as it was when I got it

That should make for easy cranking and idling. Even if that's with the advance connected, flooring the engine would put you in the 15-18 atdc range which wouldn't rev up very well but shouldn't cause any manner of misfires back through the carburetor either. I think a picture or two and a vacuum reading as Travlinman suggests would be a good next step but given the hassles you're having, I'm not sure that you'll be able to get a valid reading on the engine vacuum since it won't idle with the throttle plates closed. With the engine floored, regardless of rpm you wouldn't have much of a vacuum signal at all.

I'll see about getting a pic or 2 tomorrow. I honestly can't get a good vacuum reading, since I can't get any RPM out of it, floored it will backfire

[pyro]

What does the car do when you dump a 1/8 cup of fresh gas down the carb? Try that and start it up