I’ve got an '82 Ford Econoline that I bought new, currently 175k miles, 6-cyl 4.9L. Have never had a major problem, and have done 95% of the maintenance myself. It’s my second car (drive it about 1000 mi/yr) and has always been “Old Reliable”. But for the last three years, it’s failing emissions tests here in Tucson. The tests are for CO and hydrocarbons, under load as well as idle, and all 4 numbers are about 10 times too high.
The engine is running rich… black spark plugs, poor mileage, some smelly smoke. I’ve replaced plugs, cap, rotor, fuel and air filters, EGR valve, PCV valve… and the vapor canister is dry. I’ve verified all vacuum switches and most valves. The only obvious thing seems to be to overhaul the carb. I described the problem to the owner of the local carb shop, and he claims there’s “no way” it’s the carb. He suggests that I get a “smoke test” to see if there are any leaks in the vacuum system.
Please help… this smells like a carb problem to me. Thanks for any leads.
The first thing I would ask is, have you’ve been running gasoline containing ethanol? If so, the ethanol probably damaged internal carburator components and the carburator requires rebuilding.
Remove the dog house and the breather assembly and operate the engine until the temp gauge begins to move and then look down the carburetor throat and shut the engine off. If you see fuel dribbling out of the jets and vaporizing you likely have a bad needle and seat or float. Although it is a 1 bbl it is much safer to buy a rebuild than attempt repairing it yourself. Before starting it again I would suggest that you smell the dipstick for gasoline. If gas is indicated change the oil and filter before starting again and look carefully at the fuel pump for indications that it might be leaking.
Yes, I think the gas here is 10% ethanol. I hadn’t thought about what caused the carb problems, but your suggestion still confirms my gut, it’s the carb. I’m just wondering if there’s anything else I haven’t thought of (besides the carb).
Thanks for your reply!
The rebuild kit is $40 and the overhaul is $180. Repl carbs are about $150 up. I’ve thought about doing the rebuild and not inclined to try it on my own, so agree with your assessment. I just smelled the dipstick and it does smell of gas. I see no indication of leakage at the fuel pump… don’t see how that would influence the gas in the oil. I ran a comp. test a week ago, and the results looked OK for a 30 yr old van… 125-115-100-100-115-125. I continue to agree, it’s the carb. Almost worth the $$ to get it done and remove the unknown. Thanks much for your reply.
See my reply below. Thanks for your suggestion.
Although my memory sometimes fails me I have been very well versed in Econolines and 300 I6 Fords. The power valve and accelerator pump in the Carter carburetor can be troubling for the DIYer and the cost of a barrel of cleaning compound is quite high for a once in a lifetime use. Just for grins and giggles I would suggest that while you are pulling the oil filter and draining the oil you loosen the fuel pump mounting bolts and make certain that it isn’t leaking into the pan. And, regarding the carburetor, does yours have the MC solenoid? If so you might install the earlier non MC model with no problems. Check the state emissions standards for 79 and 92. If they are the same the older carb will work OK.
Good suggestion on the fuel pump… hadn’t thought of that. I replaced it about 10yrs/20k miles ago, but it’s certainly easy to check (but maybe not verify). When I did the compression check, the “mist” bursting out of the cylinders was very black and oily… I’m thinking maybe the gas in the oil could explain this. Are you suggesting this might explain the rich running? And no, mine doesn’t have the “feedback solenoid,” is this the same as the MC solenoid? Didn’t see “MC” referenced in the carb diagrams in the shop manual. Thanks again for your help, you do sound like you’ve been around the block with Fords.
When crankcase oil is diluted with gasoline and the engine started the gasoline vaporizes out of the oil and gets drawn into the carburator through the crankcase venting. But while it is evaporating it is not lubricating very well.
Re around the block; I drove one over 1 million miles commercially in Econolines and later serviced 2 fleets. One lasted me 386,000 miles on the original engine and was sold running well. Many engines in the fleets lasted over 300,000. And the E-150s often averaged 18+ mpg. Maintenance, maintenance, maintenance.
Yeah, no argument about maintenance. Are you thinking that the gas in the oil (and inhaled into the carb) would explain the rich running and failed emissions? That sure makes sense to me, especially for as little as I’m driving it (which is probably a blessing).
Gas in the oil is a good possibility. And because it can do so much damage while being so easily checked and repaired checking the pump just seems like the way to go. I once had a customer waiting while I replaced the fuel pump on his For 300 engine and he insisted that I not change the oil and filter since he was changing the oil when he recognized the fuel pump problem. The truck lasted 90 miles before stacking a bearing.
One thing those carbs were known for was the screws coming loose. There may also be bolts that loosen up too. The electric choke may not be getting hot enough after all these years. The float may be leaking and getting loaded up with gasoline. The rubber on the needle may be breaking up. By now, the catalytic converter is toasted.
Running rich will toast the catalyst in short order. That could be the next issue.
I neglected to mention the catConverter… I replaced it last fall, on advice from the guy at the carb shop. The old one was pretty plugged up (to look at it) and I had great hopes that the new one would solve the problem. Of course, it didn’t. And now, as you mentioned, the new one is at risk. Good thing I have only driven the van 100 or so miles since then. I’m replacing the fuel pump and changing the oil and filter today, then getting it reinspected tomorrow. I’ll post about the outcome. Thanks much for your advice.
1981-1987, The Dark Years…It is indeed the crappy Autolite feedback carb. These carbs have (had) sealed mixture controls and electronic fuel control solenoids to to adjust the fuel mixture as per instructed by the oxygen sensor…They were a nightmare in 1982 and today they are simply impossible to work on or get parts for. Good Luck…
Actually, this one is a Holly (YF1A) without feedback. Doesn’t have an oxygen sensor either. I can see how Ford had to deal with increasing complexity of regional emissions requirements, but I bought this one in PA and it was pretty simple (by comparison).
I’ve been remiss on wrapping this thread up with a “results” post… mostly since there are no “results” as yet. I did change out the fuel pump and oil (and filter), and took the truck for a spin… seemed to run fine and the smelly exhaust was gone… but I hadn’t gone a block but had a blowout. Those darned 17 year old Toyos just aren’t as reliable as they once were Talk about discouraging. So I’ve had new tires on order from Costco (discount but not yet in production), which should be in within a week or two. FINALLY I will be able to get the emissions inspection and find out whether it was indeed the fuel pump. If not, I’ll be back at the door to “carb overhaul.” I’ll post again when I’ve got more info.
Thanks much for your info and post.
Whoops! I should wait til I’m wide awake before making up carb info. I didn’t think “Holly” sounded correct, and it wasn’t… it is a Carter, and I even got the model wrong… it’s YFA-1V. I did get the part about not-feedback correct.