Carb 454 all of a sudden won't start

[WineStream]

I've tried my best to search and review the threads here for advice. I think I've found some answers, but they kinda scare me so I'm hoping for some more definitive advice from this post.

I've got a '77 Argosy moho with a carb. 454. For the last year, it has started and run just fine. Starting when cold or after a few weeks of non-use is usually as follows: push the accel. pedal to the floor 2-3 times, then fully release, turn-key, crank for 5-10 seconds, engine starts and runs at a high idle, throttle blips over the next 5 min. until things settle down to about 600RPM idle...ready to go. Warm starts are easy: don't touch anything, just turn the key and it hits right away. I just drove it last Wednesday and observed such operation.

Today, I had plans to drive to a friend's house for some welding work on the entry steps. I went out to start it...normal procedure...engine fired and ran maybe 5 seconds, then died. Unusual. I cranked it again. Not even a sputter. Pump the throttle a couple times. Crank. Nothing. Repeat, repeat, nothing, battery getting low. Attached tractor as a jumper...more of the same from the moho.

Lift the doghouse, smell gas. Remove air cleaner cover, more gas smell, top of carb is wet / shiny with fuel; pools of fuel forming on the top of the intake manifold. So I think it's flooded. Solution: hold the throttle pedal on the floor and crank. I get a couple of hits, then nothing. Same deal with subsequent tries. I even tried some starting fluid. A couple fires, then nothing. I know my gas is not old. It was just filled up from 1/4 tank about a month ago.

About 2 weeks ago, this moho made a 2 hour trip to a destination, 2 hours home, no issues. Short of a weak battery that was replaced a year ago, it's been very consistent in its starting performance. Something "sudden" must have happened.

I did a Google search as well. I saw many ideas, most revolving around a carb rebuild. Some said a cure for flooding was to hold the throttle open, other said the opposite. Some said to check fuel pressure, but obviously fuel is getting to the carb in my case. I've read a lot of info here on the forums about cam gears / chain slipping time. I'm worried that this might be the case for me. It fits with the sudden / no start situation.

Does anyone here have advice from a similar situation? Before I have the carb rebuilt and tear out the whole front end in order to get to the cam drive, I'd like to have some opinions.

[TG Twinkie]

Have you checked the fuel filter and pump. You could be flooding it. Then it's running out of gas. You get enough gas in the bowl of the carb to start or flood it. Not enough to keep it running.
I have owned several different carb engines. Always held the throttle down when flooded. But keep in mind that each time you push the throttle down in various attempts to overcome the flooding you are dumping more fuel into the engine.

[overlander64]

Greetings SineStream!

Originally Posted by WineStream

I've tried my best to search and review the threads here for advice. I think I've found some answers, but they kinda scare me so I'm hoping for some more definitive advice from this post.

I've got a '77 Argosy moho with a carb. 454. For the last year, it has started and run just fine. Starting when cold or after a few weeks of non-use is usually as follows: push the accel. pedal to the floor 2-3 times, then fully release, turn-key, crank for 5-10 seconds, engine starts and runs at a high idle, throttle blips over the next 5 min. until things settle down to about 600RPM idle...ready to go. Warm starts are easy: don't touch anything, just turn the key and it hits right away. I just drove it last Wednesday and observed such operation.

Today, I had plans to drive to a friend's house for some welding work on the entry steps. I went out to start it...normal procedure...engine fired and ran maybe 5 seconds, then died. Unusual. I cranked it again. Not even a sputter. Pump the throttle a couple times. Crank. Nothing. Repeat, repeat, nothing, battery getting low. Attached tractor as a jumper...more of the same from the moho.

Lift the doghouse, smell gas. Remove air cleaner cover, more gas smell, top of carb is wet / shiny with fuel; pools of fuel forming on the top of the intake manifold. So I think it's flooded. Solution: hold the throttle pedal on the floor and crank. I get a couple of hits, then nothing. Same deal with subsequent tries. I even tried some starting fluid. A couple fires, then nothing. I know my gas is not old. It was just filled up from 1/4 tank about a month ago.

About 2 weeks ago, this moho made a 2 hour trip to a destination, 2 hours home, no issues. Short of a weak battery that was replaced a year ago, it's been very consistent in its starting performance. Something "sudden" must have happened.

I did a Google search as well. I saw many ideas, most revolving around a carb rebuild. Some said a cure for flooding was to hold the throttle open, other said the opposite. Some said to check fuel pressure, but obviously fuel is getting to the carb in my case. I've read a lot of info here on the forums about cam gears / chain slipping time. I'm worried that this might be the case for me. It fits with the sudden / no start situation.

Does anyone here have advice from a similar situation? Before I have the carb rebuilt and tear out the whole front end in order to get to the cam drive, I'd like to have some opinions.

My first thought was weak or defective HEI ignition module. I know that these have been problematic on both my '75 Pontiac Grandville as well as my '75 Cadillac Eldorado . . . I always keep one or two spares around as inexpensive insurance policies. I would also wonder about one or more fuel filters needing attention . . . after a limited use cycle during the winter, my Cadillac nearly always needs to have both of its fuel filters replaced.

I don't know whether either of these would apply to your motorhome, but since the motors are of the same family thourhg that I would mention them.

Good luck in locating the issue!

Kevin

[dadstoy]

WineStream, I seriously doubt it is a cam/timing gear issue. Work through the basics first. It is very possible that you do have a carb issue. The Quadrajet when in perfect working order is a good carb...in any other condition, it is a piece of crap. I had the same issues with mine. I replaced it with a rebuild from RockAuto and it has made a world of difference. The quadrajets are made from pot metal and they eventually start leaking like crazy. The throttle shaft bushings also wear and allow too much air into the intake. A flooded carb/engine should not leak fuel on the top of the intake manifold. DO NOT TRY TO START THE ENGINE WITH FUEL leaking like you say it is. This is a major fire hazard!

I would run through some basic troubleshooting...

Make sure the spilled/leaked fuel has been dried up.
Pull a spark plug or two and see what they look like...all wet with fuel? Plugs can tell a lot about what is going on.
Check for spark at the spark plug...you can get a tester or use a screwdriver if you know how...again make sure there is no exposed fuel and don't get shocked!
If no spark, then check for 12 volts coming into the distributor when the key is on.
If you have 12 volts, then you may have a distributor issue...bad module, bad rotor, bad cap, bad coil.
If you have spark, then with all the fuel leaks you described at the carb, I would bet you do have a carb issue.

Again go for the basic issues before looking elsewhere.

Good luck

[ROBERTSUNRUS]

Hi, with gas all over the intake manifold, you definitely have a carb problem. Flooding like this is most likely a bad float or a needle and seat problem. Fix the carb before trying to start it again or you might have a nice fire. An engine that is flooded from pumping the pedal too much, or an over choked situation, would start with the pedal to the floor to allow more air in, but this is not the case with your situation.

[richinny]

i'll second the stuck or bad float idea. fuel should never spill out from the carb.

once all the raw fuel is dried, disconnect the fuel line, cap it and try starting the engine. it should start and stop when the carb is emptied. reconnect the fuel line (replace the filter if there is one at the inlet) and restart. REPLACE THE AIR FILTER AND HOUSING! this will limit a backfire from igniting all the raw fuel. if you're lucky any dirt causing the needle valve open will flow through and return to normal operation.

if it is cool, wet plugs from flooding might need to be pulled to get them dried quickly. you'll have some fuel running past the pistons to the oil pan. if the oil level is high you might need to address this too.

when doing things like this a fire extinguisher and a phone should be nearby!

[WineStream]

Wow, I never expected such a response overnight. Thanks to everyone.

I must admit, I didn't do my due diligence on troubleshooting before posting. When I gave up and closed up the barn last night, it was already late (for my routine, at least). After reading a few things on the internet and on the forums, I had myself scared (especially with the couple timing threads!) and I was hoping there would be a few people that had gone through this same situation and could peg the most likely failures and save me some time. Such has been the case.

I know a few people who are into carbs (one of them is NOT me!). I've tried Qjet rebuilds in the past on other vehicles and usually things were worse afterward (fault of me, not the carb). I agree, that much gas all over doesn't seem right.

I've not checked fuel pressure due to gas everywhere, I figured fuel to the carb was a checked box at this point. As handy as I am, I don't have a fitting and a gauge for checking this. Is this a "standard" item that can be picked up at Autozone, NAPA, etc. with a variety of fittings?

Ironic the module gets mentioned. I read on the 'net about that being a cause, too. I did a full tune-up over the winter including a new module, cap, rotor, wires, plugs. Things really ran better after all that up through a few days ago, so this is now my surprise: ran great for months, all of a sudden dead.

I had replaced the in-line canister fuel filter a couple months ago. Supposedly there is another filter (other than just a screen) at the carb, but that one I did not take loose as of yet. I figured there'd be carb work sometime during my owner ship to warrant that :-)

I won't have time to work on it tonight, but Wednesday night I'll start through the ignition trouble shooting and get back to the thread with my findings.

[richinny]

jason, when you disconnect the fuel line from the carb be sure to use a flare wrench on the line. rounded line nuts make for lots of extra work. since you've done this before you probable know this ;-)

[ROBERT CROSS]

Your on the right track looking at the carb/ignition first.
BTW once it's up and starting check the oil for fuel contamination BEFORE any extended running!!

Oil/filter highly advised.

Bob

[Waipio Rim]

When our coil went south we had a strong gas smell and occasional backfires when trying to start.

[Phoenix]

If you have fuel coming out of the carburetor, the float is probably stuck or full of fuel. This was a common problem on old 454's. We had one in a 1978 Chevy crewcab pickup, and we had to rebuild that carburetor about every 3-4 years, specifically for float problems. Luckily, we have an old carburetor shop here in Phoenix that still rebuilds carburetors.

Just a suggestion, but do NOT buy a rebuilt carburetor. The 454 had many different carburetors over the years, and the likelihood of getting an exact replacement is very low. Many of them will look the same, but you'll have a heck of a time getting the engine to run right.

The best bet is to rebuild your old carburetor. If it was running OK before this recent failure, it will run OK after it's rebuilt. Not so much with a swapout, which is buying a pig-in-a-poke.

We had good luck getting other parts for our old 454 from Rock Auto (online parts distributor). However, it was easier and faster having the carburetor rebuilt by the experts at this carburetor shop. Also, they guaranteed that the engine would pass emissions after the carb was rebuilt.

[WineStream]

So I finally got time to check things last night. The moho had sat untouched for about 48 hours. I pulled a plug, grounded it to the valve cover, and turned the key. Plenty of spark! Actually, the engine nearly started with the one plug out. OK, so ignition not an issue, timing issue is tabled for now, and fuel is clearly there (but likely too much fuel). So I commenced to removing the carb. From what I could see after removing the carb, the intake runners were saturated with gas.

Although I knew I was not going to rebuild it myself, I couldn't resist the urge to pop the top and see if there was something obvious. I wouldn't say obvious, but I did notice that if the float was all the way down that it didn't easily rise when pressure was applied to the the opposite side of the pivot (sticking down...hmmm). It also would stick against the side-walls for the bowl when in an upward position, too. Although, this position might be higher than it gets when fuel is in there. Nevertheless, the carb is off to the rebuilder with a request to replace the float as well.

And thanks for the tip to look at the oil level and check for gas. I've run into this many times on small engines where the fuel is gravity fed, but never thought of it in this situation. I pulled the dipstick yesterday and it's pretty clear that the oil is diluted with gas. Looks like I'm going to be crawling under the moho on the dirt floor of the barn for an oil change before I even attempt to start it after carb. repairs.

[ROBERT CROSS]

Jason,

Keep us posted....

We had the 454 in our 95 Burb...a real workhorse.

good luck


Bob

[WineStream]

For those wanting the short version: a carb rebuild solved the issue. For those wanting the long version, read on...

So I got the carb back from the rebuilder today. He found a few issues. First and foremost, he agreed that the float was sticking to the bowl walls in both the full down and full up position. With the new float, all is free and clear through the full travel. He also found that the primary metering rods had an issue (picture attached). Anyone see an issue with the rod on the left? The rebuilder seems to think I might get better fuel mileage now. There were a few other tweaks that he made to things that had gone awry. He said it was clear that this carb had been rebuilt before, apparently rather incorrectly.

So today I got home with it. The first thing I did before even trying to put the carb back on was to drain the oil pan. Thanks again to richinny and Bob Cross for the hint to check the oil level and change it. I can only speculate what might have happened if you hadn't alerted me to this. I could definitely tell when the oil drained and then it switched to gas. The color, the smell, and even the sound it was making as it was hitting the drain pan was different than when oil is draining. There was A LOT of gas in there. So, all new oil.

I put the carb back on. I figured it would take some cranking to get it going since there was no gas in the bowl. I didn't touch the pedal or anything (no fuel in the booster pump well). To my surprise, it fired right off; faster than before my issues. Maybe residual gas in the chambers had something to do with that! I had to massage the pedal a bit after about 5 seconds (I figure the bowl wasn't fully filled yet). After about 30 seconds of running, it settled in to a high idle. After it warmed up, I adjusted the idle speed and then the idle screws on the carb. It runs great.

I loaded up the family for a quick test drive (I wanted ice cream, but my wife didn't think we could park the thing at the local dairy bar). The test drive was quite successful. It's hard to describe a 10,000lb vehicle as having any sort of get up and go, but it definitely felt a bit peppier. The roll-on form 45 to 60mph was better for sure. Launching from a stop also felt better. I guess I'll find out about the fuel mileage on our next trip which will be next month to the TCT Spring Gathering in Michigan. That will be about a 4 hour trip, so we will see if it drinks a little less fuel than before.

Thanks to everyone's input here on the forums. This thread is exactly why I come here many times daily, pay to be a supporting member, and why an AIR sticker goes on every Airstream and even every vehicle (tow vehicle or not) that I own.

[dadstoy]

Job well done WineSteam! When I replaced the old Q-Jet with the rebuilt, it was like having a new engine for me. What length is your '77?

[exthemius]

Awesome news...you better keep that thing in good running order, otherwise it can't take you to DISNEY!

[WineStream]

Originally Posted by dadstoy

Job well done WineSteam! When I replaced the old Q-Jet with the rebuilt, it was like having a new engine for me. What length is your '77?

I can't take too much credit. Most of the credit lies with the people that gave advice here and the guy that rebuilt my carb. All I did was turn some wrenches. My '77 Argosy is a 24 footer, party wagon floor plan.

Originally Posted by exthemius

Awesome news...you better keep that thing in good running order, otherwise it can't take you to DISNEY!

That's the scary part of all this. I just had the moho out and moving around earlier last week. No signs of any issues. Then, Sunday, no go. Solution? Carb rebuild - major work in my opinion. I'm happy it decided to do that in my barn and not at a campground. The trip to Disney this fall could be interesting with the motorhome. Hopefully, though, it is seamless.

[TouringDan]

Jason

Looking at the problem you had and all the great advice from the forum is very heartwarming. It is exactly what the forum is all about.

Nice that this problem showed up at home rather than half way to/from Disneyworld. Glad that it all worked out well in the end.

Dan

[exthemius]

Originally Posted by WineStream

That's the scary part of all this. I just had the moho out and moving around earlier last week. No signs of any issues. Then, Sunday, no go. Solution? Carb rebuild - major work in my opinion. I'm happy it decided to do that in my barn and not at a campground. The trip to Disney this fall could be interesting with the motorhome. Hopefully, though, it is seamless.

You know, there will be a lot of us in and around the area to help out if something goes wonky.