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Gertie problems and solutions part 1: loss of power
Yahoo Message Number: 58038
I ran into a peculiar loss-of-power problem with my 1985 LD a few days ago. Symptom: it ran fine for the first two or three hours, but then the engine didn't like to go beyond a very moderate throttle. Push down just a little more on the gas (e.g., to maintain speed on a slight incline) and it started to lose power in a rhythmic way: rrrRRRrrrRRRrrrRRR, about three cycles every two seconds. I was gently lurching backward and forward in my seat a couple times a second. Very strange.
 Speed dropped considerably, of course. By the end of the day I was down to 35-40 mph on some very gentle grades (the only kind they have in Indiana ;-). It's  important to note that it wasn't missing or running roughly--just acting as if the throttle were being played with in a rhythmic way. A couple of times it backfired on downgrades.
 After stopping for a half hour, it was fine for ten or fifteen minutes, then started acting up again. This despite the fact that the temperature gauge stayed in the lower quarter of its range throughout the day, and wasn't noticeably cooler when I started again after the above-mentioned rest stop. But despite the gauge readings, the problem definitely was temperature-related, since it only appeared after I'd been running for several hours.
 This happened two afternoons in a row. The second afternoon was really bad. When I limped into a campground and spent ten minutes in the office registering, then tried to restart Gertie, I was barely able to get her going, and she ran VERY roughly--sounded and felt like she was firing on only four out of eight cylinders. I was barely able to limp to my campsite, and I saw bluish smoke coming from the exhaust pipes. I won't swear it, but I thought I smelled fuel when I stopped.
 That night I talked with an ex-mechanic friend, who suggested that the ignition coil might be at fault. He said that the old Delco-Remy coils were very cheaply made--he'd disassembled a bad one once. Once the thin layer of varnish insulating the windings began to crack from thermal stress, he said, the coil would lose its ability to generate a good spark. That would account for the rough running toward the end of the day, as well as the smoke and unburned fuel smell. Neither of us could explain the rhythmic power loss, though. He also suggested checking the fuel filters and fuel  pump.
 The next morning Gertie started and ran very roughly, with visible smoke, but steadied down after a few minutes--apparently once the engine had burned off all the unburned fuel from the previous afternoon. It continued to run just fine for the next hour, as I drove around Terre Haute. I had to try four places before I found a mechanic who would look at it. He found that the rear fuel filter (the one by the tank) looked OK, but replaced it anyway; however, the front filter (on the carb) was partially blocked, so he replaced that as well. And I had him put on a new coil--a NAPA Echlin part (not Delco!).
 His labor was just an hour--I did most of the work of taking off the engine cover (to do which you have to remove the passenger's seat!) to save him as much time as possible--so the total cost was only $180 including parts.
 And I'm happy to report that Gertie's been running like a sewing machine for the past three days...so whether it was the coil or the filter that did it, the fix seems to have worked! :-) I'm inclined to think it was the coil. I don't see how the fuel filter could possibly have been temperature-sensitive, but I know enough about electronics to know how a mess of fine wires with cracked Formvar insulation could start to arc over as the whole thing expends in the very hot underhood environment.

Andy Baird

Sedalia, Missourah
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Gertie problems and solutions part 1: loss of power
Reply #1 –
Yahoo Message Number: 58043
I'll differ with you this time, Andy. The symptoms you describe sure sound like the fuel filter! Start up and almost normal running after an idles spell is quite typical as enough of the debri can "fall to the bottom of the filter" to allow this. As it plugs back up again, the engine aga
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: Gertie problems and solutions part 1: loss of power
Reply #2 –
Yahoo Message Number: 58050
I agree with Bumper, your description fits our symptoms when our fuel filter was clogged.  Of course, you could have had 2 separate things going on as well.

Jonna
Re: Gertie problems and solutions part 1: loss of power
Reply #3 –
Yahoo Message Number: 58054
Years ago, I worked on and owned many vehicles with Chevy small block engines, all equipped with Quadrajet Carbs. The symptoms you describe could easily be the small, in-carb fuel filter. I would suggest carrying an extra set of filters. Make sure that you have the large wrench needed to replace the one in the carb.
The Q-Jet suffered from two other common problems. The first is a leaking float bowl. The cure was to install an after-market plug kit or to epoxy the bottom of the carb. Long cranking time, after the MH's engine has not been run for several days is a good indication of this problem.
The other common ailment is a sinking float. The factory floats were made from plastic foam. After time, the plastic becomes saturated with fuel and starts to sink, causing the engine to run very rich, so much so that it may barely run. I would suggest buying an extra brass float and the correct carb kit to carry as spares. You WILL eventually need them.
The ignition system has several common problems. The first is the coil that acts up only when hot. Carry a spare. The other is a sticky centrifugal advance mechanism in the distributor. When the engine is not running and with the distributor cap removed, you should be able to rotate the rotor by hand with little resistance. If it is hard to turn or does not turn, the distributor should be disassembled to lube the shafts. You can also try to use some light oil and lube it while it is still installed in the engine. It is supposed to be lubed by the engine but that does not seem to be the case.
The electronic ignition module, located inside the distributor also goes out from time to time, another item to carry.
Burned spark plug wires are common. Consider carrying either a complete set or one wire, in a length equal to the longest one on the engine.
 You should consider carrying the suggested parts as they are becoming less commonly available. Electric fuel and ignition systems have been the norm for many years now.

Larry
2001 MB
* Not to be confused with Larry W (3000 of my posts are actually from expert Larry W due to Yahoo transition mis-step)
Re: Gertie problems: loss of power
Reply #4 –
Yahoo Message Number: 58055
"The symptoms you describe sure sound like the fuel filter! Start up and almost normal running after an idles spell is quite typical as enough of the debri can 'fall to the bottom of the filter' to allow this. As it plugs back up again, the engine again looses power."
 Hmmm. Maybe, but I'm not sure. The way it happened (on two successive days) was that I'd drive for a couple of hours and then the problem would gradually appear over the next couple of hours, getting successively worse. In your scenario, the debris would have to do a lot of moving around, and in a consistent way (since the symptoms were the same both days).
 Also, it seems odd that the larger fuel filter on the tank had no clogging; one would except it to have taken the brunt of the contamination if there was contamination. The mechanic said the smaller filter on the carburetor was "restricted," based on blowing through it...but when he opened it up, there was no accumulation of junk inside that looked as if it would seriously impede fuel flow.
 Finally, I wonder about the rough running I experienced at the end of the second day and the beginning of the third day. Clearly fuel was getting to the cylinders but not being burned--hence the smoke and raw-gas smell--and that seems to point to the ignition system rather than to fuel starvation.
 Well, this is all speculation on my part--you could be right about the fuel filter. Since I had both fuel filters and the coil replaced in one go, there's no way to pinpoint what cured the problem. A true scientist  would have replaced one component at a time, testing carefully after each replacement...but I didn't have that luxury. ;-)

Andy Baird
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Gertie problems: loss of power
Reply #5 –
Yahoo Message Number: 58057
"Years ago, I worked on and owned many vehicles with Chevy small block engines..."
 I gotta tell you, with the doghouse off and that monstrous mass of machinery dominating the cab right next to where I sit, it looked like a mighty big block to me! ;-)
 Seriously, Larry, many thanks for your excellent advice. I'll acquire a set of spares next chance I get.

Andy Baird
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Gertie problems and solutions part 1: loss of power
Reply #6 –
Yahoo Message Number: 58062
Quote
I ran into a peculiar loss-of-power problem with my 1985 LD...it ran fine for the first two or three hours, but then the engine didn't like to go beyond a very moderate throttle. Push down...on the gas...and it started to lose power in a rhythmic way: RRRrrrRRR, about three cycles every two seconds. I was gently lurching backward and forward in my seat a couple times a second.
Very strange.
Andy, This exact same thing happens to Big Blue ('84 Multiplan) when it runs at highway speeds (for me that's around 60), in the heat, for more than about 5 hours.  If it's cool outside (
Re: [Life With A Lazy Daze RV] Gertie problems and solutions part 1
Reply #7 –
Yahoo Message Number: 58074
Andy: I keep thinking; what is this happened to me? Yikes.  It is a good, as in "very good thing" that you are so skilled.  Wish I had your knowledge! Good going.  Mari Susan

Andy Baird wrote:
Re: Gertie problems and solutions part 1: loss of power
Reply #8 –
Yahoo Message Number: 58089
"I'm beginning to think that the carb just gets super hot and it runs on the verge of vapor locking. Or the gas lines that run up the front of the engine just boils the gas before it gets to the carb again making a vapor lock situation. My next experiments will be to route the gas line so it can stay cooler and/or put in a carb spacer/heat shield under the carb and see if that helps"

Chuck
 Vapor lock is very common problem in carbureted RVs. On both our 1977 Chevy van and the 1983 LD, I installed supplemental electric fuel pumps, located as close to the fuel tank as possible.
Both were used occasionally, usually on hot summer's day at higher altitudes when vapor lock occurred. On one trip, the mechanical fuel pump failed on the 1983 LD. It was so nice to be able to turn the electric one on and complete the trip without having to stop, find a new pump and installing it on the road

Power for the pumps was provided by a fused switch, powered off the ignition switch so they would run only when the ignition switch was in the run position. On our 1983 LD, so many things were powered off the ignition switch that the original ignition switch started to burn up.
This was fixed by adding a 30 amp relay, operated by the ignition switch. All the accessories were wired to receive their power from the relay, removing the load from the ignition switch.

Larry Vapor lock is very common problem in carbureted RVs. On both our 1977 Chevy van and the 1983 LD, I installed supplemental electric fuel pumps, located as close to the fuel tank as possible.
Both were used occasionally, usually on hot summer's day at higher altitudes when vapor lock occurred. On one trip, the mechanical fuel pump failed on the 1983 LD. It was so nice to be able to turn the electric one on and complete the trip without having to stop, find a new pump and installing it on the road

Power for the pumps was provided by a fused switch, powered off the ignition switch so they would run only when the ignition switch was in the run position. On our 1983 LD, so many things were powered off the ignition switch that the original ignition switch started to burn up.
This was fixed by adding a 30 amp relay, operated by the ignition switch. All the accessories were wired to receive their power from the relay, removing the load from the ignition switch.

Larry
2001 MB
* Not to be confused with Larry W (3000 of my posts are actually from expert Larry W due to Yahoo transition mis-step)
Suggestions for Big Blue
Reply #9 –
Yahoo Message Number: 58105
(Data snipped for brevity)

Quote
Andy, This exact same thing happens to Big Blue ('84 Multiplan) when it runs at highway speeds (for me that's around 60), in the heat, for more than about 5 hours.  If it's cool outside ( doesn't happen.  I've been trying to debug this for a couple years now.  I've done the same things you did, new fuel filters, coil, but I also tried insulated gas lines (for vapor lock protection), new spark plug wires, electronic ignition module, K&N air filter, I even added a snorkel to get cool air to the carb, and it still occurs.  The carb doesn't leak, but I did see a post that mentioned the carb floats, which would be interesting to check, but I'm not sure how that would be heat related.

Oddly enough, after I changed the filter in my transmission and replaced the transmission fluid with synthetic, it increased the length of time before it would occur.  It used to take about 3-4 hours and that went to over 5.  I suspect the synthetic fluid runs cooler and helped with the heat situation.

I'm beginning to think that the carb just gets super hot and it runs on the verge of vapor locking. Or the gas lines that run up the front of the engine just boils the gas before it gets to the carb again making a vapor lock situation. My next experiments will be to route the gas line so it can stay cooler and/or put in a carb spacer/heat shield under the carb and see if that helps.

What's odd for me is that it has to be hot outside for it to occur.
My engine temp guage reads the same after 5 hours running in 75 degree weather as it does in 95 degree weather, but it only occurs when it's hot out.

It'd be interesting to know if the replacement of your filters and the new coil really fixed the problem for you, because it didn't for me.

I'll try to post something if I ever figure it out for Big Blue.

Keep cool, Chuck.
Hello Chuck, re: Big Blue stumbling after sever hours running time.
To be really effective in diagnosing Big blue's problem, you are going to need to temporarily install a pressure sensor in the gas line where it enters the carb with a readout gauge you can see when driving.  An electric pressure sender and gauge might be best for this purpose.  This will let you know if you should be working on a fuel or an electrical problem.
 If you choose to continue trying fixes of probable causes, there are two fuel items that I have seen cause this type of stunble.  The first is not vapor lock related, the second two are.
 The fuel pickup line in the gas tank initially had a mesh tube on the end of it.  Over time, this mesh sock can collect stuff from the bottom of the tank and become partially clogged. The clogging can worsen with both run time and fuel level dropping in the tank. This of course would shop up in dropping fuel pressure if that temporary gauge were installed.  The fix is to remove the fuel pickup and install a new sock filter.

Insulating those gas lines have proven effective at stopping hot weather vapor lock for many people with a similar problem.  Perhaps the most critical area is near the exhaust manifold and the header pipe.  Gas lines in those areas can be difficult to insulate but a thin sheet of metal placed between the manifold - header pipe and the gas line is often effective at reducing fuel line temperature bekow the boiling point for a running engine.  Up front of and on top of the engine, I've seen common aluminum foil used effectively.  Again, this is only when the problem is partial vapor lock of a running engine.

You've already had a good reply posting on adding an electric fuel pump, to which I'd add the following.  If the  problem is not a blocked pickup in the tank, this will cure a fuel vapor lock problem.  re : New pump wiring configuration:  Use the 'start' and 'run' positions of the ignition switch to signal a relay to run the electric pump but also use a relay powered by the 'run' position of the ignition switch to run the added electrical fuel pump only when the oil pressure sending unit signals engine oil pressure exists.  This is a common electric fuel pump wiring configuration on a lot of GM cars.

One caution.  The fuel lines on Big Blue were not designed for positive fuel pressure and they are also several years old.  If you do add an electric fuel pump near the tank, do add a fuel pressure regulator at the new electric pump set to the right pressure for the carb.  Also, replace all non metal sections of the fuel lines on Big Blue with new parts and check the entire line for leaks with the new fuel pump running.  I'd also remove the mechanical fuel pump and if it has one, the activation rod and put a gasketed cover plate over the opening in the block.

Lastly, I had one of those saturated plastic float problems back when there were no internet databases.  Your symptoms don't indicate the saturation of the Carter Carb's plastic float is a likely cause.
Hard starting usually prevails and the engine runs like the choke is on - Hey, with a partially sunk float, the float chamber keeps overfilling and the excess gasoline goes directly into the intake manifold.  However, it is easy to change the plastic float to a metal one and this would be a good preventative maintenance item if nothing else.  If memory serves me right, I was doing the replacements with the carb still on the (cooled down of course) engine.

'Best, Don McG
Re: Gertie problems: loss of power
Reply #10 –
Yahoo Message Number: 58113
Andy,
 I experienced something very similar to your adventure.  I was on a trip with our truck camper on my Chevy 2500 with the 350 engine.  It started running rough one afternoon.  The next morning, it started after MUCH effort, and ran rough all day, with smoke and smell.  The next morning, it would not start at all.  Had to have towed from the campground.  Turns out it was the distributor gone bad; the rotor shaft was all chewed up.  With a new distributor, it ran great.

Ted H.
'02 FL  NE-12
 From: "Andy Baird" andybaird@...>

The way it happened (on two successive days) was that I'd drive for a couple of hours and then the problem would gradually appear over the next couple of hours, getting successively worse.
Finally, I wonder about the rough running I experienced at the end of the second day and the beginning of the third day. Clearly fuel was getting to the cylinders but not being burned--hence the smoke and raw-gas smell--and that seems to point to the ignition system rather than to fuel starvation.

[Non-text portions of this message have been removed]
Re: Gertie problems and solutions part 1: loss of power
Reply #11 –
Yahoo Message Number: 58118
"I'm beginning to think that the carb just gets super hot and it runs on the verge of vapor locking. Or the gas lines that run up the front of the engine just boils the gas before it gets to the carb again making a vapor lock situation."
 That certainly sounds plausible. What if the rhythmic power loss I experienced was the result of regularly spaced vapor bubbles in the fuel line? Hmmm.
 That said, so far I've had no further problems. I drove 330 miles today, a good long run, and saw no sign of the power loss symptoms. If I learn anything more, I'll report it!

Andy
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Gertie problems
Reply #12 –
Yahoo Message Number: 58123
"I keep thinking; what if this happened to me? Yikes. It is a good, as in 'very good thing' that you are so skilled. Wish I had your knowledge!"
 But Mari Susan, I didn't have any knowledge of engines that would help me solve the problem--as I'm sure has become obvious in the ensuing discussion. ;-) No, I did exactly what you would do: first, I called a knowledgeable friend who gave me a few tips, and then I took Gertie to a mechanic.
 Similarly, I can only take a little credit for fixing the circuit breaker problem. There again, it would never have occurred to me that the breaker itself could be at fault if I hadn't been told so by friends I asked for advice. Once I suspected the breaker, I did know enough to be able to replace it...but that doesn't exactly require an EE degree. ;-)
 The lesson here is that having knowledge is good...but if you don't, knowing where to find people who have the knowledge you need (like this group) is almost as good! ;-)

Andy Baird
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: [Life With A Lazy Daze RV] Re: Gertie problems: loss of power
Reply #13 –
Yahoo Message Number: 58157
Andy You sound right on target. I never heard of a clogged filter causing flooding. Weak spark sure can. I can't imagine a clogged filter causing unburned fuel to accumulate in the cylinders.
Garry
Re: Gertie problems: loss of power and suggestions for Big Blue
Reply #14 –
Yahoo Message Number: 58162
wrote:
 
Quote
I ran into a peculiar loss-of-power problem with my 1985 LD...it ran fine for the first two or three hours, but then the engine didn't like to go beyond a very moderate throttle. Push down...on the gas...and it started to lose power in a rhythmic way: RRRrrrRRR, about three cycles every two seconds. I was gently lurching backward and forward in my seat a couple times a second.
Very strange.
Thanks to everyone for posting the ideas for the loss of power issue.

A couple quick points, I do have an electric fuel pump in line with the mechanical one.  I do have it setup to run via an oil pressure switch, so if there is oil pressure (i.e. the engine is running) the pump is on.  One question is about my setup; it is set up so both the electric and mechanical are running. I did this based on advice from another RV forum. It would be relatively easy to put in bypasses to just run one or the other, rather than both. Any cons to running both?

I thought that the electric fuel pump should solve any vapor lock issues. That's part of why I've been a little perplexed.
 I do have the gas lines insulated that run by the exhaust manifold (I was surprised how close they were to the exhaust) with a piece of sheet metal I fabricated. (I also put a heat shield around my starter because it would get heat soaked and would turn a lot slower when it was hot).
 I saw a couple posts on the sock/mesh on the end of the pickup tube in the gas tank. I'll have to check that out, it makes sense, after running for a few hours the crud/gallon in the gas tank increases.
When I stop and put in my 40-50 gallons of fresh fuel it cleans it off and it runs fine until it gets low again.

Thanks, Chuck.
Re: Gertie problems and solutions part 1: loss of power
Reply #15 –
Yahoo Message Number: 58434
Andy

Sorry, a little late to the party on this topic but thought I'd add my $.02.

On a 20 year old vehicle there could be rust or dirt