My 83 Winnebego (Chevy 454 engine) has a tough-to-diagnose problem. Possibly vapor lock.
I have additional diagnostic $$ set aside and will joyfull reward the mechanic that has the time & energy to figure it out and fix.
In 2010, Hugmobile had a complete engine replacement.
Since then, it has run greatâ€¦except:
It does an odd overheat thing when driven over an hour or 2 â€“ specifically on the way to summer festivals in the heat.
Before it dies completely, it occasionally surges and feels like it is having problems delivering fuel. i.e. the gas pedal is pushed farther down but no additional power.
The dials all show no overheating issues.
Some have guessed â€œVapour lock.â€
When it has broken down with this problem it usually is able to re-start after cooling off for 3-5 hours. But then after driving a little while (30 min or so?), the condition happens again.
Here’s what happened on the April trip to Santa Barbara:
-Drove there in 2 shifts during cool days, each 2.5 hours. Kept it around 55. Kept the tank mostly full. NO PROBLEMS!
-Drove home during a much warmer day in 1 shift.
– After 2 hours, while going up a hill, it started to do a little of the sputter thing. I made it up the hill and pulled into the next gas station. It was at 1/4 tank.
– I turned it off for 15 minutes and filled the tank.
-It drove fine for the next 2 hours – including several hills.
-When I got off the freeway and started to go up the (steep) hill to B’s house, it started to sputter. It was at 1/2 tank.
-Luckily, it made it into her parking lot where I let it cool over an hour.
-After that hour+ later, while driving it downhill during sunset, it *seemed* to exhibit the same the sputtering (meaning that the cooling did not help?) It required minimal gas to go downhill, but I tried to force it and it seemed to not be getting all the gas it should.
-Before getting back on the freeway, I filled the tank again.
-With the full tank, it made it the next 30 minutes home (including hills) with no problems!
Could it be something to do with the fuel? I could have sworn that I have driven it with much less gas with no problems – but never while so hot.
Maybe something to do with fuel level AND heat? Could filling the tank cool down the overall fuel temp? (I am clueless, obviously)
One theory is that there is water in the fuel tank?
replace fuel line
â€œwhat you need to do it crawl under huggie and look for anywhere that the fuel line gets close to anything that would be hot.â€
“We had the same problem what it was the gas line was ran to close to the manifold and the gas would vaporize when the engine got hot.”
“Look at the gas line if it is running next to the manifold that is the prob. What happen’s is the engine get’s hot not over-heating but hot like it should when the gas line get’s hot the gas will bubble and vaporize. And it will act like it is not getting any fuel and it’s not it’s getting vapors.”
“This sounds exactly like the issue I had with my Chevy, everything would be fine except in summer (I live in AZ) and would drive a while. Suddenly everything would just die, not overheated but dead. It would cool then it would run fine. We were told it was all kinds of things and it took 3 years to chase it down. It ended up being that the fuel pump had been replaced with a generic fuel pump. It just so happens the Chevy engine needs higher fuel pressure than normal, the fuel pump was fine except when it was warm and the pressure was not maintaining where it needed to be. Got a new factory not generic fuel pumpâ€¦ never had an issue again. So check out the fuel pump pressure.”
Install an inline , electric fuel pump.
“You may be able to run on your mechanical until it locks up then hit the switch for the electric one to take over .”
” electric fuel pump…….jus do it….it’ll save you headache down the road…..fifty bucks…max…….an….if it ever fails……..you’ll still have the mechanical one still pumpen………as you will leave it in place…….backup”
“Check your distributor cap and wires.”
more suggestions (from John W.):
After reading that I am beginning to suspect an ignition problem, and it’s an easy fix. I assume it has the HEI distributor, and my question is: when they replaced the engine was it a long block that all the accessories had to be moved over to? Sometimes they don’t come with a new distributor and you swap the old one in. If so I suspect an old coil or module giving up the ghost. Pop your doghouse and put a chair on the floor, the distributor is right on the back of the engine and easy to get to. If *you* are doing this number your wires and take a picture. Basically the HEI distributor contains everything in one spot under one big cap, coil and all the electronics. It gets hot in there, and at the back of the engine right under the back of the doghouse there isn’t a better recipe for thermal failure. It could be any of three parts in there: the pickup coil, the module, or the spark coil. Sometimes you can get a rebuild kit with all the parts cheaper than buying each one. None of which require any kind of massive expertise to swap out, especially if you snap a pic or two before taking out the screws.
I do not personally suspect vapor lock as Winnebago is a well respected maker of motorhomes so one would assume they did their homework and routed all the fuel lines appropriately. Although if over the years part of the fuel line was replaced it is possible the replacement is getting soft in the heat and collapsing, like kinking a garden hose.
I don’t suspect a weak fuel pump as that would show up sooner and whenever you needed a lot of power out of the engine, like up major hills. You could put in a remote fuel pressure gauge to rule it out completely if you wish. Putting in an electric pump is extra insurance, it should be mounted on the frame as close to the tank as possible and it needs be on a relay and wired so it cannot be on if the ignition is off. My family vacationed in an ’86 Winnie about the same size with no issues. Though my father did rebuild the HEI when we got it, we never had to put in an electric pump. In fact we sprayed the underside of the doghouse with expanding foam for extra soundproofing and to help keep the heat out of the interior. And we towed a jeep to use as a runabout too.