[BitterGabe]

Greetings all Ye of the FSJ forum!

OK, I have a rebuilt OEM carb (for high altitude).
I recently installed an electric fuel pump (underbody) to help my OEM mechanical fuel pump that has been replaced twice since Feb09.

When ever the outside temperature reaches 90degrees or higher, my vehicle vapor locks; simply stalls out.
Is there anyone that can help me trouble shoot this issue. It is killing me and I have lost work days to it.

+Added+
I should mention that the vehicle idles very, very rough when the motor temp reaches 200; shaking/shuttering like it is misfiring, but it is not (confirmed).
Two months ago I had a massive tune-up, timing advance included, for altitude. But, the motor oil is very, very dark and smells like gas
And recently, I have had false fuel levels in the indicator From 1/2 tank after a top-off to full tank when I know I am vapors. The fuel sending unit is brand new.
Any Ideas??

Much appreciated!
Gabe

[90grandoneer]

First, gas in the oil is not good, and that needs to be your first priority to find and fix. Gas in the oil usually comes from a diaphram problem in the fuel pump, or a badly flooded engine with the gas getting past the rings into the crankcase. In any case change the oil and filter, especially if a lot of gas is in the crankcase. A couple questions for you:
--Why did you have to replace the stock pump twice?
--Who rebuilt the carb.? Someone knowledgeable, or was it an O'Reilly special, or ??? What was done to make the carb. "high altitude" ready?
--Why the electric pump? Are you trying to pump through the aledged vapor lock by increasing volume or pressure?
--Is the stock in-line fuel filter with bypass installed by the carb.? Has it been replaced? Is it hooked up correctly?
--What kind of gas cap is on your rig?
--Do you have the other specs. that the tuner gave you? i.e. compression pressure for each cylinder, timing setting, spark plug wire resistance readings, spark plug make, gap and heat range, condition of distributor cap and rotor, etc.
--Have you checked for vacuum leaks?
--Did this all begin right after all the work was done, or were these problems present prior to the maintenance?
A couple things to make you aware of, if you're not already:
--The electric pump could be increasing pressure too much, causing the carb. float to partially unseat the needle (partially sinking the float), thereby flooding the engine. You may want to do a pressure check. Should only be 5 PSI or a little less. If pressure is OK, it could be the float adjustment is incorrect (high). There should be no need for an electric pump on a stock rig.
--These things (Grands) have a problem with ignition modules, which manifest themselves sometimes when it's really hot outside, or high under hood temps. Your run problem at temp. could be something like this.
--Making a carb. "high altitude" ready would probably mean that they reduced the jet size (should be about 10-12% from the sea level jetting for your 6000 ft. altitude), and perhaps a different (lower vacuum opening) power valve. Is this what they did?

Hope this points you toward a resolution of your problem(s). Keep us posted.

[DangerWagon]

Gabe - you didn't sell this jeep, did you?

It's funny - I just purchased a 90 Wagoneer in Colorado Springs last week that spent the better part of it's life in Monument - and was previously owned by someone in the military. It died on me last weekend while I was downtown with the wife - she was NOT impressed. Another jeep owner happened to be driving by when I stalled, and mouthed the words "vapor-lock" to me - which I'll admit I haven't had to think about in years.

Thinking I might just install fuel injection.

At any rate, your description seems similar to some recent trouble I've observed, so I joined the forum to explore further.

I am all stock, as far as I know - but I do know that the fuel pump and filter were replaced earlier this year. Previous owner cranked the idle up for some reason? I've been told that the "float needs adjusted" because there is a dead spot durring aggressive acceleration.

I will find out in a few days, but fuel consumption seems HORRIBLE. Wondering if the gas gauge is working properly. Gas cap is aftermarket locking, and doesn't seem to hold pressure (for example, there was no "release" this weekend when I took it off after alledged vapor-lock)

Not sure about my oil... will have to check that.

Did you ever get yours fixed or figure out what it was?

[BitterGabe]

Lol, are you me in an alternate, yet local universe?
Nope, as much as hate my Jeep's under-hood shenanigans, I could never sell her (see me in a few months!).
Fuel injection sounds OK, I wanted to swap out motors anyway, but not under these circumstances- or with the budget i'm on. I'm going with a GM 6L; I can not get enough positive feedback on the motor in a Jeep GrandWagoneer.

I am absolute that the problem is vapor lock.
http://en.wikipedia.org/wiki/Vapor_lock
Problem is, where in the fuel delivery does it occur?
I actually think that my fuel filter may be a major player. This past Monday/Tuesday when the weather was 80+, the outside casing of my filter rang @ 192 degrees with my hand held laser temperature gauge.
As you know, the last 2 days in Colorado Springs has been chilly and very rainy---My Jeep purrs on down the road, no problem at all! I didn't even use my back up electrical fuel pump, no need at all.

I think I'm going to relocate my fuel filter to the AC compressor area, I took the AC comp off; and that is farther away from the hotter parts of the motor and a little further down to try to get some uplift air that enters the compartment from below. As you know, the is NO air circulation under the hood of a Jeep and the filter is basically resting on the L side valve cover, hot hot hot!
I'll let you know how it works.
Please stay in touch with an of your findings!
Cheers!
I'd invite ya to go out rolling or crawling, but with our problems, I think we'd be limited to parking in the club area on Tejon and trying to look cool as we wait for a tow truck!

[carnuck]

Alcohol in the gasoline is causing these issues. It affects Motorcraft/Holley carbs far more than say Edelbrock. The power valve gets eaten up in a hurry and the electric fuel pump supplies too much pressure which forces the needle and seat open, dumping in extra gas. (I highly suggest a pressure regulator)

[smilinjack]

I had a problem vapor-locking with my '90 JGW, but an older mechanic fixed it in 5 minutes and didn't charge me for it. I now drive the old girl in any weather, any temperature and NEVER worry about vapor-lock.

Pop your hood and LOOK at the fuel line. If it's like mine you'll notice something VERY peculiar. Some brainiac engineer thought it'd be a good idea to run the line FLUSH AGAINST THE BLOCK! If you put your hand on a hot engine, you'll suffer burns. If you hold your hand an inch or so away, you'll feel the heat, but not get burned.
My mechanic took an automotive pry-bar and lifted the line up and out AWAY from the block by maybe an inch.
No more vapor-lock. Also, get an extreme or severe duty clutch for the fan. And one other suggestion. Pick up a few wooden clothes pins and place them around the fuel line. I know it sounds gimmicky but, the wood wicks away heat better than anything else. At least TRY these simple fixes before spending TONS of money on things that may not work. 'Nuff said.

[smilinjack]

Just an update. I had to go to Bradenton, FL., yesterday from where I live near Brooksville, FL.
The outside temp when I left was 91. My baby just purred on down the road. When I got to my bro's house, I helped him run a "few" errands. I had the engine temp up to 220. No probs!!! I parked it for lunch and when we came back out, the temp still hovered around 200. Baby fired right up and drove like there was NEVER a problem.
Once I got back on the road to home, the thermostat kicked in and brought the temp down to a cool 140.