A few issues on my first 100-miler

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merrill77
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A few issues on my first 100-miler

Post by merrill77 »

Took a litte shakedown cruise today - trying to decide if I should take my '77 ~250 miles to the mountains next weekend. It is in the low 80s here today - did ~110 miles of freeway and secondary roads (AMC 401).

1) Cruising at ~70, temp gauge goes up a little above what is normal when driving around the burbs. 205° thermostat with aftermarket radiator & elec fans. Is this normal?
2) After a bit more than an hour on the freeway, I noticed the oil pressure dropping. It had been sitting around 20-25 (as indicated on the dash gauge) but over the course of a few minutes, it dropped down below 10. I decided to get off the freeway. Pressure returned to normal in a few minutes on secondary roads. Later, when I got back on the freeway, oil pressure maintained at 20-25 for the final 30 min of my drive. Any theories on this? Oil level is good (changed < 1k miles ago).
3) When I stopped for gas later in the drive, there was a lot of pressure in the gas tank. I have noticed a pressure release before, but this was more. I cracked the cap partially open and it hissed for a good 30 seconds. Then when I fully opened it, it gurgled & spat fumes and some visible spray of fuel. Air rushing out of the filler was hot - almost uncomfortable to leave my fingers there. Is this something I should be concerned with?
4) At one point, I watched the fuel gauge start rising quickly and eventually peg far beyond F. I can't fully fill my tank...I've never seen the needle reach F before. Theories? Possibly related to #3?

TIA!
Chris
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Re: A few issues on my first 100-miler

Post by Stuka »

1: What electric fans are you using? Cheaper ones don't pull anywhere close to what their rated CFM is. But there are quality ones that work fine. Its one of the reasons a lot of people go with OEM electric fans from other vehicles.

Isn't the factory thermostat 195?

2: The dash gauge is known for being off. I have seen mine go down below 10, and then other times show 25 or so. An aftermarket gauge is the only way to know for sure.

3: I have never had this happen on any of mine. Does the exhaust run near the tank? How are the fuel lines routed over the engine?

4: This sounds like a grounding issue.
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letank
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Re: A few issues on my first 100-miler

Post by letank »

#2 solution

http://www.fsjnetwork.com/forum/viewtop ... 4&start=20

I had the same issue with the oil pressure being like more a slow pendulum. Trouble free for the last year, 1200 to 1600 miles, but the trips are long distance drive of over 3hrs, freeways and hill climb and slow dirt roads

#3, you can disconnect the tank vent hose at the charcoal canister for diagnostic purpose, and see if the whooosh is stopped or reduced - IIRC Year 77 is still a simple canister without feedback for the PCV valve.
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Re: A few issues on my first 100-miler

Post by merrill77 »

Stuka wrote:1: What electric fans are you using? Cheaper ones don't pull anywhere close to what their rated CFM is. But there are quality ones that work fine. Its one of the reasons a lot of people go with OEM electric fans from other vehicles.

Isn't the factory thermostat 195?
Correct you are. Don't know why I had 205 in my head. I installed a Duralast 15359 which is a 192F thermostat, according to AutoZone.
Stuka wrote: 2: The dash gauge is known for being off. I have seen mine go down below 10, and then other times show 25 or so. An aftermarket gauge is the only way to know for sure.

3: I have never had this happen on any of mine. Does the exhaust run near the tank? How are the fuel lines routed over the engine?
The exhaust runs between the driveshaft and passenger-side frame. The fuel line runs along the tank, then over to the driver-side firewall and up over the bellhousing to the fuel rail on the drivers side.

Image

As it goes up the floor/firewall, it is 10-12" from the driver-side exhaust coming down from header.

Image
Stuka wrote: 4: This sounds like a grounding issue.
Sounds likely. I wonder if that grounding issue could be caused by high pressure in the tank?
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Re: A few issues on my first 100-miler

Post by merrill77 »

letank wrote:#2 solution

http://www.fsjnetwork.com/forum/viewtop ... 4&start=20

I had the same issue with the oil pressure being like more a slow pendulum. Trouble free for the last year, 1200 to 1600 miles, but the trips are long distance drive of over 3hrs, freeways and hill climb and slow dirt roads
I'll read through that. Thanks.
letank wrote: #3, you can disconnect the tank vent hose at the charcoal canister for diagnostic purpose, and see if the whooosh is stopped or reduced - IIRC Year 77 is still a simple canister without feedback for the PCV valve.
I doubt I still have a charcoal canister. EFI and no snorkel. If it still exists, it's been moved - as it is most certainly not in the location shown in the TSM.

I re-read the fuel diagram and took a closer look at my rear fenderwell where it passes through. I discovered I had not read it correctly before - the fuel tank vent goes out of the tank, into the fenderwell, into the inner fender and then attaches to the filler. However, my line is kinked where it exits the filler. I think this is why I'm having trouble filling the tank. I'm going to leave the interior panel off and make sure that hose is not kinked, next time I fill, to see if I get better results.

Image

According to the TSM, the 49-state vehicles should have a pressure-relief (and vacuum-relief) cap. I think mine was originally purchased in AZ. If this is such a cap it doesn't appear to be working. I think that would explain the high pressure in the tank, as there is no other way for expansion vapors to escape the tank?

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Re: A few issues on my first 100-miler

Post by merrill77 »

Stuka wrote:1: What electric fans are you using? Cheaper ones don't pull anywhere close to what their rated CFM is. But there are quality ones that work fine. Its one of the reasons a lot of people go with OEM electric fans from other vehicles.
It has a pair of SPAL 11" VA09-AP8/C-27A fans that are rated at 755 CFM by the mfr. Is that a cheaper one?

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Re: A few issues on my first 100-miler

Post by letank »

you can dismantle the gas cap, and make it vented, either there are some obvious holes, or make one, with efi, the pump might pump more gas and create a vacuum, hence the venting necessary in your modified set up.

fuel lines are not OEM, so you 'may' cook the fuel as the shown set up, the newer fuel is more likely to vaporize or vapor lock than the fuel from the 80's. The OEM fuel line is inside the driver's side frame rail. Some have rerouted the fuel line on the outside edge of the frame rail for ease of installation. Do you have a fuel return line? check the fuel filter to see if you have a second outflow, which should be pointed at 12 o'clock or on top of the feeder for the "carb", but having EFI if course you may have a different installation.

if you have a catalytic converter that will cook the underside even more

most of our rigs, at least 80's and older have issues with venting when fueling, you can move the nozzle at 12 o'clock, some pumps are more likely to trigger the shut off than others.

as for electric fan, the consensus is that most electric do not get the job done, unless you have a ford contour, taurus or volvo set up... in doubt you can install the mechanical fan clutch, our rigs are shape like brick so fuel economy will not be improved unless driving at 55mph vs. 65
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Re: A few issues on my first 100-miler

Post by fulsizjeep »

GAH! I wonder how many FSJ owners have wasted their time and money on electric fan(s) for their AMC V8? The cost alone all combined must be astronomical.
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Re: A few issues on my first 100-miler

Post by RamJetFSJ »

I would think that whole freeway driving (no traffic), the radiator fans would make no difference at all. There should be more than enough air flow over the radiator. You have t look at other things like the rest of the cooling system, and timing or fueling issues.

Oil pressure loss when the motor gets hot is normal. Fix your cooling problem, and you shouldn’t see that problem any more.

You definetaly either need a fuel tank vent, or a vented cap if you no longer have the charcoal canister. Just having a pressure release cap isn’t enough, it won’t vent enough when the level of the tank goes down under use. The tank temperature concerns me though...
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Re: A few issues on my first 100-miler

Post by Stuka »

Two 750cfm fans is not nearly enough. A lot of guys used to use ford taurus fans as they pulled 2800cfm on low, 5600cfm on high.

There is nothing wrong with electric fans, and they will cool anything made, they just have to enough CFM to do the job. So I would suggest finding an OEM fan, FWD cars tend to have high CFM fans, or an after market one that actually pulls a lot of air.

There are also some GM V8 cars with electric fans that pull tons of air. Camaro's come to mind, they use electric fans for their LS engines.
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Re: A few issues on my first 100-miler

Post by Stuka »

Oh, and I think you are on the right path regarding your gas cap. It should vent with high pressures. You should be bale to buy a new one. Although its getting hard to find good quality ones :/ I had to buy a plastic one last time around.

And a kinked vent hose will make it very difficult to put fuel in your tank.
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Re: A few issues on my first 100-miler

Post by 1979bettywhite »

I agree on the 12 o'clock/upside down position of modern day gas pumps. I have no problem with venting during fill if I do this. Any other angle causes the auto shut off almost immediately.

I am very envious of the cleanliness of your undercarriage sir. Your Jeep that is. Half my time spent under the Chief these days is wiping off both new and old fluids to try and determine where leaks are coming from, lol. "oh wow, that t'case is actually silver?"
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Re: A few issues on my first 100-miler

Post by merrill77 »

1979bettywhite wrote:I agree on the 12 o'clock/upside down position of modern day gas pumps. I have no problem with venting during fill if I do this. Any other angle causes the auto shut off almost immediately.

I am very envious of the cleanliness of your undercarriage sir. Your Jeep that is. Half my time spent under the Chief these days is wiping off both new and old fluids to try and determine where leaks are coming from, lol. "oh wow, that t'case is actually silver?"
Agreed - I can't get ANY gas into my tank without inverting the filler nozzle, if it flowing faster than a trickle.

I am fortunate that it was this clean when I got it. Not sure how I'm going to keep it that clean :o
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Re: A few issues on my first 100-miler

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So I have ordered a pressure-relief replacement cap that looks similar to mine - I hope to transplant the innards into mine. If that doesn't help, well, I'll get it vented...one way or the other :)

I'm not sure what to do about the tank temperature - that is more than a little worrisome to me.

I will look for a return line.

As for the fan capacity: at low to medium speeds and even in heavy traffic, the fans are effective at keeping the temp steady. But the fan capacity seems irrelevant at highway speed, where airflow should be plenty due to the brick-like aerodynamics of our FSJs. No? The fan shroud that I have, however, does seem to block off a good bit of the radiator. THAT seems like a problem to me...as it would limit that flow at highway speed. But it sounds like the collective experience says that the fan capacity really is an issue at highway speed and my 5-minute newbie analysis is wrong. Hmmm...
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Re: A few issues on my first 100-miler

Post by Stuka »

Hwy speed cooling depends a lot on load and ambient temps. With the stock fan setup, its still pulling a lot of air when you are on the HWY. And I can say the electric fans on my newer vehicles all run when I am on the HWY.

Trust me, you need higher capacity fans.
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Re: A few issues on my first 100-miler

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merrill77 wrote: I re-read the fuel diagram and took a closer look at my rear fenderwell where it passes through. I discovered I had not read it correctly before - the fuel tank vent goes out of the tank, into the fenderwell, into the inner fender and then attaches to the filler. However, my line is kinked where it exits the filler. I think this is why I'm having trouble filling the tank. I'm going to leave the interior panel off and make sure that hose is not kinked, next time I fill, to see if I get better results.

Image
[/img]
I forgot how the 77 is plumbed, but on the 74 the rubber vent line goes up the inner fender well like yours and connect to a metal pipe that exit to the wheel well, and return to the top of the gas tank where is hooks up with a rubber hose to the top metal vent on the side the gas tank.

Image


the 78 was different the vent hook up is next to the filler hose -I added a rust free 78 gas tank to the spare part supply- It has more vent or pressure relief nipples

Image

you can find the details on tom ol jeep site, http://oljeep.com/edge_77_tsm.html

go to section 4A for the emisson chapter, the schematic is probably the CJ or truck layout, but it is simpler,

As usual depending on month of built thinks can be different
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Re: A few issues on my first 100-miler

Post by rapom »

I personally do not like 195 degree thermostats on carburated vehicles. 180 degrees max. Fuel nowdays is more unstable at high temps than it was back when your rig was new and will vapor lock, evaporate out of the carb easier. You don't have those problems with fuel injection. I agree with the others that say your fans are too small. A stock clutch fan and shroud is all you need.
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Re: A few issues on my first 100-miler

Post by merrill77 »

I'm not carbureted - Edelbrock MPFI.

But I will try upgrading to a higher capacity fan. It looks like there are some from the same brand that will match the existing mounts and more than double the flow rate.
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Re: A few issues on my first 100-miler

Post by letank »

merrill77 wrote:I'm not carbureted - Edelbrock MPFI.

But I will try upgrading to a higher capacity fan. It looks like there are some from the same brand that will match the existing mounts and more than double the flow rate.
I hope that I have done the ammeter bypass? those powerful fans use a lot of wattage. Remember that most Grand Cherokee folks are reverting from Efans to mechanical because the overheating makes their valve seat to drop and fubar the engine which is aluminum -the GM Vega is back-

posting general link to Efan evaluation

http://www.fsjnetwork.com/forum/viewtopic.php?t=12750
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Re: A few issues on my first 100-miler

Post by merrill77 »

There doesn't seem to be a consensus that reverting to the mechanical fan and shroud is a better solution than an effective electric fan.

Because I already have aftermarket radiator with fans & shroud, it is assured that reverting to mechanical would be a lot more work than buying a higher CFM fan that matches my existing setup. I bypassed the ammeter about a month ago - the charging system is healthy, based on my monitoring over the past month. From what I can see, the fans are already wired direct (with relays & fuses)...not through the fusebox.

So I'm going to try a fan upgrade to see where that gets me.
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