A funny thing happened on the way to Ouray. . .

[waggy401]

Ok, so, leaving from Las Vegas to Bryce Canyon via Zion Nat. Park this morning didn't quite work out as planned. The trip from home to Vegas was uneventful. Today, however, sucked. When we were travelling through the edge of Arizona and through the deserts of Utah, the Jeep started sputtering, loosing power, and backfiring.

At first I thought maybe we just got some bad fuel in Vegas, so we stopped in St. George at a Checkers and I replaced the fuel filter. I also thought that maybe the fuel pump wasn't putting out enough pressure - and I have a Howell TBI, mind you, and nobody carried the 14psi inline pump that it uses. Plus, this is Utah, so to find somebody open is a miracle. But, I gave the filter a try.

It got really bad going into a little town called Hurricane, to the point that we could only go 40 up the easy mountains. We stopped at another Checkers, and so far the counter people have been very helpful, even if they don't have what we need. After at least 1/2 hour trying to find a fuel pump that would work, I mentioned just putting a carb back on just to make it. Then he asked if my distributor was part of the system or not. Well, no, but then it hit me - the ignition module!

Of course, they didn't have one, but through the miracle of the internet we found one at the Autozone back in St. George. So, back we went, sputtering all the way. We got there and were able to test the module, and it failed twice. So, I bought one and put it on. I also met . . . um, shoot, I forgot his real name, but he is Maynard on this list. It's amazing who you meet on the road.

After fixing that, we decided to just forget Zion and Bryce and go to Cedar City and see how things went. It went great, for about 20 miles. Then, on a steep uphill grade, the more I pushed the pedal, the less power I got. Finally we came to a stop. I think I may have figured it out - clogged catalytic converter. I banged on it and it rattled. There on the side of the freeway in 106 degree heat, I started punching holes in the cat.

Now we are in Cedar City at the KOA waiting for the muffler shop to open in the morning. Hopefully that will fix the problem.

If not, does anyone else have any ideas? The timing seems to be fine. It only happens when it starts getting hot, and I had a small exhaust leak that is suddenly much louder (before the holes in the cat.)

Mods: feel free to move this to tech if you feel it would fit better there.

[Gambler68]

10 to 1 it's vapor lock.

[shimniok]

vac gauge

Supposedly you can put a vacuum gauge on the motor to diagnose plugged cat. I *think* if vac gradually builds up and then drops off in a cyclic pattern that is the sign of it...

Good luck with the repairs! That is a drag to have problems on a long drive.

[waggy401]

Whether it's the problem or not, the cat was definitely shot. Like I said, it rattled when I hit it - I didn't mention that tons of dust and little pieces came out.

I suppose it could be vapor lock. We are at a higher elevation, even though it's only 5700 feet. The fuel lines do go over the top of the engine fairly closely, but are as far away as possible everywhere else. I'm not sure what else can be done. Already using the hood spacer trick - can't use the vents now because only hot air comes in. I do have a fuel pressure gauge, but of course the only time I can check that is when we're stopped and it's idling just fine. And I'm not sure why it would start today, since I've never had the problem before.

Anyway, we'll put a straight pipe in in the morning and see how it goes. Thanks for the help. Any more?

[Gambler68]

yeah, vapor lock!!

really, when it's this hot, vapor lock demons come out. 5700 feet is nothing to what you'll be riding when you get here. I hope it's just the cat, problem is your symptoms are the same for both a plugged cat and vapor lock, so if you bypass the cat and it still happens..there ya go. Hopefully once you get into the cool air up torwards here it'll calm down a little. 100+ ambient temp is going to cause havoc regardless.

tricks: undo the gas cap when it happens and let the vaporized gas out.

block of ice on the intake (the gas can be FINE in the lines, and boil IN the intake..)

worst comes to worst..take off the hood and strap it to the roof. We've had to do that on Flints wag just to get over a local pass here once.

electric pump for the fuel, you add it in as a pusher with the mech. one still hooked up. May chew up some time installing.

re-route the gas lines so they dont *touch* the engine. Sorta hard unless you have alot of rubber line.

When ya make it out here, I'll show you how my cherk is set up for ideas if vaplock seems to be the problem.

Ryan

[shimniok]

I suppose it could be vapor lock. We are at a higher elevation, even though it's only 5700 feet. The fuel lines do go over the top of the engine fairly closely, but are as far away as possible everywhere else. I'm not sure what else can be done. Already using the hood spacer trick - can't use the vents now because only hot air comes in. I do have a fuel pressure gauge, but of course the only time I can check that is when we're stopped and it's idling just fine. And I'm not sure why it would start today, since I've never had the problem before.

It could be vapor lock I guess. To me that seems less likely with an electric pump and EFI. Is it possible there is a problem with the pump picking up fuel out of the tank? IE, if there is a particularly long run of hose between tank and pump? (since electrics are much better at pushing than pulling, and pulling drops the pressure in the line and thus the boiling point). Could the in tank sock be clogged? I don't know if I dare suggest this since I've never done it but others have used GM in tank pumps with success.

As I have heard it told, fuel is blended for particular temperatures etc, so ... could it be that you got a tank of gas that was better suited to a different temp or altitude? I donno ... some have said to add a little diesel to prevent vapor lock (but I don't know how much is safe)

I know this can be very frustrating to have a problem like this and not have a clear notion of the cause. Hang in there, and try to work through it logically and definitely lean on the bbs here for help... wished I could be of more help.

Michael

[shimniok]

PS: another thing to consider is an EFI problem. I don't know if you have equipment to read what is going on ... that could be illuminating. The losing power and backfire to me sounds like a lean condition and another cause might be a problem with one of the sensors.

[fulsizjeep]

Sounds like vapor lock to me and I am not familiar with fuel injection systems. Are you running a stock style air cleaner? If so, you might try flipping the lid over so it breaths in around the top. I have vapor locked mine when the engine was only 195 degrees and believe flipping the lid helps with air flow and cooling around the carb/tb. It might be worth while to do what you can to get the fuels lines (feed and return) rerouted away from heat sourses in the engine bay too. Hope things work out to get the cat removed and back on the road this morning!

[Gambler68]

I missed the EFI part. I know OEM EFI automatically compensates for altitude (it 'learns) but a pre-programmed/curve may not if it was set for a certain altitude.

[Heimeken]

Put in a clear filter just before the carb/tbi. You should always see some flow. It not it is vapor locking or something in the fuel lines. Check the condition of all the fuel lines from the tank to the new filter for cracks that may be letting air in (experience speaking).

[will e]

Hey Heimeken, shouldn't you be on the road by now?

[fulsizjeep]

Welcome!!!!!

[Heimeken]

Hey Heimeken, shouldn't you be on the road by now?

I'm leaving after work today, had to leave a day late so I plan to be there Wed. Mid day.

[fulsizjeep]

Jaime, you heard from Kenny? He has been scarce here lately. He said he was coming but we ain't so sure of that. We'll see ya there tomorrow eve!

[kennyh]

Me Kenny or the bad Kenny? I'm leaving shortly.