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post #1 of (permalink) Old 01-26-2004, 12:18 AM Thread Starter
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Load problem.

Ok.. its going to be long.. but I thought I'd try you guys before spending big bucks to replace everything under my hood.

I have a problem when my engine is under load. Acceleration or up hills is where its more promenant.

The Jeep will run up to 2000 rpms.. then almost out of nowhere.. either 2-4 minuites after running it up under load .. it stops driving the wheels.. and the wheels start turning the engine.. sometimes it just dies like that and it takes smacking the gas a couple times before it kicks back in.. other times if I lay on the gas, it goes and stops.. and goes and stops.

Things I have observed: I tihnk I'm having pump problems.. but my fuel filter is absolutely FULL of fuel.

I've burned through 2 tanks in one week. (NOT COOL.)
And only driven a bit.

I have no-problem city driving...

A friend pointed out a new Vacume leak by the 6th cylinder... so I'll pull the manifolds and replace them suckers tomorrow. (any tips anyone? new gaskets and RTV? or do I just forget the RTV?)

Here's my thoughts.
-Fix vaccume leak.
-Replace plugs.. regap.
-Open carb and ensure there's no crap in it.

Anyone got any other ideas? I'm dumbfounded here.

It's a 4.2L from a 1989. MC2100 and TFI ignition.

checked the rotor and there was some magnezium dust.. but no scortch marks.

thanks everyone.. this is really anoyying me.

I don't think I'm doing anymore mods until I've sorted my jeep out. gonna get it reliable and simple. I really hate being the guy on the trail who's always like.. "hold on.. my carb crapped out.." "hold on the ignition is messed" "hold on the breaks aren't working."
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post #2 of (permalink) Old 01-26-2004, 12:22 AM
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Re: Load problem.

Sounds like a fuel delivery problem. Either the pump isn't pumping enough, the lines are clogged, or the pickup is blocked.
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post #3 of (permalink) Old 01-26-2004, 12:53 AM Thread Starter
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Re: Load problem.

I suspected it too..

But a lack of fuel wouldn't make me burn through like 10X more then I should be.. should it?

Also, the fuel pump HAULS.. when I get out on the highway.. or about 2 grand.. the pump can fill a 2 liter bottle in about 15 seconds.

BUT.. when I went wheeling today (well spectating) the truck stalled twice.. both times i got out, and the lines from the pump to the carb were dry..

it took undoing it.. and cranking it over for 30-45 seconds till I got fuel squirting back out.

I want to replace the pump wiht an electric.. can I put it on the frame rail upfront next to the engine? I like the idea of not having to worry if the pump is pumping.. "click" "Whurrrr" "Fuel"

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post #4 of (permalink) Old 01-26-2004, 07:28 AM
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Re: Load problem.

Had a similar problem before.
Turned out to be a rusted out gas line.
Check out your lines, especially the steel one that runs from the tank to the pump.

post #5 of (permalink) Old 01-26-2004, 11:37 AM Thread Starter
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Re: Load problem.

Thanks.. so it was crap in the lines? or did the line rupture?
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post #6 of (permalink) Old 01-26-2004, 12:09 PM
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Re: Load problem.

Something to try before doing anything.
Take off the gas cap as soon as it acts up. See if it goes "whoosh." It may be the vent's plugged. As you drive it you use gas, the tank gets a vacuum, enough that the pump can't overcome it. You stop, wait, crank, the tank has a tiny leak, air gets in, vacuum goes away, pump works again.
If no "whoosh", try leaving it off and driving it - see if it still stalls.

The vacuum leak on your #6 is not causing your problem. At worst it'll cause a slight misfire.

Just because there's fuel in a clear filter, it doesn't mean it's actually flowing. And the opposite's true - just because you see air in a filter (with some fuel) it doesn't mean it's not.

And - you said you have a TFI upgrade/downgrade - see if the module is terribly hot when you stall - and see if the coil's super hot. They get intermittant when they overheat - till they quit completely.

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post #7 of (permalink) Old 01-26-2004, 02:01 PM Thread Starter
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Re: Load problem.

Thanks Rich..

I've noticed a woosh when filling the tank..

pull the cap when the tanks empty.. and it sucks air..

I also have ONE fuel line.. I don't know what the stock YJ setup is because the previous owner decided to mod it before i bought it..

but I have ONE line that runs to the front and provides fuel.

There are no return lines or vents or anything.
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post #8 of (permalink) Old 01-26-2004, 02:20 PM Thread Starter
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Re: Load problem.


If It's not the gas-cap.. and not the manifold.. and not the carb.. I was planning on replacing the fuel lines from front to back.

Again, the previous owner in all his wisdom, has about 5 rubber hoses, and 5 steel hoses under the hood. 4X that many hose clamps keeping it all together.

It literally looks liek he broke on the trail and asked everyone for every little bit of hosse thy could sacrifice.

SO... is there a reason for this? or can I just grab some rubber line and run clean from the fuel pump to the filter and filter to the carb? cause right now theres like 4 lines bettween the pump and the filter.. it also goes UNDER the block for some reason. I was going to rout it back up behind along the firewall..

Can I run soft lines from the fuel tank to the pump? or do they have to be hard lines?
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post #9 of (permalink) Old 01-26-2004, 08:57 PM
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Re: Load problem.

Since you are burning through a lot of gas, I suspect the carb is icing. My 304 with motorcraft 2100 acted like that once and I happened to pull the air filter to see the venturi's completely iced.
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post #10 of (permalink) Old 01-26-2004, 11:40 PM Thread Starter
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Re: Load problem.

I've got an open element.. but I setup a heater hose that ran from the heat sheild to the carb. Was sucking air ONLY out of there.. and it did the same thing..

Ok heres some more info.

When the engine isn't fully heated up, I can rev. the piss out of it.. right up on the highway at 3 grand..

On the way back though the engine was warm.. and it didn't do as good.. it sputtered and crap.

So I spent all afternoon in the rain () replacing the exhaust and intake gaskets.

Got it all back together, and except for a small leak by the collecter joint? its all good.

pulled the top off the carb and its all clean in there.

Took it out on the road.. got all excited because it ran like a champ..

But again on the way back it sputtered.. not as bad.. but it still did it.

Also, today, I pulled plugs, re-gapped them.. filed and cleaned them..

Anyone got anything else now? I'm just eliminating these problems bit by bit..

Thanks again for everyones help so far.
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