WHY IS MY 'S ENGINE BOGGING DOWN AT MID TO HIGH RPM
1983 Jeep CJ7
June, 9, 2012 AT 1:46 PM
Hello, I bought a used 83 CJ7 6cyl from the Greenville SC area about 2 months ago with 190K miles. The previous owner had it sitting and only drove it a few times a year. He mentioned that the vacuum system was bypassed or blocked but that it didn't matter sense there wasn't a smog test required. He also replaced the fuel pump a few years ago. So, I drove it down to FL and it ran great. What a GREAT deal. She runs perfect! Very clean and mostly stock Jeep. Well, it recently started with engine problems at high RPM or high power. Seems to bog down and feel like it's missing or not getting enough fuel. May be realated but it was low on oil after the trek to FL so I topped it off with Mobile1 High Milage and it seems to consume about 1 quart for every 2 tanks of gas. I'm not very mechanically inclined and have only done minor work with engines. Oil changes, plugs, and filters basically.
Thanks in advance for all the help and advice!
Scan for codes, check fuel pressure, check for vacuum leaks and clean throttle plate with choke cleaner first. Then have a pro check for bad valve seals or low compression.
June, 10, 2012 AT 12:36 AM
I'll try to do that next week. Thank you for the quick reply!
June, 10, 2012 AT 1:53 AM
MOST LIKELY YOU WILL BE UNABLE TO FIND ANY CODE
YOUR RIG IS ABOUT 29 YEARS OLD AND MOST LIKELY ALL OF THE REALLY UNNECESSARY EQUIPMENT HAS BEEN DISCONNECTED OR NO LONGER WORKS
ARE YOU TESTED IN YOUR REGION?
I'M ABOUT 50 MILES FROM WHERE YOU ACQUIRED YOUR JEEP
DO YOU KNOW YOUR WAY AROUND UNDER THE HOOD.I MEAN ARE YOU ABLE TO WORK ON IT. TUNING TOOLS.A REPAIR MANUAL?
DO YOU KEEP UP WITH THE MAINTENANCE. TUNE UPs. WHAT EXACTLY WAS DONE, PARTS AND SERVICE? FUEL FILTER?
DESCRIBE WHAT IS HAPPENING WHEN YOU HIT THE HIGHER RPMs. THE MORE INTENSE YOUR DESCRIPTION OR COMPARISONS TO WHAT IT DOES, THE BETTER WE MIGHT DIAGNOSE IT. AND AID YOU IN ITS REPAIR
WHAT HAS BEEN MODIFIED?
CAN YOU SEND A FEW PICS OF UNDER YOUR HOOD (IN FOCUS)?
June, 10, 2012 AT 12:19 PM
Yeah, I didn't think there'd be any codes with this one but I was going to try the other suggestions.
Disconnected or no longer working. My goal is bear necessities. If Jeep don't NEED it. I have no use for it. My only request is that she keeps the radio I just installed. Basically, I traded off my Harley for this Jeep and plan on using/treating it as well as the old hog and learning what makes her tick along the way.
No testing here!
It's too bad CJ and I aren't still up there. I would have liked to pick your brain over a beer or few.
"Knowing my way around under the hood"
Yes. Kind of. I'm willing and able but I'm new to the Jeeps. I did ALL my own work on the Harley and I loved how simple it was. There was no way I was going to let the HD shop nickel and dime me. Anyway, I did a top end overhaul, straight piped it, tuned it, lowered it, etc. I did a lot! She was far from stock or legal.
As far as cars and maintenance go. I change my own oil on schedule but I leave the other stuff to the shops due to limited vehicle diagnostics and special tools access. I only have the basics but I'm willing to buy as needed.
No service manual yet. I have been needing to get one but wanted to ask someone (expert) what to get. Do you suggest any particular one?
The previous owner had it for about 8yrs and didn't do much to it or drive a whole lot. He bought it as a restoration project and never got around to it. Then decided he'd rather have a nice Harley so we swapped our rides.
He was planning on an engine rebuild because of the mileage but it has always run great and he kept putting it off. He said he changed the: fuel pump, thermostat, clutch, and tires. Everything else, I must assume has not been done for a while.
What's going on with her: Any gear except 1st above 3k RPM and it feels like she's missing or struggling. There isn't a tach but it feels about 3k to me. It gets progressively worse thought the gears as more fuel is needed. By 4th gear going down the highway, I can't get it to go over 60 unless going down hill. When I brought it down to FL a couple months ago, I was running 75-80 no problem. I also have noticed a slight increase in gas mileage. 12.5 to 13.7 with the last couple fill-ups. This could be coincidental sense I can't really test it in a lab with exact measurements. I also feel like she's running a little hot but I can't verify that either because that gauge isn't working. I work as a pilot so I understand the leaning thing and it's effects on engines so I have a feeling it could be a fuel flow (filter) issue. At least I hope that's all it is. Simple, inexpensive fix right? Sense the previous owner had to register the Jeep just to meet me part of the way for the swap, he obviously didn't drive it much. This leads me to believe there's probably about 2 months of crap built up in the fuel filter. Whether the fuel filter fixes this thing or not. I still plan on stripping it down to the bare essentials.
I forgot to mention this earlier. But, the exhaust pipe is making a rattling noise every once in a while. This just started happening the last couple times I drove it. It usually happens when turning to the right and there's a little more side-load to the vehicle. 90deg turns while down shifting basically.
This is the best description I can come up with so far. I'm going to drive it again this morning before we head out of town. We're taking the kids to Disney for a few days. I will also try to take some pictures of it before we leave and get those uploaded within the next day or two.
I really appreciate the time you're taking to help me through this and I will take any advice you throw my way. Eventual engine rebuild, carb swap, new exhaust, family roll-cage, safer seats, and a paint job are in her future. This of corse is time/money permitting.
By the way. Nice Willys! I love the classics! I Can't wait till next year when I can officially register my Jeep as a classic. 30yrs!
If you have some time to kill. Check out my boards at MahaloBoards. Com
June, 10, 2012 AT 4:43 PM
I SUSPECT THIS COULD BE CAUSED BY SEVERAL THING OR A COMBINATION
AS YOU SAW IN MY PICS, I NOW HAVE A HOLLEY 390, ON MY SIX...THIS WAS MY FINAL ATTEMPT TO GET BETTER MPGs.
I STARTED OUT WITH THE '77 CARTER YF (STOCK 1 BARREL) ---MOVED ON TO A '79 INTAKE AND TRIED SEVERAL 2 BARREL BBDs (THIS WAS OK, I WAS ABLE TO ACHIEVE 15-16 MPGs)--I WAS GREEDY, I TRIED A WEBER DGEV (JUST COULDN'T DO ANY BETTER)----ONE DAY I WON JUST ENOUGH MONEY PLAYING THE LOTTO, I WAS ABLE TO GET THE OFFENHAUSER 4 BARREL INTAKE AND THE HOLLEY 390 (AFTER GAINING KNOWLEDGE ON USING AN O2 SENSOR AND AIR/ FUEL GAUGE) I WAS ABLE TO PROPERLY JET MY CARB.
KEEPING IN MIND THE THEORY THAT EITHER MPG LACKS OR POWER LACKS, I JETTED FOR MPG......AT THE SAME TIME, MY POWER REALLY DOESN'T LACK, WHEN I JUMP ON IT, IT DOES REALLY WELL....I'M GETTING ABOUT 18 MPG WITH A LIGHT FOOT.
I HAVE TRIED MANY OF THE MIRACLE MPG GETTERS, IN THE PAST....THE HOLLEY WAS THE FINAL TICKET FOR ME. I'VE BEEN ACCUSED OF SPENDING MORE MONEY SEEKING BETTER MPGs THAN I WOULDA SAVED....I DIDN'T CARE THAT WAS MY PERSONAL GOAL.
YOU ARE GONNA NEED SOME TOOLS TO BE A JEEP GUY
A TACH/ DWELL
A PLAIN JANE TIMING LIGHT (NO BELLS AND WHISTLES, ADVANCES ETC)
A VACUUM GAUGE
A COMPRESSION GAUGE
AND OF COURSE DECENT WRENCHES, SOCKETS, SCREWDRIVERS
I WITH YOUR RIG "HOLDING BACK" (ASSUMING THERE ARE NO VACUUM LEAKS AND EVERYTHING IS HOOKED UP CORRECTLY....WE MIGHT TACKLE THIS TOO!)
I THINK YOU ARE HAVING "LACK OF FUEL" ISSUE----OLD DIRTY FILTER--DUMB MODIFICATIONS---CARBURETOR INTERNAL (FLOATS) OR OTHER CARB PROBLEMS.......DO YOU STILL HAVE THE FILTER WITH 3 PORTS AS IN MY PIC? 1 IN, 1 TO CARB, 1 TO RETURN TO THE TANK?.... DISREGARD MY LITTLE GAUGE AND REGULATOR IN THE PIC (BELLS AND WHISTLES)
AS FAR AS TIMING---WE GOTTA HAVE THE TACH/ DWELL AND A TIMING LIGHT TO CHECK AND SET STUFF, MIGHT AS WELL GET 'EM, THESE WILL BE NEEDED LATER IN LIFE. YOUR 1ST USE OF THEM MAY SAVE YOU WAY MORE MONEY THAN YOU WOULD PAY THE OTHER GUY
IT'LL BE DONE RIGHT!!!, AS YOU WILL KNOW FOR SURE WHAT TO DO, WHEN I FINISH WITH YOU.....WHAT WE WANNA DO WITH THEM IS "SET TIMING" AND VERIFY THE "ADVANCES" ARE WORKING CORRECTLY....AN EZ TALK THRU!
BELOW IN PIC, IS A NICE LITTLE COMPACT KIT MY BUDDY PURCHASED AT "HARBOR FREIGHT" THEY CARRIED IT FOR LESS THAN $40, IT WORKS WELL TOO!....IT IS FROM WELL KNOWN COMPANY YOU MAY BE ABLE TO OBTAIN IT FROM THE INTERNET BY THE PART NUMBER AND MFG. THERE ARE MANY MFGs OF THIS KINDA STUFF, A PAWN SHOP MIGHT BE A GOOD CHEAP SOURCE.....EVEN DINOSAUR STUFF COULD STILL WORK FINE (AS LIKE WHAT I HAVE)
I WILL HANG WITH YOU ONE ON ONE, WHEN WE START, I DO "LINK" YOU ALL OVER THE WORLD TO GET MY POINTS ACROSS, AND TO CUT DOWN ON MY HUNTING AND PECKING.
YOUR THOUGHTS?.....READY TO BE "JEEP COMPETENT"?
June, 10, 2012 AT 6:16 PM
All you need now for a starter is a scantool and a universal fuel pressure tester for an EFI system- I won't be surprised if I see one in a short-
June, 11, 2012 AT 1:54 AM
IMMA STILL SORTA STUCK ON A POSSIBLE FUEL---AIR---OR A TIMING/ DISTRIBUTOR PROBLEM.
I FEEL CODING THIS OLD PUPPY IS GOING TO BE FRUITLESS
WE CAN TEST FUEL BY "WATCHING OUR WATCH" WHILE FILLING UP A VESSEL. AT LEAST ONE PINT PUMPED IN 30 SECONDS, THE CARB FEED LINE REMOVED AND SHOVED IN A QUART CONTAINER.
WE WILL DEFINITELY NEED A DWELL/TACH AND A PLAIN JANE TIMING LIGHT.
I'M NOT HERE JUST TO MAKE YOU GO.I'M HERE TO GET YOUR RIG RUNNING AS CORRECTLY AS I CAN, AND KEEPING IT AS INEXPENSIVE AS POSSIBLE. AND GIVING IT'S DADDY SOME KNOWLEDGE FOR FUTURE USE.
IF WE ARE NOT STARTING OUT WITH "KEPT UP SCHEDULED MAINTENANCE", IT'S LIKE GOLFING WITH BENT UP CLUBS. THE REGULAR TUNE-UP STUFF NEEDS TO BE CAUGHT UP. ELIMINATING THEM AS A FACTOR
LET ME KNOW WHEN YOU HAVE THE LIGHT AND DWELL/ TACH. AND AT MINIMUM YOUR FUEL FILTER HAS BEEN REPLACED. THEN VERIFY THAT YOUR FILTER IS STILL HOOKED UP WITH 5/16 PORT "IN"---5/16" PORT OUT TO CARB---1/4" PORT OUT TO FUEL TANK RETURN (FACTORY, LIKE IN MY PICS).I'M READY TO RUN YOU THRU THE TESTING
INVESTIGATE THE LINKS I GAVE YOU ABOVE.I GIVE INFO, TILL YOU ARE TIRED OF ME!
ALL I WANT IN RETURN IS ACCURATE INFO AND ACCURATE TESTING. STOP ME IF YOU GET CONFUSED OR LOST
June, 11, 2012 AT 2:28 PM
Ok. I got some pictures taken yesterday. I also checked out some of the other questions/solutions. You are certainly the guy I want handling this problem with me. The previous owner showed me a hose that's blocked off and told me that as long as there isn't emissions testing in my area, this didn't matter so I assume the non-essential parts of the vacuum system have already been removed.
Picture 8 shows a close-up of the carb and it looks like a couple lines are cut and capped.
Picture 6 shows the oil leak. Something I will address later with a new head gasket.
Picture 3 & 4 shows the hose mentioned earlier that has been disconnected and tied off.
Picture 2 looks to me like a a sensor with a wire that has broken off. Is this why my engine temp gauge isn't working? This sensor looks like it has something to do with the exhaust system.
As far as getting tools, testing kit, and manual. I will start working on all this as soon as I get back into town.
First things first. Replace the fuel filter. I recently talked with a trusted family mechanic and he told me some of the same things. Fuel filter and add an inline bulb filter as well so I can see if/when it's getting clogged again. I will be doing this unless you think it may reduce the fuel pressure. He then told me to change the plugs, wires, and dist cap to rule that out. I'll report back once all this has been completed.
I certainly appreciate your time and efforts! If good feedback is all you want. You'll get it!