BASIC DIAGNOSTICS 101

[Steve Zicht]

Just wanted to share one bizarre story with my SPEED TALK friends. Food for thought about diaging a problem.

I used to run a carburetor shop and I really enjoyed helping garages solve fuel system issues. If any of you old salts out there remember when carburetion was in its prime, that poor carburetor was blamed for anything and everything if the motor wasnt running perfectly.

Heres a bizzare incident that I simply wanted to pass on for all to read.

I guess the year was around 2000 and a good customers shop helper dropped off a carburetor for complete overhaul. It was a simple Carter two barrel BBD type with no emissions ' feedback system ' off of a 1980 Jeep CJ with a straight six cylinder engine and an automatic tranny.

I could do these things blindfolded because they were so simple. I had a very good business relationship with the shops owner whom I had known for years. If I saw something that indicated the vehicle had more problems, I would call the owner and let him know. The best example would be charcoal debris in the float bowl from a bad evap canister. It would prevent many a ' COME BACK.'

Anyway, I took the 2 barrel apart and there wasnt a thing wrong with it. Clean as a pin inside and even the choke pull off and float were fine too. Called my buddy up and said that I would start looking for another problem. Shop owner said ' SEND IT BACK BUDDY ! I'll tell the mechanic what you said.

I didnt hear anymore about it until about a week later when the business owner said he was going to return the carb again because the ASE MASTER CERTIFIED MECHANIC with at least a dozen certification patches on his sleeve said I was an idiot and needed to examine this carburetor again and really look at it closer this time. ........... LET ME INTERJECT HERE ........... and say that it was determined that the motor was completely shot and the customer was persuaded to spend $ 3000.00 and up with a new ' REMANED LONG BLOCK ' and a REMAN DISTRIBUTOR with all new tune up parts and other various components.

AFTER ALL THAT, IT STILL RAN LIKE A PIECE OF CRAP !! Mechanic, ( WHOM WAS JUST HIRED A FEW WEEKS BEFORE ) convinced the owner that if I had overhauled the carb initially like I was supposed to, this Jeep would be long gone with a very small repair bill. So I thought the carburetor was to be returned to me but................. the owner had a better idea. He had the Jeep towed to my shop and the keys were given to me and the wrecker driver was told by the tech to deliver a simple message...... YOU GOT US IN THIS MESS, YOU FIX IT IDIOT !!

HERE WE GO..................

First thing I do is start the Jeep up. HOLY MACKEREL ! This thing must be idling at 2000 rpm to just keep it running. WTF ?? I grab my vacuum gauge and find a manifold vacuum port to see whats going on here. HOLY MACKEREL AGAIN ! Its pulling barely 5 inches of vacuum at 2000 rpm. Either the cam timing is way the heck off ( Not likely with a new motor ) or theres one hell of a vacuum leak somewhere. So I start looking further and checked anything and everything affecting vacuum including the power brake booster. I even checked for a bad cat in the exhaust.Couldnt find anything yet............

So I called the owner and asked as to how the motor was switched. I learned that the intake / exhaust manifold was removed as a single piece and set aside while the motor was switched and re installed with new gaskets after the motor went back in. ( Not much to go on ) So I checked the intake system and it looked like it was installed correctly including the correct gasket. I was running out of systems to check but..................

I kept looking. It still acted like a massive intake leak. You know, like an EGR VALVE suck wide open. I confirmed that the EGR was moving freely but I did think of something else that was a thousand to one shot. The EGR VALVE on this Jeep was attached to the intake manifold just below the carburetor. I took a half inch wrench and removed it to take a look.

AND THERE IT WAS, THE INTERNAL PART OF THE EGR VALVE WAS TOTALLY MISSING AND INHALING ALL THAT EXHAUST GAS ALL THE TIME ! NO WONDER IT RAN LIKE CRAP !

A new EGR valve cost 14 dollars and I installed it and instantly it smoothed out. I reset the idle to 650 in drive, set the mixture after warm up and reset the lead on the distributor. That thing was so smooth that you couldnt feel it running. ( I NEVER DID OVERHAUL THE CARB EITHER )

I asked the owner on the phone to come up himself to get the Jeep and he test drove it with 100% satisfaction and he asked me what I found. When I told him the story and showed him the old EGR valve he blew a fuse with enough colorful language that woulkd make a Marine blush !! The tech removed the problem and re installed the problem again during the engines replacement.

It gets worse. His tech just sold an expensive engine job when a 14 dollar EGR valve would have fixed the vehicle and easily won a customers loyalty for a simple problem with proper diagnostics.

It still got worse. Mechanic tried to blame me for a major cover up and it really was a carburetor problem and I made up the EGR story to cover my butt.

UNTIL THE MECHANIC WAS SHOWN THAT THE CARBURETOR WAS NEVER OVERHAULED AT ALL ! IT WAS THE SAME ONE WITH THE ORIGINAL PARTS.

MECHANIC WAS FIRED THAT SAME DAY.

[Steve Zicht]

Heres another story. Diagnostics 101 again.

Fellah had his 1980 Oldsmobile sedan to seven garages in town with supposedly very good techs and nobody could figure this problem out. This was the very small 260 cubic inch powered V8 with an automatic and it had a horrible ping in the engine. The carburetor was a non feedback ' Daul Jet ' two barrel.

This guy spent a small fortune to get this problem remedied. He was referred to me by another shop and I really try to stay away from working on the entire car as to I just didnt have a full repair facility. But my buddy said this guy would be well worth helping out if I fixed his problem. I'll tell you why in a minute.

Looks like everyone was playing with the ignition timing on the HEI system. The only way to get the severe ping out was to retard the initial lead a long way. Trouble is with that is that little 260 had no power at all. Put the timing back to specs and the severe ping was back. We know that the EGR system has to be working properly and it appeared to be opening and closing with the " tip in ' of the throttle. This is kinda strange because other techs checked the EGR also thinking that was also the problem.

Just for kix, I disconnected the EGR hose and hooked up my vacuum pump and manually pumped it up. Once that EGR was fully opened, that engine idle should get very rough and in some cases, kill the motor.

NOTHING HAPPENED. Removed the EGR valve and the entire passageway that leads to the intake was totally stopped up with black soot or carbon.

I took a can of 2+2 carburetor cleaner and a piece of coat hanger and spend about 30 minutes clearing that crud up. Got her all put back together and reset the ignition timing and that car ran like new again. This poor guy had been dealing with other shops for 2 months and they still charged him with diagnostic fees. I felt so bad for him that I never charged him for anything. He was thrilled too !

The customer gave me his business card and said dont hesitate to call him for any legal help that I might need. HUH, LEGAL HELP ?

IT WAS OUR CITY CIRCUIT COURT JUDGE FOR OUR TRAFFIC DIVISION ! YES SIR ! I GOT MY FIRST FREE GET OUT OF JAIL CARD SHOULD I NEED IT!

[woody b]

I've had a few pinging Old's (260's and 307's) with plugged EGR passages. Since I've gotten a "smart" phone I take pictures when I think about, and inherit someone elses mess. Another shop put an injection pump on a 6.5 diesel, then sent it to me because "it still doesn't run". This is the wiring harness going to the pump.


Mid 2000's Pontiac, hard start at times. Another shop had already replaced the crank sensor, cam sensor and ignition module. Notice the backed out terminal on the ignition module connector.