tarheel

6 months ago i sent my 86 LG4 to a small body shop for work and new paint. The car is completely stock and the carb was rebuilt by a professional and it ran like new. No problems.

When i picked it up 6 months later, it barely started and had no power. We had to push it on the trailer. Engine idled badly. Engine kept backfiring through exhaust. Over the last month plus i've tried everything.

Set the timing
checked all hoses
checked all emission hoses and routing
added fuel additive
new PCV valve
new fuel filter
new spark plug wires
checked to ensure they are connected correctly
new rotor/dist. cap

First, it would backfire through carb with a spray of fuel. I then set the timing and it would crank but run only 20 sec or so and then have HARD backfiring through exhaust and shut off.
Then, suspecting a vaccum leak, i wrenched down on the mounting bolts. i bought a new gasket because i overtighten the carb mount bolts. The manifold and bottom of carb was cleaned and gasket replaced. Now, it cranks, but idles poorly and i get blue smoke from the carb and engine dies.

can someone help? I've been working on this car for over a year and cannot even drive it and it looks fantastic. I just can't fiqure out what happened.

naf

iTrader: (7)

Still having problems? Pull your trouble codes. Ensure the ECM fuses are good. Mixture Control Solenoid clicking?

tarheel

i haven't received a 'check engine' light so i assume there are no codes to pull. Is this correct?

Also, i've check all hoses for a leak.

Now, the engine will turn over well, but not crank.

At this point, i'm leaning to old fuel. When the problem started, the body shop guy would idle the car every week or so. He also said the problem started and the bad idle kept getting worse with time.

I think the bottom of the tank was stirred and stuffed up my fuel pump. The car had been sitting for over 4 years with fuel. I didn't drain it, i just added new fuel.
It's a cheap swap, so i'm gonna replace the pump and i put 5 gallons of fresh fuel and a bottle of Sea Foam.

naf

iTrader: (7)

Check for codes anyway. Verify that the light works and that no codes are stored.

You can drain the tank, or at least the lines, by disconnecting the fuel line to the pump. Maybe use an additive that helps get water out of the fuel, if you see water in the fuel when you drain it.

You should also check the fuel filter in the carb inlet.

Does the car fire with some gas poured into the carb throat?

Is the MCS clicking in the carb with ignition turned to 'run'?

tarheel

- i'll check for codes.
- I hear the clicking
- carb was rebuilt last year and new filter installed
- i disconnected the fuel line from carb...cranked the engine..and no fuel came out of line.
- new plugs/plug wires
- timing set
- new dist/rotor

one other note...when i disconnected the fuel lines that connect to the fuel pump...no gas came running out. I know there is fuel in the tank. Should the fuel just come running out?

Car ran fine in October, body shop guy said when it was idling, the car started to idle rough...as time went on...he said the idle got worse and eventually shut off and would not restart. This is when i picked it up. Engine was looping and backfiring through exhaust. Then, it was backfiring through carb and exhaust. Checked cat converter and it's not clogged at all. Read through Chiltons and everything points to bad fuel. I know there was old gas in the tank, but i kept the tank full and put maybe 25 miles on it in a year. Since this guy kept idling it each week, i suspect the tank drained down to the bad fuel and stirred the crude on the bottom of tank. i hope i'm right.
thanks for your interest!

five7kid

iTrader: (14)

That certainly sounds like a problem to me.

"Good" and "bad" fuel will mix almost immediately. Crud goes to the lowest point, the pick-up, regardless of fuel level.

Sounds like you need to find out why you aren't getting fuel to the carb.

tarheel

when i picked up this car last year, the same thing...engine would turn over forcefully, but never catch. The problem was a bad fuel pump...however, even with the bad pump i was getting some fuel to the carb. This time, no fuel at all to the carb.

I'm hoping the fuel pump is clogged from gunk in the tank.

naf

iTrader: (7)

More likely the fuel line or pickup. You can blow it through with air to clear it but any gunk will stay in the tank.

I have in the past connected the fuel pump to a small gas can with a rubber hose but that was with a non-return pump. No reason you couldn't try it here although you may want to have the return dump back into the can. And I always do this kinda stuff with an extinguisher nearby.

I recently ran into a water in gas situation myself, but that was with an 87 and I was able to jump the fuel pump to drain the tank and lines. I honestly don't know if there's a convenient place to drain our tank and lines manually.

88iroc52387

iTrader: (2)

Def. Drain the tank if you think there is alot of crud in the tank i would personally drop the whole tank clean it out, throw in a new pump, use some fresh good gas, and then give it a try. I know dropping the tank is not fun or easy but its not to hard. give it a weekend project. When i bought my beater (94 s10) it sat for over a year in a field.. the truck turned over and ran fine half way to my house but then it came clanking to a stop... Called my uncle and pulled it home with our sierra. It turned out to be bad gas. Fortuantly i just had to use some dry gas + fresh gas. but it took about 20 minutes to get it running right. Just go at it systmatically. The engine in simplest form needs Fuel, Air, Spark, and Compression. Get the fuel pump figured out, by air i mean check ur vacuum lines (which u seem to have done), then check your plugs and wires make sure u have spark, and lastly do a quick compression check to make sure everything checks out if you can of course.

tarheel

you guys have some great input...i appreciate it.

However, i do not want to drop the tank. I've been working on this car since March of 08, put close to 2k in it, waited 5 months for body work and paint and still i haven't driven it more than 50 miles total. Heck, since the new paint, it hasn't moved from under my shop shed.

I'm actually getting frustrated and using another weekend to drop a tank just isn't going to happen. It's above my skill and patience level.

I need to find another way.

I have 2 jet skis that have my attention now and i'm losing interest which sucks because down here in NC, it's cruising weather!

naf

iTrader: (7)

I wouldn't drop it until I've gotten it to run well from an alternate fuel source and then I'd consider every alternative first. Siphon it out. Block the vents and pressurize the tank. $15 Mr. Gasket fuel pump hooked to supply lines. The cure for pollution is dilution, least where I live.

five7kid

iTrader: (14)

Could very well just be a dying mechanical fuel pump. You don't have to drop the fuel tank to fix that. But, it's pretty simple to disconnect the supply line to the pump and see if fuel will siphon out. Yes, new fuel pump. No, probably a clogged pick-up sock in the fuel tank - the only cure for that is to drop the tank, pull the pick-up, replace the sock, and flush the tank.

tarheel

wow, after many hours of work and frustration, it appears the problem was indeed old, bad fuel.

The gunk in the tank must have clogged my mech. fuel pump. I installed a new pump, sprayed some carb cleaner in the carb and it started.

Ran rough and some backfiring through exhaust for about a min. then it cleared up and idles great.

Wow, i'm excited...now to reinstall the interior, wash/wax and post some pics for this site.

Thanks to everyone for their help. I learned alot about my car and plan to keep it another year or so...or when i find a new toy.

phess11

Need to put this in your gas tank. Keeps it from gunking up.

84 Z28 Bowtie

I use it religiously when not driving the car (or my mowers).
Helps immensely and helps prevent that varnish buildup in the jets of the carb.

tarheel

well, no luck...went back to the car this weekend it runs horrible again. Alot of backfiring through exhaust...i then replaced the cat converter and thus the entire cat back and now the engine sounds like its running on 2 cylinders...no power and the engine makes the car vibrate when reving it to high rpms.

Today, the car will not even start.

I'm really frustrated by this car and i guess will call a mechanic.