My 88 isuzu picup. I changed the spark plugs, they were nearly fouled. Black junk is blowing out the exhaust. (Cat might be plugged?) You need to keep your foot on the gas or the truck will die. I used carb cleaner it now runs smoother at higher rpm. What have ya got?
I just repaired my '94 and it had similiar problems. Too much fuel was flowing through the carb. Mileage dropped way off.
I rebuilt the carb but the real problem was a bent tang on the float. This resulted in the failure of the needle valve to close completely, regardless of the float level.
My guess, is carb engine? if in usa most cars had 2 systems in 88
just before the EPA rules kicked in.... so>>>> what engine.
and the others all chiming in with no fuel systems stated.
carbs and EFI are not the same, not by a MILE !
1000 points for poster with compression tests first before wallet comes out. really! (unless this is a love thing...gone wrong.. Isuzu? )
its old, and lots of things will be bad any 27 year old car./engine.
and the carb, will need to be cleaned and kitted.
no photos of spark tips posted so Black junk , means nothing.
if the black is dry, carbon, no oil , then its just rich running.
so why would a carb be rich. first let me do the macro view.
1: spark advance dead, so carb runs rich. i check that first with a timing light. if its retard the fuel can not burn, and goes rich.
2: so that test passes so must be the carb. it not oil fouling its unburned fuel. (dry carbon, or even gas soaked carbon, sniff sniff, oh gosh its is gas..... not oil......there.....)
CARB 101: dont vast numbers. wished hadn't, i stink of gas.....
so why do carbs go rich, lots ! (im retired and remember..... unlike posts below asking you to check INJECTORS, omg.)
I even have to restored old cars that use them , by ME.
1: choke stuck on. hot.
2: choke set too rich, cold and floods cold and stalls. set it leaner.
3: float level set wrong, too high it will run way to rich. it has a glass (crash and burn) fuel bowl window, and level is clear as DAY. just dont crash car and break that window... OMG , the old days,,,,,,,
4: someone (seen it) put in a wrong pump that runs 15psi and this causes the carb float valve to be over powered and that ends all normal carb float action it just floods full time and float level at infinity. use the correct pump. and check pressure to factory spec.
5: main jets drilled out by kids who want to race, or whatever....
6: emulsion tubes (air) or there jets clogged causing fuel jets to go rich.
7: the Power valve if fitted, leaks. (yes , the all do this old, sigh)
8: jets missing, seen carbs with jets in bottom of float bowl, unscrewed and drifting about.
9: last mech, didnt believe in kits, and made his own gaskets. blocking critical air ports (usually emulsion air paths) and killing a good carb.
10: lots more. find an old mech with gray/white hair and ask him to boil out your carb and kit it. (chem dips)
next time post engine type. we can tell you the right spark plugs
and correct fuel pressures, 3-5psi is best on rice burners this era.
1988 posted to 1994 years. forum. so.... my guess 1988 is it.
there are 2 engines in 88 (USA) the 4zd1 and e1.
the E1 is EFI
the D1 is carb and is 3.5 PSI fuel pressure, E1 is 35.
today I own a PLUG IN, my wide band OXY sensor and can tune any carb. even while moving fast (logs) cost me $150 bucks. luv it.
see red arrow that is the windwo.
now the factory spec, sans photos.
on float level.
and the CAT test.
use a Vacuum gauge.
here are all CAT tests. (easy and hard,)
http://www.fixkick.com/sensors/tests/cat-con-tests.html
please next time post what engine is in car, and what fuel system is in car. (nobody does, but ill just keep asking , thank you)
this post will help others, fix carbs, im sure. i could write book, but no need, the library is still full of books on topic, (dusty)
I have the same exact problem with my 94 isuzu pickup. Did you ever figure out what the issue was?
Blow-by from the oil and fuel are collected on the tip of the spake plugs.
I would do a compression test before I invest money on the truck.
If you are getting even pressure above 160 psi then it's work fixing.
If it's uneven pressure and below 160 psi then look for Spark Plug Non Fouler kit at your local auto part store.
It's just a shield for the plug with a small hole on the bottom.
Make sure you bring a spark plug with you to match it up.
Good luck
Black out the tailpipe sign of carbon built up in the engine from your plugs being so bad .....buy some seafoam brand gas treatment that stuff is good may help clear it up.....
If you haven't changed the oil recently change it! then maybe dirty injectors, bad fuel filter...I'm leaning towards fuel filter because the more pressure your pump gives it will overcome some blockages/poor fuel flow...and run better so try replacing it, or maybe it's bad fuel. Try running it on premium fuel to clean the injectors and lines and give it a good reving once the engine is warm...
Good luck
Several factors can contribute to spark plug fouling:
- The air/fuel
ratio may be too rich as a result of incorrect carburetor adjustment or a poorly
performing fuel injection system.
- Worn piston rings or valve seals may allow too
much oil to leak into the combustion chamber, leading to oil fouling.
- The
ignition system may not be performing properly.
- Prolonged idling or continuous
low-speed driving may keep the spark plug from reaching its optimum operating
temperature. Using too cold a spark plug can lead to the same problem.
- A dirty air cleaner can create a too-rich condition which can lead to
fouling.
Have each of the above checked and corrected.
Fuel, oil and carbon fouling can all be the result of different
causes but, once a spark plug is fouled, it will not provide adequate voltage to
the firing tip and that cylinder will not fire properly.
In many cases, the
spark plug cannot be cleaned sufficiently to restore normal operation.
Hence, I always recommend that a plug be replace, once it becomes fouled.
Cheers,
Scott
"If this has helped you in any way, please be kind enough to rate this solution"
1,073 views
Usually answered in minutes!
Was the plugs all you changed?
I have the same exact problem with my 94 isuzu pickup. Did you ever figure out what the issue was?
×