mtrdrms

Hey all,
Just replaced the head gaskets on a 93 pickup 4x4 auto that I don't have much prior knowledge of. It was running ok beforehand but had a code 52 (no pigtail present?!), no cat converter (?) and was burning coolant. Upon teardown I found the headgasket failed at the number 1 cylinder. No biggie, all new toyota gaskets, headbolts, timing belt, pulleys, new knock sensor and pigtail and back in business.
Almost.
Now it will run but barely. It shakes like it's running on 3 cylinders.
So I've checked ignition timing and it's 10 btdc. I've checked for spark on all cylinders and it's strong. Its getting fuel ( a lot in fact it's coming out the tailpipe!). No codes. Anyone have any ideas? Could the timing belt be off a tooth? I'll try anything! I gotta get this thing out of my garage!
Thanks,
Andy

coloyota1023

I would disconnect the efi fuse and dizzy and check compression on all 6 cylinders. Spec I think is 145-170 psi if I remember correctly

mtrdrms

Ok so compression looked good. 125-150 on all except #1. 117. I'm not too worried about this because even if there was an out of spec cylinder, the engine would still run. What concerns me is the spark plugs. 4 and 5 looked new and all of them were covered in gas...


Now this after maybe a grand total of 30 seconds run time.

Thoughts?

Obmi

This is where I would start. I really don't know but I'm just trying to be helpful. NGK diagnostic guide

mtrdrms

Appreciate it. It seems like it's getting way too much fuel. What would cause that on start up?

mtrdrms

Ok so it's SUPER rich. If I run it for no more than 30 seconds, gas pours out of the exhaust flanges and tail pipe. What would cause such a rich condition? Did I damage the injectors somehow? Maybe a temp sensor issue? Stumped!

superex87

Three big things I can think of.
1. Grounded injector harness - the injectors on this truck fire in a batch ( they all fire at the same time). Key on, engine off, the injectors get +12v. The ecu ground them to turn them on and off. Bad distributor could possibly do something similar.

2. Engine temp sensor - tells the computer what the engine coolant temperature is. If it is broken it could be telling the computer is -30 degrees therefore adding a ton of fuel.

3. Cold start injector stuck open/ on.

It seams according to your plugs though that two cylinders are not firing at all. Either they are not getting fuel or spark. I would check spark with a spark tester first.

mtrdrms

Thanks a ton, super! I checked over all the engine grounds and cleaned them but I forgot about the harness ground. That's the one on the passenger side rear cam cap, right? I'll have to check that. Not sure how to check the temp sensor but man, it was working well when I tore it down. Also I checked for spark on all cylinders with a spark tester and all were good. Today I replaced the spark plugs and it seemed better but not much.

mtrdrms

Unfortunately the harness ground at the back of the passenger side cylinder head is good. Any other harness ground that I may have missed?

mtrdrms

Any other suggestions before I set this thing on fire?

ksti

Could be the fuel pressure regulator dumping too much fuel into those particular injectors.
Looks like some of those spark plugs are getting washed out from it.

mtrdrms

Is it getting too much vacuum? How would I test it?

ksti

Your going to need a good vac gauge, and a FRM (Factory Repair Manual).
You need to perform this test carefully so you don't get improper readings.

I would also check your VSV and other "vacuum lines" to make sure they are
hooked up properly as this can also cause the fuel pressure to be erratic.

I'm sure their are multiple threads here on this concern.
Good luck.

Janos01

Check your distributor cap for broken contacts, change that and the rotor if needed. Check your ignition coil, cat and O2 sensor. It is also possible you have bad/leaky injectors that are dumping too much fuel in the engine.

krusty_45

Defiantly washed spark plugs.

Stuck injectors, too much fuel pressure, cold start injector, I would start with FP