1993 Chevy Van G20

[Sarge]

About 4 days ago my oil pump crapped out on. Considering the van has 224K miles and the pump was original, not bad. A day or so later tho I've got more problems. First off the new stuff:

oil pump
oil pan gasket
plugs
wires
rotor
cap

OK, now she wont go over 55 without feeling like it's laboring. Mileage is down into the 5mpg range. Slight hesitation on no set pattern on pulling hills and dropping of speed while pulling hill as well. Oil leak, most likely either the valve covers or the oil pressure sensor (1/2 qt a day). Gas showing up in the oil. All plug wires are seated good, all plugs look good and uniform. Van is burning a slight bit of oil. Uses a TBI system.

Sarge

 

[87manche]

When the pump failed did it run with no pressure for a time?
I'm not too big into SBC motors, but what you've got sounds like an extremely rich condition. Did you check all the sensor connectors? Any chance you knocked off an O2 sensor lead or something while you were under there? We've got a 90 here that's the same van, I know that I would dread working under there with how tight it is.

 

[Sarge]

All sensors connected and working. Motor ran with no pressure for a short while. About 100 foot to gas station and then roughly a mile towards home. Ran freakin' great for a day after the new pump.

Sarge

 

[summitlt]

If it were me, id check compression. See if you destroyed a cylinder or a ring.

 

[8Mud]

I'd like to help you out, I've had more than a few Chev. engines apart and back together again. But haven't really seen what you discribe. A few guesses?
Maybe check the plugs for oil fouling and do a compression test (boy that will be fun in the van).
There is no reason for the timing to be off (or is there?), but it is pretty easy to check. There is a wire to unplug (have to look in the book for the location) that stops the advance and a simple timing light will do.
The motors have a habit of leaking across the head gasket. They reworked the heads in the mid 80's and there isn't much gasket between the water, jacket, the oil passages and the cylinders.
The bolts for the intake have a habit of backing out, but that usually causes a really high idle.
It's got to be tight for the harnesses in there, the probability of dislodging a connector or clamping a wire between two pieces is high. I've done both in my PU and it has a lot more room in the engine area than the Van.

 

[Sarge]

Well a bud suggested that the injection system is running extra high pressure and dumping fuel. He mentioned a vac diaphragm but I'll be danged if I can find what he's talking bout. She does run rich, more evident on start up...lots of black smoke. Haven't done anything to the top end for any wires to be pinched there. Another possibility was a bad temp sensor but it works right. All plugs look good and even uniform which surprised me. Some slight oil burning shows on the plugs which doesn't surprise me.

Sarge

 

[Sarge]

Well, compression check tells me not to worry so much. Time to either rebuild the motor or replace the van it seems.

Sarge

 

[8Mud]

You've eleminated two out of four. If the plugs aren't fouling and the compression isn't low. That leaves timing, fuel or sensors. Possibly ignition. Spark color is easy to check.
A quick check with a timing light can tell you alot. Chevy motor advances a lot. Chances are with it idling you will barely see the timing mark, if at all. There is a plug to disconnect that eliminates the advance from the ECU, to set initial timing.
Next thing to check is the sensors and IAC.
I kinked a fuel return line once that gave me all sorts of grief. It wanted to stall at lower RPM's. I kept thinking it was the IAC, I was wrong.
To bad we aren't nieghbors, I've got a 350 rebuild that runs just fine, you'd be welcome to have (I seriously have to move some junk out of the garage). The shipping would be murder though. I really hate to toss it.
I've got the shop manual and the 92 light duty truck fuel and emissions service manual here if you want me to look anything up. My scanner is broken, but my camera works. I'm looking at a picture of the fuel regulator, very top of the TBI (on the side) square mount with four screws, with a raised cylinder in the middle thats the spring guide. It only has four pieces, cover, spring seat, spring and diaphram. The ID and serial numbers (for the TBI) are on the flat surfice just under the fuel regulator. Be carefull with the fuel regulator it holds pressure. Your supposed to dicconnect the fuel pump and run the motor till it dies to relieve the pressure.
It's way to early to give up yet.
Can you check your codes with the key methode?

 

[8Mud]

The book says. Lack of power sluggish, or spongy (don't really know what that means).
Fuel system
1. contaminated fuel
2. restricted fuel filter
Ignition system
1.Proper ignition voltage
2.igntion timing and proper operation of EST.
Exhaust system
1: Engine at normal operating temp. connect a vacuum gauge
2. Operate engine at 1000 RPM record vacuum
3. Increase RPM slowly to 2500, record vacuum at 2500 RPM
4. If vacuum at 2500 RPM decreases more tha 10 kPa (or 3 inches of vacuum) probable exhaust restriction.
5. Disconnect the down pipe and repeat the test.
Additional checks
1. ECM/PCM gorunds
2. EGR
3 Torque converter clutch
4 A/C
5 Generator output voltage
Engine mechanical
Engine compression, valve timing, worn camshaft. Additional tests in Engine section.

If you get this far, I'll give you the hesitation, sag (I guess that's what happens when they get spongy) and stumble section. And then maybe the cuts out or misses section. The rough, unstable incorrect idle or stalling section or the excessive exhaust, emissions or odors section.
Maybe we can make our own section. Spongy, sagged, unstable with odors section or how to troubleshoot a prostitute.

This looked interesting
Sensors
1. Oxygen (O2) sensor for silicon contamination from fuel, or use of improper sealant (never use any sealant on any waterprooof connectors). The sensor may have a white, powdery coating and result in high but false signal voltage (rich exhaust indication). The ECM/PCU will then reduce the amount of fuel delivered to the engine, causing a severe driveablity problem.
The O2 sensor will do strange things if it's covered in soot, oil, coolant or whatever. I had a slight coolant leak into one cylinder, the O2 sensor would run the motor rich and then lean it way out depending on the temperature.

 

[Sarge]

Sorry I wasn't clear. My compression readings were terrible hence the need for a rebuild or replace of the van. Looking at possibly replacing the van.

Sarge

 

[8Mud]

I usually pull a head and check the ridge at the top of the cylinder bore as an indicator of the general health of the motor. Chev.s are actually pretty easy to ring. Taking off all the harnesses and junk is the hard part, then getting it back together again. They kind of go back together like a puzzle and one step out of sequence (like running the harness on the wrong side of the tranny dipstick) and you run out of cable length real quick.
Making the motors maintenance friendly was pretty far down on there list of design goals.
Good luck.

 

[Tom in KY]

Just a thought, The valve springs have been known to fail and give a BAD compression reading. This was a problem on GM 305 and 350 from 78-86? I know of one van with all springs replaced twice and another that was salvaged from a junk yard. A guy was going to take the springs from a van and found 4 broken springs. They replaced the springs and sold it. As hard as it is to check, it may be worth it.

 

[Tom in KY]

I'll give you the hesitation, sag (I guess that's what happens when they get spongy) and stumble section. And then maybe the cuts out or misses section. The rough, unstable incorrect idle or stalling section or the excessive exhaust, emissions or odors section.
Maybe we can make our own section. Spongy, sagged, unstable with odors section or how to troubleshoot a prostitute.

This looked interesting.

Just stand at a distance and give directions, like a certain famous TV preacher was supposed to have done. All the while working out his own evil deed. Hey! It keeps the stinky off!

Sorry, bad taste breeds.

 

[Sarge]

Well, really low compression, huge ridge on top and more movement now on the bottom than before. Cylinder walls look like crap, metal flakes in the oil. Oddly enough the dang thing started running great again today...other than drinking gas and oil like a wino with some Thunderbird. Put $10 in and managed to make 20 miles before I ran out. All wires and sensors attached correctly and tight. May sound ood but I don't have the money to fix the dang thing. Time to buy another. Can get a loan to replace it but not to rebuild it.

Sarge

 

[Sarge]

Replaced it with a Freightliner Sprinter. Sweet turbo-diesel! Thanks for the help guys. While I didn't fix it you gave me the ideas where to look and determine I didn't really want to.

Sarge