FN723

I'm making another attempt to get the car running again. It was three years ago the last time the car was drivable. I was driving down the street and it just suddenly without warning quit running. Since then I have replaced the ignition control module, coil pack, crankshaft position sensor, Ignition switch and computer. Then recently replaced the ignition control module again,, Idle air control valve, EGR valve, spark plug wires, spark plugs. Then because it's been sitting I replaced the gas, fuel filter and cleaned the fuel injectors. The gas never did completely go bad.

The spark plug wires are getting fire. The cylinders are getting gas but it will only occasionally ignite almost like a cough. I don't know what else to try.

gs72

If you haven’t moved the distributor since it died. Bring the #1 cyl up to the compression stroke and put the timing mark on tdc. Remove the dist cap and see how close the rotor is to #1 plug wire post. If it is way off timing chain jumped and your cam timing is off. If thats the case the timing chain set needs to be replaced. If you already moved the dist. The only way to check it is to remove the front cover. You can also drop the exhaust and try to start it, that will rule out plugged cats. Either one of these conditions will create a crank no start condition while you still have spark and fuel.

Greg Rogers

If you squirt a little gas in the throttle body and it will start and run and then quit, you know it is fuel problem. Those era cars had quite a problem with the fuel pumps- just a long distance guess... good luck!

joe_padavano

A 1987 D88 uses the transverse Buick V6 with a coil pack and crank trigger ignition. There is no distributor.

Has the timing chain slipped? Is the fuel pressure at least 45 PSI? The fact that the injectors are getting fuel doesn't mean that they are getting enough to run the engine. Conversely, if an injector is stuck open, you'll get a rich condition and the engine still won't start. Does the oil smell like gasoline?

FN723

I haven't tried gas since it's horizontal but I did try starting fluid and it didn't help.

FN723

When I first put the new ignition module on it, it started and ran pretty rough. I backed it out about 100' out of my shop and it died again and haven't been able to start it again since. I don't believe it was running that badly to point the finger at a timing chain. If it had a rubber timing belt maybe. I haven't checked the fuel pressure. I have the tools to do that and will check that out. I'm kind of nose blind but can't detect any smell of gas in the oil.

FN723

This model doesn't have a distributor, it's fully electronic.

gs72

Sorry not sure when gm went to fuel injection. I am a ford mechanic by trade. However ford went to fuel injection between 87 and 88 so i guess it makes sense that gm did around the same time. My point was to verify base engine condition before going off to the races changing parts. I would still recommend loosening the exhaust at the manifolds and pulling it back a quarter of and inch and try to start it to rule out plugged exhaust. Once you verify cam timing and proper fuel delivery. As i said not super familiar with this engine but is the crank sensor tone ring on the hub or the rubber mounted portion of the balancer? Have seen the later slip and cause a no start, have also seen the crank bolt loosen allowing the crank pulley and tone ring walk off the crank snout enough to not be inline with the crank sensor.
Just throwing some ideas and experiences out there.

FN723

I will try taking the exhaust loose.

I'm not sure how to check the cam timing. Will have to look into that. The crank shaft position sensor is a hard device which is locked in a bracket which can't move. It functions by a piece of sheetmetal on the harmonic balancer pass through it. I looked at it yesterday and the sheetmetal is still passing directly through the center of it.

Schurkey

Connect a scan tool, see what in the data stream looks suspicious. If the RPM while cranking is "0", you have a crank sensor problem. If the coolant temperature is -40, you have a coolant temp sensor problem, Etc.

Cranking compression test (If the cam timing is wrong, the compression numbers will be VERY odd)

Fuel pressure test

Fouled spark plugs?

FN723

I'm going to have to do testing another time when I can get some help. I can't get a good enough seal to tell. By the time I can get to the gauge the pressure is down to 15 psi and falling. The way the engine is made you can't really get to the spark plug holes.

I believe the problem is related to the ignition. When I removed a plug to put the compression tester on the plug was wet with gas. I will have to jury rig something to get a fuel pressure gauge on. It isn't fitting at all.

Schurkey

Compression test or fuel pressure test?

What are you using for a compression tester and a fuel pressure tester? The fuel rail should have a standard schrader valve for use with a fuel pressure tester. Most any compression tester should work, AT LEAST on the front three cylinders.

Since we know the plugs are fouled, how about yanking them all out, cleaning or replacing them, and just try to re-start the engine?

rustyroger

A quick and dirty check for spark is to simply put an inductive timing light on each of the plug leads in turn. No light = no spark.
Also I have come across a number of European cars of around the same vintage with similar symptoms - won't start, wet plugs - that just had a bad temperature sensor. The unsophisticated ecu's back then simply read the engine temperature as absolute zero and pretty much continuously injected fuel. If this is your problem a new temperature sensor should be all you need, and an oil & filter change of course!.

Roger.

matt69olds

Either clean or preferably install fresh plugs. Try to start it. Make sure you have injector pulse and spark. You may also try to start it as is with the gas pedal to the floor, that will put the PCM in “clear flood mode”, shutting off injector pulse to clear out the fuel saturated cylinders.

FN723

I've only been able to try the compression test and I'm using a compression tester. I have a fuel pressure tester for the gas but haven't been able to adapt it yet. The tester is a Harbor Freight model and doesn't come with anything to screw on the valve.

None of the spark plugs are fouled with anything other than un-burnt gas. They were recently replaced when I put a new ignition module and spark plug wires on.

FN723

I figure the problem is some sensor somewhere. The car does seem to run once in a while even if it will only go 100'. The temperature sensor is one thing that has never been replaced. I believe it has two, one for the gauge and one for the computer so I will have to determine which is which. It would be something cheap and easy to try anyway.

It's been suggested the timing chain may have slipped. I can't stand the idea of that. When I replaced the crankshaft sensor it would have made it easier to remove the harmonic balancer and I spent four days trying to get the bolt off and gave up.

FN723

Holding the pedal to the floor didn't help. It seems to do better after the car has sat for a couple days. I haven't been able to work on it since Sunday and when I tried to start it this morning it very briefly tried.

FN723

The valves ended up being the problem. I managed to do a compression test today and here are the results.
#1 15 psi
#3 90 psi
#5 15 psi
#2 90 psi
#4 28 psi
#6 28 psi
I think with the car I fixed the initial problem but it sitting for the last few years has stuck the valves. Think I would have any luck freeing the valves up without pulling the heads?

Schurkey

I would be checking to see if they're sticking open. I bet they're already shut, but bent or burned. If they were actually open, I figure you'd have "zero" compression.

But hey, you could yank the valve covers, and pop the valve-end of the rocker arms with a plastic-tipped mallet a few times. That would open the valves an eighth-inch, the valve springs would forcefully return the valve to the seat--possibly crushing any carbon build-up between valve and seat. While you're in there, look for broken valve springs. Re-test when you've smacked all of 'em three-four times each. Don't bust the plastic rocker retainers, and don't hit them so hard you push the valve into the piston--or lose a pushrod.

Have you used that compression tester on a known-good engine to see if the gauge is anywhere near accurate? You said that the compression test would be down to "15 pounds and falling" and that's not how a properly-functioning compression tester works.

FN723

I don't remember the last time I used that compression tester so I couldn't answer that question. Today I started with the #1 cylinder and when I was only getting 15 psi I had my doubts so I blew compressed air in it and it was real close to the pressure in the tank so I accepted the results.

Schurkey

Does the compression tester HOLD PRESSURE reliably? If it doesn't, of course your readings are low. Could be that your two best results happened when the pressure release valve on the compression tester actually sealed.

Does this compression tester THREAD into the spark-plug hole, or PUSH in using a rubber cone to seal?

FN723

The other day when I first used the tester it didn't hold pressure. The release button on the side the slightest touch will release the pressure and perhaps it was touching something when I did the test. Today though it's working right. It does screw into the spark plug hole. I believe this is the one I'm using. https://shop.advanceautoparts.com/p/...7827/9090029-P

gs72

How many miles are on this car? In your original post you said you were driving it and it quit and never ran again. Do you recall if it died on a decel after a moderate to hard accel. That is usually when high milage motors jump time (or during shut down). The odds that all or most of your valves went bad at the same time is pretty slim. Your compression numbers support a jumped timing chain. I know it is not what anyone wants to hear but it is worth a look. Otherwise you will remove the heads have them reworked and still have the same issue.

FN723

The car has a little less than 104,000 miles on it. It was in 2016 the last time the car was usable. I was just driving on a flat level street at 30 mph when it suddenly died. The car had had some bad mechanical work done on it before I got it, particular with the ignition. Someone had put regular spark plug wires on the car and it was burning out ignition modules. I never knew that was a problem and kept replacing ignition modules. This year I purchased another new ignition module and changed the wires to graphite wires and the car started again. It ran a little rough but I drove the car about 100' to get it out of my shop and turned the motor off. It now won't start again.

Is there a way to check to see if the car has jumped time without pulling the timing cover? I tried for four days to get the bolt off the harmonic balancer and couldn't get it off. I think I would round the corners off the bolt before it would give. I already used a 24" breaker bar with a piece of pipe over the handle and it won't give.

BSiegPaint

edit

FN723

Update, you guys were right about the timing. I finally got the timing chain out. It appears the damper had broken and allowed the chain to slip. It wore about ten teeth off the upper sprocket.

Ended up costing me over 200 bucks to get the harmonic balancer bolt off. Other people I talked to said I needed a better impact wrench so I bought one only to see the bolt laugh at the wrench. Then I went back to using a breaker bar and broke another one so I had to go out and buy a 3/4" drive breaker bar, extension and socket. Still I had to climb up on the breaker bar and jump up and down before the bolt would come loose.

FN723

Always something.

I completed changing the timing chain and gear project today and it will start but discovered one of the fuel injectors is leaking badly at the fuel rail. So I guess I've got to get a set of O-rings now.

FN723

I got the fuel injectors fixed and now when you first start it it won't stay running for more than a second unless you push a little on the gas pedal.

Schurkey

Charge the battery, start the engine, keep it running long enough for the computer to re-learn idle speed, etc.

"I" would connect a scan tool, so that I could watch the data stream while all this is going on. Who knows? Maybe you figure out another sensor or actuator is faulty.

Did you ever perform a cranking compression test after changing the timing chain?

FN723

The only scan tool I have is one of these OBD1 testers that just makes the check engine light blink like Morris code. It's not showing anything wrong.

I haven't checked the compression again since I changed the timing chain. I was going to do that tomorrow. This evening I was going to do something easier and clean the MAF sensor. About a month ago I changed the Idle Air Control valve and discovered last week it was defective. I purchased another one and when I went to take the other one off it just fell apart.

I don't know what to make of it but after I replaced the timing chain and put it back together the car started and ran fine with one of the fuel injectors spraying fuel on the engine. After I replaced the O-rings on the fuel injectors is when it wouldn't stay running when started.

I did what you suggested and kept it running until it got up to it's normal running temperature and it would stay running. Now after being about to walk around it while it's running have a new symptom. The exhaust is now making a putt putt noise. I've never had the heads off so I don't think it's developed an exhaust leak. I did clean the MAF sensor but it's something that looks old. I don't think it's something I've replaced since I've had the car.

Schurkey

That isn't a scan tool. It isn't even a decent code-reader.

I had one made by Thexton, about thirty years ago. ALMOST but not quite useless.

You connect a real scan tool to that vehicle, you're in for a wonderful learning experience.

FN723

Spent most of the day today trying to do a compression test and it's inconclusive. I managed to tear up the tester on the plugs on the back side of the motor. The ones on the front ran between 100 psi and 120 psi.

I then put it back together and drove it around some, once getting it up to 55. The car ran fine except at idle. It's still running rough and making the putt putt noise at the exhaust. I took the MAF sensor loose from the filter and blew about 5 psi compressed air into it while it was running and it killed the motor immediately. I then put it back together and just unplugged the MAF sensor and it made no difference. The only other symptom it's making is it seems to be running hot. There is no warning light coming on but the electric fan is running constantly and if feels hotter than I think it should.

olds 307 and 403

I hate these cars for that reason. Hardly any check engine lights and basically a part swapping nightmare.

Schurkey

Let me guess: YOU don't have access to a decent scan tool, either.

Schurkey

The engine should run with even less compression than that...but it won't run right.

120 psi is way low compared to what I'd expect (150-ish)

Did the engine crank as fast as you'd expect (battery not discharged, starter not defective, etc?) What altitude are you at? High altitude reduces cranking pressure. Throttle open at least part-way? Fast-idle seems to work just as well as WFO, but curb idle might not.

Is the gauge accurate? I connect my gauges to my compressed air supply in the shop from time to time to verify that the gauges aren't goofy.

FN723

Altitude isn't an issue where I'm at, I'm near Dallas which is about 500' above sea level.

The battery is alright and cranks fine. I've got it now where I only have to hold the accelerator down for just a few moments before it will stay running on it's own. It's just has a rough idle which won't go away even after driving it for a while.

I believe the gauge is accurate however the valve which is suppose to hold pressure now is no longer working. At first I was reading it while the car was running. Then I buggered up the adapter trying to tighten it into the spark plug holes so I have doubts if I was getting a seal. I'm going to have to purchase another compression tester and do the test again. It would be helpful if I could put a 90 degree elbow on the adapter but the tester I have seems to be metric thread so I couldn't put a 1/4" elbow on it.

Schurkey

I'm about 800'. I routinely saw 150-ish compression pressure numbers on older, stock engines.

There's a thousand suspects. We've already talked about scan tools. Maybe now is a good time to suggest a cylinder-balance test. This is WAY easier if the engine has a distributor. Coil packs and waste-spark make this test a little less accurate.

Connect a tach, or (better still) a vacuum gauge to manifold vacuum. Get the engine to idle on it's own. Connect a jumper wire or (better still) a 12V test light to a good engine ground. Put a small nail in the other end of the jumper wire, or use the pointy end of the test light. This goes better if you wipe a little silicone dielectric grease on the nail or point of the test-light.

Slide the nail or the point of the test light BETWEEN the plug wire and the plug wire boot, at the coil pack or at the spark plug--whichever is easier. This will ground the spark to that cylinder. Do one spark plug wire at a time.

Watch the vacuum gauge or tach. The vacuum and RPM should DROP every time you ground a plug wire, and recover when you remove the pointy probe. Any cylinder that DOES NOT DROP or drops less than the others is a dead or weak cylinder.

This test is hard on the catalyst. Don't waste time with the spark grounded. And allow the engine to recover between spark plug groundings. But...let's face it...your catalyst is probably shot anyway.

The Schrader valve that holds pressure may be loose, or have some grit holding it open. It screws out just like a tire valve stem core. It LOOKS like a tire valve stem core. It is NOT a tire valve stem core, because the spring pressure is much less. Or at least, it should be. Take it out, clean it off, screw it back in firmly. See what happens. I bought a baggie of five replacement valves from Snap-On, but that was twenty years ago. Snappy (and others) probably still sell them, though.

A "Running" compression test is going to give different results from a "Cranking" compression test, and neither one will be accurate if the valve at the bottom is seeping. It's been years since I've done a running compression test. Seems to me, the valve is REMOVED for a running test, INSTALLED AND FUNCTIONAL for a cranking compression test. But I'd have to look at my notes and confirm how to do a running test.

The more-important thing is whether you screwed-up the plug-hole threads in the cylinder head.

MOST spark plugs in automotive use are 14mm x 1.25. Certain Ford and Chrysler products used 18 mm x 1.5 threads. Newer cars, and motorcycles might use 12 mm or 10 mm plug threads. And I'm sure there's stuff out there using truly oddball threads.

MOST compression testers that have a quick-connect in the hose, use Milton "M" (also called "Industrial Interchange") quick-coupler plugs. If you were to find or fabricate a 90-degree adapter, you'd want 14 mm x 1.25 threads of the proper reach on one side, the 90 degree elbow, and a Milton "M" coupler plug on the other side. Should be easy enough--BUT--do you have enough room to spin a 90 degree adapter without hitting the exhaust manifold or other obstructions? And when it's screwed into the head...you may not have the 90 degree fitting aligned in a direction that allows you to connect the compression tester.

FN723

At present I'm not accepting the readings I was getting from the compression tester I have. I figure it's been leaking some and not giving me a correct number. This week I plan on getting a new one. I didn't damage the spark plug holes, I damaged the top of the adapter where the hose on the tester screws in. The back side of the motor is difficult to get to and I can't see at all when I'm trying to put a socket on it. I managed to get the socket on it crooked and chewed up the top of it. If it wasn't for other issues with the tester I might put the adapter in my lathe and clean it up. I did take the valve apart and clean it but it still won't hold pressure at all.

The compression tester I have has a quick connector on it but it's up by the gauge. It would be a lot more helpful if it was on the other end. It's difficult enough to get the adapter screwed into the cylinder block and then have to bend and thread a rubber hose into the adapter. It can sometimes take hours to get the hose attached on the back side of this motor.

I started doing a compression test running because the tester quit holding the pressure. In any case I think it was reading higher running than cranking.

The cylinder-balance test sounds interesting but I've been unable so far to find a vacuum line on this car. I've read somewhere the putt putt noise the exhaust is making could be a result of a vacuum leak so I've been looking for a vacuum leak.

olds 307 and 403

Nope, mine is pretty good for the price. Early EFI was just painful. A ton of trouble shooting, following flow charts, slapping on parts and hoping for the best. The dealer scan tool was the best. I really liked using the Next Generation Star tester as an apprentice at the dealer.

FN723

I'm apprehensive about a scanner. They are expensive and I don't do well with things electronic. I wouldn't be buying one that was in the $400.00 range and I wouldn't know which cheaper one might get the job done. I probably need one as I have a 95 Chevrolet van as well.

I did the compression test this morning and the #1 cylinder was the culprit. It tested at 60 psi where the rest of them tested between 105 and 140. Perhaps not great but good enough if I could just bring the #1 cylinder up to at least 105. I just hope the valve is just stuck. It wasn't doing that three years ago when parked.

The valve must have been bent or burnt. Never could get it to seal. I ran a can of seafoam though the engine and it had no affect. The last thing I did was hook up the cylinder to compressed air and it just blew air straight out the exhaust at TDC. I'm going to remove both heads and have a valve job done.