1988 Park Avenue Won't Start

[Jakal]

Hi, this is my first post. I'm a poor college student, and my car isn't helping me towards my pursuit of a degree. My 1988 Buick Park Avenue will not start. For the last few weeks, the car was hard to start, having to press the accelerator peddle about halfway to get it to start. And when it did start, it would idle very badly, and feel like the motor was hardly turning (about 400 rpm's). Then after 5 - 10 seconds, it would idle and run fine. Over time, i would have to give it more gas to start, and it would take longer for the engine to act right (20 - 30 seconds). Now it won't start at all.

Thinking it was timing related, i have replaced the timing chain, tensioner, timing cam sensor and magnet, crank position sensor, and the balancer. I'm unable to obtain a fuel pressure tester in my area, but i loosened the fuel line and turned on the ignition and fuel came out; if that is any help.

I don't have any trouble codes, but then again, i had to remove the battery so AutoZone could charge it (it died from the repeated attempts to start the car). Any info would be greatly appreciated. The long freezing walks to class are almost unbearable.

[wrightz28]

Welcome to AF!

Pushing the accelerator shuts the fuel injectors OFF usually at about 3/4 travel.

There are several possibilities. i suggest trying some basic good ol fashion diagnostics before replacing any more parts. You need to verify the 3 thing required to run a combustion engine are present:

Spark: nice and blue
Fuel: definately get a hold of that gauge, IIRC s/b in the vacinity of 50 PSI.
Compression: even within 10% acriss all cyls.

[Jakal]

Ok, so i got a fuel pressure gauge. I hooked it up to the fuel rail, and i get a steady 43 psi. I even removed the spark plug, left the spark plug wire on, and grounded the plug to the engine to check whether the spark is reaching the electrodes, and it is. I haven't checked the compression, but i just can't imagine that that would be the problem, since after the rough start problem, it would run fine.

So i'm about out of options to try next. Maybe something with the fuel injectors or the ECM? How would i even test those?

[Mickey#1]

Did you check for spark at each of the three front cylinders?
Are the plugs wet?

[Bassasasin]

Which engine do you have?
My book shows 4 different engines available, including diesel.

Right... Turn it over for a few cranks and then pull a plug and check it for gas. If its dry then theres no gas. If wet then theres no spark.

You could get some starter fluid and spray it first thing while cold. If it fires on it and seems to run only when someone is spraying it in the intake then its fuel. If not you have a ignition problem.

If they are very wet you may have dirty fuel injector. When the key is first turned on the

My diagnostics point to first checking the choke system. Your symptoms concur with the choke sticking closed or fuel.

And
If it runs rough and clears.
Injection pump timing.
Injector nossle malfunction.
Air in system.

Hopefully you havent given it more issues.

Good Luck

[Jakal]

Thanks for the replies, here is what i've done so far. I sprayed a good 5 to 6 shots of carbureator spray into the throttle body with the throttle valve open of course, but it still wouldn't start. I couldn't check all the combustion chambers for compression because the compression tool hose was bent badly. I was able to check cylinder 1 and it read 90 psi max. It read 30psi at first stroke, 60 on the second stroke, then 90. Is that normal?

I checked the exhaust tip when the engine was turning, so i don't think that it is a clogged catalytic converter. I checked the spark plugs, but it was kind of hard to decide if they were wet or dry. They weren't dripping wet, but they weren't completely dry. I honestly don't even know what to try next. I'm becoming sick thinking about what a garage is going to charge me to get this thing fixed

P.S. My engine is a 3800, it says that on top of the intake.

[Bassasasin]

Lets see...need to verify.
Smell the spark plugs immediately..
Should be pretty wet with fuel after ten seconds of cranking without spark.

1. Good spark at proper time to cylinders.
Even if not timed right it would backfire.
2. Good Fuel
3. Good Compression
4. Exhaust/intake clear

Thats about it.

[Jakal]

Ok, i ran a compression test on all the cylinders. My chilton manual says that the specified compression for my engine should be 100 P.S.I. per cylinder. I did notice something peculiar though. I removed the spark plugs one by one to see the condition of them, and the number 3 & 6 plugs looked very sutty. One of them even had some crunk inside the spark plug, I think it was the number 3 plug (I'm not sure if spraying carbueator spray into the intake isn't the culprit of that tho). The rest of the spark plugs still look brand new.

I also noticed that the number 3 & 6 terminals on the coil pack are across from each other, at the end of the coil pack. The coil pack is a one piece design, with all the coil terminals (1 thru 6) on one coil pack. Is it possible that i have a cracked coil pack? I don't see any obvious cracking signs, or arching. I already tested the spark on the number 6 plug, and there was a spark at the spark plug electrode. Here are the compression readings from the cylinders if that helps any.

Cylinder - P.S.I.
__________________

1 - 93
2 - 85
3 - 110
4 - 125
5 - 93
6 - 90

[Mickey#1]

Sure sounds like the 3,6 coil is bad. It may be sparking but the spark could be weak making it hard to start in the colder weather. Mine did exactly that until one very cold day when it refused to start.

[Bassasasin]

Originally Posted by Jakal

One of them even had some crunk inside the spark plug, I think it was the number 3 plug (I'm not sure if spraying carbueator spray into the intake isn't the culprit of that tho). The rest of the spark plugs still look brand new.

Ah the ol' Crunk problem.. Actually the plugs should look java colored.
Check for proper spark timing while trying to start.
Crank it for a while and smell for gas, exhaust, intake, etc.

So far the engine should run on those pressures.
If you loose the fuel line it should blast out... 45psi during cranking.

As per your mention of spraying with the throttle body valve fully open.. that wasnt good.. shouldnt need to do that. Just spray in there with it at idle and closed.



Good Luck

[Jakal]

How do i check for proper spark timing? I think this engine has electronic spark timing. Is there a special tool for checking it?

[Bassasasin]

The Harmonic balancer wheel has the Crankshaft sensor located in it. It sends timing if its working and has not been damaged. Some have put it in and found it later damaged. Some have replaced the harmonic balancer wheel and it wouldnt work right.
To check timing you would have to find the compression stroke TDC on a cylinder, mark or find marks (#1) on the harmonic balancer wheel and mark its position, set up a timing light and crank it. I know of no "special" tool.



Bass

[Jakal]

Cool thx, i'll try that next. I actually replaced the crank positioning sensor again a couple of days ago thinking that i had a bad one, but no dice.

So i definiately have compression. For the most part, i have spark (I'm seeing the electrodes on the spark plugs spark). Is it ok to take a fuel injector out one by one and see if it is spraying instead of peeing? It's not gonna mess up the motor when i turn it over with a fuel injector removed from the throttle body intake is it? As always, thx for the replies.

[Bassasasin]

Nah..leave them in. Dont want an unsafe condition..
Peeing just dont let it idle smooth.. that happened back in the 70-80's when they would wear out.
They just get dirty now with the new metals they use.

You got spark? and it wont run?
Then you dont have gas..

[wrightz28]

Originally Posted by Jakal

Ok, so i got a fuel pressure gauge. I hooked it up to the fuel rail, and i get a steady 43 psi.

Can you descirbe your test method for us?

BTW-Those are some erratic compression numbers.