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1987 Chevy S-10 will not run

Tiny
COURIER81
  • MEMBER
  • 1987 CHEVROLET S-10
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 128,000 MILES
87 s 10 pickup with the 2.8 liter. TBI Auto.

One day it would spin but not crank. The engine rotated sounded a little faster than normal. Eventually it made a slight attempt to run and then quickly stalled. I disconnected the wire under the dash that you disconnect when you set the timing. After a few tries it ran, and I quickly attempted to make it home. Almost got home and then it died. It is home now, but the engine will turn over (like faster and eventually it will try to crank, but then quickly die). Here is what I have changed:

The pick up coil, ignition module, rotor and distributor, fuel pump.

Before I disconnected the computer, I got a code about the spark control module.

It is getting plenty of gas, and fire. I have tried to reset the timing, and it seems right on, but like before it will not run.

Any ideas?

Sincerely Brian
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Thursday, May 20th, 2010 AT 12:57 PM

7 Replies

Tiny
INTERNETMECHANIC
  • MECHANIC
  • 700 POSTS
Sometimes, cranking speeds that are faster than normal means a problem with compression?
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Thursday, May 20th, 2010 AT 1:38 PM
Tiny
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Ok, sorry it took so long to respond. This is what I have found since posting the original question.
I purchased a compression gauge from harbor freight and it reads an average of about 50 psi. That is one both sides of the v6. Gas pressure is 30 psi (specs call for 10 to 13 psi of cranking fuel pressure). The timing is right on. I have replaced the distributor, ignition module and spark control module. All plugs are new, distributor cap and rotor are new, as well as the wires.

A weird thing is that if I attempt to crank it after it has sat a while, it will briefly (and I mean just for a second) it sounds like it will start, then all it will do is turn like nothing is working.

The check engine light does illuminate to let me know the computer is powered, but no codes. Not since the first one before the battery was disconnected.

I'm at a loss here, any ideas?
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Monday, May 31st, 2010 AT 9:36 AM
Tiny
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If I understand your post correctly? Your fuel pressure is too high for TBI. You may have a clogged return line?

You could disconnect the return line, aim into proper container, see if vehicle will start. Doing that could present a fire hazzard, that is your responsibility. I'm not sure how fast or how much gas will run out of return line?

You did visually check for spark at the plugs, correct, engine cranking?
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Monday, May 31st, 2010 AT 11:38 AM
Tiny
COURIER81
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Thanks for your reply.

I did check for spark going to the plug with a inline spark tester, but I did not pull the plug and check for spark at it...there are new, so I haven't thought about that. The engine is cranking, everything turns, and I am pretty sure the rotor is turning too, because it lights up the timing light it is supposed to.

I tested the fuel pressure in two places:

1. Right out of the main fuel line above the tank
2. right after the filter but before the injectors. I believe it was about 30 psi, but well above the 10 - 13 required. However, I did not check the return line.

I'll do the two things you said check for this afternoon and get back to you. Thanks for your help.


https://www.2carpros.com/forum/automotive_pictures/484983_kidsyouthcars_048_1.jpg

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Monday, May 31st, 2010 AT 1:16 PM
Tiny
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Ok, I re-checked the compression and fuel pressure. I guess the first test I did, I wasn't apying too much attention.

On Compression:

of the three cylinders on the passenger side: 2 were at 50 psi, the no. 1 cylinder read 30.

On the driver side:

one cylinder read 80 psi, one read 50, the last one I could not read because the dip stick was in the way and I couldn't get enough room to put the fitting in the socket.

Fuel pressure: a consistent 15 psi, and the return is clear and flowing.

Spark plugs have spark.

Sorry about my 2nd post, I messed that one up totally.
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Monday, May 31st, 2010 AT 5:34 PM
Tiny
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Engine cranking, can you see the injector spray pattern? MOD gives the minimum compression spec at 100 psi.
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Tuesday, June 1st, 2010 AT 9:55 AM
Tiny
COURIER81
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I can see the injector spray pattern. They are both cone shaped. As a matter of fact, I unplugged the Coolant Temp Sensor (to make the comp. Overcompensate for it) and I could definitely tell it was spraying extra gas and the cone shape was more defined.

On the compression side of things, can a blown head gasket or burnt valve cause it not to run at all?

Also, I was thinking, what if, when I placed the new distributor, could I have got it on there 180 degree to the wrong. Like I said before, when I place the timing light on it, the timing light lights right on the timing mark -- which I was told was 10 btdc.
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Tuesday, June 1st, 2010 AT 7:35 PM

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