1993 no start

[stewyn]

hey guys,

So I've got one i cant figure out...

The other day my truck just suddenly died on me on the way home. There wasn't much the led up to it, I had been driving for approx. 10 miles, and the engine had a tiny sputter, went to give it a little gas and it shut off completely and would not restart had to get a tow home. Next day it began,
-still would not start, cranks as usual.After many many tires i get the slightest sign of combustion, one, single, extremely weak cylinder fire.
-tried gas down the tb, nothing. jets as spraying gas on their own just fine, nice cone shape.
-checked for spark on every plug, all fire just fine.
-timing is still fine,went tdc #1 and checked the dizzy and it lined up just fine with #1
-pulled the obd1 code #33. map sensor. got a new one... still nothin.
- compression test 1.150psi 2.160psi
                                  3.150psi 4.160psi
                                  5.120psi 6.150psi
                                  7.130psi 8.150psi

-unhooked the battery for an hour to rest truck, code cleared.
-------still no start. this truck has ran perfectly fine up until now. only 148547 miles.

Your input is greatly appreciated.

[tlaw91]

Sounds like you need a distributor, maybe the gear is wore out or it’s not providing enough power in the spark, may be weak. Sounds like a distributor issue. Co workers grand wagoner did this once. Needed a cam too totally wiped it out. Anyways your truck was made just after I was born so I may be useless, just thought I’d throw it out there.


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[diyer2]

Ignition Control Module in the distributor?

 

$45

[Uncle Redhead]

Probably won't help since you have spark but this is what happened when my distributor went bad. I would have intermittent start issues at first. Sometimes she would fire right up sometimes not. Finally after a year she did not fire up at all. I After replacing the usual things cap, rotor, ignition module I finally spent some time with a meter and found out I had power all the way up to the distributor but no spark. At the base of the distributor shaft there is an electronic device (smarter people on this forum know what it is) that I believe works like the points on an old distributor (now I am showing my age). This is where I figured the problem was. I could have rebuilt the distributor but opted on getting another however I doubt it is as good as OEM. Due to some family illness issues I had to let the truck sit for 3 years. I recently put the distributor in and with a little fuel down the throttle body she fired right up. Now I am doing the fuel pump, etc. but am determined to get her back on the road. I have 175,000 miles on her. I ftel your frustration. I spent many any hour with a volt/ohm meter in the hot sun trying to figure my issue out.

[stewyn]

Something in the distributor was my first guess as well, but just installed brand new distributor, came with everything new, cap rotor, ICU and pick up unit, gave it a few cranks and i got more out of it then before. It sputtered almost like to tdc compression. cap and rotor are lined up as well as i can by eye ball.

 

This really hurts my  head

[riverbanks]

The map code,makes me think the egr is stuck open?

[stewyn]

I checked into the egr as well. its fairly new, within the last year or so. i am able to move the diaphragm by pushing on it with no effort.

[riverbanks]

Ok,still seems like a breathing problem,what about unscrewing o2 sensor and try it, maybe clogged cat

[stewyn]

did not think of that one.  just went and tried and.... nothing

[riverbanks]

Are you doing this with timing wire disconnected?try it if not,code 33,low vacuum,you checked egr,what about any other vacuum on intake,intact?how about vac line to map,plugged at intake port?what about trying it with map unplugged?and is it possible that the coil is failing with a little heat"activity",got enough to show you spark in beginning but not long afterwards

[stewyn]

yes Ive tried both with the wire connected and not. Ive checked all the vacuum lines and they are all in good shape and connected. have not checked the port tho, ill look at that one in the morning. when installed the map i tried plugged and not. i do suppose the coil could be weak, do you know how to test one?

[riverbanks]

In Haynes manual,the primary ohm resistance should be approximately 0.1,that's,+ to - with the leads,, secondary resistance should be 5k to 25k ohms,that's + to coil wire tower,one other item,how much slop is in timing chain?I test by alternator nut on pulley,a little back and forth to feel for play,that's if belt is tight, otherwise,try at crank pulley bolt

[stewyn]

Coil was intermittently testing good, got a new one installed and it fired right up and purred! 

 

thanks a bunch for all your input!