what could it be?

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MStars

MStars

10 Year 15 Year
Joined
Mar 1, 2007
Threads
29
Messages
150
Location
Dallas, TX
My 87 2wd EFI automatic truck is not starting.

This only occurs when it is cold outside. I have narrowed it down to within a few degrees. If it is above 26 degrees outside then the truck fires right up on the first turn and drives like a dream. However if it's below 26 degrees then it won't start. It cranks or turns over like it normally does but it never fires up. It is like clockwork, if it's cold then it won't start. If its even a few degrees warmer then vroom vroom. I changed the coolant temp sensor a while back and that fixed a few different problems so I don't think it's that.

As far as I can tell there are 0 other symptoms. It doesn't run poorly or have anything wrong with it when it's running. Just that very first start up when it's 26 or below won't work.

What could it be ?

Thanks for all the help as usual with this thing. If it's not one thing it's another

Matt
 
If it just cranks and wont start it has to be a no spark, or no fuel issue... Could be a bad connection somewhere that's temp sensitive... I had a similar issue on my Honda a few weeks ago, 2 bad soldered joints on a circuit board and it wouldn't start when warm... Let if cool down, and it fired right up...

Next time it happens, check for spark to narrow it down, and if it stays cold long enough, try to work backwards... I hate electrical gremlins, best of luck! :D
 
I wouldn't even know where to begin checking anything electrical. The electrical things could be so touchy that within 1 degree guaranteed it will either start or not? I mean it's at the exact temp everytime that it either works or doesn't work. Sorry for the amateur questions but whats the easiest way to check for a spark? Just because it's cold I'd either get a spark or not get a spark give or take 1 degree outside?
 
The quick and easy way is to have a spare spark plug handy, pull one of the wires off of a plug on the engine, and stick it on the spare plug. Hold the end of the plug onto a metal part of the engine and have someone try to start it. You should see the spark plug sparking between the electrodes. Or if you have a timing gun, you can hook that up, and if it flashes, then you have spark.

The next time it's cold enough to not start, you could also try using a hair dryer to heat up different components, and check if it starts after each one... You may be able to find the problem that way... But finding out if it's spark or fuel will narrow down the search.

Yes, a bad electrical connection can be that temp sensitive... Metal expands and contracts with temp, and it's easy to imagine it bending or shrinking away from a connection and causing problems at a very specific temp.
 
nope no check engine light. Everything seems perfectly normal except it doesn't fire up. Soon as it clicks over to around 27 degrees vroom vroom and I'm in business.

Thanks Wristy I will give that a try. Just pour it right in the tank to add to the gas thats already in there?

thanks guys.

Matt
 
yep, just pour it in. after a few miles of driving it will mix in real good.

if the bottle says treats 10 gallons and you have a full tank of what, like 13 gal or so?, add an extra half bottle
 
Both my 86 and 87, the check engine light is on when the key is on before cranking. If it's EFI I wonder if your fuel pump is running. My fuel pump didn't work when the ck engine light wasn't on. When I played with ground wire the light came and the fuel pump ran and fired up.

Not to say that's your problem, but I think that ck engine light should be on when your ignition is in the on position and not running.
 
k tomorrow afternoon gonna try Wristy's solution with the Heet. Should be getting cold this weekend so if that doesn't solve it then I guess I gotta check the EFI relay and the ground.

Thanks
 
First do the dry gas. Then... If it isn't starting, can you get a hair dryer to it? Warm up something and try starting it. Lather, rinse, repeat till found.
 
added a bottle of HEET today while it was warm and drove it around a while. Now just tried to start it while it's 13 degrees out and she started up. Took 2 tries but she started. I think I"ll use another bottle next time I fill it up and hopefully that solves it for good. A while back I had no gas cap and just was using a tight plastic tied tight so likely got some type of condensation moisture in there. Thinking back it all makes sense and I hope this solves it.

Thanks for all the suggestions guys I really appreciate it. Only because of you guys does this little 2wd beast keep on truckin.
 
ya I read the back before using ;) I got the IsoHEET, more concentrated and it treats 20 gallons like you say. I just filled the tank and used about 3/4 of the bottle and called it good. Just tried it again to make sure earlier wasn't a fluke and it started right up again.

keepin that gf in line? =)

Thanks for the help
 
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