ok so ive had my car for about three years now, its a 1990 civic sedan dx and its only a piece of **** on hot days. for some reason whenever the temperature is above 75 degrees it will not start, but it will crank all day. i know its not the battery and i deffinately have gas. it makes spark because 90% of the time it starts. my father researched it alittle bit and concluded that it is the main fuel pump relay because apparently its a known problem with ef's, however ive never heard of such a problem. i bought a new fuel pump relay but it is not the main. if you could tell me the main fp relay's part number id be appreciative. but i really dont think its the fp relay, i think its something with the fuel pump, lines or injectors because it only wont work if its left in direct sun light on a hot day. if its cool/at night time it starts perfectly and never gives me a problem. ive tried taking it to a local mechanic and he said nothing is wrong with it because it turned right over for him. thanks for any help you guys can offer.

 

Sound like the main relay alright..

Check here: https://honda-tech.com/zerothread?id=1655954

And read the links that are posted...

 

http://autorepair.about.com/cs...c.htm

To test

 

my buddies did that exact same thing, turned out to be his computer he ended up replacing it with 3 different ones they all did the same thing until he finally got a good one and starts fine ever since...

 

wow that was fast, just curious why does the main relay deside to be a douchebag when its hot out? id assume since its electrical it wouldnt be weather biased.