Ok so I ran into this problem about 3 weeks ago. I thought it was the main relay and it wasnt. it was a 10amp fuse blown that they call the alternator solenoid fuse. Car started up and ran great... then it did it again on the freeway on my way to seattle a week after i fix the problem. It seems to only happen on the freeway going 45mph+. My car is a 1990 civic lx with a built dohc zc swap.
The alternator is newer and the battery is located to the back. I put a 30 amp fuse cuz it keeps popping 10-25 amp fuses. I put a 30 in there and it does fine in town but after being on the freeway anywhere from 10-45mins it dies. the 30amp fuse doesnt pop but the car will die. Im sick and tired of this problem. I need some real advice.

It seems to do fine intown but when i get on the freeway it dies after a period of time. Sometimes it does it and sometimes it doesnt. I really hate it and want to just torch the car cuz i cant figure out wtf is wrong with it.

Is the alt over charging cuz I have a big battery relocated in the back? The battery is grounded in the back of the car. Never gave me a problem till recently. Is the alternator solenoid going out? does it even have one? Please help... no other site online gives a reasonable answer and I know you guys at htech can help. please help....

 

i had the same problem on my hatch, after going threw every wire through out the car that didn't fix it. changed battery, alternator, fuse boxes still no luck. changed the fuel pump and never had that problem again.

 

I have to go with fuel pump also. Mine sat for 2 years and when I tried to start it it would blow that fuse. I wasnt getting fuel so i replaced the fuel pump. never had the problem again.

 

Same thing happened to me befor with the fuel pump except it happened after I replaced mine I pinched my positve wire for the fuel pump. Blew the fuse had to trop the tank again. Fix the wire and carefully put it back togeather problem fixed lol. Jus a thought if u replaced ur pump lately

 

Oh ps. If that fuse blows your fuel pump won't run and you won't get spark eaither