Hi
I bought a 1990 hyundai excel a few months back. The seller said it had been sitting many years when he bought it. Ran well while he briefly had it. He changed fuel pump.

it worked for about 3 weeks for me. Then suddenly after stopped at a store, would work.

took to my mechanic. We changed started, spark plugs, and distributor thus far. We have concluded it is something electrical.
mechanical checked relays and what’s sending and receiving power (sorry I can’t get more specific)

We bought a new ecu but we’re still not getting the 5 volts to anything.

Today we tried to run a diagnostic on the m.u.t. checker fuse. But it doesn’t seem to be working. We are trying to bypass that fuse but can’t figure out how. Also would love hints at trying to get a diagnostic.

we are talking to the builders of the new ecu but haven’t gotten word back.

any thoughts?

thanks

That’s the mut fuse at the top