1995 Sephia Starting Woes

[SopherBunch]

1995 Sephia LS 1.6 SOHC

Okay, let's start with the problem:

Car starts up no problem. Warms up, drives great for a couple of hours. May due this for a couple of days. Then some days it won't start at all. Some days it will start in the morning, but later in the day won't yet again.

Things we've replaced:
fuel pump
both fuel filters
Cleaned battery terminals
Plugs
Wires

NOW GET THIS- I went to test the fuel pressure regulator. According to the manual, you're supposed to have 25ish psi of pressure when having the key in the "on" position. Says fuel pump will come on for two seconds building the pressure. This one doesn't. BUT, when you turn over the engine, it shoots up to 40 psi. Now the wiring on the fuel pump that the mechanic installed looks hoaky at best. Am I wrong to assume that maybe this could be the problem with starting? The manual could be wrong? Every car with fuel injection i've ever worked on has always had pressurized fuel lines. Oh, and according to the manual, under normal operating temps, the fuel pressure regulator should run about 41-53 psi. This one is running bout 41-46 psi.

WHAT AM I MISSING?

[SopherBunch]

Also wanted to add this:
When I went to relieve the pressure to "T" in the fuel pressure gauge, there wasn't any pressure in the lines. This is also the 2nd fuel pump in less than a month.

[ron1004]

Welcome to the forum.

The same circuit (ECU and FP relay) that switches the fuel pump on when you crank the engine, should also turn the FP on when you first turn the ignition switch on. When the ignition switch is turned on the FP should run and stop after a few seconds if it does not see pulses from the engine cranking.

When you have starting difficulties try jumping the diagnostic plug (DLC).

AFAIK the fuel pressure should be about 40~45 psi.

There's a check valve (NRV) in the discharge of the fuel pump which should allow the fuel rail to stay pressurised for some time after the pump has stopped - best inspect that valve.

[SopherBunch]

But if there isn't any fuel pressure by just turning on the key, does that indicate a failure at the pump, wiring, and where else?

And could that cause this problem of intermittent starting?

Where can I find a wiring diagram for the fuel pump harness?

[ron1004]

Originally Posted by SopherBunch

But if there isn't any fuel pressure by just turning on the key, does that indicate a failure at the pump, wiring, and where else?

And could that cause this problem of intermittent starting?

Where can I find a wiring diagram for the fuel pump harness?

That could be the cause if the intermittent start problem.

You can find the wiring schematic in the ETM section on the KiaTech web site.

[SopherBunch]

Thanks all for the link to kiatech! I should be able to troubleshoot this gremlin now!