Juancm

i have problem,i have a 98 blazer lt and the problem is that sometime the engine is harder to start and it stumble,but there's no codes .any idea on what should i start checking and if any one knows a web site for vacuum hose diagram 98 blazer

old_master

Have you checked the fuel pressure? If so, what is it and does it hold? Vacuum line schematic should be on a white sticker on the radiator support.

Juancm

i dont have a fuel pressure tester and the engine light come on but when i plug in my scanner it doesnt read it and all the guages goes crazy i think i have a short what u think

DelCoch

I think you have the wrong type scanner. A fuel pressure test gauage is about 35 bucks at AutoZone, a good investment if own a Blazer and want to DIY.

Juancm

i got code p300 and am going to get the Fuel Pressure Tester tomorrow so i let ya know what are the results

old_master

P0300 could be caused by low fuel pressure. Check the fuel pressure with the key on and the engine off. Post what the pressure is and if it remains above 55psi for 3 to 5 minutes after the pump shuts off.

Juancm

ok i got the fuel pressure tester and it was 60psi and less then 20sec it drop to 37 psi

old_master

Your leakdown is excessive. To determine what's leaking, a shut off valve must be installed in the fuel pressure line between the fuel pump and the fuel pressure service port. Energize the pump and allow it to build pressure. Shut off the valve just as the fuel pump shuts off. Watch fuel pressure for drop. If pressure still drops, the problem is under the upper intake manifold. Could be a line, the pressure regulator, or an injector. If pressure holds, the fuel pump check valve is leaking, and it's time for a new fuel pump module.

Juancm

can u show me a picture were is this shut off valve must be installed.or where is the fuel pressure line excalty located and if it is the fuel pump is it in the fuel tank?

Juancm

and when it cold outside it start with no problem unless you warm up the car and then shut off .it's hard to get the car started

old_master

The valve assembly has fuel line adapters on each end and is installed inline at the fuel filter. Send me a PM with your email address and I will send you a picture of the tool. The fuel pump is located in the fuel tank and requires removal of the tank to replace the fuel pump.