Hello fellow 4.0 owners. I have a 94 OHV that just started running horrible a couple days ago. It ran fine in the morning and went to start it in the evening and it started missing and stalling. I've done the ether vacuum leak test, grounded the motor to the battery and check my plug wires. I loaded a video of it spitting and spudering, HELP please?

 

What is your fuel pressure?

 

That is a great question, I don't have a gauge to check it.

 

There's a Schrader valve on the passenger side fuel rail located just in front of the ignition coil. You should be able to get a cheap fuel pressure gauge set from harbor freight and screw it into that valve.

 

What should the pressure be? I am almost positive it's not the pump because I can smooth it out with the throttle around 3000 rpm.

 

At idle, on the 94 with the under hood fuel rail mounted fuel pressure regulator, with it's vacuum hose Attached, the pressure should be 25-35 psi. With the vacuum hose removed & plugged 35-45 psi.

Some of the other common items that can be causing your issue would be worn spark plugs (pull a couple and visually inspect them) bad ignition coil, or a clogged catalytic converter (can be tested at a muffler shop) I wouldn't throw parts at it though just do a good inspection and see what you find.

 

It's been hard starting for sometimes and it has a bunch of blow-by, I bet the cat is clogged. But checking plugs is first on the list. Thank you for your help