What to do when there no psi on cyl 4 to get the psi up agan"?"

The more power your asking from the engine increase the chance you got of damaging the engine

Sorry Kylar if one cylinder is down to 30 psi you either have to look inside the engine to locate the problem, or get a replacement engine.

Jacko

did you use fuel addetive to stop fuel in carbs going off when you laid it up and winterize the cylinders etc ? check compressions , sparks and fuel is in all carbs as if you have sparks then carbs need stripping and cleaning ie, jets and float needles ! compressions to be no less than 100 psi on all 4 cyls !

Maybe a leak-down test on number 4 could find it. Cylinder wall wear, maybe?
At least you got a good head if you have to rebuild the engine, that is, if worse comes to worse.

Most 4 cyl engines with PFI run between 35 and 45 psi at idle.

I say as long as it runs ok and there are no codes coming up that set off the check engine lite, just keep driving.

This engine offered a 4-inch bore, 3-inch stroke and a compression ratio of 8.9 to 1.

each cylinder should have the plugs removed, and each cylinder should have atleast 150 psi, with no more than a 10% difference between the 8 cyl .

most engines period will cary atleast 90 to 180 psi depending on the number of cyl.

fuel pump issue. Soon it wont run at all. Fuel presure should stay consistant with key on.
6 cyl 60 - 66 psi
4 cyl 41 - 47 psi

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/thomas_c50676e836a18949

Remove the plug and check the compression for that cylinder it should be between 120 psi and 150 psi, if it is low it is a mechanical issue (bad valve or worn piston rings). If commpression is low remove the valve cover and turn over the motor confirming that both valves for that cylinder are opening to there correct travel or height if not it is a faulty hydraulic lifter or worn cam. Also check the valve lash clearance the clearance is usually .012" for the exhaust valve and .008" for the intake valve to check the lash turn the motor over until the valve shuts completely for each valve, then use a feeler gauge go no go procedure. Has the wire been replaced for the plug? If this motor has coil on plug type disregard plug wire question.

First check plug and make sure the right plug for this vehicle,make sure that the heat rating for this plug is correct. Your problem could be a wrong heat rating plug been installed. Also make sure that the misfire is due to a bad plug and NOT a bad injector or injector wiring or uneven compression or even bad coil. Check injector wiring and make sure it not shorting or broken. To check injector pulse use a NOID light can be bought at almost any auto parts store like Auto-zone etc. Also compression can be checked with compression guage. A rule of thumb to go by is if any cylinder has more than 10 PSI in difference in compression there is a problem like a burnt valv etc. Here is a n example cyl# 1 170psi cyl#2 176 psi cyl#172psi cyl# 4 150 psi, there is a problem with cylinder # 4 and will cause a miss from cylinder #4. Good luck and thank for using FIX YA