Did fuel pressure test today and here the numbers key on engine off 60 psi 10 minutes later psi 35.key on key off psi 60 10 minutes later psi 41.engine running psi 50.with key on psi start at 60 then would drop to around 50 in 1-2 min then slow drop from there same with key off.is this normal are is there some thing wrong.engine is running rich and only get around 8-10 mpg on highway and bogs down randomly at any speed.

 

Makes a difference what year your vehicle is.

Key on, engine off, fuel pump running:
1995 and older: 55psi to 61psi
1996 & newer: 60psi to 66psi

10 minutes after the pump shuts off, pressure must be at least:
1995 & older: 50psi
1996 & newer: 55psi

 

my bad its a 95 and 10 min later is that with the key still on and motor not running.if so it drop to 35 psi so what does that mean.and i searched and i read were you said to do the test with the motor cold i did it with the motor hot so does this mean that my reading will be low when i do it when it cold.going to do it tomorrow if stop rain its been a monsoon here to day. thanks captain

 

show just did a fuel pressure test after a few cycle of the key with key on motor off psi 58 then start to fall instantly start to drop after 10 min it held at 28 psi. so what i have read on here this a sign of a leak in the fuel system.so know i m gone to get some feinting to check the pump it self. so to make sure i,m doing this right i need to check it after the fuel pump filter and what should the pressure there be and do you let ti stay on key on for ten minutes like you do at the check value. and sorry forgot its a 95 4.3 cpi odb 1.5 all show going to put a new fuel filter on before i do the test at the pump to make sure that there is no doubt in the fuel flter .thank for looking and any help will be very appreciated

 

most the times i seen it drop really quickly after the pump is done priming it has been a leak in the tank itself. so you wont actually see any visable leaks under the truck but rather the pump or the small rubber line attached to the pump in the tank has a crack in it.

i just messed with a s10 the other day, i think it was a bit newer but it was 60-66psi key on engine off and idling was somewhere in the 50s, dont remember exactly but around 55

 

hope not really don't want to have to drop the tank the bolt are rusted solid on the strap and i hate to see what the lockring looks like.just got back from lowes with the feinting need to make the fuel stop at the tester to see if it in the pump. and the with the engine idling mine was 50 but when you give it gas the psi didn't barley move wonder if that nomal.try to post the results later on what i find. thanks

when i did the first test a while back i did it with the motor hot and didn't know that i need to do it when the motor was cold after reading on her that captain hook had posted.but while i was searching on here i found a post that was having the same problem and they said thy unplugged bank 1 02 sensor. show i went and check and found that mine was broke around the bottom of the sensor show i just unplugged it and it stat running fine plugs burn clean again and the mpg in proved so i just left it of and went on at the time this was not my DD then my DD took crap and the trans went out so i start driving the blazer more and the more i drove it start to develop a miss so changed plugs and cap acdelco and msd wires . it help a little but the miss was still there like random so i thought it might be where the 02 sensor was unhook show went to replace it and found out somemoreon weid it into the bosit so i just left it unplugged and delta with the miss. but know it is start to die randomly cold are hot engine and the miss is get worse and some time when it die it start right back up then dies again and then it start up and stay runing but the rpm climb up to 2500-3000 and i have to cut it off to get it idle right again and that is why im posting again on fuel pressure.wasnt able to get to finsh my pressure test to day on the pump going to do it tomorrow and on the 02 sensor going to put a new exhausts from y back and new 02 sensors Monday show if anyone has any other suggestions i real appreciate the heip

 

finally had time to do a pressure test on the pump yesterday after the the snow and flu last two weeks.show after i hook the tester to the filter and turn the key on no pressure show check everything and it was no leaks so i took the tester off and hook the fuel line back and she start right up. check the pressure at the intake 0 come to find out tester was bad show had to go and find another tester and let the motor cool back down to start all over because the test that i used to check a the filter was the same one and want to make sure it wasn't the tester on the first post that was leaking.show take two key on motor off psi 58 then after 10 min 48.I now it suppose to be 50 but 2 psi really make that much of a differences and it didn't drop as quick as it did with the other tester bad one.as i was waiting i took the butterfly thing out of the top of the intake sorry cant remember what it called and what i could see was some wash off on the regulator side and on the end of the regulator was real washed clean and now that it warmed up here it stop die on me but still has a random misfire.hope to get time tomorrow to check the pump and was wondering does the motor need to be cold when checking at the filter.thanks

 

Your fuel pressure tests, in both of your posts, is OK. The leakdown tests in your first post fail. The leakdown test in post #7 is close, but technically out of spec. The concern is that they are not consistent. The washing on the regulator might be an intermittent leak causing different leakdown readings. If leakdown is excessive in the plenum, it would cause longer cranking time to start due to the rich mixture and longer time to pressurize the system. It will also cause the engine to run rich. Might want to check pressure at the filter to make sure there are no leaks in the tank. All pressure and flow must end at the tester, no fuel is allowed to reach the engine. What is the Key on, engine off, fuel pump running pressure, and 10 minutes after the pump shuts off?

 

thank captain the first two test where done with a loner from oreilly and the last one was with the one i bought you never know what you going to get with a loner. the mpg are down and I don't have a hard starting problem the only time I have trouble is when it dies while driving and I drop in to neutral and try to restart, sometime it does right away and most of the time I have to pull over and put it in park to get it to start and when it start it backfires through the intake and you can smell gas a few second and then it clears up and off we go.the plugs are burning clean one thing I learned from my drag-racing day was how to read plugs.lord i miss the day of carburetors and distribute,sorry about that just having a flashback there. thank just trying to get this thing running right so I can start the fun stuff and hit the trail and thanks for the help. rick

 

i kinda sceamed over the thread,but simply put get a fuel pressure kit from autozone etc,it'll come with the adapters to plum into the fuel filter. if it fails there its the pump. it'll save you cash from the spider injection if its the culprit.