1995 blazer no start,runs if you make it run

[jeremypt]

i have a 1995 moneypit and the problem is that when you turn the key to "on" the fuel pump relay comes on, the fuel pump hums. when you crank the engine, it wont start, but if you mist fuel directly into the engine, it will start and run PERFECT as long as you leave it running. you can shut it off and start it back up immediately, but if it sits for more than 2 minutes or so, it will not start back up. i am currently waiting on the sending unit (which was too rusted to remove the lines from to replace the fuel pump which was done last year), and im hoping that the pump is where the problem lies. it did this off and on for a while and i just thought-ahh its a blazer, but now its constant and i need to figure this out. i love this truck and its beautiful for a 95 michigan truck, i just want to be done with these nickel and dime problems. ANY advice will be appreciated especially anyone who has encountered this problem please respond, i dont want to be convicted of insurance fraud HAHA.

[drdd]

search on this forum:

cpi
washing
nut kit

Originally Posted by jeremypt

i have a 1995 moneypit and the problem is that when you turn the key to "on" the fuel pump relay comes on, the fuel pump hums. when you crank the engine, it wont start, but if you mist fuel directly into the engine, it will start and run PERFECT as long as you leave it running. you can shut it off and start it back up immediately, but if it sits for more than 2 minutes or so, it will not start back up. i am currently waiting on the sending unit (which was too rusted to remove the lines from to replace the fuel pump which was done last year), and im hoping that the pump is where the problem lies. it did this off and on for a while and i just thought-ahh its a blazer, but now its constant and i need to figure this out. i love this truck and its beautiful for a 95 michigan truck, i just want to be done with these nickel and dime problems. ANY advice will be appreciated especially anyone who has encountered this problem please respond, i dont want to be convicted of insurance fraud HAHA.

[BlazerLT]

Search for any of these:

cpi injector
nut kit
washing
plenum

[paulleeber]

I have the same exact problem with my blazer Have you found out what the problem is? If you do can you email me [email protected] and I will do the same for you

[BlazerLT]

Originally Posted by paulleeber

I have the same exact problem with my blazer Have you found out what the problem is? If you do can you email me [email protected] and I will do the same for you

How about we have the guy post here and how about you not being so selfish about this in your first post here and have him contact you directly.

We all would like to see the outcome.

If you think this forum is your own private information source, you best be moving along to somewhere else. We share information here, NOT hog it for ourselves.

[adrbar]

check the fuel pump, not using the rail valve, disconnect the high side line directly, reason being if it is the regulator you eliminate it, the fuel pump needs to be high on the spec side. it must also hold that opressure when you key off, if it doesnt its the pump. Mine held 65 psi, but only when it was running, once i keyed off, it bled back into the pump.

the opump should run for two seconds on key on, then the pump will shut off, the whole time the gauge should remain fairly steady, if it drops off and keeps dropping, replace the pump. if it is ok, reconnect the fule line, then do the same check using the schrader valve on the fuel line. if the test shows the fuel pressure dropping, the problem is the fuel regulator or the spider assembly in the plenum, depending on your type of system.

good luck.

[paulleeber]

Originally Posted by adrbar

check the fuel pump, not using the rail valve, disconnect the high side line directly, reason being if it is the regulator you eliminate it, the fuel pump needs to be high on the spec side. it must also hold that opressure when you key off, if it doesnt its the pump. Mine held 65 psi, but only when it was running, once i keyed off, it bled back into the pump.

the opump should run for two seconds on key on, then the pump will shut off, the whole time the gauge should remain fairly steady, if it drops off and keeps dropping, replace the pump. if it is ok, reconnect the fule line, then do the same check using the schrader valve on the fuel line. if the test shows the fuel pressure dropping, the problem is the fuel regulator or the spider assembly in the plenum, depending on your type of system.

good luck.

Thank you. I had the fuel pump problem about 6 months ago as you discribed it. Problem I found was the the rubber sealing the little vibration accumulator directly in front of the fuel but was broken down and crumbling thus leaking fuel pressure.

With the current sympton as described the feul pressure is good and holds at about 65 psi like you said while running or in the start position.
even after key shutoff.

it seems like there is no fuel delivery only durring cranking because even with the good pressure I need to spray fuel to get it started. There must be a different way the fuel injection delivers fuel durring cranking than when the key is in the run position. Any other ideas?

[adrbar]

actually there is not, i have become really good friends with the chevy technician, who ended up helping me out on the side, but basically this is how that system is designed:

the key is timed to prime the pump for two seconds at key on, the engine pcm (computer) knows the car when in order should start right up, so it does not start the pump until key on and running. key word being running, if there is a leak in an injector or the fuel system has insufficient pressures, it cant start to put the computer in run mode, utilizing the sensors.

i asked him about your adding fuel to the mixture, and he says that there are two things you need to do, one is watch the pressure while connected to your rail and if you are dropping pressure, even slowly, fuel could be coming through the regulator and back out, the way to test that is to pinch the rubber return line under by the fuel filter. if it stays steady or slows down some your regulator is bad. if it doesnt it could still be bad because it could be leaking into the plenum area, either way, a bad regulator. 69.99 at autozone, put one in myself.

the second thing it could be is a leaking spider assembly, but to test either of the last two systems, remove the spider, apply fuel pressure with key on, please do this carefully, and look for leaks in the poppet/injectors and the regulator.

hope this helps, basically you are running lean, like i was.

[jeremypt]

i changed the regulator and still have the same problem, only pumping 45 psi now and heating up fuel pump relays so i guess ill change the pump AGAIN!

[paulleeber]

Originally Posted by adrbar

actually there is not, i have become really good friends with the chevy technician, who ended up helping me out on the side, but basically this is how that system is designed:

the key is timed to prime the pump for two seconds at key on, the engine pcm (computer) knows the car when in order should start right up, so it does not start the pump until key on and running. key word being running, if there is a leak in an injector or the fuel system has insufficient pressures, it cant start to put the computer in run mode, utilizing the sensors.

i asked him about your adding fuel to the mixture, and he says that there are two things you need to do, one is watch the pressure while connected to your rail and if you are dropping pressure, even slowly, fuel could be coming through the regulator and back out, the way to test that is to pinch the rubber return line under by the fuel filter. if it stays steady or slows down some your regulator is bad. if it doesnt it could still be bad because it could be leaking into the plenum area, either way, a bad regulator. 69.99 at autozone, put one in myself.

the second thing it could be is a leaking spider assembly, but to test either of the last two systems, remove the spider, apply fuel pressure with key on, please do this carefully, and look for leaks in the poppet/injectors and the regulator.

hope this helps, basically you are running lean, like i was.

Hi

double checked my fuel pump measurements and you were right as soon as the pump shut off pressure went right down. Where is the pressure regulator and how does it come off MIne is a 1995 blazer with vortec 4.3 later engine. I will double check tonight by taking a measurement right at the fuel filter but I just replaced the fuel pump 6 months ago.

[adrbar]

its sets next to the fuel plenum in the spider, you need to remove the upper plenum, then you'll see it at the back of the module.

[BlazerLT]

Originally Posted by jeremypt

i changed the regulator and still have the same problem, only pumping 45 psi now and heating up fuel pump relays so i guess ill change the pump AGAIN!

Replace the INJECTOR, not just the REGULATOR.

[ZL1power69]

Originally Posted by jeremypt

i have a 1995 moneypit and the problem is that when you turn the key to "on" the fuel pump relay comes on, the fuel pump hums. when you crank the engine, it wont start, but if you mist fuel directly into the engine, it will start and run PERFECT as long as you leave it running. you can shut it off and start it back up immediately, but if it sits for more than 2 minutes or so, it will not start back up. i am currently waiting on the sending unit (which was too rusted to remove the lines from to replace the fuel pump which was done last year), and im hoping that the pump is where the problem lies. it did this off and on for a while and i just thought-ahh its a blazer, but now its constant and i need to figure this out. i love this truck and its beautiful for a 95 michigan truck, i just want to be done with these nickel and dime problems. ANY advice will be appreciated especially anyone who has encountered this problem please respond, i dont want to be convicted of insurance fraud HAHA.

read this thread;
http://www.automotiveforums.com/vbul...d.php?t=455035
i listed the part#'s for the cpi, nut kit, and upper intake gasket.
before i replaced these parts, the truck would start(even with a hole in one of the fuel lines) but it ran like shit. Hope this helps and good luck.

[paulleeber]

Originally Posted by paulleeber

Hi

double checked my fuel pump measurements and you were right as soon as the pump shut off pressure went right down. Where is the pressure regulator and how does it come off MIne is a 1995 blazer with vortec 4.3 later engine. I will double check tonight by taking a measurement right at the fuel filter but I just replaced the fuel pump 6 months ago.

Ok here is something I found that may help out anyone with the same problem....

I checked the pressure directly at the fuel filter outlet and sure enough the pressure was dropping off as soon as the pump shut off. According to what I've been told pressure should remain even after pump goes off.

Just had replaced the pump last year but what was bad at that time wasn't really the pump it was the little pulse dampner right in front of the pump. the rubber that slides over the fuel line tube was crumbling (I later found this problem listed in service bulletin from chev) Since I was there I replaced the pump as well. The pulse dampener I got along with the pump at Autozone. Every thing was fine for about a year.

then I had the problems mentioned above with the hard starting. When I took out the gas tank and looked at everything it looked fine. So before changing anything I thought I would do a little testing. I bled my aircompressor down to 60psi (same as fuel fressure should and forced air into the fuel outlet on the pump it self. the pump held pressure fine.
Then I reassembled the pump and pulse dampner onto the assy that goes into the tank and put air into the fuel outlet. This is where I found what was causing the fuel pressure to leak down. One end of the pulse dampener was not sealing around the tubing properly.

So today I went to the chevy dealer and bought one fron them. The material looked different than the after market unit. I talked to several people about this and most times the complete unit is swaped durring a fuel pump including the sender unit as one assy. If this is the case then the pulse dampner gets changed too.

I think what we see when people complain about constantly haveing to change feul pumps in these vehicles is really a problem with the pulse dampner. I will know for sure tonight and will report back

[jeremypt]

i changed the pump in my truck and it runs fine now, but now it heats up the fuel pump relay, and my alternator decided it didnt want to work anymore, hey at least all the parts are warrantied now, i might as well put another 100k miles on the old girl. any thoughts on the relay getting hot would be helpful, however i know it's not wiring,i think it may have something to do with the oil pressure switch, which engages the other side of the relay, after the prime. possibly a bad ground somewhere-any suggestions?