Chevy Blazer Fuel Pump and Pressure Regulator Problems

FIXED!! - I originally put a pressure gauge and it was reading 48lbs, i thought that was enough, however it was not.. I replaced the pump and the fuel filter and now i got 60 lbs (key on - not started) 54 lbs (running) Now it starts no issues.

You should be near 61 lbs (key on - not started) for proper starting. 55 - 61 lbs for starting, the higher the better.

A plugged fuel filter will cause the fuel pump to work harder and eventual damage it. Cheap and reasonable replaceable part.

A fuel pressure tester is a easy way to figure out if your pump is working when key is turned on., I noticed the new pump has a new wiring design. They changed the way it connects because the connection were failing either shorting out or ground would break. So its a good idea to change it out if you have over 150,000 miles on it anyhow.

Replies to this message:

freakist (Nov 15, 2011 7:55 pm)

#201 of 208 Re: 2000 blazer wont start [bigdaddy71] by mperu99

Nov 15, 2011 (5:32 pm)

Replying to: bigdaddy71 (Nov 15, 2011 10:05 am)

the wiring can be big issue, no grounding

or shorting in the connection...

Replies to this message:

bigdaddy71 (Dec 09, 2011 3:22 pm)

#202 of 208 Re: 2000 Chevy Blazer won't start / low fuel pressure [mperu99] by freakist

Nov 15, 2011 (7:55 pm)

Replying to: mperu99 (Nov 15, 2011 5:30 pm)

I had a circumstance once wherein I had a short inside the oil pressure sender, and this kept blowing the fuse on the ecm "b" bus, which killed the fuel pump relay. whatever you do, don't try putting in larger fuses to get it to run longer if you find the ecm fuses keep blowing. it may require pulling each sensor and bench testing it, but too many amps through the ecm sensor feed circuits will roast the ecm board, or set fire to wiring. newer vehicles with extra sensor stuff in the tank could be in severe danger if you attempt to put in a larger fuse when a circumstance like mine comes up. Luckily somebody got wise and stopped making the metal bodied senders, probably just because of the potential of underhood fires. careful work is in order when dealing with fuel tanks and lines, just sayin! Good skill to you!

#203 of 208 Re: 2000 blazer wont start [mperu99] by bigdaddy71

Dec 09, 2011 (3:22 pm)

Replying to: mperu99 (Nov 15, 2011 5:32 pm)

after about 2 or 3 days it will start and run for about 5 minutes but then it cuts off and wont start again for 2 or 3 days, help?

#204 of 208 1994 blazer - sputters and "starves for gas" by spoiled513

Dec 09, 2011 (7:40 pm)

i have a 94 blazer, ran great for a while, now it sputters and acts like its running out of gas, i know its none of the following: fuel pump, fuel filter, radiator, spark plugs.... all this has been chaged within the past week just as maint. but it still wont run... it throws out the right psi from the fuel pump but just acts like it isnt getting gas.. what could this be?!?! its driving me crazy!
please help me !!!

#205 of 208 97 blazer fuel pump by darque

Jan 18, 2012 (1:18 am)

i replaced the fuel pump with aftermarket pump. it turned over, started and dies. sputters everytime. no fuel? im a amateur diy guy who just ordered a fuel pressure gauge, not here yet but i thought id write anyway my questions are kinda unique to the other 21 pages of detroit pump issues. prior to begin the fix, it used to run when primed dumping bit into inject, pep boys diagnosed bad fuel pump and it did not have any "obvious" other issues with fuel except for my car not starting ever unless fuel injector primed. fuel filter 1 year old as well. i also replaced the ignition module 9-12 months back.

what i did.
i got the tank out, and with a free junkyard aftermarket fuel pump (from a friend owns the junkyard w his promise he knew it worked [for how long is another story]) i busted the vapor valve on the tank and two of the three fuel line nipples on the old pump getting it out. so i have no idea what order these return to. + the pump had a different 4pin connector then the orig, so i had to splice the 4 wires into the new switch. grey,purple,2blacks*

we replaced the pump with the junkyard one and went key on pump on makes sound turn over bamb starts up and dies everytime until the batt drained. if nothing else directly was problem prior to this the day before im concerned its only one of three things...

1. junkyard part!!!!!. but the pump does work!!!
2. fuel ~ possible reverse of the fuel lines. the new pump has 0 labels for the vent the out and the in. but the old one has vent in the middle f on the right (forward/fuel?) and r on the left (reverse/return) assuming i might have switched these i removed again and they seemed to only go on one way... the right one seems to be bigger so i assume its for getting the fuel to motor. that one fits perfectly on the new pump. the other two also seem to only fit back one way but idk? can they be on backwards?

3. the electrical connection. spliced the 4 wires together with the new connector. 1)grey to grey 2)purple to purple and the 3&4) black wires. could i have made a mistake and reversed a ground to something else? i do get power when key on. is that enough indicator to my electrical being correct? could the pump in anyway run backwards? i really doubt it but idk? my assumption is the fuel lines backwards and or electrical backwards> ?

so i do not know what else the pump needs to work if its humming? it does humm a lot longer than 5 -10 seconds once in a while... tank seemed clean inside as well. i assume the last thing i did is the first place to suspect but i am not eliminating other issues but i have huge gut feeling its something stupid...
always is with me.

i did notice the old pump had a oring on top of cap under connectors and nipples and i did not use that one on the new pump. is there a potential vacuum leak issue? i cant see honestly what the top oring could actually do if anything but prevent spillage. there is no openings and no vents it seems like an extra spare oring. any help would help but i dont have the right volt meter i only have amp meter and no pressure gauge yet. if someone could eliminate or confirm my gut feelings it would help narrow it down thanks.

#206 of 208 1999 Blazer 4.3L fuel psi problems by blevins1

Sep 26, 2012 (1:48 pm)

I have 1999 Blazer 4.3L. We have replaced the fuel pump twice with different brands, 5 different pressure regulators, check the volume of the pump, checked wiring for voltage drop, replaced the spider, checked injectors for leak down, blown out and checked all fuel lines, checked the relay and wiring. All these checked out. We are unable to get the fuel pressure up to 60-66 psi required for the engine to run smooth on acceleration, engines idles fine. If we restrict the fuel return at the tank and raise the fuel rail psi up to 60-66 psi the engine runs great with no hesitation or back firing. Any more ideas of what it could be?

#207 of 208 Re: fuel pump or pressure regulator [marblaze] by redspawnsilver

Jan 24, 2013 (12:46 pm)

Replying to: marblaze (Oct 28, 2009 7:04 pm)

He said he replaced those... please read the OP before replying....

#208 of 208 Fuel Pump Electrical Question by gimpy_blazer

Feb 20, 2013 (1:03 pm)

So, my 1998 Blazer (4WD, 2 dr) is having fuel pressure issues. Just turn the key, I get ~48-50 psi at the rail and it doesn't want to start with that. You do hear the fuel pump run for 2 sec.

However, if I jump the car (attach a battery charger boost to the positive, negative grounded on the body) it jumps up to ~60 psi when the key is turned. Crank it and starts fine.

Initially I believed the starting issues were either a low battery, old starter motor, or poor grounds. So, I just put in a nice strong CCA rated battery and starter motor. I also cleaned the grounds near the battery (found two there).

So, my question is: do I need a new fuel pump, or is there a specific place in the electric system that I should check for poor grounds, etc.? Conversely, could I somehow can the circuit to runt the pump longer or at higher power?

Thanks for any advice.

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