2000 blazer hard to start
 

hello everyone im a new member..but ive used this forum for good help before. well i have a 2000 blazer 4x4, 4.3v6. lately its been hard to start after it sits over nite. i thought it was the battery so i replaced it with a different one and same problem happens. engine cranks, i hear fuel pump start and have good psi at check point..i can keep cranking until battery dies, or until i hook up another battery to it, then it starts with no problem. while running i can see it recharges to 14v or so. i can start it up right away for a while, but once it sits over nite it will not start at all unless i hook it up to another battery. any help would be greatly appreciated thanks.

So.. it might be safe to say your battery wont hold a charge or it's discharging overnight.
to find if that's the case, buy a test light. One with bulb not LED and remove the neg terminal and put light between cable and battery with nothing turned on in the truck. If it glows more than dim, something is discharging it.
So oyu replaced it with another battery but it's not new either.

Take the car to a parts store and have the battery checked.

it does hold a charge and it does not discharge

What is the fuel pressure that you are getting? I had exactly the same problem with my 98. I thought that 45-50 PSI was good. I actually had to pour gas in the throttle body to get it started initially. Once it was started the engine would start immediately unless I let the truck sit until it had cooled off or over night. Make sure you get over 60 psi and it holds the pressure. Normal pressure is 65 psi. Just me experience.

i was getting from 55 to 60ish..i was thinking of replacing fuel filter tomorrow, i did oil change and spark plugs yesterday. it started fine for a while but once i went to work and let it sit for 3 hrs or so it did the same thing..keeps cranking but wont start. then it just started with no problem. this morning when i went outside to start it it wont..

Change the fuel filter first and if that does not work read below.

I just installed a brand new fuel pump assembly in my 2000 Blazer and the new pump with new filter only produced 60 psi. Have you put a fuel pressure gauge on the engine and once you have initial fuel pressure with the key on turn the key off and see if the pressure drops off slowly over time? Does the pressure drop while cranking the engine? If the pressure goes down I would seriously consider changing the fuel pressure regulator which is a heck of a lot cheaper than a fuel pump. That might be an idea for you since you are getting fairly good pressure now. I seriously doubt that it is the fuel pump if it is pushing 60psi.

Have you ever or know of anyone that changed the injectors in this engine? Does the truck when running run rough at idle or sluggish? The reason I ask is because you will have to dig into the intake that far just to change the pressure regulator, if you go that route, since it is part of the fuel spider (injector assembly) it might just be a good idea to just change the whole assembly and know that base is covered. It is an easy install but a bit more money of course. Just a thought.

Not a good test. If you start it by the book, the pressure will drop because the manifold has vacuum as the throttle plate is closed.
I'm thinking you should see the gauge flutter with every intake stroke, whatever that's worth.

If you crank it with pedal to the floor THEN it shouldnt drop.
But the PCM has ALSO reduced fuel flow because it thinks you want to clear a flooding condition.

cool cool cool, thanks for the info..but, i have no clue if any before me replaced the injectors, i seriously doubt it, and i meself have not replaced them..will change filter tomorrow and let ya guys know the results.

Pettyfrog made a good point about the MAF sensor possibly being dirty. Go to the link he provided. I usually use brake cleaner but they actually make a spray cleaner which is specifically named MAF sensor cleaner. It is available at most any auto parts store.

cleaned MAF sensor and it definitely worked better, changed fuel filter but nothing happened still not running but...i hooked pressure gauge again to see what was up an it was lower than before around 40-50, when i hook up another battery to jump i notice that the pressure jumps up to spec and it starts right away no problem..so safe to say pump is shot? hahaha

Hey I just bought a 2000 Jimmy today and it's having similar symptoms. Haven't checked the fuel pressure yet, but it pops right off and runs great with a shot of starting fluid. It seems that sometimes it wants to start with a boost and sometimes not. So I'm not sure yet if it's the battery or pump. With yours starting everytime with a boost, I would definitely have it load tested first before I replaced the pump.

yea it starts once it gets that extra kick from another battery. i was going to check all wires down there to see if any of them are grounding out or if i am getting right amount of voltage to the pump. how would i load test it?

also @pontiac have you changed the fuel filter? that mite just do the trick, the filter could just be clogged. getting at the pump is a bit of a pain haha.

Remove the connections to the battery and using a wire brush and clean all parts of the connections (battery side and cable). check the fuel pressure again, key on but not started. Reason for this procedure is to eliminate the chance that the connections are corroded and not supplying full voltage to the system. When jumper cables are used they bypass the connections to the trucks battery. If you have a multi-meter you might want to check the output voltage of your battery by connecting the red lead to the large lug on the back of the alternator and black to a good ground on the engine or body, but not the battery. It should be above 12 volts DC. If not jump the truck off and let it charge the battery for a while, with the jumper cables disconnected. While the truck is running verify that the voltage is 13.5 vdc or better. Once the truck has been shut off recheck battery voltage at previously mentioned locations. It should be higher than 12 vdc. Turn the key on, not running, and check fuel pressure. Hopefully it will be better and around 60psi. Recheck the battery voltage and fuel pressure again after letting the truck set maybe over night. They should be close to the same. If pressure is still low and you have over 12 volts from the battery, key on not running I would consider swapping out the fuel pressure regulator or maybe the fuel injector spider. The pressure regulator is part of the spider and you have to do basically the same procedure to change. If you do not have 12+ volts then I would recommend swapping a know good battery into the Blazer and see if it makes a difference. It should. Recheck pressure and try to start the engine. Hope that the information helps. As stated earlier by another member the pressure should drop a bit once the engine starts so expect it.

Sorry, I went off for the weekend. I'll be messing with mine today. 70Camaroman has some good points. Load testing can be done at most auto stores. It simulates a load on the battery while checking the amps it puts out. It CAN drop. I've charged several batteries that came up to 12 volts, but crap out at the first sign of load. Amps is what actually powers things.

Following the above mentioned items do the following load test, if you don't want to take it to an auto parts store. Best way I have found to load test a "well charged" battery at home, unless you actually have a load tester, is to hook up a multi-meter and either have a friend watch it or yourself. Remove the coil plug and crank the engine over watching the voltage and see how far it drops. It will drop. If it drops below 9.5 volts your battery needs to be replaced.

awesome, i will try this today. i actually bought a muti-meter yesterday to test charge on bat, 12.26v. i'll test load today and see what happens, but i think its just that pump. yesterday i had me brother turn key on and i listened at the tank, pump sounded weak and tired. ill also test and see if im gettin right voltage back there. will report back with findings. peace.

ok i got down at the pump to test voltage to it..it turns on but i did not get any reading. any of you guys know which wire is the power at the connector? i tried to look it up on here but it kept showing me a square looking connector, thats not the same connector i have on my pump. any one know or have a link?

OK, I think I have this figured out. Crawl out from under your truck. I checked my truck today. Key on 12.5 volts I have 44 psi= won't run/ Add ****ty jumper cables 13.4 [email protected] 50-51 psi= starts to hit but voltage goes down immediately and won't run ( I'm thinking like yours if I had my better cables it would have boosted my voltage better and cranked)/ Hit it with starting fluid to initially crank it and voltage goes up to 14.5= psi goes up to 55 and it runs. So our pumps are so weak that they will produce enough pressure to barely run @ 14 volts but not enough to run @ 12.5 volts. I ordered a pump only off ebay for 20 bucks (this is for sale) Isn't it stange that we have the same problem at the same time?

dude! thats exactly the same thing that me damn truck does. well im glad that im not the only one experiencing this (not that its a good thing that you are) i thought i was going nuts or something. i still want to see how much voltage i get down at the pump thou, just want to be sure before i throw the cash down for a pump. those things are ridiculously expensive.

https://blazerforum.com/forum/attach...uel_pump_r-jpg

Gray to black

Sender is purple to blk/wh-strip

If you have the flat connector then the butt-splice may be bad in one or both. Why we suggest solder splice or twist on wire nuts filled with silicon or dielectric grease.

For you guys with the problems you would not believe how many GM vehicles have fuel pump issues like what you are experiencing. By the way Pontiacman, I would be seriously leery of a $20.00 fuel pump. That is unless it is fun for you to drop fuel tanks. They always seem to go bad with over a half of a tank of fuel in them. I have heard it mentioned on other threads that there is a ground connection by the fuel tank which can get corroded and effect fuel pump performance but requires the tank to be dropped. I have never personally seen or worked on one myself but if you have the tank down see that it has a clean and tight connection.

If the description doesnt say it's an actual Delphi, AC Delco, Walbro, Denso or Bosch, then it's probably the same chinese knockoff crap pump you get with an Airtex. I listed those in MY order of preference.

That's for future readers' reference; the poster says he's fixing it to sell. Ie pass it on to the next guy. I am not judging, just saying!

cool pettyfog, thanks for the info. yea i def want to check everything before i go and buy a pump. i looked on ebay and found some running for 60 bucks or so. safe to trust or should i just buy one at local part store? i mean the savings is amazing but i dont want to be doing this again in the near future..such a pain in the ass.

Yeah, I know it's cheap pump, but I just can't pop 300+ on something I'm just going to sell, for 20 bucks I'll give it a shot. I put an Airtex on a friends Blazer over a year ago and it's still going. I have a lift and a buddy to help. If it's no good the pressure gauge will tell me. If you do buy an Airtex make sure that you don't get the two black wires crossed, (that happened to me on my friends Blazer) it will run but will cause egr codes and fuel gauge problems (nasty stuff) Just make sure that the thicker black wire from the truck harness (ground)goes to the ground of the pump motor. My pump should be here Thursday or Friday and I'll report back.

If the pump works for you please post the Ebay sellers name and the auction number so others can acquire the same pump. I know that I would be game since I buy Blazers, Jimmy's and Bravada's with issues to repair and sell.

{Most of rant deleted - but saved- because of wrong context}

If you CLEARLY state 'I am using these cheap parts so I can sell it'.. that's alright with me. I dont even care if you dont disclose that to the buyer.. not my problem or my job!

I just do not think it serves a good purpose on a solutions thread.

ok, i got a little of time today to mess around with me truck 'fore i have to got o work. i tried voltage again at pump and the only reading i got was around 5 volts on the purple wire. is this right wire to be measuring at? im pretty sure i need 12v, right? any help is greatly appreciated. thanks.

The grey one is the hot for the pump motor. The purple is the voltage for the fuel sending unit

You have to remember there are only two times which you will have voltage at the pump. 1 is when the key is initially turned on so that the system can build pressure. 2. when the engine is cranked and the crankshaft position sensor is triggered and makes a signal to the PCM. If you are turning the key on then crawling under the truck in hopes of finding voltage at the fuel pump plug then you will not. The only way around this is to put a jumper wire across the connections at the fuel pump relay so as to apply power with the relay removed. I do not know the pins which to jump and unless you are "sure" which ones they are do not attempt. I suppose the best way to accomplish what you are attempting is to hook up your multimeter and lay it on the ground where you can see it while you turn on the key.

yea i had me brother in the truck turning the key on while i was down at pump with meter. this is when i got the reading of 5v from the purple wire. i got class today so i wont get to have "fun" messing around with it until tomorrow haha. i should have 12v at the wires when key is turned on right? both purple and grey?

No. 5v on almost all sensors and senders is correct. It's regulated to provide truest readings.
12 v on most switches or things that use power to move things.

So purple would be 5 cause it feeds the fuel gauge, {if you ground that purple, the fuel gauge should go to MAX.}

The gray 12 v because it drives the fuel pump.

awesome, thanks for the info. i will return with findings once i get the chance to give it a try.

siddhartha, How did we get from having fuel pressure to wondering if we have voltage at the pump? Did I miss something?

@70: i noticed that the pressure was low when i cranked with just me battery, but once i hooked up another battery (giving it a jump) the fuel pressure shot up to spec...so i was wondering if voltage had something to do with it, before i go out and spend the cash for a new pump. i haven't tested anything yet, weather out here has been bad.

What we are trying to say is, the pump is weak. A fuel pump has an electric motor which will build more pressure when provided with more voltage, but a pump at startup only has 12.5 or so volts to work with. Jump starting provides the other cars charging power to the party. raising voltage to around 14 volts and increasing pressure. While it's true you may have a weak connection or relay, having 45 or 50 psi now, it's very likely you have weak pump.

how did that pump work out for ya pontiacguy?

Just to make sure everything is squared away swap in a known good battery. I just had exactly the same issue with a Oldsmobile Bravada (same as the Blazer). Key on initially, 50+ fuel pressure but when I cranked the engine it fell too low to start the engine even though the engine turned over relatively well. I installed a battery which I knew was good , 12.5 volts before install and knowing it was fully charged and the fuel pressure jumped to 64 PSI and stayed over 57 PSI and the engine started right away. I will bet your battery has a weak cell. Try it and let us know.

You definately need to make sure the battery is good! The pump came last night. I'm in the middle of a tranny swap today, so It'll be tomorrow probably. I'll let you know.

New $20 pump in. Fires right up and runs well!