Thanks alot for your help. I hope i can help someone, like you have helped me. i read alot of your posts and you are always there with the right advice. Thanks alot. Iwill check everything at the pump when i change it and let you know if it works right. its always nice to know that the advice you give solves the problem. Oh Well I'm out to the garage to drop the tank and change the pump. [:'(]something i wasn't looking forward to do.

 

Just come in from pulling the tank, comes to find out the person who had it before me put a new tank on BUT !!! didn't change the pump . They just put the old in with the new. the fuel lines are all rusty in the worst way, so it looks like i will be changing the whole unit . I can't see using the old rusty stuff just setting mysef up for a leak later down the line. any good places where i can get the whole unit at a decent price? thanks again

 

AC Delco units off eBay would be the first thing I would look for.

You are looking for:
ACDELCO Part # MU12 {2 Door #25163488}
ACDELCO Part # MU13 {4 Door #25163489}

*EDIT* - whoops, the above info is for a '96 as the thread title stated...

Here is the proper info for a '95.

Pump:
ACDELCO Part # EP381{DOES NOT INCL STRAINER. #25163473}
Strainer:
ACDELCO Part # TS92{#25168246}
Sending Unit (lines & fuel level sending unit,etc):
Well... There are 4 available AC Delco units...
ACDELCO Part #25029911 - Sender Fuel - Sender HARN Tagged SFG
ACDELCO Part #25168316 - Sender Fuel - Code SFK, SFW, SFJ
ACDELCO Part #FLS1023 - Sender Fuel All Makes - Sender HARN Tagged SFG
ACDELCO Part #FLS1033 - Sender Fuel All Makes - Code SFK, SFW

It looks as though the 2door uses code SFG, but the 4door has 2 available designs with the difference being in the SFJ code...

At the very least I would get the AC Delco pump, but the manufacturer of the rest is up to you. If you can find the appropriate ACDelco sending unit for a comparable price, I would go with that, but if it is going to be a lot more expensive than yours, buy a different brand.

 

UPDATE: PROBLEM RESOLVED!

Blazer Folks,

I just wanted to give you guys an update on my problem. This past weekend was somewhat hellish, because I spent a lot of time running back and forth to parts stores. However, I was able to resolve the problem.

I bit the bullet and bought a fuel pressure gauge first. It was 50 bucks, but well worth it, because it eliminated the possibility of the problem originating at the pump, filter, or regulator! The readings came back well within factory specs, both with the engine off and on.

So I went ahead and still replaced the fuel filter, since I already bought it anyway. It was a monster getting the original off, but I was already expecting it. Indeed, it appeared to have never been replaced. However, the new part DIDN'T FIT, so I had to take it back and get the right one. (By the way, the fuel filter for 95-97s is different from the 98+ Blazers!)

So...I scratched my head on this one, because I knew my electrical system was A-OK. I even took it to AutoZone to have my battery tested, just to be sure. The battery charge was just fine.

So I started playing with things. I unplugged the MAF sensor and it FIRED RIGHT UP. So my attention turned to the air intake. Closer inspection revealed that motor oil had splashed up into the filter, apparently from the oil filter when I changed it last. So last night I removed the entire assembly and took it into the house. I used my K&N cleaner and cleaned the filter thoroughly. I took care to wipe off the excess filter oil with a paper towel (to prevent future clogging of the MAF). I then cleaned the MAF sensor thoroughly, using electrical cleaner and a Q-tip. I let it dry overnight, slapped it back together, and put it on my truck as I was leaving for work.

Lo and behold, it fired up right away! After turning it off and on, it fired up again! So now I know what happened. The air blockage made the sensor say "don't give it fuel." Cleaning the entire air intake assembly resolved the problem.

So again, dear friends, here's the lesson: Look for the cheapest solution first! I spent most of the weekend troubleshooting my truck, but I still saved hundreds of dollars I could have given a mechanic to replace things that weren't broken -- so my weekend was a good one.

Now I have turned my attention to fabricating a shield of some sort. Heat's not a problem, because I have a big blower that works like a charm. What I'm thinking of doing is buying an aluminum pan, drilling holes in it, and placing it directly underneath the air filter to shield it from splashing oil or water. What do you guys think?

Also, I have a message for Scrachead:

I noticed you said you could hear the fuel pump relay clicking. This may be a sign to check your electrical connection to the pump again. The reason I think this is because my headlight relay started making a loud clicking noise shortly before my headlight switch blew. Since our trucks are just one year apart in age, it would make me think that's the case.

Too bad I didn't see your posts before you dropped the tank -- but then again, seeing what bad shape your tank was in, you probably needed to do that anyway! [&:]

And Kyle:

Thanks for posting the part numbers, because the '96 information will still help me, if and when the pump blows later on down the road.

 

Hello Psychropod:

when i changed the cpi unit i checked the MAF and it was clean . I think through i will do it again just to be extra sure , can it be checked electronily if i take it to a parts store? When i pulled the sending unit i did find that where the pump connected to the tube there was a rubber type sleeve , i'm thinking it was a shock arrester of some type. Anyway, where the pump connected, the rubber sleeve appeared not to make a good seal. maybe because of that the pump was pumping some fuel back into the tank and that would explain the drop in psi. by bumping the pump i was able to over come the blowback only momentarily. I've decided to change the whole unit which was a no brainer decision. The blazer has 160,000 miles on it and the pump was the orginal .why they didn't change it when they changed the tank is be-on me. the new tank is two years old so they had been driving it until i aquired it.The parts should be here Saturday so i have time to check everything else . what i really would like to get is a wiring diagram of the fuel system, anyone have one ? This is the best blazer site , keep up the great work everyone !! thanks

 

Hello Everyone: First off i want to thank everyone who gave me advice on fixing the Blazer thanks.
I changed the whole sender and pump this morning , what a job !!! just to let you know that it is back on the road and runs so nice. Until later, Thanks Again

Roman

 

Scrachead,

Great to know your problem was solved. As for the previous owner not replacing the pump when the tank was replaced -- it seems boneheaded, but pumps aren't cheap. It may have simply been beyond their budget at the time.

And I HATE to admit it, but my problem still exists, though on a lesser level. A week ago, I noticed the voltage was dropping in my battery. I made a mental note to replace it on Friday. Lo and behold, it died Thursday night. When I questioned my wife, it turned out the battery was older than I thought. This time I got one with more cold cranking amps. My truck still requires 2-3 turns to crank up, but it is not happening quite as frequently as before. I'm really thinking the next things I should check are: [ol][*]the fuel pump relay,[*]the wiring between the battery and ground,[*]the wiring to the starter,[*]the starter itself,[*]the ignition switch, and[*]the fuel injection system.[/ol]I don't think the ignition switch is the problem, because I'm not seeing problems with other accessories, like the dash lights. Everybody else who had an ignition switch problem described this. Since the pressure from the Schrader valve checked out fine, then if it's a fuel problem, it's got to be happening in the intake. I don't want to believe the problem is in there, because I'm not getting any SES codes -- so before I open up all that crap, I need to check the cheapest thing first, which is to make sure the wiring to the starter isn't corroded, badly connected, or shorted.

The problem is that the weather has been constantly cold and wet, and I don't have a garage. I need a warm, dry day to do this. I'll keep you guys posted.

Kyle, does this mean I could just totally upgrade my existing SCFI to the later MFI? Does it require any computer changes? If it turns out to be a leak in the intake, I may just go ahead and do this if I have to open it up anyway.

Added 3/3/2008: Note that I edited my post to add checking the fuel pump relay. Pre-'98s like mine don't have a relay box under the hood. Instead, the relays are scattered all over the place. Three relays are in the glove box, and I believe one of them is for the fuel pump. The problem is that NOTHING ANYWHERE says what each relay controls. the fershlugginer Haynes manual doesn't mention it, and neither does the owner's manual. I'm about to start ripping out my dreds. Anybody know the answer to this?

Added 3/6/2008: Well, since nobody could tell me which of the three relays in the glove box was the right one, I had a "duh" moment. I pulled each one, one at a time, until I didn't hear the fuel pump whirr when I turned the key. It was the first one. So I swapped in the other two, and they made no difference. This eliminated the relay as the source of the problem.

This morning, while attempting to start it, I noticed that the starter intermittently cranks. I don't know why I didn't notice that before, but based on my symptoms, that's the next thing I'm replacing, since I doubt it's ever been done before. While I'm in there, I will also check the battery cables and grounds.

But meanwhile, my water pump crashed and burned on 3/3, the same day of my last post! Since this is beyond the scope of this thread, check out my other post for details. So this weekend I'm replacing both the starter and the water pump. I'll also change the

 

Admins, don't get mad...I'm bumping this because it might help somebody...

 

Hey gang sorry to digg up an old thread. My brother has a 2000 4x4 Blazer LS. He had purchased this truck from my brother in law who has replaced the fuel pump last year or so. He has recently replaced the fuel filter ( say within the past month). It's been just sitting at my house waiting on both of us to have time to look at it. So tonight right off the bat i attach a FP gauge. it read 35 psi. After getting it started we drove it up into the shop. As it sits now the fuel pump kicks on inadvertatadly. I honestly can't find the relay in the glove box or behind it. I also have been told that there is a grounding strap of some sort on the tank (which we can't find either). The only way we can get the pump to even kick on momentarily is by taking a rubber malett to the tank where the pump sits in the tank. I am thinking faulty wire connection at the tank, or the pump. Also how can we check the pump without pulling it out for addiquit voltage? So where do we start? Thanks for any help! p.s. sorry i don't hang out here very mutch, the forum i frequant preffers us to repost in related threads, so if i need to start my on i can do that. Thanks Again Bill